Minor fixes

docs/GIT-BEHAVIOUR.md

@@ -230,6 +230,7 @@ the same results.
 | `gitdir:$S/work/` | yes (trailing `/` means `/**`) |
 | `gitdir:$S/work` | no |
 | `gitdir:$S/work/**` | yes |
+| `gitdir:$S/***`, `gitdir:$S/***/.git`, `gitdir:$S/work/****/proj/` | yes: a segment of three or more stars is `**`, matching any number of directories, zero included; mixed with other characters (`$S/***proj/`, `$S/w***/.git`) the stars are a single `*` *(2.47.3, 2.56.0)* |
 | `gitdir:$S/work/proj/.git` | yes |
 | `gitdir:work/` | yes (relative pattern gets an implicit `**/` prefix) |
 | `gitdir/i:<upper-cased path>/WORK/` | yes |

env.go

@@ -81,7 +81,8 @@ type Env struct {
 	// GlobalConfig lists the global configuration files, read in order.
 	// Writes go to the last one that exists, or to the last one if none
 	// exists: for git's [XDG file, ~/.gitconfig] this picks ~/.gitconfig
-	// unless only the XDG file exists.
+	// unless only the XDG file exists. A symbolic link exists if its target
+	// does.
 	GlobalConfig []string
 
 	// Command holds the values given on the command line (git -c,
@@ -379,7 +380,9 @@ func (e Env) writeTarget(s Scope) (string, Scope, error) {
 			return "", 0, ErrNoScope
 		}
 		for _, v := range slices.Backward(e.GlobalConfig) {
-			if _, err := os.Lstat(v); err == nil {
+			// A link to nothing does not exist, as for git: the write
+			// goes to the other file, not to the link's target.
+			if _, err := os.Stat(v); err == nil {
 				return v, s, nil
 			}
 		}

env_test.go

@@ -615,6 +615,12 @@ func TestEnvIncludeIf(t *testing.T) {
 			{"gitdir:" + s + "/work", false},
 			{"gitdir:" + s + "/work/**", true},
 			{"gitdir:" + s + "/w*/", true},
+			{"gitdir:" + s + "/***", true},
+			{"gitdir:" + s + "/***/.git", true},
+			{"gitdir:" + s + "/work/****/proj/", true},
+			{"gitdir:" + s + "/***/***/***/.git", true},
+			{"gitdir:" + s + "/***proj/", false},
+			{"gitdir:" + s + "/w***/.git", false},
 			{"gitdir:" + s + "/work/proj/.git", true},
 			{"gitdir:" + s + "/work/proj/.git/", false},
 			{"gitdir:" + s + "/work/proj", false},
@@ -1111,6 +1117,32 @@ func TestEnvWritePath(t *testing.T) {
 	}
 }
 
+func TestEnvWritePathDanglingLink(t *testing.T) {
+	// A ~/.gitconfig that links to nothing does not exist: with an XDG
+	// file, git writes there; without, through the link (git 2.56).
+	dir := tempDir(t)
+	xdg := filepath.Join(dir, "xdg")
+	home := filepath.Join(dir, "home")
+	symlink(t, filepath.Join(dir, "dotfiles", "gitconfig"), home)
+	env := gitconfig.Env{GlobalConfig: []string{xdg, home}}
+
+	got, err := env.WritePath(gitconfig.ScopeGlobal)
+	require.NoError(t, err)
+	assert.Equal(t, home, got)
+
+	writeFile(t, xdg, "")
+	got, err = env.WritePath(gitconfig.ScopeGlobal)
+	require.NoError(t, err)
+	assert.Equal(t, xdg, got)
+
+	require.NoError(t, env.UpdateScope(gitconfig.ScopeGlobal, func(f *gitconfig.File) error {
+		return f.Set("a.k", "v")
+	}))
+	_, err = os.Stat(filepath.Join(dir, "dotfiles"))
+	assert.ErrorIs(t, err, fs.ErrNotExist)
+	assert.Equal(t, "[a]\n\tk = v\n", readFile(t, xdg))
+}
+
 // unsetenv unsets an environment variable for the duration of the test.
 func unsetenv(t *testing.T, key string) {
 	t.Setenv(key, "")

glob.go

@@ -5,7 +5,7 @@ import "strings"
 // The patterns of includeIf "gitdir:" and "onbranch:" are matched as paths:
 // '*' and '?' do not match '/', "**/" at the start of a segment matches any
 // number of directories, "**" ending the pattern after a '/' (or alone)
-// matches anything, "[...]" is a class of characters ("[!...]" or "[^...]"
+// matches anything, a segment of more stars ("***") is "**", "[...]" is a class of characters ("[!...]" or "[^...]"
 // negated, "a-z" a range, "[:digit:]" a named class) and '\' quotes the
 // next character. A pattern with an unterminated class, or an unknown class
 // name, matches nothing, as in git.
@@ -42,18 +42,20 @@ func compileGlob(p string) ([]globToken, bool) {
 	for i := 0; i < len(p); {
 		c := p[i]
 		switch {
-		case c == '*' && segStart && i+1 < len(p) && p[i+1] == '*' && (i+2 == len(p) || p[i+2] == '/'):
-			if i+2 == len(p) {
+		case c == '*' && segStart && starSegment(p[i:]) > 1:
+			// As in git, a segment of three or more stars is "**" too.
+			i += starSegment(p[i:])
+			if i == len(p) {
 				toks = append(toks, globToken{kind: globAll})
-				i += 2
 				continue
 			}
 			if len(toks) == 0 || toks[len(toks)-1].kind != globDirs {
 				// "**/**/" is "**/".
 				toks = append(toks, globToken{kind: globDirs})
 			}
-			i += 3
-			continue // still at the start of a segment
+			// Past the '/': still at the start of a segment.
+			i++
+			continue
 		case c == '*':
 			for i < len(p) && p[i] == '*' {
 				i++
@@ -85,6 +87,19 @@ func compileGlob(p string) ([]globToken, bool) {
 	return toks, true
 }
 
+// starSegment returns the number of stars p starts with, if they make up a
+// whole segment (the end of p or a '/' follows), 0 otherwise.
+func starSegment(p string) int {
+	n := 0
+	for n < len(p) && p[n] == '*' {
+		n++
+	}
+	if n < len(p) && p[n] != '/' {
+		return 0
+	}
+	return n
+}
+
 // compileClass compiles the class starting at p[start], and returns the
 // index past its end, or false if it is not terminated or names an unknown
 // class. lastColon is the index of the last ":]" in p.

interop_test.go

@@ -768,6 +768,13 @@ var gitScenarios = []gitScenario{
 				"gitdir:" + s + "/work",
 				"gitdir:" + s + "/work/**",
 				"gitdir:" + s + "/w*/",
+				"gitdir:" + s + "/***",
+				"gitdir:" + s + "/***/.git",
+				"gitdir:" + s + "/work/****/proj/",
+				"gitdir:" + s + "/***/***/***/.git",
+				"gitdir:" + s + "/***proj/",
+				"gitdir:" + s + "/w***/.git",
+				"onbranch:***",
 				"gitdir:" + s + "/work/proj/.git",
 				"gitdir:" + s + "/work/proj/.git/",
 				"gitdir:work/",