Add GnuDebuglink

Closes #260

src/gnu_debuglink.rs

@@ -0,0 +1,80 @@
+use reader::{Reader, ReaderOffset};
+use endianity::{EndianBuf, Endianity};
+use parser::Result;
+use Section;
+
+/// The `GnuDebuglink` struct represents the external debuginfo information
+/// found in the `.gnu_debuglink` section.
+#[derive(Debug, Clone, Copy)]
+pub struct GnuDebuglink<R: Reader> {
+    gnu_debuglink_section: R,
+}
+
+impl<'input, Endian> GnuDebuglink<EndianBuf<'input, Endian>>
+where
+    Endian: Endianity
+{
+    /// Constructs a new `GnuDebuglink` instance from the data in the
+    /// `.gnu_debuglink` section.
+    ///
+    /// It is the caller's responsibility to read the `.gnu_debuglink` section
+    /// and present it as a `&[u8]` slice. This means using some ELF loader on
+    /// Linux, a Mach-O loader on OSX, etc.
+    ///
+    /// ```
+    /// use gimli::{GnuDebuglink, LittleEndian};
+    ///
+    /// # let buf = [0x00, 0x01, 0x02, 0x03];
+    /// # let read_gnu_debuglink_section_somehow = || &buf;
+    /// let gnu_debuglink = GnuDebuglink::new(read_gnu_debuglink_section_somehow(), LittleEndian);
+    /// ```
+    pub fn new(gnu_debuglink_section: &'input [u8], endian: Endian) -> Self {
+        Self::from(EndianBuf::new(gnu_debuglink_section, endian))
+    }
+}
+
+impl<R: Reader> GnuDebuglink<R> {
+    /// Returns the filename of the debug information file.
+    pub fn filename(&self) -> Result<R> {
+        self.gnu_debuglink_section.clone().read_null_terminated_slice()
+    }
+
+    /// Returns the CRC32 checksum of the debug information file.
+    pub fn crc32(&self) -> Result<u32> {
+        let mut section = self.gnu_debuglink_section.clone();
+        let base = section.len() - ReaderOffset::from_u32(4);
+        section.skip(base)?;
+        section.read_u32()
+    }
+}
+
+impl<R: Reader> Section<R> for GnuDebuglink<R> {
+    fn section_name() -> &'static str {
+        ".gnu_debuglink"
+    }
+}
+
+impl<R: Reader> From<R> for GnuDebuglink<R> {
+    fn from(gnu_debuglink_section: R) -> Self {
+        GnuDebuglink {
+            gnu_debuglink_section,
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use endianity::LittleEndian;
+
+    #[test]
+    fn reference() {
+        let section = [
+            0x6c, 0x69, 0x62, 0x74, 0x65, 0x73, 0x74, 0x2e, 0x64, 0x65, 0x62,
+            0x75, 0x67, 0x00, 0x00, 0x00, 0x52, 0xa7, 0xfd, 0x0a];
+        let gnu_debuglink = GnuDebuglink::new(&section, LittleEndian);
+
+        assert_eq!(gnu_debuglink.filename().unwrap().buf(), "libtest.debug".as_bytes());
+        assert_eq!(gnu_debuglink.crc32().unwrap(), 0x0afda752);
+    }
+}

src/lib.rs

@@ -173,6 +173,9 @@ pub use constants::*;
 mod endianity;
 pub use endianity::{BigEndian, EndianBuf, Endianity, LittleEndian, NativeEndian, RunTimeEndian};
 
+mod gnu_debuglink;
+pub use gnu_debuglink::GnuDebuglink;
+
 pub mod leb128;
 
 mod parser;