fix: Parse installation config path more robustly

This adds the `-z`/`--null` and `--name-only` options in the `git`
invocation that tries to obtain the configuration file path
associated with the `git` installation itself. The benefits are:

- Parsing is more reliable for paths containing unusual characters,
  because `-z`/`--null` causes all paths to be output literally.

  Previously, `"` characters were trimmed from the ends, but this
  would not always extract a correct path, because when a path
  contains characters that cause `git` to enclose it in double
  quotes, those characters are usually represented in a symbolic
  form, usually with `\` escapes.

  In some scenarios, such as usually on Windows when the escaped
  character is itself a `\` and not in the leading position, the
  mangled path would be usable, but more often it would not.

- The volume of output is less, because `--name-only` casues values
  not to be included in the output.

- The combination of `-z`/`--null` and `--name-only` makes the
  output format simpler, and the parsing logic is accordingly
  simpler.

`git` has supported the `-z`/`--null` and `--name-only` options
even before support for `--show-origin` was added in Git 2.8.0, so
this change should have no effect on Git version compatibility.

gix-path/src/env/git/mod.rs

@@ -90,7 +90,7 @@ pub(super) static EXE_INFO: Lazy<Option<BString>> = Lazy::new(|| {
             cmd.creation_flags(CREATE_NO_WINDOW);
         }
         // git 2.8.0 and higher support --show-origin.
-        cmd.args(["config", "-l", "--show-origin"])
+        cmd.args(["config", "-lz", "--show-origin", "--name-only"])
             .current_dir(env::temp_dir())
             .stdin(Stdio::null())
             .stderr(Stdio::null());
@@ -138,8 +138,8 @@ pub(super) fn install_config_path() -> Option<&'static BStr> {
 
 fn first_file_from_config_with_origin(source: &BStr) -> Option<&BStr> {
     let file = source.strip_prefix(b"file:")?;
-    let end_pos = file.find_byte(b'\t')?;
-    file[..end_pos].trim_with(|c| c == '"').as_bstr().into()
+    let end_pos = file.find_byte(b'\0')?;
+    file[..end_pos].as_bstr().into()
 }
 
 /// Given `config_path` as obtained from `install_config_path()`, return the path of the git installation base.

gix-path/src/env/git/tests.rs

@@ -17,12 +17,15 @@ fn config_to_base_path() {
 
 #[test]
 fn first_file_from_config_with_origin() {
-    let macos = "file:/Applications/Xcode.app/Contents/Developer/usr/share/git-core/gitconfig	credential.helper=osxkeychain\nfile:/Users/byron/.gitconfig	push.default=simple\n";
+    let macos =
+        "file:/Applications/Xcode.app/Contents/Developer/usr/share/git-core/gitconfig\0credential.helper\0file:/Users/byron/.gitconfig\0push.default\0";
     let win_msys =
-        "file:C:/git-sdk-64/etc/gitconfig	core.symlinks=false\r\nfile:C:/git-sdk-64/etc/gitconfig	core.autocrlf=true";
-    let win_cmd = "file:C:/Program Files/Git/etc/gitconfig	diff.astextplain.textconv=astextplain\r\nfile:C:/Program Files/Git/etc/gitconfig	filter.lfs.clean=gix-lfs clean -- %f\r\n";
-    let win_msys_old = "file:\"C:\\ProgramData/Git/config\"	diff.astextplain.textconv=astextplain\r\nfile:\"C:\\ProgramData/Git/config\"	filter.lfs.clean=git-lfs clean -- %f\r\n";
-    let linux = "file:/home/parallels/.gitconfig	core.excludesfile=~/.gitignore\n";
+        "file:C:/git-sdk-64/etc/gitconfig\0core.symlinks\0file:C:/git-sdk-64/etc/gitconfig\0core.autocrlf\0";
+    let win_cmd =
+        "file:C:/Program Files/Git/etc/gitconfig\0diff.astextplain.textconv\0file:C:/Program Files/Git/etc/gitconfig\0filter.lfs.clean\0";
+    let win_msys_old =
+        "file:C:\\ProgramData/Git/config\0diff.astextplain.textconv\0file:C:\\ProgramData/Git/config\0filter.lfs.clean\0";
+    let linux = "file:/home/parallels/.gitconfig\0core.excludesfile\0";
     let bogus = "something unexpected";
     let empty = "";