globset: fix bug where trailing . in file name was incorrectly handled

I'm not sure why I did this, but I think I was trying to imitate the
contract of [`std::path::Path::file_name`]:

> Returns None if the path terminates in `..`.

But the status quo clearly did not implement this. And as a result, if
you have a glob that ends in a `.`, it was instead treated as the empty
string (which only matches the empty string).

We fix this by implementing the semantic from the standard library
correctly.

Fixes #2990

[`std::path::Path::file_name`]: https://doc.rust-lang.org/std/path/struct.Path.html#method.file_name

CHANGELOG.md

@@ -23,6 +23,8 @@ Bug fixes:
   Ignore a UTF-8 BOM marker at the start of `.gitignore` (and similar files).
 * [BUG #2944](https://github.com/BurntSushi/ripgrep/pull/2944):
   Fix a bug where the "bytes searched" in `--stats` output could be incorrect.
+* [BUG #2990](https://github.com/BurntSushi/ripgrep/issues/2990):
+  Fix a bug where ripgrep would mishandle globs that ended with a `.`.
 
 Feature enhancements:
 

crates/globset/src/pathutil.rs

@@ -4,21 +4,25 @@ use bstr::{ByteSlice, ByteVec};
 
 /// The final component of the path, if it is a normal file.
 ///
-/// If the path terminates in `.`, `..`, or consists solely of a root of
-/// prefix, file_name will return None.
+/// If the path terminates in `..`, or consists solely of a root of prefix,
+/// file_name will return `None`.
 pub(crate) fn file_name<'a>(path: &Cow<'a, [u8]>) -> Option<Cow<'a, [u8]>> {
-    if path.last_byte().map_or(true, |b| b == b'.') {
+    if path.is_empty() {
         return None;
     }
     let last_slash = path.rfind_byte(b'/').map(|i| i + 1).unwrap_or(0);
-    Some(match *path {
+    let got = match *path {
         Cow::Borrowed(path) => Cow::Borrowed(&path[last_slash..]),
         Cow::Owned(ref path) => {
             let mut path = path.clone();
             path.drain_bytes(..last_slash);
             Cow::Owned(path)
         }
-    })
+    };
+    if got == &b".."[..] {
+        return None;
+    }
+    Some(got)
 }
 
 /// Return a file extension given a path's file name.

tests/regression.rs

@@ -1461,3 +1461,18 @@ rgtest!(r2944_incorrect_bytes_searched, |dir: Dir, mut cmd: TestCommand| {
     let got = cmd.args(&["--stats", "-m2", "foo", "."]).stdout();
     assert!(got.contains("10 bytes searched\n"));
 });
+
+// See: https://github.com/BurntSushi/ripgrep/issues/2990
+rgtest!(r2990_trip_over_trailing_dot, |dir: Dir, _cmd: TestCommand| {
+    dir.create_dir("asdf");
+    dir.create_dir("asdf.");
+    dir.create("asdf/foo", "");
+    dir.create("asdf./foo", "");
+
+    let got = dir.command().args(&["--files", "-g", "!asdf/"]).stdout();
+    eqnice!("asdf./foo\n", got);
+
+    // This used to ignore the glob given and included `asdf./foo` in output.
+    let got = dir.command().args(&["--files", "-g", "!asdf./"]).stdout();
+    eqnice!("asdf/foo\n", got);
+});