pull,deb: add top-level --pocket option

- pull: select the pocket to download the source package from
- deb: build against dependencies from a specific pocket:
  - local mode: enable '{series}-{pocket}' suite on archive sources
  - cross mode: include the pocket suite in required repositories

src/deb/cross.rs

@@ -38,6 +38,7 @@ pub fn setup_environment(
 pub fn ensure_repositories(
     arch: &str,
     series: &str,
+    pocket: Option<&str>,
     ctx: Arc<Context>,
 ) -> Result<(), Box<dyn Error>> {
     let local_arch = crate::get_current_arch();
@@ -74,12 +75,19 @@ pub fn ensure_repositories(
             }
 
             // Ensure all suites (pockets) are enabled, excluding 'proposed'
-            let required_suites = [
+            // unless explicitly requested through the 'pocket' option
+            let mut required_suites = vec![
                 series.to_string(),
                 format!("{}-updates", series),
                 format!("{}-backports", series),
                 format!("{}-security", series),
             ];
+            if let Some(p) = pocket {
+                let pocket_suite = format!("{series}-{p}");
+                if !required_suites.contains(&pocket_suite) {
+                    required_suites.push(pocket_suite);
+                }
+            }
             for suite in required_suites {
                 if !source.suite.contains(&suite) {
                     source.suite.push(suite);
@@ -95,6 +103,18 @@ pub fn ensure_repositories(
 
     if !has_ports {
         // Add ports repository for the target architecture
+        let mut ports_suites = vec![
+            format!("{series}"),
+            format!("{series}-updates"),
+            format!("{series}-backports"),
+            format!("{series}-security"),
+        ];
+        if let Some(p) = pocket {
+            let pocket_suite = format!("{series}-{p}");
+            if !ports_suites.contains(&pocket_suite) {
+                ports_suites.push(pocket_suite);
+            }
+        }
         let ports_entry = crate::apt::sources::SourceEntry {
             enabled: true,
             components: vec![
@@ -105,12 +125,7 @@ pub fn ensure_repositories(
             ],
             architectures: vec![arch.to_string()],
             uri: "http://ports.ubuntu.com/ubuntu-ports".to_string(),
-            suite: vec![
-                format!("{series}"),
-                format!("{series}-updates"),
-                format!("{series}-backports"),
-                format!("{series}-security"),
-            ],
+            suite: ports_suites,
         };
         sources.push(ports_entry);
     }

src/deb/local.rs

@@ -17,6 +17,7 @@ pub async fn build(
     version: &str,
     arch: &str,
     series: &str,
+    pocket: Option<&str>,
     build_root: &str,
     cross: bool,
     ppa: Option<&[&str]>,
@@ -53,7 +54,7 @@ pub async fn build(
     if cross {
         log::debug!("Setting up environment for local cross build...");
         cross::setup_environment(&mut env, arch, ctx.clone())?;
-        cross::ensure_repositories(arch, series, ctx.clone())?;
+        cross::ensure_repositories(arch, series, pocket, ctx.clone())?;
     }
 
     let mut sources = apt::sources::load(Some(ctx.clone()))?;
@@ -116,6 +117,19 @@ pub async fn build(
         }
     }
 
+    // Enable the requested pocket on archive sources, so build-dependencies
+    // are resolved from that pocket
+    if let Some(pocket_name) = pocket {
+        let pocket_suite = format!("{series}-{pocket_name}");
+        log::info!("Enabling pocket '{}' for build dependencies", pocket_suite);
+        for source in &mut sources {
+            if crate::deb::is_archive_source(&source.uri) && !source.suite.contains(&pocket_suite) {
+                source.suite.push(pocket_suite.clone());
+                modified = true;
+            }
+        }
+    }
+
     if modified {
         apt::sources::save_legacy(Some(ctx.clone()), sources, "/etc/apt/sources.list")?;
 

src/deb/mod.rs

@@ -19,6 +19,7 @@ pub enum BuildMode {
 pub async fn build_binary_package(
     arch: Option<&str>,
     series: Option<&str>,
+    pocket: Option<&str>,
     cwd: Option<&Path>,
     cross: bool,
     mode: Option<BuildMode>,
@@ -99,6 +100,7 @@ pub async fn build_binary_package(
                 &version,
                 arch,
                 series,
+                pocket,
                 &build_root,
                 cross,
                 ppa,
@@ -107,7 +109,7 @@ pub async fn build_binary_package(
             )
             .await?
         }
-    };
+    }
 
     // Retrieve produced .deb files
     let remote_files = build_ctx.list_files(Path::new(&build_root))?;
@@ -256,6 +258,15 @@ fn find_dsc_file(
     Ok(dsc_path)
 }
 
+/// Check whether an apt source URI points to a distribution archive
+/// (as opposed to a PPA or another third-party repository)
+pub(crate) fn is_archive_source(uri: &str) -> bool {
+    uri.contains("archive.ubuntu.com")
+        || uri.contains("security.ubuntu.com")
+        || uri.contains("ports.ubuntu.com")
+        || uri.contains("deb.debian.org")
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -303,6 +314,7 @@ mod tests {
         crate::deb::build_binary_package(
             arch,
             Some(series),
+            None,
             Some(&cwd),
             cross,
             None,