image: substantial API cleanup/rework

Try to make the handling of directories a bit less ad-hoc.  Add lots of
docs.

Signed-off-by: Allison Karlitskaya <[email protected]>

Author: allisonkarlitskaya

src/dumpfile.rs

@@ -226,7 +226,7 @@ impl<'a, W: Write> DumpfileWriter<'a, W> {
     fn write_dir(&mut self, path: &mut PathBuf, dir: &Directory) -> Result<()> {
         // nlink is 2 + number of subdirectories
         // this is also true for the root dir since '..' is another self-ref
-        let nlink = dir.entries.values().fold(2, |count, inode| {
+        let nlink = dir.inodes().fold(2, |count, inode| {
             count + {
                 match inode {
                     Inode::Directory(..) => 1,
@@ -239,8 +239,8 @@ impl<'a, W: Write> DumpfileWriter<'a, W> {
             write_directory(fmt, path, &dir.stat, nlink)
         })?;
 
-        for (name, inode) in &dir.entries {
-            path.push(name.as_ref());
+        for (name, inode) in dir.sorted_entries() {
+            path.push(name);
 
             match inode {
                 Inode::Directory(ref dir) => {

src/erofs/writer.rs

@@ -485,7 +485,7 @@ impl<'a> InodeCollector<'a> {
 
         let mut entries = vec![];
 
-        for (name, inode) in &dir.entries {
+        for (name, inode) in dir.sorted_entries() {
             let child = match inode {
                 image::Inode::Directory(dir) => self.collect_dir(dir, me),
                 image::Inode::Leaf(leaf) => self.collect_leaf(leaf),

src/fs.rs

@@ -112,7 +112,7 @@ fn write_leaf(leaf: &Leaf, dirfd: &OwnedFd, name: &OsStr, repo: &Repository) ->
 }
 
 fn write_directory_contents(dir: &Directory, fd: &OwnedFd, repo: &Repository) -> Result<()> {
-    for (name, inode) in &dir.entries {
+    for (name, inode) in dir.entries() {
         match inode {
             Inode::Directory(ref dir) => write_directory(dir, fd, name, repo),
             Inode::Leaf(ref leaf) => write_leaf(leaf, fd, name, repo),