consolidate pathspec_prefix and common_prefix

The implementation from pathspec_prefix (slightly modified) replaces the
current common_prefix, because it also respects glob characters.

Based on a patch by Clemens Buchacher.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

dir.c

@@ -34,56 +34,52 @@ int fnmatch_icase(const char *pattern, const char *string, int flags)
 	return fnmatch(pattern, string, flags | (ignore_case ? FNM_CASEFOLD : 0));
 }
 
-static int common_prefix(const char **pathspec)
+size_t common_prefix_len(const char **pathspec)
 {
-	const char *path, *slash, *next;
-	int prefix;
+	const char *n, *first;
+	size_t max = 0;
 
 	if (!pathspec)
-		return 0;
-
-	path = *pathspec;
-	slash = strrchr(path, '/');
-	if (!slash)
-		return 0;
-
-	/*
-	 * The first 'prefix' characters of 'path' are common leading
-	 * path components among the pathspecs we have seen so far,
-	 * including the trailing slash.
-	 */
-	prefix = slash - path + 1;
-	while ((next = *++pathspec) != NULL) {
-		int len, last_matching_slash = -1;
-		for (len = 0; len < prefix && next[len] == path[len]; len++)
-			if (next[len] == '/')
-				last_matching_slash = len;
-		if (len == prefix)
-			continue;
-		if (last_matching_slash < 0)
-			return 0;
-		prefix = last_matching_slash + 1;
+		return max;
+
+	first = *pathspec;
+	while ((n = *pathspec++)) {
+		size_t i, len = 0;
+		for (i = 0; first == n || i < max; i++) {
+			char c = n[i];
+			if (!c || c != first[i] || is_glob_special(c))
+				break;
+			if (c == '/')
+				len = i + 1;
+		}
+		if (first == n || len < max) {
+			max = len;
+			if (!max)
+				break;
+		}
 	}
-	return prefix;
+	return max;
 }
 
 int fill_directory(struct dir_struct *dir, const char **pathspec)
 {
 	const char *path;
-	int len;
+	size_t len;
 
 	/*
 	 * Calculate common prefix for the pathspec, and
 	 * use that to optimize the directory walk
 	 */
-	len = common_prefix(pathspec);
+	len = common_prefix_len(pathspec);
 	path = "";
 
 	if (len)
 		path = xmemdupz(*pathspec, len);
 
 	/* Read the directory and prune it */
 	read_directory(dir, path, len, pathspec);
+	if (*path)
+		free((char *)path);
 	return len;
 }
 

dir.h

@@ -64,6 +64,7 @@ struct dir_struct {
 #define MATCHED_RECURSIVELY 1
 #define MATCHED_FNMATCH 2
 #define MATCHED_EXACTLY 3
+extern size_t common_prefix_len(const char **pathspec);
 extern int match_pathspec(const char **pathspec, const char *name, int namelen, int prefix, char *seen);
 extern int match_pathspec_depth(const struct pathspec *pathspec,
 				const char *name, int namelen,

setup.c

@@ -266,34 +266,9 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
 
 char *pathspec_prefix(const char **pathspec)
 {
-	const char **p, *n, *prev;
-	unsigned long max;
+	size_t len = common_prefix_len(pathspec);
 
-	if (!pathspec)
-		return NULL;
-
-	prev = NULL;
-	max = PATH_MAX;
-	for (p = pathspec; (n = *p) != NULL; p++) {
-		int i, len = 0;
-		for (i = 0; i < max; i++) {
-			char c = n[i];
-			if (prev && prev[i] != c)
-				break;
-			if (!c || c == '*' || c == '?')
-				break;
-			if (c == '/')
-				len = i+1;
-		}
-		prev = n;
-		if (len < max) {
-			max = len;
-			if (!max)
-				break;
-		}
-	}
-
-	return max ? xmemdupz(prev, max) : NULL;
+	return len ? xmemdupz(*pathspec, len) : NULL;
 }
 
 /*