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15438d5a56
check_leading_path() and has_dirs_only_path() both always use the default cache, which could be a caveat for adding parallelism (which is a concern and even a GSoC proposal). Reimplement these two in terms of new threaded_check_leading_path() and threaded_has_dirs_only_path() that take their own copy of the cache. Signed-off-by: Jared Hance <jaredhance@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
328 lines
9.2 KiB
C
328 lines
9.2 KiB
C
#include "cache.h"
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/*
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* Returns the length (on a path component basis) of the longest
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* common prefix match of 'name_a' and 'name_b'.
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*/
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static int longest_path_match(const char *name_a, int len_a,
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const char *name_b, int len_b,
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int *previous_slash)
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{
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int max_len, match_len = 0, match_len_prev = 0, i = 0;
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max_len = len_a < len_b ? len_a : len_b;
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while (i < max_len && name_a[i] == name_b[i]) {
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if (name_a[i] == '/') {
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match_len_prev = match_len;
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match_len = i;
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}
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i++;
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}
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/*
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* Is 'name_b' a substring of 'name_a', the other way around,
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* or is 'name_a' and 'name_b' the exact same string?
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*/
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if (i >= max_len && ((len_a > len_b && name_a[len_b] == '/') ||
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(len_a < len_b && name_b[len_a] == '/') ||
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(len_a == len_b))) {
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match_len_prev = match_len;
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match_len = i;
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}
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*previous_slash = match_len_prev;
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return match_len;
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}
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static struct cache_def default_cache;
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static inline void reset_lstat_cache(struct cache_def *cache)
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{
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cache->path[0] = '\0';
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cache->len = 0;
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cache->flags = 0;
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/*
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* The track_flags and prefix_len_stat_func members is only
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* set by the safeguard rule inside lstat_cache()
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*/
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}
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#define FL_DIR (1 << 0)
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#define FL_NOENT (1 << 1)
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#define FL_SYMLINK (1 << 2)
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#define FL_LSTATERR (1 << 3)
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#define FL_ERR (1 << 4)
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#define FL_FULLPATH (1 << 5)
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/*
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* Check if name 'name' of length 'len' has a symlink leading
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* component, or if the directory exists and is real, or not.
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*
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* To speed up the check, some information is allowed to be cached.
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* This can be indicated by the 'track_flags' argument, which also can
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* be used to indicate that we should check the full path.
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*
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* The 'prefix_len_stat_func' parameter can be used to set the length
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* of the prefix, where the cache should use the stat() function
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* instead of the lstat() function to test each path component.
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*/
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static int lstat_cache_matchlen(struct cache_def *cache,
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const char *name, int len,
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int *ret_flags, int track_flags,
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int prefix_len_stat_func)
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{
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int match_len, last_slash, last_slash_dir, previous_slash;
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int save_flags, max_len, ret;
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struct stat st;
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if (cache->track_flags != track_flags ||
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cache->prefix_len_stat_func != prefix_len_stat_func) {
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/*
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* As a safeguard rule we clear the cache if the
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* values of track_flags and/or prefix_len_stat_func
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* does not match with the last supplied values.
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*/
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reset_lstat_cache(cache);
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cache->track_flags = track_flags;
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cache->prefix_len_stat_func = prefix_len_stat_func;
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match_len = last_slash = 0;
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} else {
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/*
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* Check to see if we have a match from the cache for
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* the 2 "excluding" path types.
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*/
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match_len = last_slash =
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longest_path_match(name, len, cache->path, cache->len,
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&previous_slash);
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*ret_flags = cache->flags & track_flags & (FL_NOENT|FL_SYMLINK);
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if (!(track_flags & FL_FULLPATH) && match_len == len)
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match_len = last_slash = previous_slash;
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if (*ret_flags && match_len == cache->len)
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return match_len;
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/*
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* If we now have match_len > 0, we would know that
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* the matched part will always be a directory.
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*
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* Also, if we are tracking directories and 'name' is
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* a substring of the cache on a path component basis,
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* we can return immediately.
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*/
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*ret_flags = track_flags & FL_DIR;
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if (*ret_flags && len == match_len)
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return match_len;
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}
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/*
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* Okay, no match from the cache so far, so now we have to
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* check the rest of the path components.
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*/
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*ret_flags = FL_DIR;
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last_slash_dir = last_slash;
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max_len = len < PATH_MAX ? len : PATH_MAX;
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while (match_len < max_len) {
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do {
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cache->path[match_len] = name[match_len];
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match_len++;
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} while (match_len < max_len && name[match_len] != '/');
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if (match_len >= max_len && !(track_flags & FL_FULLPATH))
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break;
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last_slash = match_len;
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cache->path[last_slash] = '\0';
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if (last_slash <= prefix_len_stat_func)
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ret = stat(cache->path, &st);
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else
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ret = lstat(cache->path, &st);
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if (ret) {
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*ret_flags = FL_LSTATERR;
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if (errno == ENOENT)
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*ret_flags |= FL_NOENT;
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} else if (S_ISDIR(st.st_mode)) {
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last_slash_dir = last_slash;
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continue;
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} else if (S_ISLNK(st.st_mode)) {
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*ret_flags = FL_SYMLINK;
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} else {
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*ret_flags = FL_ERR;
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}
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break;
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}
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/*
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* At the end update the cache. Note that max 3 different
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* path types, FL_NOENT, FL_SYMLINK and FL_DIR, can be cached
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* for the moment!
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*/
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save_flags = *ret_flags & track_flags & (FL_NOENT|FL_SYMLINK);
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if (save_flags && last_slash > 0 && last_slash <= PATH_MAX) {
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cache->path[last_slash] = '\0';
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cache->len = last_slash;
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cache->flags = save_flags;
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} else if ((track_flags & FL_DIR) &&
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last_slash_dir > 0 && last_slash_dir <= PATH_MAX) {
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/*
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* We have a separate test for the directory case,
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* since it could be that we have found a symlink or a
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* non-existing directory and the track_flags says
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* that we cannot cache this fact, so the cache would
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* then have been left empty in this case.
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*
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* But if we are allowed to track real directories, we
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* can still cache the path components before the last
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* one (the found symlink or non-existing component).
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*/
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cache->path[last_slash_dir] = '\0';
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cache->len = last_slash_dir;
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cache->flags = FL_DIR;
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} else {
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reset_lstat_cache(cache);
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}
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return match_len;
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}
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static int lstat_cache(struct cache_def *cache, const char *name, int len,
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int track_flags, int prefix_len_stat_func)
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{
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int flags;
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(void)lstat_cache_matchlen(cache, name, len, &flags, track_flags,
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prefix_len_stat_func);
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return flags;
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}
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#define USE_ONLY_LSTAT 0
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/*
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* Return non-zero if path 'name' has a leading symlink component
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*/
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int threaded_has_symlink_leading_path(struct cache_def *cache, const char *name, int len)
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{
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return lstat_cache(cache, name, len, FL_SYMLINK|FL_DIR, USE_ONLY_LSTAT) & FL_SYMLINK;
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}
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/*
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* Return non-zero if path 'name' has a leading symlink component
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*/
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int has_symlink_leading_path(const char *name, int len)
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{
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return threaded_has_symlink_leading_path(&default_cache, name, len);
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}
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/*
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* Return zero if path 'name' has a leading symlink component or
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* if some leading path component does not exists.
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*
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* Return -1 if leading path exists and is a directory.
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*
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* Return path length if leading path exists and is neither a
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* directory nor a symlink.
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*/
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int check_leading_path(const char *name, int len)
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{
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return threaded_check_leading_path(&default_cache, name, len);
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}
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/*
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* Return zero if path 'name' has a leading symlink component or
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* if some leading path component does not exists.
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*
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* Return -1 if leading path exists and is a directory.
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*
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* Return path length if leading path exists and is neither a
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* directory nor a symlink.
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*/
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int threaded_check_leading_path(struct cache_def *cache, const char *name, int len)
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{
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int flags;
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int match_len = lstat_cache_matchlen(cache, name, len, &flags,
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FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
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if (flags & FL_NOENT)
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return 0;
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else if (flags & FL_DIR)
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return -1;
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else
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return match_len;
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}
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/*
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* Return non-zero if all path components of 'name' exists as a
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* directory. If prefix_len > 0, we will test with the stat()
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* function instead of the lstat() function for a prefix length of
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* 'prefix_len', thus we then allow for symlinks in the prefix part as
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* long as those points to real existing directories.
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*/
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int has_dirs_only_path(const char *name, int len, int prefix_len)
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{
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return threaded_has_dirs_only_path(&default_cache, name, len, prefix_len);
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}
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/*
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* Return non-zero if all path components of 'name' exists as a
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* directory. If prefix_len > 0, we will test with the stat()
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* function instead of the lstat() function for a prefix length of
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* 'prefix_len', thus we then allow for symlinks in the prefix part as
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* long as those points to real existing directories.
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*/
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int threaded_has_dirs_only_path(struct cache_def *cache, const char *name, int len, int prefix_len)
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{
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return lstat_cache(cache, name, len,
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FL_DIR|FL_FULLPATH, prefix_len) &
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FL_DIR;
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}
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static struct removal_def {
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char path[PATH_MAX];
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int len;
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} removal;
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static void do_remove_scheduled_dirs(int new_len)
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{
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while (removal.len > new_len) {
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removal.path[removal.len] = '\0';
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if (rmdir(removal.path))
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break;
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do {
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removal.len--;
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} while (removal.len > new_len &&
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removal.path[removal.len] != '/');
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}
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removal.len = new_len;
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}
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void schedule_dir_for_removal(const char *name, int len)
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{
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int match_len, last_slash, i, previous_slash;
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match_len = last_slash = i =
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longest_path_match(name, len, removal.path, removal.len,
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&previous_slash);
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/* Find last slash inside 'name' */
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while (i < len) {
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if (name[i] == '/')
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last_slash = i;
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i++;
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}
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/*
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* If we are about to go down the directory tree, we check if
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* we must first go upwards the tree, such that we then can
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* remove possible empty directories as we go upwards.
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*/
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if (match_len < last_slash && match_len < removal.len)
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do_remove_scheduled_dirs(match_len);
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/*
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* If we go deeper down the directory tree, we only need to
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* save the new path components as we go down.
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*/
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if (match_len < last_slash) {
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memcpy(&removal.path[match_len], &name[match_len],
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last_slash - match_len);
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removal.len = last_slash;
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}
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}
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void remove_scheduled_dirs(void)
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{
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do_remove_scheduled_dirs(0);
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}
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