From 867f72bf434a05b9eadf851a81564be5173fbba5 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 9 Jul 2009 13:23:59 -0700 Subject: [PATCH] Prepare symlink caching for thread-safety This doesn't actually change the external interfaces, so they are still thread-unsafe, but it makes the code internally pass a pointer to a local 'struct cache_def' around, so that the core code can be made thread-safe. The threaded index preloading will want to verify that the paths leading up to a pathname are all real directories. Signed-off-by: Linus Torvalds Signed-off-by: Junio C Hamano --- symlinks.c | 75 +++++++++++++++++++++++++++++------------------------- 1 file changed, 40 insertions(+), 35 deletions(-) diff --git a/symlinks.c b/symlinks.c index 8dcd63261..08ad35330 100644 --- a/symlinks.c +++ b/symlinks.c @@ -38,13 +38,13 @@ static struct cache_def { int flags; int track_flags; int prefix_len_stat_func; -} cache; +} default_cache; -static inline void reset_lstat_cache(void) +static inline void reset_lstat_cache(struct cache_def *cache) { - cache.path[0] = '\0'; - cache.len = 0; - cache.flags = 0; + cache->path[0] = '\0'; + cache->len = 0; + cache->flags = 0; /* * The track_flags and prefix_len_stat_func members is only * set by the safeguard rule inside lstat_cache() @@ -70,23 +70,23 @@ static inline void reset_lstat_cache(void) * of the prefix, where the cache should use the stat() function * instead of the lstat() function to test each path component. */ -static int lstat_cache(const char *name, int len, +static int lstat_cache(struct cache_def *cache, const char *name, int len, int track_flags, int prefix_len_stat_func) { int match_len, last_slash, last_slash_dir, previous_slash; int match_flags, ret_flags, save_flags, max_len, ret; struct stat st; - if (cache.track_flags != track_flags || - cache.prefix_len_stat_func != prefix_len_stat_func) { + if (cache->track_flags != track_flags || + cache->prefix_len_stat_func != prefix_len_stat_func) { /* * As a safeguard rule we clear the cache if the * values of track_flags and/or prefix_len_stat_func * does not match with the last supplied values. */ - reset_lstat_cache(); - cache.track_flags = track_flags; - cache.prefix_len_stat_func = prefix_len_stat_func; + reset_lstat_cache(cache); + cache->track_flags = track_flags; + cache->prefix_len_stat_func = prefix_len_stat_func; match_len = last_slash = 0; } else { /* @@ -94,10 +94,10 @@ static int lstat_cache(const char *name, int len, * the 2 "excluding" path types. */ match_len = last_slash = - longest_path_match(name, len, cache.path, cache.len, + longest_path_match(name, len, cache->path, cache->len, &previous_slash); - match_flags = cache.flags & track_flags & (FL_NOENT|FL_SYMLINK); - if (match_flags && match_len == cache.len) + match_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK); + if (match_flags && match_len == cache->len) return match_flags; /* * If we now have match_len > 0, we would know that @@ -121,18 +121,18 @@ static int lstat_cache(const char *name, int len, max_len = len < PATH_MAX ? len : PATH_MAX; while (match_len < max_len) { do { - cache.path[match_len] = name[match_len]; + cache->path[match_len] = name[match_len]; match_len++; } while (match_len < max_len && name[match_len] != '/'); if (match_len >= max_len && !(track_flags & FL_FULLPATH)) break; last_slash = match_len; - cache.path[last_slash] = '\0'; + cache->path[last_slash] = '\0'; if (last_slash <= prefix_len_stat_func) - ret = stat(cache.path, &st); + ret = stat(cache->path, &st); else - ret = lstat(cache.path, &st); + ret = lstat(cache->path, &st); if (ret) { ret_flags = FL_LSTATERR; @@ -156,9 +156,9 @@ static int lstat_cache(const char *name, int len, */ save_flags = ret_flags & track_flags & (FL_NOENT|FL_SYMLINK); if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) { - cache.path[last_slash] = '\0'; - cache.len = last_slash; - cache.flags = save_flags; + cache->path[last_slash] = '\0'; + cache->len = last_slash; + cache->flags = save_flags; } else if ((track_flags & FL_DIR) && last_slash_dir > 0 && last_slash_dir <= PATH_MAX) { /* @@ -172,11 +172,11 @@ static int lstat_cache(const char *name, int len, * can still cache the path components before the last * one (the found symlink or non-existing component). */ - cache.path[last_slash_dir] = '\0'; - cache.len = last_slash_dir; - cache.flags = FL_DIR; + cache->path[last_slash_dir] = '\0'; + cache->len = last_slash_dir; + cache->flags = FL_DIR; } else { - reset_lstat_cache(); + reset_lstat_cache(cache); } return ret_flags; } @@ -188,16 +188,17 @@ static int lstat_cache(const char *name, int len, void invalidate_lstat_cache(const char *name, int len) { int match_len, previous_slash; + struct cache_def *cache = &default_cache; /* FIXME */ - match_len = longest_path_match(name, len, cache.path, cache.len, + match_len = longest_path_match(name, len, cache->path, cache->len, &previous_slash); if (len == match_len) { - if ((cache.track_flags & FL_DIR) && previous_slash > 0) { - cache.path[previous_slash] = '\0'; - cache.len = previous_slash; - cache.flags = FL_DIR; + if ((cache->track_flags & FL_DIR) && previous_slash > 0) { + cache->path[previous_slash] = '\0'; + cache->len = previous_slash; + cache->flags = FL_DIR; } else { - reset_lstat_cache(); + reset_lstat_cache(cache); } } } @@ -207,7 +208,8 @@ void invalidate_lstat_cache(const char *name, int len) */ void clear_lstat_cache(void) { - reset_lstat_cache(); + struct cache_def *cache = &default_cache; /* FIXME */ + reset_lstat_cache(cache); } #define USE_ONLY_LSTAT 0 @@ -217,7 +219,8 @@ void clear_lstat_cache(void) */ int has_symlink_leading_path(const char *name, int len) { - return lstat_cache(name, len, + struct cache_def *cache = &default_cache; /* FIXME */ + return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK; } @@ -228,7 +231,8 @@ int has_symlink_leading_path(const char *name, int len) */ int has_symlink_or_noent_leading_path(const char *name, int len) { - return lstat_cache(name, len, + struct cache_def *cache = &default_cache; /* FIXME */ + return lstat_cache(cache, name, len, FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT) & (FL_SYMLINK|FL_NOENT); } @@ -242,7 +246,8 @@ int has_symlink_or_noent_leading_path(const char *name, int len) */ int has_dirs_only_path(const char *name, int len, int prefix_len) { - return lstat_cache(name, len, + struct cache_def *cache = &default_cache; /* FIXME */ + return lstat_cache(cache, name, len, FL_DIR|FL_FULLPATH, prefix_len) & FL_DIR; } -- 2.26.2