support for executable bit check (#301)

git-worktree/src/fs.rs

@@ -3,7 +3,7 @@ use std::path::Path;
 /// Common knowledge about the worktree that is needed across most interactions with the work tree
 #[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
 #[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone, Copy)]
-pub struct Context {
+pub struct Capabilities {
     /// If true, the filesystem will store paths as decomposed unicode, i.e. `ä` becomes `"a\u{308}"`, which means that
     /// we have to turn these forms back from decomposed to precomposed unicode before storing it in the index or generally
     /// using it. This also applies to input received from the command-line, so callers may have to be aware of this and
@@ -15,29 +15,50 @@ pub struct Context {
     pub ignore_case: bool,
     /// If true, we assume the the executable bit is honored as part of the files mode. If false, we assume the file system
     /// ignores the executable bit, hence it will be reported as 'off' even though we just tried to set it to be on.
-    pub file_mode: bool,
+    pub executable_bit: bool,
     /// If true, the file system supports symbolic links and we should try to create them. Otherwise symbolic links will be checked
     /// out as files which contain the link as text.
     pub symlink: bool,
 }
 
-impl Context {
+impl Capabilities {
     /// try to determine all values in this context by probing them in the given `git_dir`, which
     /// should be on the file system the git repository is located on.
     /// `git_dir` is a typical git repository, expected to be populated with the typical files like `config`.
     ///
     /// All errors are ignored and interpreted on top of the default for the platform the binary is compiled for.
-    pub fn probe(git_dir: impl AsRef<std::path::Path>) -> Self {
+    pub fn probe(git_dir: impl AsRef<Path>) -> Self {
         let root = git_dir.as_ref();
-        let ctx = Context::default();
-        Context {
+        let ctx = Capabilities::default();
+        Capabilities {
             symlink: Self::probe_symlink(root).unwrap_or(ctx.symlink),
             ignore_case: Self::probe_ignore_case(root).unwrap_or(ctx.ignore_case),
             precompose_unicode: Self::probe_precompose_unicode(root).unwrap_or(ctx.precompose_unicode),
-            ..ctx
+            executable_bit: Self::probe_file_mode(root).unwrap_or(ctx.executable_bit),
         }
     }
 
+    #[cfg(unix)]
+    fn probe_file_mode(root: &Path) -> std::io::Result<bool> {
+        use std::os::unix::fs::{MetadataExt, OpenOptionsExt};
+
+        // test it exactly as we typically create executable files, not using chmod.
+        let test_path = root.join("_test_executable_bit");
+        let res = std::fs::OpenOptions::new()
+            .create_new(true)
+            .write(true)
+            .mode(0o777)
+            .open(&test_path)
+            .and_then(|f| f.metadata().map(|m| m.mode() & 0o100 == 0o100));
+        std::fs::remove_file(test_path)?;
+        res
+    }
+
+    #[cfg(not(unix))]
+    fn probe_file_mode(root: &Path) -> std::io::Result<bool> {
+        Ok(false)
+    }
+
     fn probe_ignore_case(git_dir: &Path) -> std::io::Result<bool> {
         std::fs::metadata(git_dir.join("cOnFiG")).map(|_| true).or_else(|err| {
             if err.kind() == std::io::ErrorKind::NotFound {
@@ -84,36 +105,36 @@ impl Context {
 }
 
 #[cfg(windows)]
-impl Default for Context {
+impl Default for Capabilities {
     fn default() -> Self {
-        Context {
+        Capabilities {
             precompose_unicode: false,
             ignore_case: true,
-            file_mode: false,
+            executable_bit: false,
             symlink: false,
         }
     }
 }
 
 #[cfg(target_os = "macos")]
-impl Default for Context {
+impl Default for Capabilities {
     fn default() -> Self {
-        Context {
+        Capabilities {
             precompose_unicode: true,
             ignore_case: true,
-            file_mode: true,
+            executable_bit: true,
             symlink: true,
         }
     }
 }
 
 #[cfg(all(unix, not(target_os = "macos")))]
-impl Default for Context {
+impl Default for Capabilities {
     fn default() -> Self {
-        Context {
+        Capabilities {
             precompose_unicode: false,
             ignore_case: false,
-            file_mode: true,
+            executable_bit: true,
             symlink: true,
         }
     }

git-worktree/src/index.rs

@@ -7,7 +7,7 @@ pub mod checkout {
     #[derive(Default, Clone, Copy)]
     pub struct Options {
         /// capabilities of the file system
-        pub fs: crate::fs::Context,
+        pub fs: crate::fs::Capabilities,
         /// If true, we assume no file to exist in the target directory, and want exclusive access to it.
         /// This should be enabled when cloning.
         pub destination_is_initially_empty: bool,
@@ -81,7 +81,12 @@ pub(crate) mod entry {
         find: &mut Find,
         root: &std::path::Path,
         index::checkout::Options {
-            fs: crate::fs::Context { symlink, .. },
+            fs:
+                crate::fs::Capabilities {
+                    symlink,
+                    executable_bit,
+                    ..
+                },
             ..
         }: index::checkout::Options,
         buf: &mut Vec<u8>,
@@ -103,20 +108,18 @@ pub(crate) mod entry {
                     path: root.to_path_buf(),
                 })?;
                 let mut options = OpenOptions::new();
-                options.write(true).create_new(true);
+                options.create_new(true).write(true);
                 #[cfg(unix)]
-                if entry.mode == git_index::entry::Mode::FILE_EXECUTABLE {
+                if executable_bit && entry.mode == git_index::entry::Mode::FILE_EXECUTABLE {
                     use std::os::unix::fs::OpenOptionsExt;
                     options.mode(0o777);
                 }
 
-                {
-                    let mut file = options.open(&dest)?;
-                    file.write_all(obj.data)?;
-                    // NOTE: we don't call `file.sync_all()` here knowing that some filesystems don't handle this well.
-                    //       revisit this once there is a bug to fix.
-                }
-                update_fstat(entry, dest.symlink_metadata()?)?;
+                let mut file = options.open(&dest)?;
+                file.write_all(obj.data)?;
+                // NOTE: we don't call `file.sync_all()` here knowing that some filesystems don't handle this well.
+                //       revisit this once there is a bug to fix.
+                update_fstat(entry, file.metadata()?)?;
             }
             git_index::entry::Mode::SYMLINK => {
                 let obj = find(&entry.id, buf).ok_or_else(|| index::checkout::Error::ObjectNotFound {

git-worktree/tests/fs/mod.rs

@@ -2,7 +2,7 @@
 fn from_probing_cwd() {
     let dir = tempfile::tempdir().unwrap();
     std::fs::File::create(dir.path().join("config")).unwrap();
-    let ctx = git_worktree::fs::Context::probe(dir.path());
+    let ctx = git_worktree::fs::Capabilities::probe(dir.path());
     dbg!(ctx);
     let entries: Vec<_> = std::fs::read_dir(dir.path())
         .unwrap()

git-worktree/tests/index/mod.rs

@@ -17,7 +17,7 @@ mod checkout {
     #[test]
     fn allow_symlinks() -> crate::Result {
         let opts = opts_with_symlink(true);
-        if !git_worktree::fs::Context::probe(std::env::current_dir()?.join("..").join(".git")).symlink {
+        if !git_worktree::fs::Capabilities::probe(std::env::current_dir()?.join("..").join(".git")).symlink {
             eprintln!("IGNORING symlink test on file system without symlink support");
             // skip if symlinks aren't supported anyway.
             return Ok(());
@@ -30,7 +30,7 @@ mod checkout {
 
     fn opts_with_symlink(symlink: bool) -> Options {
         index::checkout::Options {
-            fs: git_worktree::fs::Context {
+            fs: git_worktree::fs::Capabilities {
                 symlink,
                 ..Default::default()
             },