fix: no description causes segfault

apt-pkg-c/package.h

@@ -175,9 +175,13 @@ inline bool Version::is_downloadable() const noexcept { return ptr->Downloadable
 inline bool Version::is_installed() const noexcept { return ptr->ParentPkg().CurrentVer() == *ptr; }
 
 // This is for backend records lookups. You can also get package files from here.
-inline DescriptionFile Version::unsafe_description_file() const noexcept {
-	return DescriptionFile{
-		std::make_unique<DescFileIterator>(ptr->TranslatedDescription().FileList())};
+inline DescriptionFile Version::unsafe_description_file() const {
+	auto desc_file = ptr->TranslatedDescription();
+	// Must check if DescFileIterator is null first.
+	// See https://gitlab.com/volian/rust-apt/-/issues/28
+	if (desc_file.end()) { throw std::runtime_error("DescFile doesn't exist"); }
+
+	return DescriptionFile{std::make_unique<DescFileIterator>(desc_file.FileList())};
 }
 
 // You go through here to get the package files.

src/raw/package.rs

@@ -166,7 +166,7 @@ pub mod raw {
 
 		// This is for backend records lookups.
 		// You can also get package files from here.
-		pub fn unsafe_description_file(self: &Version) -> DescriptionFile;
+		pub fn unsafe_description_file(self: &Version) -> Result<DescriptionFile>;
 
 		// You go through here to get the package files.
 		pub fn unsafe_version_file(self: &Version) -> VersionFile;
@@ -343,7 +343,7 @@ impl raw::Version {
 	pub fn version_files(&self) -> Option<RawVersionFile> { self.unsafe_version_file().make_safe() }
 
 	pub fn description_files(&self) -> Option<RawDescriptionFile> {
-		self.unsafe_description_file().make_safe()
+		self.unsafe_description_file().ok()?.make_safe()
 	}
 }
 

tests/cache.rs

@@ -135,6 +135,19 @@ mod cache {
 		dbg!(cand_desc);
 	}
 
+	// This should not segfault, but has in the past.
+	// See https://gitlab.com/volian/rust-apt/-/issues/28
+	#[test]
+	fn no_description() {
+		let cache = new_cache!(&["tests/files/cache/no-description_0.0.1.deb"]).unwrap();
+
+		let pkg = cache.get("no-description").unwrap();
+		let cand = pkg.candidate().unwrap();
+		if let Some(desc) = cand.description() {
+			println!("{desc}");
+		}
+	}
+
 	#[test]
 	fn version_uris() {
 		let cache = new_cache!().unwrap();

tests/files/cache/no-description_0.0.1/DEBIAN/control

@@ -0,0 +1,7 @@
+Package: no-description
+Version: 0.0.1
+Section: base
+Priority: optional
+Architecture: all
+Depends: htop, python3-rich
+Maintainer: Your Name <[email protected]>