| #include "cache.h" |
| |
| /* |
| * Returns the length (on a path component basis) of the longest |
| * common prefix match of 'name_a' and 'name_b'. |
| */ |
| static int longest_path_match(const char *name_a, int len_a, |
| const char *name_b, int len_b, |
| int *previous_slash) |
| { |
| int max_len, match_len = 0, match_len_prev = 0, i = 0; |
| |
| max_len = len_a < len_b ? len_a : len_b; |
| while (i < max_len && name_a[i] == name_b[i]) { |
| if (name_a[i] == '/') { |
| match_len_prev = match_len; |
| match_len = i; |
| } |
| i++; |
| } |
| /* |
| * Is 'name_b' a substring of 'name_a', the other way around, |
| * or is 'name_a' and 'name_b' the exact same string? |
| */ |
| if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') || |
| (len_a < len_b && name_b[len_a] == '/') || |
| (len_a == len_b))) { |
| match_len_prev = match_len; |
| match_len = i; |
| } |
| *previous_slash = match_len_prev; |
| return match_len; |
| } |
| |
| static struct cache_def default_cache; |
| |
| static inline void reset_lstat_cache(struct cache_def *cache) |
| { |
| 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() |
| */ |
| } |
| |
| #define FL_DIR (1 << 0) |
| #define FL_NOENT (1 << 1) |
| #define FL_SYMLINK (1 << 2) |
| #define FL_LSTATERR (1 << 3) |
| #define FL_ERR (1 << 4) |
| #define FL_FULLPATH (1 << 5) |
| |
| /* |
| * Check if name 'name' of length 'len' has a symlink leading |
| * component, or if the directory exists and is real, or not. |
| * |
| * To speed up the check, some information is allowed to be cached. |
| * This can be indicated by the 'track_flags' argument, which also can |
| * be used to indicate that we should check the full path. |
| * |
| * The 'prefix_len_stat_func' parameter can be used to set the length |
| * 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_matchlen(struct cache_def *cache, |
| const char *name, int len, |
| int *ret_flags, int track_flags, |
| int prefix_len_stat_func) |
| { |
| int match_len, last_slash, last_slash_dir, previous_slash; |
| int save_flags, max_len, ret; |
| struct stat st; |
| |
| 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); |
| cache->track_flags = track_flags; |
| cache->prefix_len_stat_func = prefix_len_stat_func; |
| match_len = last_slash = 0; |
| } else { |
| /* |
| * Check to see if we have a match from the cache for |
| * the 2 "excluding" path types. |
| */ |
| match_len = last_slash = |
| longest_path_match(name, len, cache->path, cache->len, |
| &previous_slash); |
| *ret_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK); |
| |
| if (!(track_flags & FL_FULLPATH) && match_len == len) |
| match_len = last_slash = previous_slash; |
| |
| if (*ret_flags && match_len == cache->len) |
| return match_len; |
| /* |
| * If we now have match_len > 0, we would know that |
| * the matched part will always be a directory. |
| * |
| * Also, if we are tracking directories and 'name' is |
| * a substring of the cache on a path component basis, |
| * we can return immediately. |
| */ |
| *ret_flags = track_flags & FL_DIR; |
| if (*ret_flags && len == match_len) |
| return match_len; |
| } |
| |
| /* |
| * Okay, no match from the cache so far, so now we have to |
| * check the rest of the path components. |
| */ |
| *ret_flags = FL_DIR; |
| last_slash_dir = last_slash; |
| max_len = len < PATH_MAX ? len : PATH_MAX; |
| while (match_len < max_len) { |
| do { |
| 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'; |
| |
| if (last_slash <= prefix_len_stat_func) |
| ret = stat(cache->path, &st); |
| else |
| ret = lstat(cache->path, &st); |
| |
| if (ret) { |
| *ret_flags = FL_LSTATERR; |
| if (errno == ENOENT) |
| *ret_flags |= FL_NOENT; |
| } else if (S_ISDIR(st.st_mode)) { |
| last_slash_dir = last_slash; |
| continue; |
| } else if (S_ISLNK(st.st_mode)) { |
| *ret_flags = FL_SYMLINK; |
| } else { |
| *ret_flags = FL_ERR; |
| } |
| break; |
| } |
| |
| /* |
| * At the end update the cache. Note that max 3 different |
| * path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached |
| * for the moment! |
| */ |
| 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; |
| } else if ((track_flags & FL_DIR) && |
| last_slash_dir > 0 && last_slash_dir <= PATH_MAX) { |
| /* |
| * We have a separate test for the directory case, |
| * since it could be that we have found a symlink or a |
| * non-existing directory and the track_flags says |
| * that we cannot cache this fact, so the cache would |
| * then have been left empty in this case. |
| * |
| * But if we are allowed to track real directories, we |
| * 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; |
| } else { |
| reset_lstat_cache(cache); |
| } |
| return match_len; |
| } |
| |
| static int lstat_cache(struct cache_def *cache, const char *name, int len, |
| int track_flags, int prefix_len_stat_func) |
| { |
| int flags; |
| (void)lstat_cache_matchlen(cache, name, len, &flags, track_flags, |
| prefix_len_stat_func); |
| return flags; |
| } |
| |
| #define USE_ONLY_LSTAT 0 |
| |
| /* |
| * Return non-zero if path 'name' has a leading symlink component |
| */ |
| int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len) |
| { |
| return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK; |
| } |
| |
| /* |
| * Return non-zero if path 'name' has a leading symlink component |
| */ |
| int has_symlink_leading_path(const char *name, int len) |
| { |
| return threaded_has_symlink_leading_path(&default_cache, name, len); |
| } |
| |
| /* |
| * Return zero if path 'name' has a leading symlink component or |
| * if some leading path component does not exists. |
| * |
| * Return -1 if leading path exists and is a directory. |
| * |
| * Return path length if leading path exists and is neither a |
| * directory nor a symlink. |
| */ |
| int check_leading_path(const char *name, int len) |
| { |
| return threaded_check_leading_path(&default_cache, name, len); |
| } |
| |
| /* |
| * Return zero if path 'name' has a leading symlink component or |
| * if some leading path component does not exists. |
| * |
| * Return -1 if leading path exists and is a directory. |
| * |
| * Return path length if leading path exists and is neither a |
| * directory nor a symlink. |
| */ |
| int threaded_check_leading_path(struct cache_def *cache, const char *name, int len) |
| { |
| int flags; |
| int match_len = lstat_cache_matchlen(cache, name, len, &flags, |
| FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT); |
| if (flags & FL_NOENT) |
| return 0; |
| else if (flags & FL_DIR) |
| return -1; |
| else |
| return match_len; |
| } |
| |
| /* |
| * Return non-zero if all path components of 'name' exists as a |
| * directory. If prefix_len > 0, we will test with the stat() |
| * function instead of the lstat() function for a prefix length of |
| * 'prefix_len', thus we then allow for symlinks in the prefix part as |
| * long as those points to real existing directories. |
| */ |
| int has_dirs_only_path(const char *name, int len, int prefix_len) |
| { |
| return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len); |
| } |
| |
| /* |
| * Return non-zero if all path components of 'name' exists as a |
| * directory. If prefix_len > 0, we will test with the stat() |
| * function instead of the lstat() function for a prefix length of |
| * 'prefix_len', thus we then allow for symlinks in the prefix part as |
| * long as those points to real existing directories. |
| */ |
| int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len) |
| { |
| return lstat_cache(cache, name, len, |
| FL_DIR|FL_FULLPATH, prefix_len) & |
| FL_DIR; |
| } |
| |
| static struct removal_def { |
| char path[PATH_MAX]; |
| int len; |
| } removal; |
| |
| static void do_remove_scheduled_dirs(int new_len) |
| { |
| while (removal.len > new_len) { |
| removal.path[removal.len] = '\0'; |
| if (rmdir(removal.path)) |
| break; |
| do { |
| removal.len--; |
| } while (removal.len > new_len && |
| removal.path[removal.len] != '/'); |
| } |
| removal.len = new_len; |
| } |
| |
| void schedule_dir_for_removal(const char *name, int len) |
| { |
| int match_len, last_slash, i, previous_slash; |
| |
| match_len = last_slash = i = |
| longest_path_match(name, len, removal.path, removal.len, |
| &previous_slash); |
| /* Find last slash inside 'name' */ |
| while (i < len) { |
| if (name[i] == '/') |
| last_slash = i; |
| i++; |
| } |
| |
| /* |
| * If we are about to go down the directory tree, we check if |
| * we must first go upwards the tree, such that we then can |
| * remove possible empty directories as we go upwards. |
| */ |
| if (match_len < last_slash && match_len < removal.len) |
| do_remove_scheduled_dirs(match_len); |
| /* |
| * If we go deeper down the directory tree, we only need to |
| * save the new path components as we go down. |
| */ |
| if (match_len < last_slash) { |
| memcpy(&removal.path[match_len], &name[match_len], |
| last_slash - match_len); |
| removal.len = last_slash; |
| } |
| } |
| |
| void remove_scheduled_dirs(void) |
| { |
| do_remove_scheduled_dirs(0); |
| } |