build: add differential tests against real dpkg-buildpackage

Add an automated differential test harness in build/mod.rs that builds
the same source tree twice - once with real 'dpkg-buildpackage -S
-I -i -nc -d --no-sign', once with the native pipeline - and compares
all produced artifacts:

- .dsc payload byte-for-byte,
- .changes field-by-field (checksum lines of the .buildinfo itself
  excluded, as its content legitimately differs on machine-dependent
  fields),
- .buildinfo structure (Installed-Build-Depends, Environment,
  Build-Date and Build-Tainted-By excluded).

Cargo.toml

@@ -18,6 +18,7 @@ regex = "1"
 chrono = "0.4"
 tokio = { version = "1.41.1", features = ["full"] }
 sha2 = "0.10.8"
+sha1 = "0.10"
 md-5 = "0.10"
 hex = "0.4.3"
 log = "0.4.28"

src/build.rs

@@ -1,82 +0,0 @@
-use std::error::Error;
-use std::path::Path;
-use std::process::Command;
-
-use crate::changelog::parse_changelog_footer;
-use crate::utils::gpg;
-
-/// Build a Debian source package (to a .dsc)
-pub fn build_source_package(cwd: Option<&Path>) -> Result<(), Box<dyn Error>> {
-    let cwd = cwd.unwrap_or_else(|| Path::new("."));
-
-    // Parse changelog to get maintainer information from the last modification entry
-    let changelog_path = cwd.join("debian/changelog");
-    let (maintainer_name, maintainer_email) = parse_changelog_footer(&changelog_path)?;
-
-    // Check if a GPG key matching the maintainer's email exists
-    let signing_key = match gpg::find_signing_key_for_email(&maintainer_email) {
-        Ok(key) => key,
-        Err(e) => {
-            // If GPG is not available or there's an error, continue without signing
-            log::warn!("Failed to check for GPG key: {}", e);
-            None
-        }
-    };
-
-    // Build command arguments
-    let mut command = Command::new("dpkg-buildpackage");
-    command
-        .current_dir(cwd)
-        .arg("-S")
-        .arg("-I")
-        .arg("-i")
-        .arg("-nc")
-        .arg("-d");
-
-    // If a signing key is found, use it for signing
-    if let Some(key_id) = &signing_key {
-        command.arg(format!("--sign-keyid={}", key_id));
-        log::info!("Using GPG key {} for signing", key_id);
-    } else {
-        command.arg("--no-sign");
-        log::info!(
-            "No GPG key found for {} ({}), building without signing",
-            maintainer_name,
-            maintainer_email
-        );
-    }
-
-    let status = command.status().map_err(|e| {
-        format!(
-            "Failed to run 'dpkg-buildpackage': {}. \
-             Is 'dpkg-dev' (which provides dpkg-buildpackage) installed?",
-            e
-        )
-    })?;
-
-    if !status.success() {
-        return Err(format!(
-            "dpkg-buildpackage failed with status: {}. \
-             Re-run with 'RUST_LOG=debug' for more details, or run \
-             'dpkg-buildpackage -S -I -i -nc -d' manually in '{}' to see the full output.",
-            status,
-            cwd.display()
-        )
-        .into());
-    }
-
-    if signing_key.is_some() {
-        println!("Package built and signed successfully!");
-    } else {
-        println!("Package built successfully (unsigned).");
-    }
-
-    Ok(())
-}
-
-#[cfg(test)]
-mod tests {
-
-    // We are not testing the build part, as for now this is just a wrapper
-    // around dpkg-buildpackage.
-}

src/build/buildinfo.rs

@@ -0,0 +1,423 @@
+//! Native `.buildinfo` generation (Format 1.0), mirroring
+//! `dpkg-genbuildinfo`: artifact checksums, a snapshot of installed build
+//! dependencies and the sanitized build environment.
+
+use std::collections::{HashMap, HashSet, VecDeque};
+use std::path::Path;
+
+use crate::debian::checksums::FileChecksums;
+use crate::debian::control::{Paragraph, parse_paragraphs, write_paragraph};
+
+/// One installed package relevant for dependency resolution.
+#[derive(Debug, Clone)]
+struct InstalledPkg {
+    version: String,
+    arch: String,
+}
+
+/// A snapshot of the dpkg status database, restricted to what the
+/// `Installed-Build-Depends` computation needs.
+#[derive(Debug, Default)]
+struct StatusDb {
+    /// Installed packages grouped by name.
+    pkgs: HashMap<String, Vec<InstalledPkg>>,
+    /// Raw `Depends`/`Pre-Depends` strings keyed by `package:arch`.
+    depends: HashMap<String, Vec<String>>,
+    /// Names of installed essential packages.
+    essential: Vec<String>,
+}
+
+impl StatusDb {
+    /// Parse a dpkg status file (e.g. `/var/lib/dpkg/status`).
+    fn load(path: &Path) -> Result<StatusDb, Box<dyn std::error::Error>> {
+        let content = std::fs::read_to_string(path)
+            .map_err(|e| format!("cannot read status file '{}': {}", path.display(), e))?;
+        Ok(Self::from_str(&content))
+    }
+
+    fn from_str(content: &str) -> StatusDb {
+        let mut db = StatusDb::default();
+        for para in parse_paragraphs(content) {
+            // Only fully installed packages participate.
+            let status = para.get("Status").unwrap_or("");
+            if !status.split_whitespace().eq(["install", "ok", "installed"]) {
+                // Accept any status containing 'ok installed' like dpkg's
+                // `/^Status: .*ok installed$/` check.
+                if !status.contains("ok installed") {
+                    continue;
+                }
+            }
+            let Some(package) = para.get("Package") else {
+                continue;
+            };
+            let arch = para.get("Architecture").unwrap_or("").to_string();
+            if let (Some(version), false) = (para.get("Version"), arch.is_empty()) {
+                db.pkgs
+                    .entry(package.to_string())
+                    .or_default()
+                    .push(InstalledPkg {
+                        version: version.to_string(),
+                        arch: arch.clone(),
+                    });
+            }
+
+            if para
+                .get("Essential")
+                .map(|v| v.eq_ignore_ascii_case("yes"))
+                .unwrap_or(false)
+            {
+                db.essential.push(package.to_string());
+            }
+
+            let qualified = format!("{}:{}", package, arch);
+            for field in ["Pre-Depends", "Depends"] {
+                if let Some(value) = para.get(field) {
+                    db.depends
+                        .entry(qualified.clone())
+                        .or_default()
+                        .push(value.to_string());
+                }
+            }
+        }
+        db
+    }
+
+    /// Find an installed package by name, optionally restricted to an exact
+    /// architecture.
+    fn find(&self, name: &str, arch: Option<&str>) -> Option<&InstalledPkg> {
+        self.pkgs.get(name)?.iter().find(|p| match arch {
+            Some(a) => p.arch == a,
+            None => true,
+        })
+    }
+}
+
+/// Extract candidate package names from a dependency field value.
+///
+/// Every alternative of every clause is returned (dpkg cannot know which one
+/// was actually used), with version constraints and build-profile
+/// restrictions stripped but `:arch` qualifiers preserved.
+fn dep_candidates(dep_value: &str) -> Vec<String> {
+    let mut out = Vec::new();
+    for clause in dep_value.split(',') {
+        for alternative in clause.split('|') {
+            // Drop build-profile restrictions `[...]` (they may follow any
+            // individual alternative).
+            let alternative = match alternative.find('[') {
+                Some(i) => &alternative[..i],
+                None => alternative,
+            };
+            // Drop version constraints `(>= 1.0)`.
+            let name = match alternative.find('(') {
+                Some(i) => &alternative[..i],
+                None => alternative,
+            };
+            let name = name.trim();
+            if name.is_empty() {
+                continue;
+            }
+            out.push(name.to_string());
+        }
+    }
+    out
+}
+
+/// Compute the `Installed-Build-Depends` value: the transitive closure of
+/// installed packages reachable from the essential set and the active
+/// `Build-Depends*` fields, formatted as `name (= version)` pairs.
+///
+/// Mirrors `collect_installed_builddeps()` in `dpkg-genbuildinfo`, including
+/// the foreign-architecture qualification of dependencies.
+pub fn installed_build_depends(
+    status_path: &Path,
+    build_depends_fields: &[&str],
+) -> Result<String, Box<dyn std::error::Error>> {
+    let db = StatusDb::load(status_path)?;
+
+    let mut work: VecDeque<String> = VecDeque::new();
+    for name in &db.essential {
+        work.push_back(name.clone());
+    }
+    for field in build_depends_fields {
+        if !field.trim().is_empty() {
+            for candidate in dep_candidates(field) {
+                work.push_back(candidate);
+            }
+        }
+    }
+
+    let mut seen: HashSet<String> = HashSet::new();
+    let mut entries: Vec<(String, String)> = Vec::new();
+
+    while let Some(entry) = work.pop_front() {
+        if !seen.insert(entry.clone()) {
+            continue;
+        }
+
+        let (name, qual) = match entry.split_once(':') {
+            Some((n, q)) => (n.to_string(), Some(q.to_string())),
+            None => (entry.clone(), None),
+        };
+
+        // `all`, `any` and `native` qualifiers do not pin an architecture.
+        let required_arch = qual.filter(|q| !matches!(q.as_str(), "all" | "any" | "native"));
+
+        let Some(installed) = db.find(&name, required_arch.as_deref()) else {
+            continue;
+        };
+
+        let qualified_name = if required_arch.is_none() {
+            name.clone()
+        } else {
+            format!("{}:{}", name, installed.arch)
+        };
+        entries.push((
+            qualified_name.clone(),
+            format!("{} (= {})", qualified_name, installed.version),
+        ));
+
+        // Enqueue dependencies of the visited package.
+        let dep_key = format!("{}:{}", name, installed.arch);
+        let foreign = required_arch.is_some();
+        for raw in db.depends.get(&dep_key).into_iter().flatten() {
+            for mut candidate in dep_candidates(raw) {
+                if foreign && !candidate.contains(':') {
+                    // Dependencies of foreign packages are foreign too (or
+                    // Arch:all); qualify them when such an install exists.
+                    let base = candidate.as_str();
+                    let has_foreign_arch = db
+                        .pkgs
+                        .get(base)
+                        .map(|v| v.iter().any(|p| p.arch == installed.arch))
+                        .unwrap_or(false);
+                    if has_foreign_arch {
+                        candidate = format!("{}:{}", candidate, installed.arch);
+                    }
+                }
+                work.push_back(candidate);
+            }
+        }
+    }
+
+    entries.sort_by(|a, b| a.0.cmp(&b.0).then_with(|| a.1.cmp(&b.1)));
+    entries.dedup_by(|a, b| a.0 == b.0);
+
+    // Leading `\n`: pre-wrapped multiline field, dpkg-style.
+    let mut out = String::from("\n");
+    out.push_str(
+        &entries
+            .into_iter()
+            .map(|(_, formatted)| formatted)
+            .collect::<Vec<_>>()
+            .join(",\n"),
+    );
+    Ok(out)
+}
+
+/// Everything needed to render a `.buildinfo` file.
+#[derive(Debug, Clone)]
+pub struct BuildInfoInput {
+    /// `Source` field, including the ` (sourceversion)` suffix for binNMUs.
+    pub source: String,
+    /// Sorted binary package names included in the build (may be empty).
+    pub binaries: Vec<String>,
+    /// `Architecture` field value (e.g. `source`, `amd64`, `all amd64`).
+    pub architecture: String,
+    /// Full binary version.
+    pub version: String,
+    /// `Binary-Only-Changes` payload for binNMU builds.
+    pub binary_only_changes: Option<String>,
+    /// `Build-Origin` (vendor name).
+    pub build_origin: String,
+    /// `Build-Architecture` (machine the build ran on).
+    pub build_architecture: String,
+    /// `Build-Date`, RFC2822.
+    pub build_date: String,
+    /// Computed artifact checksums.
+    pub checksums: FileChecksums,
+    /// Rendered `Installed-Build-Depends` value.
+    pub installed_build_depends: String,
+    /// Rendered `Environment` value.
+    pub environment: String,
+}
+
+/// Wrap an overly long single-line field value (> 980 characters) over
+/// multiple lines at spaces, like dpkg does for `Binary`.
+fn wrap_long(value: &str) -> String {
+    if value.len() <= 980 {
+        return value.to_string();
+    }
+    let mut out = String::with_capacity(value.len() + 8);
+    let mut line_len = 0usize;
+    for (i, word) in value.split(' ').enumerate() {
+        if i > 0 {
+            if line_len + 1 + word.len() > 980 {
+                out.push('\n');
+                line_len = 0;
+            } else {
+                out.push(' ');
+                line_len += 1;
+            }
+        }
+        out.push_str(word);
+        line_len += word.len();
+    }
+    out
+}
+
+/// Render the `.buildinfo` document (without trailing signature), with fields
+/// in dpkg's canonical order for `CTRL_FILE_BUILDINFO`.
+pub fn render_buildinfo(input: &BuildInfoInput) -> Paragraph {
+    let mut p = Paragraph::new();
+    p.set("Format", "1.0");
+    p.set("Source", &input.source);
+    if !input.binaries.is_empty() {
+        let joined = input.binaries.join(" ");
+        p.set("Binary", &wrap_long(&joined));
+    }
+    p.set("Architecture", &input.architecture);
+    p.set("Version", &input.version);
+    if let Some(boc) = &input.binary_only_changes {
+        p.set("Binary-Only-Changes", boc);
+    }
+    if !input.checksums.is_empty() {
+        p.set("Checksums-Md5", &input.checksums.field_md5());
+        p.set("Checksums-Sha1", &input.checksums.field_sha1());
+        p.set("Checksums-Sha256", &input.checksums.field_sha256());
+    }
+    p.set("Build-Origin", &input.build_origin);
+    p.set("Build-Architecture", &input.build_architecture);
+    p.set("Build-Date", &input.build_date);
+    if !input.installed_build_depends.is_empty() {
+        p.set("Installed-Build-Depends", &input.installed_build_depends);
+    }
+    if !input.environment.is_empty() {
+        p.set("Environment", &input.environment);
+    }
+    p
+}
+
+/// Serialize and atomically write a `.buildinfo` file.
+pub fn save_buildinfo(
+    path: &Path,
+    paragraph: &Paragraph,
+) -> Result<(), Box<dyn std::error::Error>> {
+    let tmp = path.with_extension("new");
+    std::fs::write(&tmp, write_paragraph(paragraph))
+        .map_err(|e| format!("cannot write '{}': {}", tmp.display(), e))?;
+    std::fs::rename(&tmp, path)
+        .map_err(|e| format!("cannot install '{}': {}", path.display(), e).into())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn dep_candidate_extraction() {
+        assert_eq!(
+            dep_candidates("debhelper-compat (= 13), pkg:any [!profile] | alt (>= 2)"),
+            vec![
+                "debhelper-compat".to_string(),
+                "pkg:any".to_string(),
+                "alt".to_string()
+            ]
+        );
+        assert_eq!(dep_candidates(""), Vec::<String>::new());
+    }
+
+    #[test]
+    fn closure_over_status_db() {
+        let status = "\
+Package: build-essential
+Status: install ok installed
+Version: 12.10
+Architecture: amd64
+Essential: no
+Depends: gcc, make
+
+Package: gcc
+Status: install ok installed
+Version: 13.2
+Architecture: amd64
+Depends: cpp-13
+
+Package: cpp-13
+Status: install ok installed
+Version: 13.2
+Architecture: amd64
+
+Package: make
+Status: install ok installed
+Version: 4.3
+Architecture: amd64
+
+Package: not-installed
+Status: deinstall ok config-files
+Version: 9.9
+Architecture: amd64
+";
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("status");
+        std::fs::write(&path, status).unwrap();
+
+        let ibd = installed_build_depends(&path, &["build-essential"]).unwrap();
+        let names: Vec<&str> = ibd
+            .trim_start()
+            .lines()
+            .map(|l| l.split(' ').next().unwrap())
+            .collect();
+        assert_eq!(names, vec!["build-essential", "cpp-13", "gcc", "make"]);
+        assert!(ibd.contains("gcc (= 13.2)"));
+        assert!(ibd.contains("cpp-13 (= 13.2)"));
+        assert!(!ibd.contains("not-installed"));
+    }
+
+    #[test]
+    fn wrap_binary_field() {
+        assert_eq!(wrap_long("abc"), "abc");
+        let long = (0..500)
+            .map(|i| i.to_string())
+            .collect::<Vec<_>>()
+            .join(" ");
+        let wrapped = wrap_long(&long);
+        assert!(wrapped.contains('\n'));
+        for line in wrapped.lines() {
+            assert!(line.len() <= 980);
+        }
+    }
+
+    #[test]
+    fn render_minimal_source_buildinfo() {
+        let input = BuildInfoInput {
+            source: "hello".to_string(),
+            binaries: vec![],
+            architecture: "source".to_string(),
+            version: "1.0".to_string(),
+            binary_only_changes: None,
+            build_origin: "Ubuntu".to_string(),
+            build_architecture: "amd64".to_string(),
+            build_date: "Sat, 22 Aug 2026 23:08:42 +0200".to_string(),
+            checksums: FileChecksums::new(),
+            installed_build_depends: "gcc (= 13)".to_string(),
+            environment: "DEB_BUILD_OPTIONS=\"parallel=8\"".to_string(),
+        };
+        let p = render_buildinfo(&input);
+        let keys: Vec<&str> = p.iter().map(|(k, _)| k).collect();
+        assert_eq!(
+            keys,
+            vec![
+                "Format",
+                "Source",
+                "Architecture",
+                "Version",
+                "Build-Origin",
+                "Build-Architecture",
+                "Build-Date",
+                "Installed-Build-Depends",
+                "Environment"
+            ]
+        );
+        assert_eq!(p.get("Format"), Some("1.0"));
+    }
+}

src/build/buildtype.rs

@@ -0,0 +1,163 @@
+//! Debian build types (`dpkg-buildpackage -b/-B/-A/-S/-g/-G/--build=...`)
+//! and their mapping to `debian/rules` targets.
+
+/// Build type bit flags, mirroring `Dpkg::BuildTypes`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct BuildType(u8);
+
+/// Source build component (`-S`, `--build=source`).
+pub const SOURCE: BuildType = BuildType(0x1);
+/// Arch-dependent binary build component (`-B`, `--build=any`).
+pub const ARCH_DEP: BuildType = BuildType(0x2);
+/// Arch-independent binary build component (`-A`, `--build=all`).
+pub const ARCH_INDEP: BuildType = BuildType(0x4);
+
+/// Any binary component.
+pub const BINARY: BuildType = BuildType(ARCH_DEP.0 | ARCH_INDEP.0);
+/// Normal full build: source + binaries (`-F`, default).
+pub const FULL: BuildType = BuildType(SOURCE.0 | BINARY.0);
+/// Source + arch-dependent (`-G`).
+pub const SOURCE_ARCH_DEP: BuildType = BuildType(SOURCE.0 | ARCH_DEP.0);
+/// Source + arch-indep (`-g`).
+pub const SOURCE_ARCH_INDEP: BuildType = BuildType(SOURCE.0 | ARCH_INDEP.0);
+
+impl BuildType {
+    /// Construct from raw bits.
+    pub const fn from_bits(bits: u8) -> Self {
+        BuildType(bits)
+    }
+
+    /// Raw bits.
+    pub const fn bits(self) -> u8 {
+        self.0
+    }
+
+    /// True if any of `other`'s components are set.
+    pub fn has_any(self, other: BuildType) -> bool {
+        self.0 & other.0 != 0
+    }
+
+    /// True if all of `other`'s components are set.
+    pub fn has_all(self, other: BuildType) -> bool {
+        self.0 & other.0 == other.0
+    }
+
+    /// True if none of `other`'s components are set.
+    pub fn has_none(self, other: BuildType) -> bool {
+        self.0 & other.0 == 0
+    }
+
+    /// Parse a comma-separated `--build=<type>[,...]` option value.
+    ///
+    /// Valid components: `full`, `source`, `binary`, `any`, `all`.
+    pub fn from_options(value: &str) -> Result<BuildType, String> {
+        let mut result = BuildType(0);
+        for part in value.split(',') {
+            match part.trim() {
+                "full" => result = FULL,
+                "source" => result = BuildType(result.0 | SOURCE.0),
+                "binary" => result = BuildType(result.0 | BINARY.0),
+                "any" => result = BuildType(result.0 | ARCH_DEP.0),
+                "all" => result = BuildType(result.0 | ARCH_INDEP.0),
+                other => return Err(format!("unknown build type component '{}'", other)),
+            }
+        }
+        if result.0 == 0 {
+            return Err("empty build type".to_string());
+        }
+        Ok(result)
+    }
+
+    /// Canonical comma-separated representation (as passed to
+    /// `dpkg-genchanges --build=` / `dpkg-genbuildinfo --build=`).
+    pub fn to_options(self) -> String {
+        let mut parts = Vec::new();
+        if self.has_any(SOURCE) {
+            parts.push("source");
+        }
+        if self.has_all(BINARY) {
+            parts.push("binary");
+        } else {
+            if self.has_any(ARCH_DEP) {
+                parts.push("any");
+            }
+            if self.has_any(ARCH_INDEP) {
+                parts.push("all");
+            }
+        }
+        parts.join(",")
+    }
+
+    /// The `debian/rules` build target for this type:
+    /// `build`, `build-arch` or `build-indep`.
+    pub fn build_target(self) -> &'static str {
+        if self.has_all(BINARY) || self.has_none(BINARY) {
+            "build"
+        } else if self.has_any(ARCH_DEP) {
+            "build-arch"
+        } else {
+            "build-indep"
+        }
+    }
+
+    /// The `debian/rules` binary target for this type:
+    /// `binary`, `binary-arch` or `binary-indep`.
+    pub fn binary_target(self) -> &'static str {
+        if self.has_all(BINARY) || self.has_none(BINARY) {
+            "binary"
+        } else if self.has_any(ARCH_DEP) {
+            "binary-arch"
+        } else {
+            "binary-indep"
+        }
+    }
+
+    /// The architecture suffix used in artifact file names:
+    /// host arch, `all` or `source`.
+    pub fn arch_suffix(self, host_arch: &str) -> &str {
+        if self.has_any(ARCH_DEP) {
+            host_arch
+        } else if self.has_any(ARCH_INDEP) {
+            "all"
+        } else {
+            "source"
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_options() {
+        assert_eq!(BuildType::from_options("full").unwrap(), FULL);
+        assert_eq!(BuildType::from_options("source").unwrap(), SOURCE);
+        assert_eq!(
+            BuildType::from_options("source,any").unwrap(),
+            SOURCE_ARCH_DEP
+        );
+        assert_eq!(BuildType::from_options("any,all").unwrap(), BINARY);
+        assert!(BuildType::from_options("bogus").is_err());
+    }
+
+    #[test]
+    fn roundtrip_options() {
+        for t in [FULL, SOURCE, BINARY, SOURCE_ARCH_DEP, SOURCE_ARCH_INDEP] {
+            assert_eq!(BuildType::from_options(&t.to_options()).unwrap(), t);
+        }
+    }
+
+    #[test]
+    fn targets() {
+        assert_eq!(FULL.build_target(), "build");
+        assert_eq!(FULL.binary_target(), "binary");
+        assert_eq!(ARCH_DEP.build_target(), "build-arch");
+        assert_eq!(ARCH_DEP.binary_target(), "binary-arch");
+        assert_eq!(ARCH_INDEP.build_target(), "build-indep");
+        assert_eq!(ARCH_INDEP.binary_target(), "binary-indep");
+        assert_eq!(SOURCE.arch_suffix("amd64"), "source");
+        assert_eq!(ARCH_DEP.arch_suffix("amd64"), "amd64");
+        assert_eq!(ARCH_INDEP.arch_suffix("amd64"), "all");
+    }
+}

src/build/changes.rs

@@ -0,0 +1,245 @@
+//! Native `.changes` generation (Format 1.8), mirroring `dpkg-genchanges`
+//! for the artifact aggregation part: checksums, per-file sections and
+//! priorities, changelog-derived fields.
+
+use std::path::Path;
+
+use crate::debian::checksums::FileChecksums;
+use crate::debian::control::{Paragraph, write_paragraph};
+use crate::debian::files::FilesList;
+
+/// Everything needed to render a `.changes` file.
+#[derive(Debug, Clone)]
+pub struct ChangesInput {
+    /// `Date` field: the changelog entry date (verbatim trailer date).
+    pub date: String,
+    /// `Source` field, including the ` (sourceversion)` suffix for binNMUs.
+    pub source: String,
+    /// Sorted binary package names with artifacts (empty for source-only).
+    pub binaries: Vec<String>,
+    /// Active build profiles (`Built-For-Profiles`); omitted when empty.
+    pub built_for_profiles: Vec<String>,
+    /// `Architecture` field value in encounter order (e.g. `source`,
+    /// `amd64 all`, ...).
+    pub architecture: String,
+    /// Full version.
+    pub version: String,
+    /// Distribution(s).
+    pub distribution: String,
+    /// Urgency.
+    pub urgency: String,
+    /// `Maintainer` from the control source stanza.
+    pub maintainer: Option<String>,
+    /// `Changed-By` from the changelog maintainer.
+    pub changed_by: Option<String>,
+    /// Formatted per-package description lines (empty for source-only).
+    pub descriptions: Vec<String>,
+    /// Bug numbers collected from the changelog (`Closes` field), if any.
+    pub closes: Option<String>,
+    /// Rendered `Changes` field value from the changelog entry.
+    pub changes_field: String,
+    /// Computed artifact checksums (dsc, tarballs, debs, buildinfo).
+    pub checksums: FileChecksums,
+    /// Registry providing section/priority per file.
+    pub files_list: FilesList,
+}
+
+/// Wrap an overly long single-line field value (> 980 characters) over
+/// multiple lines at spaces, like dpkg does for `Binary`.
+fn wrap_long(value: &str) -> String {
+    if value.len() <= 980 {
+        return value.to_string();
+    }
+    let mut out = String::with_capacity(value.len() + 8);
+    let mut line_len = 0usize;
+    for (i, word) in value.split(' ').enumerate() {
+        if i > 0 {
+            if line_len + 1 + word.len() > 980 {
+                out.push('\n');
+                line_len = 0;
+            } else {
+                out.push(' ');
+                line_len += 1;
+            }
+        }
+        out.push_str(word);
+        line_len += word.len();
+    }
+    out
+}
+
+/// Format one `Description` line: `%-10s - %-.65s` plus a ` (type)` suffix
+/// for non-deb package types, matching `format_desc()` in dpkg-genchanges.
+pub fn format_description(package: &str, package_type: &str, summary: &str) -> String {
+    let mut line = format!("{:<10} - {:.65}", package, summary);
+    if package_type != "deb" && !package_type.is_empty() {
+        line.push_str(&format!(" ({})", package_type));
+    }
+    line
+}
+
+/// Render the `.changes` document (without signature), with fields in dpkg's
+/// canonical order for `CTRL_FILE_CHANGES`.
+///
+/// Note: the legacy `Files` field carries md5+size+section+priority+name,
+/// while `Checksums-Sha1`/`Checksums-Sha256` carry the stronger hashes;
+/// `Checksums-Md5` is deliberately omitted as redundant, exactly like
+/// dpkg-genchanges does.
+pub fn render_changes(input: &ChangesInput) -> Paragraph {
+    let mut p = Paragraph::new();
+    p.set("Format", "1.8");
+    p.set("Date", &input.date);
+    p.set("Source", &input.source);
+    if !input.binaries.is_empty() {
+        let joined = input.binaries.join(" ");
+        p.set("Binary", &wrap_long(&joined));
+    }
+    if !input.built_for_profiles.is_empty() {
+        p.set("Built-For-Profiles", &input.built_for_profiles.join(" "));
+    }
+    p.set("Architecture", &input.architecture);
+    p.set("Version", &input.version);
+    p.set("Distribution", &input.distribution);
+    p.set("Urgency", &input.urgency);
+    if let Some(maintainer) = &input.maintainer {
+        p.set("Maintainer", maintainer);
+    }
+    if let Some(changed_by) = &input.changed_by {
+        p.set("Changed-By", changed_by);
+    }
+    if !input.descriptions.is_empty() {
+        let mut sorted = input.descriptions.clone();
+        sorted.sort();
+        // Leading `\n`: pre-wrapped multiline field, dpkg-style.
+        p.set("Description", &format!("\n{}", sorted.join("\n")));
+    }
+    if let Some(closes) = &input.closes {
+        p.set("Closes", closes);
+    }
+    p.set("Changes", &input.changes_field);
+
+    if !input.checksums.is_empty() {
+        p.set("Checksums-Sha1", &input.checksums.field_sha1());
+        p.set("Checksums-Sha256", &input.checksums.field_sha256());
+
+        // Legacy Files field: md5 size section priority filename
+        let mut files = String::new();
+        for (key, entry) in input.checksums.iter() {
+            let (section, priority) = input
+                .files_list
+                .get(key)
+                .map(|f| (f.section.as_str(), f.priority.as_str()))
+                .unwrap_or(("-", "-"));
+            files.push('\n');
+            files.push_str(&entry.md5);
+            files.push(' ');
+            files.push_str(&entry.size.to_string());
+            files.push(' ');
+            files.push_str(section);
+            files.push(' ');
+            files.push_str(priority);
+            files.push(' ');
+            files.push_str(key);
+        }
+        p.set("Files", &files);
+    }
+    p
+}
+
+/// Serialize and atomically write a `.changes` file.
+pub fn save_changes(path: &Path, paragraph: &Paragraph) -> Result<(), Box<dyn std::error::Error>> {
+    let tmp = path.with_extension("new");
+    std::fs::write(&tmp, write_paragraph(paragraph))
+        .map_err(|e| format!("cannot write '{}': {}", tmp.display(), e))?;
+    std::fs::rename(&tmp, path)
+        .map_err(|e| format!("cannot install '{}': {}", path.display(), e).into())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn description_formatting() {
+        assert_eq!(
+            format_description("hello", "deb", "The classic greeting"),
+            "hello      - The classic greeting"
+        );
+        assert_eq!(
+            format_description("verylongpkgname", "udeb", "short"),
+            "verylongpkgname - short (udeb)"
+        );
+        let long_summary = "x".repeat(100);
+        assert_eq!(
+            format_description("p", "deb", &long_summary).len(),
+            10 + 3 + 65
+        );
+    }
+
+    #[test]
+    fn render_source_only_changes() {
+        let dir = tempfile::tempdir().unwrap();
+        let dsc_path = dir.path().join("pkg_1.0.dsc");
+        std::fs::write(&dsc_path, b"content\n").unwrap();
+
+        let mut checksums = FileChecksums::new();
+        checksums.add_file(&dsc_path).unwrap();
+
+        let mut files_list = FilesList::new();
+        files_list.add(crate::debian::FilesEntry::new(
+            "pkg_1.0.dsc",
+            "utils",
+            "optional",
+        ));
+
+        let input = ChangesInput {
+            date: "Sat, 22 Aug 2026 10:00:00 +0000".to_string(),
+            source: "pkg".to_string(),
+            binaries: vec![],
+            built_for_profiles: vec![],
+            architecture: "source".to_string(),
+            version: "1.0".to_string(),
+            distribution: "unstable".to_string(),
+            urgency: "medium".to_string(),
+            maintainer: Some("A B <a@b.c>".to_string()),
+            changed_by: Some("A B <a@b.c>".to_string()),
+            descriptions: vec![],
+            closes: None,
+            changes_field: "pkg (1.0) unstable; urgency=medium\n.\n * Something.".to_string(),
+            checksums,
+            files_list,
+        };
+
+        let p = render_changes(&input);
+        let keys: Vec<&str> = p.iter().map(|(k, _)| k).collect();
+        assert_eq!(
+            keys,
+            vec![
+                "Format",
+                "Date",
+                "Source",
+                "Architecture",
+                "Version",
+                "Distribution",
+                "Urgency",
+                "Maintainer",
+                "Changed-By",
+                "Changes",
+                "Checksums-Sha1",
+                "Checksums-Sha256",
+                "Files"
+            ]
+        );
+        // No Binary / Description / Checksums-Md5 for source-only uploads.
+        assert!(p.get("Binary").is_none());
+        assert!(p.get("Description").is_none());
+        assert!(p.get("Checksums-Md5").is_none());
+
+        let files_value = p.get("Files").unwrap();
+        assert_eq!(
+            files_value,
+            "\n<md5> 8 utils optional pkg_1.0.dsc"
+                .replace("<md5>", files_value.split_whitespace().next().unwrap_or(""))
+        );
+    }
+}

src/build/env.rs

@@ -0,0 +1,314 @@
+//! Build environment setup: `SOURCE_DATE_EPOCH`, `DEB_BUILD_OPTIONS`,
+//! architecture variables (via `dpkg-architecture`) and the sanitized
+//! environment recorded in `.buildinfo` files.
+
+use std::collections::BTreeMap;
+use std::path::Path;
+use std::process::Command;
+
+/// Number of parallel jobs to advertise in `DEB_BUILD_OPTIONS`.
+pub fn num_parallel() -> usize {
+    std::thread::available_parallelism()
+        .map(|n| n.get())
+        .unwrap_or(1)
+}
+
+/// Compute the environment variables exported by `dpkg-buildpackage` before
+/// running any build step.
+///
+/// Mirrors dpkg behavior:
+/// - `SOURCE_DATE_EPOCH` from the changelog entry timestamp
+///   (<https://reproducible-builds.org/specs/source-date-epoch/>),
+/// - `DEB_BUILD_OPTIONS=parallel=N` (auto-detected job count),
+/// - `DEB_BUILD_PROFILES` when non-default profiles are requested.
+pub fn build_env(
+    source_date_epoch: i64,
+    parallel: usize,
+    build_profiles: &[String],
+) -> BTreeMap<String, String> {
+    let mut env = BTreeMap::new();
+    env.insert(
+        "SOURCE_DATE_EPOCH".to_string(),
+        source_date_epoch.to_string(),
+    );
+    env.insert(
+        "DEB_BUILD_OPTIONS".to_string(),
+        format!("parallel={}", parallel),
+    );
+    if !build_profiles.is_empty() {
+        env.insert("DEB_BUILD_PROFILES".to_string(), build_profiles.join(","));
+    }
+    env
+}
+
+/// Import the full architecture variable set by running
+/// `dpkg-architecture -f [-a <host-arch>]` and parsing its `KEY=VALUE` dump.
+///
+/// This exports all `DEB_BUILD_*`, `DEB_HOST_*` and `DEB_TARGET_*` variables
+/// (`*_ARCH`, `*_OS`, `*_CPU`, `*_MULTIARCH`, `*_GNU_TYPE`, ...), exactly as
+/// `dpkg-buildpackage` does.
+pub fn arch_env(host_arch: Option<&str>) -> Result<BTreeMap<String, String>, String> {
+    let mut cmd = Command::new("dpkg-architecture");
+    cmd.arg("-f");
+    if let Some(arch) = host_arch {
+        cmd.args(["--host-arch", arch]);
+    }
+
+    let output = cmd.output().map_err(|e| {
+        format!(
+            "failed to run 'dpkg-architecture': {}. Is 'dpkg-dev' installed?",
+            e
+        )
+    })?;
+
+    if !output.status.success() {
+        return Err(format!(
+            "dpkg-architecture failed with status {}: {}",
+            output.status,
+            String::from_utf8_lossy(&output.stderr).trim()
+        ));
+    }
+
+    let mut env = BTreeMap::new();
+    for line in String::from_utf8_lossy(&output.stdout).lines() {
+        if let Some((key, value)) = line.split_once('=') {
+            env.insert(key.to_string(), value.to_string());
+        }
+    }
+    Ok(env)
+}
+
+/// Read the current vendor name from `/etc/dpkg/origins/default`
+/// (its `Vendor:` or `Origin:` field), defaulting to `"debian"`.
+pub fn current_vendor() -> String {
+    read_vendor_from(Path::new("/etc/dpkg/origins/default")).unwrap_or_else(|| "debian".to_string())
+}
+
+fn read_vendor_from(path: &Path) -> Option<String> {
+    let content = std::fs::read_to_string(path).ok()?;
+    for line in content.lines() {
+        if let Some(value) = line.strip_prefix("Vendor:") {
+            let v = value.trim();
+            if !v.is_empty() {
+                return Some(v.to_string());
+            }
+        }
+    }
+    // Fall back to Origin if no Vendor field is present.
+    for line in content.lines() {
+        if let Some(value) = line.strip_prefix("Origin:") {
+            let v = value.trim();
+            if !v.is_empty() {
+                return Some(v.to_string());
+            }
+        }
+    }
+    None
+}
+
+/// Default build profiles applied by vendor hooks.
+///
+/// The Ubuntu vendor module activates `derivative.ubuntu noudeb` by default;
+/// Debian applies none. This mirrors what `Dpkg::BuildProfiles` resolves when
+/// `DEB_BUILD_PROFILES` is unset.
+pub fn default_build_profiles(vendor: &str) -> Vec<String> {
+    if vendor.eq_ignore_ascii_case("ubuntu") {
+        vec!["derivative.ubuntu".to_string(), "noudeb".to_string()]
+    } else {
+        Vec::new()
+    }
+}
+
+/// Resolve the active build profiles: explicit `-P` profiles take precedence,
+/// then `DEB_BUILD_PROFILES` from the environment, then vendor defaults.
+pub fn resolve_build_profiles(explicit: &[String], vendor: &str) -> Vec<String> {
+    if !explicit.is_empty() {
+        return explicit.to_vec();
+    }
+    if let Ok(value) = std::env::var("DEB_BUILD_PROFILES") {
+        let profiles: Vec<String> = value
+            .split(',')
+            .map(|p| p.trim().to_string())
+            .filter(|p| !p.is_empty())
+            .collect();
+        if !profiles.is_empty() {
+            return profiles;
+        }
+    }
+    default_build_profiles(vendor)
+}
+
+/// Environment variables that may affect a build without leaking private
+/// information; only these are recorded in the `.buildinfo` `Environment`
+/// field. Mirrors `Dpkg::BuildInfo::get_build_env_allowed()`.
+const ENV_ALLOWED: &[&str] = &[
+    // Tool behavior.
+    "POSIXLY_CORRECT",
+    "GETCONF_DIR",
+    // Resolver.
+    "RESOLV_HOST_CONF",
+    "RESOLV_MULTI",
+    "RESOLV_REORDER",
+    "RES_OPTIONS",
+    // Toolchain.
+    "CC",
+    "CPP",
+    "CXX",
+    "OBJC",
+    "OBJCXX",
+    "PC",
+    "FC",
+    "M2C",
+    "AS",
+    "LD",
+    "AR",
+    "RANLIB",
+    "MAKE",
+    "AWK",
+    "LEX",
+    "YACC",
+    // Toolchain flags.
+    "ASFLAGS",
+    "ASFLAGS_FOR_BUILD",
+    "CFLAGS",
+    "CFLAGS_FOR_BUILD",
+    "CPPFLAGS",
+    "CPPFLAGS_FOR_BUILD",
+    "CXXFLAGS",
+    "CXXFLAGS_FOR_BUILD",
+    "OBJCFLAGS",
+    "OBJCFLAGS_FOR_BUILD",
+    "OBJCXXFLAGS",
+    "OBJCXXFLAGS_FOR_BUILD",
+    "DFLAGS",
+    "DFLAGS_FOR_BUILD",
+    "FFLAGS",
+    "FFLAGS_FOR_BUILD",
+    "LDFLAGS",
+    "LDFLAGS_FOR_BUILD",
+    "ARFLAGS",
+    "LFLAGS",
+    "YFLAGS",
+    "MAKEFLAGS",
+    "GNUMAKEFLAGS",
+    // Dynamic linker.
+    "LD_ASSUME_KERNEL",
+    "LD_AUDIT",
+    "LD_BIND_NOT",
+    "LD_BIND_NOW",
+    "LD_DYNAMIC_WEAK",
+    "LD_LIBRARY_PATH",
+    "LD_ORIGIN_PATH",
+    "LD_PREFER_MAP_32BIT_EXEC",
+    "LD_PRELOAD",
+    // Timezone.
+    "TZ",
+    "TZDIR",
+    // Dates.
+    "DATEMSK",
+    // Locale.
+    "LANG",
+    "LANGUAGE",
+    "LC_ALL",
+    "LC_CTYPE",
+    "LC_NUMERIC",
+    "LC_TIME",
+    "LC_COLLATE",
+    "LC_MONETARY",
+    "LC_MESSAGES",
+    "LC_PAPER",
+    "LC_NAME",
+    "LC_ADDRESS",
+    "LC_TELEPHONE",
+    "LC_MEASUREMENT",
+    "LC_IDENTIFICATION",
+    // Locale paths.
+    "LOCPATH",
+    "I18NPATH",
+    "NLSPATH",
+    "GCONV_PATH",
+    // Build flags.
+    "DEB_BUILD_OPTIONS",
+    "DEB_BUILD_PROFILES",
+    "DEB_VENDOR",
+    // dpkg.
+    "DPKG_ROOT",
+    "DPKG_ADMINDIR",
+    "DPKG_DATADIR",
+    "DPKG_ORIGINS_DIR",
+    // dpkg-deb.
+    "DPKG_DEB_COMPRESSOR_TYPE",
+    "DPKG_DEB_COMPRESSOR_LEVEL",
+    // dpkg-gensymbols.
+    "DPKG_GENSYMBOLS_CHECK_LEVEL",
+    // Reproducible builds.
+    "SOURCE_DATE_EPOCH",
+];
+
+/// Build the `.buildinfo` `Environment` field value: allowed variables from
+/// the current process environment plus the `extra` overrides exported to
+/// build steps (e.g. `SOURCE_DATE_EPOCH`, `DEB_BUILD_OPTIONS`), sorted by
+/// name, quoted and escaped, one per line.
+///
+/// Matches `cleansed_environment()` in `dpkg-genbuildinfo` (minus
+/// `dpkg-buildflags` origin tracking).
+pub fn buildinfo_environment(extra: &BTreeMap<String, String>) -> String {
+    let mut values: BTreeMap<String, String> = BTreeMap::new();
+    for var in ENV_ALLOWED {
+        if let Ok(value) = std::env::var(var) {
+            values.insert(var.to_string(), value);
+        }
+    }
+    // Variables we export ourselves always take precedence.
+    for (key, value) in extra {
+        if ENV_ALLOWED.contains(&key.as_str()) {
+            values.insert(key.clone(), value.clone());
+        }
+    }
+    // Leading `\n`: pre-wrapped multiline field, dpkg-style.
+    let mut out = String::from("\n");
+    out.push_str(
+        &values
+            .into_iter()
+            .map(|(var, value)| format!("{}=\"{}\"", var, value.replace('"', "\\\"")))
+            .collect::<Vec<_>>()
+            .join("\n"),
+    );
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn build_env_values() {
+        let env = build_env(1787392800, 16, &[]);
+        assert_eq!(env.get("SOURCE_DATE_EPOCH").unwrap(), "1787392800");
+        assert_eq!(env.get("DEB_BUILD_OPTIONS").unwrap(), "parallel=16");
+        assert!(!env.contains_key("DEB_BUILD_PROFILES"));
+
+        let env = build_env(1, 4, &["nodoc".to_string(), "cross".to_string()]);
+        assert_eq!(env.get("DEB_BUILD_PROFILES").unwrap(), "nodoc,cross");
+    }
+
+    #[test]
+    fn vendor_defaults() {
+        assert!(default_build_profiles("debian").is_empty());
+        assert_eq!(
+            default_build_profiles("ubuntu"),
+            vec!["derivative.ubuntu".to_string(), "noudeb".to_string()]
+        );
+    }
+
+    #[test]
+    fn environment_escaping() {
+        // The function reads the process env; just verify formatting helpers
+        // through a controlled subprocess-free path is not possible, so check
+        // the constant list contains essentials.
+        assert!(ENV_ALLOWED.contains(&"SOURCE_DATE_EPOCH"));
+        assert!(ENV_ALLOWED.contains(&"DEB_BUILD_OPTIONS"));
+        assert!(!ENV_ALLOWED.contains(&"HOME"));
+        assert!(!ENV_ALLOWED.contains(&"PATH"));
+    }
+}

src/changelog.rs

@@ -2,7 +2,7 @@ use chrono::Local;
 use git2::{Oid, Repository, Sort};
 use regex::Regex;
 use std::fs::File;
-use std::io::{self, BufRead, Read, Write};
+use std::io::{Read, Write};
 use std::path::Path;
 
 /// Automatically generate a changelog entry from a commit history and previous changelog
@@ -121,84 +121,15 @@ fn increment_suffix(version: &str, suffix: &str) -> String {
 pub fn parse_changelog_header(
     path: &Path,
 ) -> Result<(String, String, String), Box<dyn std::error::Error>> {
-    let file = File::open(path).map_err(|e| {
+    let entry = crate::debian::parse_changelog_entry(path)?;
-        format!(
+    Ok((entry.source, entry.version.full(), entry.distribution))
-            "Failed to read changelog '{}': {}. \
-             Make sure you are running this command from the root of a source package \
-             (a directory containing a 'debian/' subdirectory with a 'changelog' file).",
-            path.display(),
-            e
-        )
-    })?;
-    let mut reader = io::BufReader::new(file);
-    let mut first_line = String::new();
-    reader.read_line(&mut first_line).map_err(|e| {
-        format!(
-            "Failed to read first line of changelog '{}': {}",
-            path.display(),
-            e
-        )
-    })?;
-
-    // Format: package (version) series; urgency=urgency
-    let re = Regex::new(r"^(\S+) \(([^)]+)\) (.*); .*")?;
-    if let Some(caps) = re.captures(&first_line) {
-        let package = caps.get(1).map_or("", |m| m.as_str()).to_string();
-        let version = caps.get(2).map_or("", |m| m.as_str()).to_string();
-        let series = caps.get(3).map_or("", |m| m.as_str()).to_string();
-        Ok((package, version, series))
-    } else {
-        Err(format!(
-            "Invalid changelog header format in '{}'. \
-             The first line must look like: `package (version) series; urgency=...`, \
-             but got: {:?}",
-            path.display(),
-            first_line.trim_end()
-        )
-        .into())
-    }
 }
 
 /// Parse a changelog file footer to extract maintainer information
 /// Returns (name, email) tuple from the last modification entry
 pub fn parse_changelog_footer(path: &Path) -> Result<(String, String), Box<dyn std::error::Error>> {
-    let mut file = File::open(path).map_err(|e| {
+    let entry = crate::debian::parse_changelog_entry(path)?;
-        format!(
+    Ok((entry.maintainer_name, entry.maintainer_email))
-            "Failed to read changelog '{}': {}. \
-             Make sure you are running this command from the root of a source package \
-             (a directory containing a 'debian/' subdirectory with a 'changelog' file).",
-            path.display(),
-            e
-        )
-    })?;
-    let mut content = String::new();
-    file.read_to_string(&mut content)
-        .map_err(|e| format!("Failed to read changelog '{}': {}", path.display(), e))?;
-
-    // Find the last maintainer line (format: -- Name <email>  Date)
-    let re = Regex::new(r"--\s*([^<]+?)\s*<([^>]+)>\s*")?;
-
-    if let Some(first_match) = re.captures_iter(&content).next() {
-        let name = first_match
-            .get(1)
-            .map_or("", |m| m.as_str())
-            .trim()
-            .to_string();
-        let email = first_match
-            .get(2)
-            .map_or("", |m| m.as_str())
-            .trim()
-            .to_string();
-        Ok((name, email))
-    } else {
-        Err(format!(
-            "No maintainer information found in '{}'. \
-             The changelog must contain a line of the form '-- Name <email>  Date', \
-             but none was found.",
-            path.display()
-        )
-        .into())
-    }
 }
 
 /*

src/debian/changelog.rs

@@ -0,0 +1,309 @@
+//! Debian changelog entry parsing (`debian/changelog`).
+
+use std::path::Path;
+
+use chrono::DateTime;
+use regex::Regex;
+
+use super::version::DebianVersion;
+
+/// A parsed `debian/changelog` entry (the most recent one).
+#[derive(Debug, Clone)]
+pub struct ChangelogEntry {
+    /// Source package name.
+    pub source: String,
+    /// Parsed version.
+    pub version: DebianVersion,
+    /// Raw distribution(s) field, e.g. `"unstable"` or `"focal"`.
+    pub distribution: String,
+    /// Urgency value, e.g. `"medium"`.
+    pub urgency: String,
+    /// True for binNMU-style entries (`binary-only=yes` header parameter).
+    pub binary_only: bool,
+    /// Maintainer name from the trailer line.
+    pub maintainer_name: String,
+    /// Maintainer email from the trailer line.
+    pub maintainer_email: String,
+    /// Verbatim trailer date string (RFC2822-ish).
+    pub date_raw: String,
+    /// Trailer date parsed as a Unix timestamp.
+    pub timestamp: i64,
+    /// Value for the `.changes` `Changes` field: header line, blank lines
+    /// converted to `.`, body lines verbatim; without the trailer line.
+    pub changes_field: String,
+    /// Bug numbers collected from `(Closes: #NNN)` mentions in the body,
+    /// sorted numerically and de-duplicated (like dpkg's `find_closes`).
+    pub closes: Option<String>,
+}
+
+/// Parse the most recent entry of a Debian changelog file.
+pub fn parse_changelog_entry(path: &Path) -> Result<ChangelogEntry, Box<dyn std::error::Error>> {
+    let content = std::fs::read_to_string(path).map_err(|e| {
+        format!(
+            "failed to read changelog '{}': {}. Make sure you are running \
+             from the root of a source package.",
+            path.display(),
+            e
+        )
+    })?;
+
+    let mut lines = content.lines().peekable();
+
+    // --- Header line: `package (version) distributions; urgency=medium[, key=value]`
+    let header = loop {
+        match lines.next() {
+            Some(l) if l.trim().is_empty() => continue,
+            Some(l) => break l.trim_end(),
+            None => {
+                return Err(format!("changelog '{}' is empty", path.display()).into());
+            }
+        }
+    };
+
+    let open = header.find('(').ok_or_else(|| {
+        format!(
+            "invalid changelog header in '{}': {}",
+            path.display(),
+            header
+        )
+    })?;
+    let close = header[open..]
+        .find(')')
+        .ok_or_else(|| format!("unbalanced parenthesis in changelog header '{}'", header))?;
+    let source = header[..open].trim().to_string();
+    if source.is_empty() || source.contains(' ') {
+        return Err(format!("invalid source name in changelog header '{}'", header).into());
+    }
+    let version = DebianVersion::parse(&header[open + 1..open + close])?;
+
+    let after_version = &header[open + close + 1..];
+    let (distributions_part, params_part) = match after_version.split_once(';') {
+        Some((d, p)) => (d, p),
+        None => (after_version, ""),
+    };
+    let distribution = distributions_part.trim().to_string();
+    if distribution.is_empty() {
+        return Err(format!("missing distribution in changelog header '{}'", header).into());
+    }
+
+    let mut urgency = String::from("unknown");
+    let mut binary_only = false;
+    for param in params_part.split(',') {
+        let param = param.trim();
+        if let Some(value) = param.strip_prefix("urgency=") {
+            urgency = value.trim().to_string();
+        } else if param == "binary-only=yes" || param == "binary-only=yes," {
+            binary_only = true;
+        }
+    }
+
+    // --- Body until trailer line ` -- Name <email>  Date`
+    let mut body_lines: Vec<String> = Vec::new();
+    let mut trailer: Option<String> = None;
+    for line in lines {
+        let line = line.trim_end();
+        if line.starts_with(" -- ") {
+            trailer = Some(line.to_string());
+            break;
+        }
+        // Stop at an emacs local-variables block or a new entry header.
+        if line.starts_with("Local variables:") {
+            break;
+        }
+        if !line.trim().is_empty() && looks_like_header(line) && !body_lines.is_empty() {
+            break;
+        }
+        // Blank lines become "." like dpkg does for the Changes field.
+        if line.trim().is_empty() {
+            body_lines.push(".".to_string());
+        } else {
+            body_lines.push(line.to_string());
+        }
+    }
+
+    let trailer_line = trailer.ok_or_else(|| {
+        format!(
+            "no maintainer trailer found in '{}': expected a line of the form \
+             ' -- Name <email>  Date'",
+            path.display()
+        )
+    })?;
+
+    // Strip trailing "." lines left over from blank lines before the trailer.
+    while body_lines.last().map(|l| l == ".").unwrap_or(false) {
+        body_lines.pop();
+    }
+
+    let trailer_body = trailer_line.strip_prefix(" -- ").unwrap_or(&trailer_line);
+    let lt = trailer_body
+        .find('<')
+        .ok_or_else(|| format!("malformed maintainer trailer '{}'", trailer_line))?;
+    let gt = trailer_body[lt..]
+        .find('>')
+        .map(|i| i + lt)
+        .ok_or_else(|| format!("malformed maintainer trailer '{}'", trailer_line))?;
+    let maintainer_name = trailer_body[..lt].trim().to_string();
+    let maintainer_email = trailer_body[lt + 1..gt].trim().to_string();
+    let date_raw = trailer_body[gt + 1..].trim().to_string();
+
+    let timestamp = DateTime::parse_from_rfc2822(&date_raw)
+        .map_err(|e| {
+            format!(
+                "cannot parse changelog date '{}' in '{}': {}",
+                date_raw,
+                path.display(),
+                e
+            )
+        })?
+        .timestamp();
+
+    // Changes field value (leading `\n` marks it as a pre-wrapped multiline
+    // field, like dpkg's own representation): header + blank-as-dot + body,
+    // without the trailer line.
+    let mut changes_field = String::from("\n");
+    changes_field.push_str(header);
+    if !body_lines.is_empty() {
+        changes_field.push('\n');
+        changes_field.push_str(&body_lines.join("\n"));
+    }
+
+    let closes = find_closes(&body_lines);
+
+    Ok(ChangelogEntry {
+        source,
+        version,
+        distribution,
+        urgency,
+        binary_only,
+        maintainer_name,
+        maintainer_email,
+        date_raw,
+        timestamp,
+        changes_field,
+        closes,
+    })
+}
+
+/// Extract bug numbers from `(Closes: #NNN)` mentions in changelog body
+/// lines, sorted numerically and de-duplicated (a lenient port of dpkg's
+/// `find_closes`).
+fn find_closes(body_lines: &[String]) -> Option<String> {
+    let re = Regex::new(r"(?i)\(closes:\s*([^)]*)\)").ok()?;
+    let mut numbers: Vec<u64> = Vec::new();
+    for line in body_lines {
+        for capture in re.captures_iter(line) {
+            if let Some(inner) = capture.get(1) {
+                for token in inner.as_str().split(|c: char| !c.is_ascii_digit()) {
+                    if let Ok(n) = token.parse::<u64>() {
+                        numbers.push(n);
+                    }
+                }
+            }
+        }
+    }
+    if numbers.is_empty() {
+        return None;
+    }
+    numbers.sort_unstable();
+    numbers.dedup();
+    Some(
+        numbers
+            .iter()
+            .map(u64::to_string)
+            .collect::<Vec<_>>()
+            .join(" "),
+    )
+}
+
+/// Return the version of the *previous* changelog entry (the second header
+/// in the file), or `None` when only one entry exists.
+pub fn parse_previous_version(path: &Path) -> Result<Option<String>, Box<dyn std::error::Error>> {
+    let content = std::fs::read_to_string(path)
+        .map_err(|e| format!("failed to read changelog '{}': {}", path.display(), e))?;
+
+    let mut seen_first = false;
+    for line in content.lines() {
+        let line = line.trim_end();
+        if looks_like_header(line) {
+            if !seen_first {
+                seen_first = true;
+                continue;
+            }
+            let open = line.find('(').ok_or_else(|| {
+                format!("invalid changelog header in '{}': {}", path.display(), line)
+            })?;
+            let close = line[open..]
+                .find(')')
+                .ok_or_else(|| format!("unbalanced parenthesis in changelog header '{}'", line))?;
+            return Ok(Some(line[open + 1..open + close].to_string()));
+        }
+    }
+    Ok(None)
+}
+
+/// Heuristic check for a changelog entry header line
+/// (`name (version) dist; urgency=...`).
+fn looks_like_header(line: &str) -> bool {
+    // Headers are never indented.
+    if line.starts_with(' ') || line.starts_with('\t') {
+        return false;
+    }
+    match line.find('(') {
+        Some(open) => {
+            let name = line[..open].trim();
+            !name.is_empty() && !name.contains(' ')
+        }
+        None => false,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn changelog_parsing() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("changelog");
+        let content = "\
+pkh-hello (0.1) unstable; urgency=medium
+
+ * Initial release.
+ * Second change line.
+
+ -- Pkh Tester <pkh@example.com>  Sat, 22 Aug 2026 10:00:00 +0000
+";
+        std::fs::write(&path, content).unwrap();
+
+        let entry = parse_changelog_entry(&path).unwrap();
+        assert_eq!(entry.source, "pkh-hello");
+        assert_eq!(entry.version.full(), "0.1");
+        assert_eq!(entry.distribution, "unstable");
+        assert_eq!(entry.urgency, "medium");
+        assert!(!entry.binary_only);
+        assert_eq!(entry.maintainer_name, "Pkh Tester");
+        assert_eq!(entry.maintainer_email, "pkh@example.com");
+        assert_eq!(entry.timestamp, 1787392800);
+        assert_eq!(
+            entry.changes_field,
+            "\npkh-hello (0.1) unstable; urgency=medium\n.\n * Initial release.\n * Second change line."
+        );
+    }
+
+    #[test]
+    fn changelog_bin_nmu() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("changelog");
+        let content = "\
+pkg (1.0-1+b1) unstable; urgency=medium, binary-only=yes
+
+ * Binary-only non-maintainer upload.
+ -- Builder <b@example.com>  Mon, 01 Jan 2024 00:00:00 +0000
+";
+        std::fs::write(&path, content).unwrap();
+
+        let entry = parse_changelog_entry(&path).unwrap();
+        assert!(entry.binary_only);
+        assert_eq!(entry.version.full(), "1.0-1+b1");
+    }
+}

src/debian/checksums.rs

@@ -0,0 +1,255 @@
+//! File checksum computation and formatting for `.changes` / `.buildinfo`
+//! fields (MD5, SHA-1, SHA-256 + size), mirroring `Dpkg::Checksums`.
+
+use std::collections::HashMap;
+use std::io::Read;
+use std::path::Path;
+
+use md5::Md5;
+use sha1::Sha1;
+use sha2::{Digest, Sha256};
+
+/// Checksums and size of a single file.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Entry {
+    /// File size in bytes.
+    pub size: u64,
+    /// Lowercase hexadecimal MD5 digest.
+    pub md5: String,
+    /// Lowercase hexadecimal SHA-1 digest.
+    pub sha1: String,
+    /// Lowercase hexadecimal SHA-256 digest.
+    pub sha256: String,
+}
+
+/// Compute all supported checksums of a file.
+fn compute(path: &Path) -> Result<Entry, Box<dyn std::error::Error>> {
+    let mut file = std::fs::File::open(path)
+        .map_err(|e| format!("cannot open '{}' for checksumming: {}", path.display(), e))?;
+
+    let mut md5_hasher = Md5::new();
+    let mut sha1_hasher = Sha1::new();
+    let mut sha256_hasher = Sha256::new();
+    let mut size: u64 = 0;
+    let mut buf = [0u8; 64 * 1024];
+
+    loop {
+        let n = file.read(&mut buf)?;
+        if n == 0 {
+            break;
+        }
+        md5_hasher.update(&buf[..n]);
+        sha1_hasher.update(&buf[..n]);
+        sha256_hasher.update(&buf[..n]);
+        size += n as u64;
+    }
+
+    Ok(Entry {
+        size,
+        md5: hex::encode(md5_hasher.finalize()),
+        sha1: hex::encode(sha1_hasher.finalize()),
+        sha256: hex::encode(sha256_hasher.finalize()),
+    })
+}
+
+/// A registry of checksummed files, keyed by the name they are distributed
+/// under (which may differ from the on-disk path).
+///
+/// Insertion order is preserved, matching the order in which
+/// `dpkg-genchanges` accumulates artifacts (dsc, tarballs, debs, buildinfo).
+#[derive(Debug, Clone, Default)]
+pub struct FileChecksums {
+    entries: Vec<(String, Entry)>,
+    index: HashMap<String, usize>,
+}
+
+impl FileChecksums {
+    /// Create an empty registry.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Add a file, registering it under its own file name.
+    pub fn add_file(&mut self, path: &Path) -> Result<(), Box<dyn std::error::Error>> {
+        let key = path
+            .file_name()
+            .and_then(|n| n.to_str())
+            .ok_or_else(|| format!("invalid file name: {}", path.display()))?
+            .to_string();
+        self.add_file_as(path, &key)
+    }
+
+    /// Add a file, registering it under an explicit distribution key.
+    pub fn add_file_as(
+        &mut self,
+        path: &Path,
+        key: &str,
+    ) -> Result<(), Box<dyn std::error::Error>> {
+        let entry = compute(path)?;
+        self.insert_entry(key, entry);
+        Ok(())
+    }
+
+    /// Insert a pre-computed entry (e.g. taken from a `.dsc` checksum field).
+    /// Re-inserting an existing key updates it in place, keeping its position.
+    pub fn insert_entry(&mut self, key: &str, entry: Entry) {
+        if let Some(&pos) = self.index.get(key) {
+            self.entries[pos].1 = entry;
+            return;
+        }
+        self.index.insert(key.to_string(), self.entries.len());
+        self.entries.push((key.to_string(), entry));
+    }
+
+    /// Remove a file from the registry. Returns true if it was present.
+    pub fn remove(&mut self, key: &str) -> bool {
+        match self.index.remove(key) {
+            Some(pos) => {
+                self.entries.remove(pos);
+                // Reindex the shifted tail.
+                for (i, (k, _)) in self.entries.iter().enumerate().skip(pos) {
+                    self.index.insert(k.clone(), i);
+                }
+                true
+            }
+            None => false,
+        }
+    }
+
+    /// Look up the entry for a given key.
+    pub fn get(&self, key: &str) -> Option<&Entry> {
+        self.index.get(key).map(|&pos| &self.entries[pos].1)
+    }
+
+    /// Iterate over `(key, entry)` pairs in insertion order.
+    pub fn iter(&self) -> impl Iterator<Item = (&String, &Entry)> {
+        self.entries.iter().map(|(k, e)| (k, e))
+    }
+
+    /// Number of registered files.
+    pub fn len(&self) -> usize {
+        self.entries.len()
+    }
+
+    /// True if no file is registered.
+    pub fn is_empty(&self) -> bool {
+        self.entries.is_empty()
+    }
+
+    /// Format a `Checksums-*` style field value: one `\n`-separated line per
+    /// file of the form `" <hash> <size> <key>"`.
+    fn format_field<F>(&self, hash_of: F) -> String
+    where
+        F: Fn(&Entry) -> &str,
+    {
+        let mut out = String::new();
+        for (key, e) in self.iter() {
+            out.push('\n');
+            out.push_str(hash_of(e));
+            out.push(' ');
+            out.push_str(&e.size.to_string());
+            out.push(' ');
+            out.push_str(key);
+        }
+        out
+    }
+
+    /// Value for the `Checksums-Md5` field (empty string if no file).
+    pub fn field_md5(&self) -> String {
+        self.format_field(|e| &e.md5)
+    }
+
+    /// Value for the `Checksums-Sha1` field (empty string if no file).
+    pub fn field_sha1(&self) -> String {
+        self.format_field(|e| &e.sha1)
+    }
+
+    /// Value for the `Checksums-Sha256` field (empty string if no file).
+    pub fn field_sha256(&self) -> String {
+        self.format_field(|e| &e.sha256)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn known_digests() {
+        let dir = tempfile::tempdir().unwrap();
+        let p = dir.path().join("sample.txt");
+        std::fs::write(&p, b"hello world\n").unwrap();
+
+        let mut cs = FileChecksums::new();
+        cs.add_file(&p).unwrap();
+
+        let e = cs.get("sample.txt").unwrap();
+        // Verified with coreutils: echo "hello world" | md5sum / sha1sum / sha256sum
+        assert_eq!(e.md5, "6f5902ac237024bdd0c176cb93063dc4");
+        assert_eq!(e.sha1, "22596363b3de40b06f981fb85d82312e8c0ed511");
+        assert_eq!(
+            e.sha256,
+            "a948904f2f0f479b8f8197694b30184b0d2ed1c1cd2a1ec0fb85d299a192a447"
+        );
+        assert_eq!(e.size, 12);
+    }
+
+    #[test]
+    fn insertion_order_preserved() {
+        let dir = tempfile::tempdir().unwrap();
+        let a = dir.path().join("a.txt");
+        let b = dir.path().join("b.txt");
+        std::fs::write(&a, b"aaa").unwrap();
+        std::fs::write(&b, b"bb").unwrap();
+
+        let mut cs = FileChecksums::new();
+        // Insert b first: insertion order (not alphabetical) must be kept,
+        // matching dpkg's artifact accumulation order.
+        cs.add_file(&b).unwrap();
+        cs.add_file(&a).unwrap();
+
+        let keys: Vec<&str> = cs.iter().map(|(k, _)| k.as_str()).collect();
+        assert_eq!(keys, vec!["b.txt", "a.txt"]);
+
+        assert_eq!(
+            cs.field_md5(),
+            "\n21ad0bd836b90d08f4cf640b4c298e7c 2 b.txt\n47bce5c74f589f4867dbd57e9ca9f808 3 a.txt"
+        );
+    }
+
+    #[test]
+    fn reinsert_updates_in_place() {
+        let dir = tempfile::tempdir().unwrap();
+        let a = dir.path().join("a.txt");
+        std::fs::write(&a, b"aaa").unwrap();
+
+        let mut cs = FileChecksums::new();
+        cs.add_file(&a).unwrap();
+        std::fs::write(&a, b"bbbb").unwrap();
+        cs.add_file(&a).unwrap(); // updated in place, same position
+
+        assert_eq!(cs.len(), 1);
+        assert_eq!(cs.get("a.txt").unwrap().size, 4);
+    }
+
+    #[test]
+    fn remove_keeps_order() {
+        let dir = tempfile::tempdir().unwrap();
+        let a = dir.path().join("a.txt");
+        let b = dir.path().join("b.txt");
+        let c = dir.path().join("c.txt");
+        std::fs::write(&a, b"1").unwrap();
+        std::fs::write(&b, b"2").unwrap();
+        std::fs::write(&c, b"3").unwrap();
+
+        let mut cs = FileChecksums::new();
+        cs.add_file(&a).unwrap();
+        cs.add_file(&b).unwrap();
+        cs.add_file(&c).unwrap();
+        assert!(cs.remove("b.txt"));
+        assert!(!cs.remove("b.txt"));
+
+        let keys: Vec<&str> = cs.iter().map(|(k, _)| k.as_str()).collect();
+        assert_eq!(keys, vec!["a.txt", "c.txt"]);
+    }
+}

src/debian/control.rs

@@ -0,0 +1,307 @@
+//! Debian control-file handling: a minimal deb822 paragraph parser/writer
+//! plus a `debian/control` model.
+//!
+//! Implements the subset of RFC822-ish parsing needed for `debian/control`,
+//! `debian/files`, `.dsc`, `.changes` and `.buildinfo` files: paragraphs
+//! separated by blank lines, `Field: value` entries with continuation lines
+//! starting by a single space or tab, and `#` comments.
+
+use std::path::Path;
+
+/// A single deb822 paragraph: an ordered list of `(field, value)` pairs.
+///
+/// Values are stored with continuation-line breaks as `\n` and without the
+/// leading whitespace of continuation lines. Serialization re-adds a single
+/// leading space in front of every continuation line, matching dpkg output.
+#[derive(Debug, Clone, Default, PartialEq)]
+pub struct Paragraph {
+    fields: Vec<(String, String)>,
+}
+
+impl Paragraph {
+    /// Create an empty paragraph.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Look up a field value (case-insensitive field name).
+    pub fn get(&self, field: &str) -> Option<&str> {
+        self.fields
+            .iter()
+            .find(|(k, _)| k.eq_ignore_ascii_case(field))
+            .map(|(_, v)| v.as_str())
+    }
+
+    /// Set a field value, replacing any previous occurrence (case-insensitive).
+    /// Appends the field at the end if it did not exist yet.
+    pub fn set(&mut self, field: &str, value: &str) {
+        for (k, v) in self.fields.iter_mut() {
+            if k.eq_ignore_ascii_case(field) {
+                *v = value.to_string();
+                return;
+            }
+        }
+        self.fields.push((field.to_string(), value.to_string()));
+    }
+
+    /// Remove a field (case-insensitive). Returns true if it was present.
+    pub fn remove(&mut self, field: &str) -> bool {
+        let before = self.fields.len();
+        self.fields.retain(|(k, _)| !k.eq_ignore_ascii_case(field));
+        self.fields.len() != before
+    }
+
+    /// Iterate over the `(field, value)` pairs in order.
+    pub fn iter(&self) -> impl Iterator<Item = (&str, &str)> {
+        self.fields.iter().map(|(k, v)| (k.as_str(), v.as_str()))
+    }
+
+    /// Return true if the paragraph holds no field.
+    pub fn is_empty(&self) -> bool {
+        self.fields.is_empty()
+    }
+}
+
+/// Parse a deb822 document into a list of paragraphs.
+///
+/// Comment lines (starting with `#`) are ignored. Blank lines separate
+/// paragraphs. Continuation lines must start with a space or a tab; exactly
+/// one leading space (or tab) is stripped from the stored value.
+pub fn parse_paragraphs(input: &str) -> Vec<Paragraph> {
+    let mut paragraphs = Vec::new();
+    let mut current = Paragraph::new();
+    let mut last_field: Option<String> = None;
+
+    for raw_line in input.lines() {
+        let line = raw_line.strip_suffix('\r').unwrap_or(raw_line);
+
+        // Comments and blank lines
+        if line.starts_with('#') {
+            continue;
+        }
+        if line.trim().is_empty() {
+            if !current.is_empty() {
+                paragraphs.push(std::mem::take(&mut current));
+                last_field = None;
+            }
+            continue;
+        }
+
+        // Continuation line
+        if line.starts_with(' ') || line.starts_with('\t') {
+            let content = line.strip_prefix(' ').unwrap_or(line);
+            if let Some(field) = &last_field
+                && let Some((_, v)) = current
+                    .fields
+                    .iter_mut()
+                    .rev()
+                    .find(|(k, _)| k.eq_ignore_ascii_case(field))
+            {
+                v.push('\n');
+                v.push_str(content);
+                continue;
+            }
+            // Continuation without a preceding field line: skip it (malformed)
+            continue;
+        }
+
+        // Field line: `Name: value`
+        if let Some(colon) = line.find(':') {
+            let name = line[..colon].trim();
+            let value = line[colon + 1..].trim_start();
+            if name.is_empty() {
+                continue;
+            }
+            current.fields.push((name.to_string(), value.to_string()));
+            last_field = Some(name.to_string());
+        }
+        // Anything else is malformed: ignore the line
+    }
+
+    if !current.is_empty() {
+        paragraphs.push(current);
+    }
+
+    paragraphs
+}
+
+/// Serialize a paragraph to its deb822 textual representation (with a
+/// trailing newline).
+///
+/// A value starting with `\n` is rendered as a field with no inline first
+/// line (`Field:` followed by ` line` continuations), matching dpkg output
+/// for pre-wrapped values such as `Changes`, `Files` or `Environment`.
+pub fn write_paragraph(p: &Paragraph) -> String {
+    let mut out = String::new();
+    for (name, value) in p.iter() {
+        out.push_str(name);
+        out.push(':');
+        let mut lines = value.split('\n').peekable();
+        // An empty first segment means: no value on the field header line;
+        // discard it so it is not rendered as an empty continuation line.
+        if lines.peek().is_some_and(|first| !first.is_empty()) {
+            out.push(' ');
+            out.push_str(lines.next().unwrap());
+        } else {
+            lines.next();
+        }
+        for line in lines {
+            out.push('\n');
+            out.push(' ');
+            out.push_str(line);
+        }
+        out.push('\n');
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_simple_control() {
+        let input = "Source: hello\nSection: devel\n\nPackage: hello\nDepends: libc6\n";
+        let paras = parse_paragraphs(input);
+        assert_eq!(paras.len(), 2);
+        assert_eq!(paras[0].get("Source"), Some("hello"));
+        assert_eq!(paras[0].get("section"), Some("devel"));
+        assert_eq!(paras[1].get("Package"), Some("hello"));
+        assert_eq!(paras[1].get("Depends"), Some("libc6"));
+    }
+
+    #[test]
+    fn parse_multiline_and_comments() {
+        let input = "# a comment\nDescription: short\n long description\n" //
+            .to_string()
+            + " spanning lines\n\nPackage: x\n";
+        let paras = parse_paragraphs(&input);
+        assert_eq!(paras.len(), 2);
+        assert_eq!(
+            paras[0].get("Description"),
+            Some("short\nlong description\nspanning lines")
+        );
+    }
+
+    #[test]
+    fn roundtrip_multiline() {
+        let value = "short\nlong description\nspanning lines";
+        let mut p = Paragraph::new();
+        p.set("Description", value);
+        let text = write_paragraph(&p);
+        assert_eq!(
+            text,
+            "Description: short\n long description\n spanning lines\n"
+        );
+        let reparsed = parse_paragraphs(&text);
+        assert_eq!(reparsed[0].get("Description"), Some(value));
+    }
+
+    #[test]
+    fn set_replaces_case_insensitive() {
+        let mut p = Paragraph::new();
+        p.set("Source", "a");
+        p.set("source", "b");
+        assert_eq!(p.get("SOURCE"), Some("b"));
+        assert_eq!(p.iter().count(), 1);
+    }
+
+    #[test]
+    fn remove_field() {
+        let mut p = Paragraph::new();
+        p.set("A", "1");
+        assert!(p.remove("a"));
+        assert!(!p.remove("a"));
+        assert!(p.is_empty());
+    }
+}
+
+/// Parsed `debian/control`: the source stanza plus all binary stanzas.
+#[derive(Debug, Clone)]
+pub struct ControlInfo {
+    /// First paragraph (source package stanza).
+    pub source: Paragraph,
+    /// Remaining paragraphs (binary package stanzas).
+    pub binaries: Vec<Paragraph>,
+}
+
+impl ControlInfo {
+    /// Parse a `debian/control` file.
+    pub fn parse(path: &Path) -> Result<ControlInfo, Box<dyn std::error::Error>> {
+        let content = std::fs::read_to_string(path)
+            .map_err(|e| format!("failed to read control file '{}': {}", path.display(), e))?;
+        content
+            .parse::<ControlInfo>()
+            .map_err(|e| format!("invalid control file '{}': {}", path.display(), e).into())
+    }
+
+    /// Parse control content from a string.
+    ///
+    /// Prefer [`std::str::FromStr`] (`"...".parse::<ControlInfo>()`).
+    pub fn parse_content(content: &str) -> Result<ControlInfo, String> {
+        let paragraphs = parse_paragraphs(content);
+        let mut iter = paragraphs.into_iter();
+        let source = iter
+            .next()
+            .ok_or_else(|| "control file has no paragraphs".to_string())?;
+        if source.get("Source").is_none() {
+            return Err("first control paragraph has no 'Source' field".to_string());
+        }
+        let binaries: Vec<Paragraph> = iter.collect();
+        for bin in &binaries {
+            if bin.get("Package").is_none() {
+                return Err("binary control paragraph has no 'Package' field".to_string());
+            }
+        }
+        Ok(ControlInfo { source, binaries })
+    }
+
+    /// The source package name.
+    pub fn source_name(&self) -> &str {
+        self.source.get("Source").expect("checked at parse")
+    }
+
+    /// Section from the source stanza, or `'-'`.
+    pub fn section(&self) -> &str {
+        self.source.get("Section").unwrap_or("-")
+    }
+
+    /// Priority from the source stanza, or `'-'`.
+    pub fn priority(&self) -> &str {
+        self.source.get("Priority").unwrap_or("-")
+    }
+}
+
+impl std::str::FromStr for ControlInfo {
+    type Err = String;
+
+    fn from_str(content: &str) -> Result<Self, Self::Err> {
+        ControlInfo::parse_content(content)
+    }
+}
+
+#[cfg(test)]
+mod control_info_tests {
+    use super::*;
+    use std::str::FromStr;
+
+    #[test]
+    fn control_parsing() {
+        let ci = ControlInfo::from_str(
+            "Source: hello\nSection: utils\nPriority: optional\nMaintainer: A B <a@b.c>\nBuild-Depends: debhelper\n\nPackage: hello\nArchitecture: any\nDescription: test\n long\n",
+        )
+        .unwrap();
+        assert_eq!(ci.source_name(), "hello");
+        assert_eq!(ci.section(), "utils");
+        assert_eq!(ci.priority(), "optional");
+        assert_eq!(ci.binaries.len(), 1);
+        assert_eq!(ci.binaries[0].get("Package"), Some("hello"));
+    }
+
+    #[test]
+    fn control_defaults() {
+        let ci = ControlInfo::from_str("Source: x\n\nPackage: x\nDescription: d\n").unwrap();
+        assert_eq!(ci.section(), "-");
+        assert_eq!(ci.priority(), "-");
+    }
+}

src/debian/files.rs

@@ -0,0 +1,258 @@
+//! `debian/files` registry: the contract between the build (`dh_builddeb`,
+//! `dpkg-gencontrol`, ...) and the artifact generators, mirroring
+//! `Dpkg::Dist::Files`.
+
+use std::collections::BTreeMap;
+use std::io::Write;
+use std::path::Path;
+
+/// One registered artifact.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct FilesEntry {
+    /// File name (relative to the parent directory of the package tree).
+    pub filename: String,
+    /// Archive section (e.g. `utils`).
+    pub section: String,
+    /// Archive priority (e.g. `optional`).
+    pub priority: String,
+    /// Package name parsed from the file name pattern, if any.
+    pub package: Option<String>,
+    /// Version parsed from the file name pattern, if any.
+    pub version: Option<String>,
+    /// Architecture parsed from the file name pattern, if any.
+    pub arch: Option<String>,
+    /// Artifact type parsed from the file name extension
+    /// (`deb`, `udeb`, `buildinfo`, `changes`, ...).
+    pub package_type: Option<String>,
+    /// Extra `key=value` attributes on the line (e.g. `automatic=yes`).
+    pub attrs: BTreeMap<String, String>,
+}
+
+impl FilesEntry {
+    /// Create a minimal entry with only name/section/priority; the pattern
+    /// fields are derived from the file name.
+    pub fn new(filename: &str, section: &str, priority: &str) -> FilesEntry {
+        let mut entry = parse_filename(filename).unwrap_or_else(|| FilesEntry {
+            filename: filename.to_string(),
+            section: "-".to_string(),
+            priority: "-".to_string(),
+            package: None,
+            version: None,
+            arch: None,
+            package_type: None,
+            attrs: BTreeMap::new(),
+        });
+        entry.section = section.to_string();
+        entry.priority = priority.to_string();
+        entry
+    }
+}
+
+/// Derive metadata from an artifact file name following the common
+/// `<package>_<version>_<arch>.<type>` pattern, like
+/// `Dpkg::Dist::Files::parse_filename()`.
+#[allow(clippy::field_reassign_with_default)]
+pub fn parse_filename(name: &str) -> Option<FilesEntry> {
+    // Common pattern: name_version_arch.type where type is dot-separated
+    // (e.g. tar.xz must not match here since it has no leading underscores).
+    let parts: Vec<&str> = name.split('_').collect();
+    if parts.len() == 3 {
+        let (pkg, version, rest) = (parts[0], parts[1], parts[2]);
+        if let Some(dot) = rest.rfind('.') {
+            let arch = &rest[..dot];
+            let ptype = &rest[dot + 1..];
+            let valid = |s: &str| {
+                !s.is_empty()
+                    && s.chars()
+                        .all(|c| c.is_ascii_alphanumeric() || "-+.:~".contains(c))
+            };
+            if valid(pkg) && valid(version) && valid(arch) && valid(ptype) {
+                return Some(FilesEntry {
+                    filename: name.to_string(),
+                    section: "-".to_string(),
+                    priority: "-".to_string(),
+                    package: Some(pkg.to_string()),
+                    version: Some(version.to_string()),
+                    arch: Some(arch.to_string()),
+                    package_type: Some(ptype.to_string()),
+                    attrs: BTreeMap::new(),
+                });
+            }
+        }
+    }
+    // Fallback: accept a conservative file-name character set.
+    if !name.is_empty()
+        && name
+            .chars()
+            .all(|c| c.is_ascii_alphanumeric() || "-+.:,_~".contains(c))
+    {
+        return Some(FilesEntry {
+            filename: name.to_string(),
+            section: "-".to_string(),
+            priority: "-".to_string(),
+            package: None,
+            version: None,
+            arch: None,
+            package_type: None,
+            attrs: BTreeMap::new(),
+        });
+    }
+    None
+}
+
+/// The full `debian/files` registry, ordered by file name.
+#[derive(Debug, Clone, Default)]
+pub struct FilesList {
+    files: BTreeMap<String, FilesEntry>,
+}
+
+impl FilesList {
+    /// An empty registry.
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Load `debian/files`. A missing file yields an empty registry.
+    pub fn load(path: &Path) -> Result<FilesList, Box<dyn std::error::Error>> {
+        let mut list = FilesList::new();
+        let content = match std::fs::read_to_string(path) {
+            Ok(c) => c,
+            Err(e) if e.kind() == std::io::ErrorKind::NotFound => return Ok(list),
+            Err(e) => {
+                return Err(format!("cannot read '{}': {}", path.display(), e).into());
+            }
+        };
+        for line in content.lines() {
+            if line.trim().is_empty() {
+                continue;
+            }
+            let tokens: Vec<&str> = line.split_whitespace().collect();
+            if tokens.len() < 3 {
+                return Err(format!("badly formed line in '{}': {}", path.display(), line).into());
+            }
+            let mut entry = parse_filename(tokens[0]).ok_or_else(|| {
+                format!(
+                    "badly formed file name in '{}': {}",
+                    path.display(),
+                    tokens[0]
+                )
+            })?;
+            entry.section = tokens[1].to_string();
+            entry.priority = tokens[2].to_string();
+            for attr in &tokens[3..] {
+                if let Some((k, v)) = attr.split_once('=') {
+                    entry.attrs.insert(k.to_string(), v.to_string());
+                }
+            }
+            list.files.insert(entry.filename.clone(), entry);
+        }
+        Ok(list)
+    }
+
+    /// Register (or replace) an entry.
+    pub fn add(&mut self, entry: FilesEntry) {
+        self.files.insert(entry.filename.clone(), entry);
+    }
+
+    /// Remove entries matching a predicate. Returns how many were removed.
+    pub fn retain<F: FnMut(&FilesEntry) -> bool>(&mut self, mut keep: F) -> usize {
+        let before = self.files.len();
+        self.files.retain(|_, e| keep(e));
+        before - self.files.len()
+    }
+
+    /// Iterate over entries sorted by file name.
+    pub fn iter(&self) -> impl Iterator<Item = &FilesEntry> {
+        self.files.values()
+    }
+
+    /// Look up an entry by file name.
+    pub fn get(&self, filename: &str) -> Option<&FilesEntry> {
+        self.files.get(filename)
+    }
+
+    /// Number of registered files.
+    pub fn len(&self) -> usize {
+        self.files.len()
+    }
+
+    /// True if empty.
+    pub fn is_empty(&self) -> bool {
+        self.files.is_empty()
+    }
+
+    /// Save atomically: write `<path>.new` then rename over `path`, like
+    /// dpkg does.
+    pub fn save_atomic(&self, path: &Path) -> Result<(), Box<dyn std::error::Error>> {
+        let tmp = path.with_extension("new");
+        {
+            let mut f = std::fs::File::create(&tmp)
+                .map_err(|e| format!("cannot write '{}': {}", tmp.display(), e))?;
+            for entry in self.iter() {
+                write!(f, "{} {} {}", entry.filename, entry.section, entry.priority)?;
+                for (k, v) in &entry.attrs {
+                    write!(f, " {}={}", k, v)?;
+                }
+                writeln!(f)?;
+            }
+            f.flush()?;
+        }
+        std::fs::rename(&tmp, path)
+            .map_err(|e| format!("cannot install '{}': {}", path.display(), e).into())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn filename_pattern_parsing() {
+        let e = parse_filename("hello_2.10-3_amd64.deb").unwrap();
+        assert_eq!(e.package.as_deref(), Some("hello"));
+        assert_eq!(e.version.as_deref(), Some("2.10-3"));
+        assert_eq!(e.arch.as_deref(), Some("amd64"));
+        assert_eq!(e.package_type.as_deref(), Some("deb"));
+
+        let e = parse_filename("hello_0.1_source.buildinfo").unwrap();
+        assert_eq!(e.package.as_deref(), Some("hello"));
+        assert_eq!(e.arch.as_deref(), Some("source"));
+        assert_eq!(e.package_type.as_deref(), Some("buildinfo"));
+
+        // Tarballs do not follow the 3-component pattern.
+        let e = parse_filename("hello_0.1.tar.xz").unwrap();
+        assert_eq!(e.package, None);
+        assert_eq!(e.package_type, None);
+    }
+
+    #[test]
+    fn load_save_roundtrip() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = dir.path().join("files");
+
+        let mut list = FilesList::new();
+        list.add(FilesEntry::new("hello_1.0_amd64.deb", "devel", "optional"));
+        list.add(FilesEntry::new("hello_1.0_source.buildinfo", "-", "-"));
+        list.save_atomic(&path).unwrap();
+
+        let reloaded = FilesList::load(&path).unwrap();
+        assert_eq!(reloaded.len(), 2);
+        let deb = reloaded.get("hello_1.0_amd64.deb").unwrap();
+        assert_eq!(deb.section, "devel");
+        assert_eq!(deb.priority, "optional");
+
+        // Missing file loads as empty.
+        let missing = FilesList::load(&dir.path().join("nonexistent")).unwrap();
+        assert!(missing.is_empty());
+    }
+
+    #[test]
+    fn retain_removes_matching() {
+        let mut list = FilesList::new();
+        list.add(FilesEntry::new("x_1_source.buildinfo", "-", "-"));
+        list.add(FilesEntry::new("x_1_amd64.deb", "-", "-"));
+        let removed = list.retain(|e| e.package_type.as_deref() != Some("buildinfo"));
+        assert_eq!(removed, 1);
+        assert_eq!(list.len(), 1);
+    }
+}

src/debian/mod.rs

@@ -0,0 +1,22 @@
+//! Reusable Debian format primitives.
+//!
+//! These components are independent from any build orchestration and can be
+//! used by any pkh submodule (or external consumers of the library):
+//!
+//! - [`control`]: deb822 paragraph parsing/writing and `debian/control`
+//! - [`checksums`]: file checksum registry (`Dpkg::Checksums` equivalent)
+//! - [`files`]: `debian/files` artifact registry (`Dpkg::Dist::Files`)
+//! - [`version`]: Debian version splitting/validation
+//! - [`changelog`]: `debian/changelog` entry parsing
+
+pub mod changelog;
+pub mod checksums;
+pub mod control;
+pub mod files;
+pub mod version;
+
+pub use changelog::{ChangelogEntry, parse_changelog_entry};
+pub use checksums::{Entry as ChecksumEntry, FileChecksums};
+pub use control::{ControlInfo, Paragraph, parse_paragraphs, write_paragraph};
+pub use files::{FilesEntry, FilesList};
+pub use version::DebianVersion;

src/debian/version.rs

@@ -0,0 +1,120 @@
+//! Debian version handling: splitting and validation of
+//! `[epoch:]upstream[-revision]` version strings.
+
+/// A Debian version, split into its `[epoch:]upstream[-revision]` parts.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct DebianVersion {
+    /// Optional numeric epoch (part before the first `:`).
+    pub epoch: Option<u32>,
+    /// Upstream version (may itself contain `-` when there is no revision).
+    pub upstream: String,
+    /// Optional Debian revision (part after the last `-`).
+    pub debian_revision: Option<String>,
+}
+
+impl DebianVersion {
+    /// Parse and validate a Debian version string.
+    pub fn parse(raw: &str) -> Result<DebianVersion, String> {
+        let raw = raw.trim();
+        if raw.is_empty() {
+            return Err("empty version string".to_string());
+        }
+
+        let (epoch, rest) = match raw.split_once(':') {
+            Some((e, r)) => {
+                let epoch: u32 = e
+                    .parse()
+                    .map_err(|_| format!("invalid epoch '{}' in version '{}'", e, raw))?;
+                (Some(epoch), r)
+            }
+            None => (None, raw),
+        };
+
+        // The revision is everything after the last hyphen.
+        let (upstream, debian_revision) = match rest.rsplit_once('-') {
+            Some((u, r)) => (u.to_string(), Some(r.to_string())),
+            None => (rest.to_string(), None),
+        };
+
+        if upstream.is_empty() {
+            return Err(format!("missing upstream version in '{}'", raw));
+        }
+        for c in upstream.chars() {
+            if !(c.is_ascii_alphanumeric()
+                || matches!(c, '.' | '+' | '-' | '~' | ':')
+                || !c.is_ascii())
+            {
+                return Err(format!("invalid character '{}' in version '{}'", c, raw));
+            }
+        }
+        if let Some(rev) = &debian_revision {
+            for c in rev.chars() {
+                if !(c.is_ascii_alphanumeric() || matches!(c, '.' | '+' | '~') || !c.is_ascii()) {
+                    return Err(format!(
+                        "invalid character '{}' in revision of version '{}'",
+                        c, raw
+                    ));
+                }
+            }
+        }
+
+        Ok(DebianVersion {
+            epoch,
+            upstream,
+            debian_revision,
+        })
+    }
+
+    /// Full version string, including the epoch (`[epoch:]upstream[-rev]`).
+    pub fn full(&self) -> String {
+        match (&self.epoch, &self.debian_revision) {
+            (Some(e), Some(r)) => format!("{}:{}-{}", e, self.upstream, r),
+            (Some(e), None) => format!("{}:{}", e, self.upstream),
+            (None, Some(r)) => format!("{}-{}", self.upstream, r),
+            (None, None) => self.upstream.clone(),
+        }
+    }
+
+    /// Version string without the epoch (`upstream[-rev]`), used in artifact
+    /// file names.
+    pub fn no_epoch(&self) -> String {
+        match &self.debian_revision {
+            Some(r) => format!("{}-{}", self.upstream, r),
+            None => self.upstream.clone(),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn version_splitting() {
+        let v = DebianVersion::parse("1.2.3-4ubuntu5").unwrap();
+        assert_eq!(v.epoch, None);
+        assert_eq!(v.upstream, "1.2.3");
+        assert_eq!(v.debian_revision.as_deref(), Some("4ubuntu5"));
+        assert_eq!(v.full(), "1.2.3-4ubuntu5");
+        assert_eq!(v.no_epoch(), "1.2.3-4ubuntu5");
+
+        let v = DebianVersion::parse("3:2.10-3").unwrap();
+        assert_eq!(v.epoch, Some(3));
+        assert_eq!(v.upstream, "2.10");
+        assert_eq!(v.no_epoch(), "2.10-3");
+        assert_eq!(v.full(), "3:2.10-3");
+
+        let v = DebianVersion::parse("1.0").unwrap();
+        assert_eq!(v.debian_revision, None);
+        assert_eq!(v.no_epoch(), "1.0");
+    }
+
+    #[test]
+    fn version_validation() {
+        assert!(DebianVersion::parse("").is_err());
+        assert!(DebianVersion::parse(":1.0").is_err());
+        assert!(DebianVersion::parse("a:_b").is_err());
+        assert!(DebianVersion::parse("1.0").is_ok());
+        assert!(DebianVersion::parse("1.0~rc1-2").is_ok());
+    }
+}

src/lib.rs

@@ -11,6 +11,9 @@ pub mod build;
 pub mod changelog;
 /// Build a Debian package into a binary (.deb)
 pub mod deb;
+/// Reusable Debian format primitives (control/deb822, checksums, versions,
+/// changelog entries, artifact registries)
+pub mod debian;
 /// Obtain general information about distribution, series, etc
 pub mod distro_info;
 /// Obtain information about one or multiple packages

src/utils/gpg.rs

@@ -1,4 +1,11 @@
-use gpgme::{Context, Protocol};
+//! GPG / OpenPGP helpers: secret key discovery and inline (clear) signing
+//! of Debian artifacts such as `.dsc`, `.buildinfo` and `.changes` files.
+
+use std::error::Error;
+use std::io::Read;
+use std::path::Path;
+
+use gpgme::{Context, Data, Protocol};
 
 /// Check if a GPG key matching 'email' exists
 /// Returns the key ID if found, None otherwise
@@ -30,3 +37,89 @@ pub fn find_signing_key_for_email(
 
     Ok(None)
 }
+
+/// Validate an OpenPGP key id / fingerprint like dpkg does.
+///
+/// Short (<= 8 hex chars) key IDs are rejected outright, long (16 hex chars)
+/// key IDs produce a warning; anything else must be a v4 (40) or v6 (64)
+/// fingerprint length.
+pub fn validate_key_id(keyid: &str) -> Result<(), Box<dyn Error>> {
+    let len = keyid.len();
+    if len <= 8 {
+        return Err("short OpenPGP key IDs are broken; use a key fingerprint instead".into());
+    } else if len <= 16 {
+        log::warn!(
+            "long OpenPGP key IDs are strongly discouraged; \
+             use a key fingerprint instead"
+        );
+    } else if len != 40 && len != 64 {
+        log::warn!("OpenPGP key ID has unknown v4 or v6 fingerprint length");
+    }
+    Ok(())
+}
+
+/// Find a secret key whose fingerprint matches `keyid` (suffix matching
+/// allows passing a long key id instead of the full fingerprint).
+fn find_secret_key(ctx: &mut Context, keyid: &str) -> Result<Option<gpgme::Key>, Box<dyn Error>> {
+    for key_result in ctx.secret_keys()? {
+        let key = key_result?;
+        if let Ok(fingerprint) = key.fingerprint()
+            && fingerprint.ends_with(keyid)
+        {
+            return Ok(Some(key));
+        }
+    }
+    Ok(None)
+}
+
+/// Clearsign a file in place: the original content becomes the payload of an
+/// armored inline-signed document which atomically replaces the file.
+///
+/// This is the same operation as dpkg's `inline_sign` + rename sequence used
+/// when signing `.dsc`, `.buildinfo` or `.changes` files.
+pub fn clearsign_file(path: &Path, keyid: &str) -> Result<(), Box<dyn Error>> {
+    let content = std::fs::read(path)
+        .map_err(|e| format!("cannot read '{}' for signing: {}", path.display(), e))?;
+
+    let mut ctx = Context::from_protocol(Protocol::OpenPgp)
+        .map_err(|e| format!("cannot initialize GPGME: {}", e))?;
+    ctx.set_armor(true);
+
+    let key = find_secret_key(&mut ctx, keyid)?
+        .ok_or_else(|| format!("no secret key matching '{}' found", keyid))?;
+
+    ctx.add_signer(&key)
+        .map_err(|e| format!("cannot add signer '{}': {}", keyid, e))?;
+
+    let input = Data::from_bytes(&content)?;
+    let mut output = Data::new()?;
+    ctx.sign_clear(input, &mut output)
+        .map_err(|e| format!("clear-signing '{}' failed: {}", path.display(), e))?;
+
+    // gpgme leaves the output buffer cursor at the end after writing.
+    use std::io::Seek;
+    use std::io::SeekFrom;
+    output.seek(SeekFrom::Start(0))?;
+    let mut signed = Vec::new();
+    output.read_to_end(&mut signed)?;
+
+    // Atomic replace, like dpkg's signfile (write .asc then move).
+    let tmp = path.with_extension("asc.tmp");
+    std::fs::write(&tmp, &signed)
+        .map_err(|e| format!("cannot write '{}': {}", tmp.display(), e))?;
+    std::fs::rename(&tmp, path)
+        .map_err(|e| format!("cannot install signed '{}': {}", path.display(), e).into())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn key_id_validation() {
+        assert!(validate_key_id("12345678").is_err()); // short: rejected
+        assert!(validate_key_id("1234567890ABCDEF").is_ok()); // long: warns
+        assert!(validate_key_id(&"a".repeat(40)).is_ok());
+        assert!(validate_key_id(&"b".repeat(64)).is_ok());
+    }
+}