Merge branch 'lt/core-optim'

* lt/core-optim:
  Optimize symlink/directory detection
  Avoid some unnecessary lstat() calls
  is_racy_timestamp(): do not check timestamp for gitlinks
  diff-lib.c: rename check_work_tree_entity()
  diff: a submodule not checked out is not modified
  Add t7506 to test submodule related functions for git-status
  t4027: test diff for submodule with empty directory
  Make git-add behave more sensibly in a case-insensitive environment
  When adding files to the index, add support for case-independent matches
  Make unpack-tree update removed files before any updated files
  Make branch merging aware of underlying case-insensitive filsystems
  Add 'core.ignorecase' option
  Make hash_name_lookup able to do case-independent lookups
  Make "index_name_exists()" return the cache_entry it found
  Move name hashing functions into a file of its own
  Make unpack_trees_options bit flags actual bitfields

1 files changed, 49 insertions, 33 deletions

diff --git a/symlinks.c b/symlinks.c
index be9ace6c04..5a5e781a15 100644
--- a/symlinks.c
+++ b/symlinks.c
@@ -1,48 +1,64 @@
 #include "cache.h"
 
-int has_symlink_leading_path(const char *name, char *last_symlink)
-{
+struct pathname {
+	int len;
 	char path[PATH_MAX];
-	const char *sp, *ep;
-	char *dp;
-
-	sp = name;
-	dp = path;
-
-	if (last_symlink && *last_symlink) {
-		size_t last_len = strlen(last_symlink);
-		size_t len = strlen(name);
-		if (last_len < len &&
-		    !strncmp(name, last_symlink, last_len) &&
-		    name[last_len] == '/')
-			return 1;
-		*last_symlink = '\0';
+};
+
+/* Return matching pathname prefix length, or zero if not matching */
+static inline int match_pathname(int len, const char *name, struct pathname *match)
+{
+	int match_len = match->len;
+	return (len > match_len &&
+		name[match_len] == '/' &&
+		!memcmp(name, match->path, match_len)) ? match_len : 0;
+}
+
+static inline void set_pathname(int len, const char *name, struct pathname *match)
+{
+	if (len < PATH_MAX) {
+		match->len = len;
+		memcpy(match->path, name, len);
+		match->path[len] = 0;
 	}
+}
+
+int has_symlink_leading_path(int len, const char *name)
+{
+	static struct pathname link, nonlink;
+	char path[PATH_MAX];
+	struct stat st;
+	char *sp;
+	int known_dir;
 
-	while (1) {
-		size_t len;
-		struct stat st;
+	/*
+	 * See if the last known symlink cache matches.
+	 */
+	if (match_pathname(len, name, &link))
+		return 1;
 
-		ep = strchr(sp, '/');
-		if (!ep)
-			break;
-		len = ep - sp;
-		if (PATH_MAX <= dp + len - path + 2)
-			return 0; /* new name is longer than that??? */
-		memcpy(dp, sp, len);
-		dp[len] = 0;
+	/*
+	 * Get rid of the last known directory part
+	 */
+	known_dir = match_pathname(len, name, &nonlink);
+
+	while ((sp = strchr(name + known_dir + 1, '/')) != NULL) {
+		int thislen = sp - name ;
+		memcpy(path, name, thislen);
+		path[thislen] = 0;
 
 		if (lstat(path, &st))
 			return 0;
+		if (S_ISDIR(st.st_mode)) {
+			set_pathname(thislen, path, &nonlink);
+			known_dir = thislen;
+			continue;
+		}
 		if (S_ISLNK(st.st_mode)) {
-			if (last_symlink)
-				strcpy(last_symlink, path);
+			set_pathname(thislen, path, &link);
 			return 1;
 		}
-
-		dp[len++] = '/';
-		dp = dp + len;
-		sp = ep + 1;
+		break;
 	}
 	return 0;
 }