pxar: Include symlink target in DirectoryEntry

This allows to read the target path of a symbolic link in the
Decoder::read_directory_entry() function and stores it in the DirectoryEntry.
By this the Decoder::read_link() function becomes obsolete and is therefore
removed.

Signed-off-by: Christian Ebner <c.ebner@proxmox.com>

src/pxar/decoder.rs

@@ -31,6 +31,8 @@ pub struct DirectoryEntry {
     pub xattr: PxarAttributes,
     /// Payload size
     pub size: u64,
+    /// Target path for symbolic links
+    pub target: Option<PathBuf>,
 }
 
 /// Trait to create ReadSeek Decoder trait objects.
@@ -78,6 +80,7 @@ impl Decoder {
             entry,
             xattr,
             size,
+            target: None,
         })
     }
 
@@ -135,6 +138,10 @@ impl Decoder {
             PXAR_PAYLOAD => header.size - HEADER_SIZE,
             _ => 0,
         };
+        let target = match header.htype {
+            PXAR_SYMLINK => Some(self.inner.read_link(header.size)?),
+            _ => None,
+        };
 
         Ok(DirectoryEntry {
             start: entry_start,
@@ -143,6 +150,7 @@ impl Decoder {
             entry,
             xattr,
             size,
+            target,
         })
     }
 
@@ -370,26 +378,4 @@ impl Decoder {
 
         Ok(data)
     }
-
-    /// Read the target of a hardlink in the archive.
-    pub fn read_link(&mut self, offset: u64) -> Result<(PathBuf, PxarEntry), Error> {
-        self.seek(SeekFrom::Start(offset))?;
-        let mut header: PxarHeader = self.inner.read_item()?;
-        if header.htype != PXAR_FILENAME {
-            bail!("Expected PXAR_FILENAME, encountered 0x{:x?}", header.htype);
-        }
-        let _filename = self.inner.read_filename(header.size)?;
-
-        header = self.inner.read_item()?;
-        check_ca_header::<PxarEntry>(&header, PXAR_ENTRY)?;
-        let entry: PxarEntry = self.inner.read_item()?;
-
-        header = self.inner.read_item()?;
-        if header.htype != PXAR_SYMLINK {
-            bail!("Expected PXAR_SYMLINK, encountered 0x{:x?}", header.htype);
-        }
-        let target = self.inner.read_link(header.size)?;
-
-        Ok((target, entry))
-    }
 }

src/pxar/fuse.rs

@@ -7,7 +7,7 @@ use std::convert::TryFrom;
 use std::ffi::{CStr, CString, OsStr};
 use std::fs::File;
 use std::io::BufReader;
-use std::os::unix::ffi::{OsStrExt, OsStringExt};
+use std::os::unix::ffi::OsStrExt;
 use std::path::Path;
 use std::sync::Mutex;
 
@@ -445,11 +445,8 @@ impl Session  {
 
     extern "C" fn readlink(req: Request, inode: u64) {
         Self::run_in_context(req, inode, |ctx| {
-            let (target, _) = ctx
+            let target = ctx.entry.target.as_ref().ok_or_else(|| libc::EIO)?;
-                .decoder
+            let link = CString::new(target.as_os_str().as_bytes()).map_err(|_| libc::EIO)?;
-                .read_link(ctx.ino_offset)
-                .map_err(|_| libc::EIO)?;
-            let link = CString::new(target.into_os_string().into_vec()).map_err(|_| libc::EIO)?;
             let _ret = unsafe { fuse_reply_readlink(req, link.as_ptr()) };
 
             Ok(())