context: copy symlinks as symlinks and improve error messages

src/distro_info.rs

@@ -110,11 +110,30 @@ fn parse_series_csv(content: &str) -> Result<Vec<SeriesInformation>, Box<dyn Err
     Ok(series_info_list)
 }
 
+/// List the distributions known to pkh (e.g. "debian", "ubuntu")
+pub fn supported_dists() -> Vec<String> {
+    DATA.dist.keys().cloned().collect()
+}
+
 /// Get time-ordered list of series information for a distribution, development series first
 pub async fn get_ordered_series(dist: &str) -> Result<Vec<SeriesInformation>, Box<dyn Error>> {
-    let series_info = &DATA.dist.get(dist).unwrap().series;
+    let dist_data = DATA.dist.get(dist).ok_or_else(|| {
+        format!(
+            "Unknown distribution '{}'. Supported distributions are: {}.",
+            dist,
+            supported_dists().join(", ")
+        )
+    })?;
+    let series_info = &dist_data.series;
     let content = if Path::new(series_info.local.as_str()).exists() {
-        std::fs::read_to_string(format!("/usr/share/distro-info/{dist}.csv"))?
+        std::fs::read_to_string(format!("/usr/share/distro-info/{dist}.csv"))
+            .map_err(|e| {
+                format!(
+                    "Failed to read distribution series data for '{dist}' \
+                     from '{}': {}. The 'distro-info' package provides these CSV files.",
+                    series_info.local, e
+                )
+            })?
     } else {
         reqwest::get(series_info.network.as_str())
             .await?
@@ -188,13 +207,20 @@ pub async fn get_dist_from_series(series: &str) -> Result<String, Box<dyn Error>
 /// Get the package pockets available for a given distribution
 ///
 /// Example: get_dist_pockets(ubuntu) => ["proposed", "updates", ""]
-pub fn get_dist_pockets(dist: &str) -> Vec<String> {
-    let mut pockets = DATA.dist.get(dist).unwrap().pockets.clone();
+pub fn get_dist_pockets(dist: &str) -> Result<Vec<String>, Box<dyn Error>> {
+    let dist_data = DATA.dist.get(dist).ok_or_else(|| {
+        format!(
+            "Unknown distribution '{}'. Supported distributions are: {}.",
+            dist,
+            supported_dists().join(", ")
+        )
+    })?;
+    let mut pockets = dist_data.pockets.clone();
 
     // Explicitely add 'main' pocket, which is just the empty string
     pockets.push("".to_string());
 
-    pockets
+    Ok(pockets)
 }
 
 /// Get the sources URL for a distribution, series, pocket, and component
@@ -210,8 +236,17 @@ pub fn get_sources_url(base_url: &str, series: &str, pocket: &str, component: &s
 /// Get the archive base URL for a distribution
 ///
 /// Example: ubuntu => http://archive.ubuntu.com/ubuntu
-pub fn get_base_url(dist: &str) -> String {
-    DATA.dist.get(dist).unwrap().base_url.clone()
+pub fn get_base_url(dist: &str) -> Result<String, Box<dyn Error>> {
+    DATA.dist.get(dist)
+        .map(|d| d.base_url.clone())
+        .ok_or_else(|| {
+            format!(
+                "Unknown distribution '{}'. Supported distributions are: {}.",
+                dist,
+                supported_dists().join(", ")
+            )
+            .into()
+        })
 }
 
 /// Obtain the URLs for the archive keyrings of a distribution series
@@ -246,7 +281,15 @@ pub async fn get_keyring_urls(series: &str) -> Result<Vec<String>, Box<dyn Error
                 Ok(urls)
             }
         } else {
-            let series_num = get_debian_series_number(series).await?.unwrap();
+            let series_num = get_debian_series_number(series)
+                .await?
+                .ok_or_else(|| {
+                    format!(
+                        "Could not determine the version number for Debian series '{series}'. \
+                         Make sure the 'distro-info' package is installed, which provides the \
+                         series CSV data used to map series names to version numbers."
+                    )
+                })?;
             // Replace {series_num} placeholder with the actual series number
             Ok(vec![
                 dist_data
@@ -297,9 +340,23 @@ pub async fn get_components(
 
 /// Map a Debian series name to its version number
 pub async fn get_debian_series_number(series: &str) -> Result<Option<String>, Box<dyn Error>> {
-    let series_info = &DATA.dist.get("debian").unwrap().series;
+    let dist_data = DATA.dist.get("debian").ok_or_else(|| {
+        format!(
+            "Debian distribution data is missing from the built-in configuration. \
+             This is a bug; supported distributions are: {}.",
+            supported_dists().join(", ")
+        )
+    })?;
+    let series_info = &dist_data.series;
     let content = if Path::new(series_info.local.as_str()).exists() {
-        std::fs::read_to_string(series_info.local.as_str())?
+        std::fs::read_to_string(series_info.local.as_str())
+            .map_err(|e| {
+                format!(
+                    "Failed to read Debian series data from '{}': {}. \
+                     The 'distro-info' package provides this file.",
+                    series_info.local, e
+                )
+            })?
     } else {
         reqwest::get(series_info.network.as_str())
             .await?