longest_ancestor_length(): take a string_list argument for prefixes

Change longest_ancestor_length() to take the prefixes argument as a
string_list rather than as a colon-separated string.  This will make
it easier for the caller to alter the entries before calling
longest_ancestor_length().

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Jeff King <peff@peff.net>

cache.h

@@ -718,7 +718,7 @@ const char *real_path_if_valid(const char *path);
 const char *absolute_path(const char *path);
 const char *relative_path(const char *abs, const char *base);
 int normalize_path_copy(char *dst, const char *src);
-int longest_ancestor_length(const char *path, const char *prefix_list);
+int longest_ancestor_length(const char *path, struct string_list *prefixes);
 char *strip_path_suffix(const char *path, const char *suffix);
 int daemon_avoid_alias(const char *path);
 int offset_1st_component(const char *path);

path.c

@@ -570,30 +570,27 @@ int normalize_path_copy(char *dst, const char *src)
 
 /*
  * path = Canonical absolute path
- * prefix_list = Colon-separated list of absolute paths
+ * prefixes = string_list containing absolute paths
  *
- * Determines, for each path in prefix_list, whether the "prefix" really
+ * Determines, for each path in prefixes, whether the "prefix" really
  * is an ancestor directory of path.  Returns the length of the longest
  * ancestor directory, excluding any trailing slashes, or -1 if no prefix
- * is an ancestor.  (Note that this means 0 is returned if prefix_list is
- * "/".) "/foo" is not considered an ancestor of "/foobar".  Directories
+ * is an ancestor.  (Note that this means 0 is returned if prefixes is
+ * ["/"].) "/foo" is not considered an ancestor of "/foobar".  Directories
  * are not considered to be their own ancestors.  path must be in a
  * canonical form: empty components, or "." or ".." components are not
- * allowed.  prefix_list may be null, which is like "".
+ * allowed.  Empty strings in prefixes are ignored.
  */
-int longest_ancestor_length(const char *path, const char *prefix_list)
+int longest_ancestor_length(const char *path, struct string_list *prefixes)
 {
-	struct string_list prefixes = STRING_LIST_INIT_DUP;
 	char buf[PATH_MAX+1];
 	int i, max_len = -1;
 
-	if (prefix_list == NULL || !strcmp(path, "/"))
+	if (!strcmp(path, "/"))
 		return -1;
 
-	string_list_split(&prefixes, prefix_list, PATH_SEP, -1);
-
-	for (i = 0; i < prefixes.nr; i++) {
-		const char *ceil = prefixes.items[i].string;
+	for (i = 0; i < prefixes->nr; i++) {
+		const char *ceil = prefixes->items[i].string;
 		int len = strlen(ceil);
 
 		if (len == 0 || len > PATH_MAX || !is_absolute_path(ceil))
@@ -611,7 +608,6 @@ int longest_ancestor_length(const char *path, const char *prefix_list)
 		}
 	}
 
-	string_list_clear(&prefixes, 0);
 	return max_len;
 }
 

setup.c

@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "dir.h"
+#include "string-list.h"
 
 static int inside_git_dir = -1;
 static int inside_work_tree = -1;
@@ -627,10 +628,11 @@ static dev_t get_device_or_die(const char *path, const char *prefix, int prefix_
 static const char *setup_git_directory_gently_1(int *nongit_ok)
 {
 	const char *env_ceiling_dirs = getenv(CEILING_DIRECTORIES_ENVIRONMENT);
+	struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
 	static char cwd[PATH_MAX+1];
 	const char *gitdirenv, *ret;
 	char *gitfile;
-	int len, offset, offset_parent, ceil_offset;
+	int len, offset, offset_parent, ceil_offset = -1;
 	dev_t current_device = 0;
 	int one_filesystem = 1;
 
@@ -655,7 +657,12 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
 	if (gitdirenv)
 		return setup_explicit_git_dir(gitdirenv, cwd, len, nongit_ok);
 
-	ceil_offset = longest_ancestor_length(cwd, env_ceiling_dirs);
+	if (env_ceiling_dirs) {
+		string_list_split(&ceiling_dirs, env_ceiling_dirs, PATH_SEP, -1);
+		ceil_offset = longest_ancestor_length(cwd, &ceiling_dirs);
+		string_list_clear(&ceiling_dirs, 0);
+	}
+
 	if (ceil_offset < 0 && has_dos_drive_prefix(cwd))
 		ceil_offset = 1;
 

test-path-utils.c

@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "string-list.h"
 
 int main(int argc, char **argv)
 {
@@ -30,7 +31,12 @@ int main(int argc, char **argv)
 	}
 
 	if (argc == 4 && !strcmp(argv[1], "longest_ancestor_length")) {
-		int len = longest_ancestor_length(argv[2], argv[3]);
+		int len;
+		struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
+
+		string_list_split(&ceiling_dirs, argv[3], PATH_SEP, -1);
+		len = longest_ancestor_length(argv[2], &ceiling_dirs);
+		string_list_clear(&ceiling_dirs, 0);
 		printf("%d\n", len);
 		return 0;
 	}