refs_ref_iterator_begin(): new function
[gitweb.git] / sha1_file.c
index b5e827ac9e716db9fad69960058f1bf2fa50c9d3..29bbc5f427c9fe390f15876775fa7e27bc15e4fb 100644 (file)
@@ -129,8 +129,10 @@ enum scld_error safe_create_leading_directories(char *path)
                *slash = '\0';
                if (!stat(path, &st)) {
                        /* path exists */
-                       if (!S_ISDIR(st.st_mode))
+                       if (!S_ISDIR(st.st_mode)) {
+                               errno = ENOTDIR;
                                ret = SCLD_EXISTS;
+                       }
                } else if (mkdir(path, 0777)) {
                        if (errno == EEXIST &&
                            !stat(path, &st) && S_ISDIR(st.st_mode))
@@ -158,13 +160,85 @@ enum scld_error safe_create_leading_directories(char *path)
 
 enum scld_error safe_create_leading_directories_const(const char *path)
 {
+       int save_errno;
        /* path points to cache entries, so xstrdup before messing with it */
        char *buf = xstrdup(path);
        enum scld_error result = safe_create_leading_directories(buf);
+
+       save_errno = errno;
        free(buf);
+       errno = save_errno;
        return result;
 }
 
+int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
+{
+       /*
+        * The number of times we will try to remove empty directories
+        * in the way of path. This is only 1 because if another
+        * process is racily creating directories that conflict with
+        * us, we don't want to fight against them.
+        */
+       int remove_directories_remaining = 1;
+
+       /*
+        * The number of times that we will try to create the
+        * directories containing path. We are willing to attempt this
+        * more than once, because another process could be trying to
+        * clean up empty directories at the same time as we are
+        * trying to create them.
+        */
+       int create_directories_remaining = 3;
+
+       /* A scratch copy of path, filled lazily if we need it: */
+       struct strbuf path_copy = STRBUF_INIT;
+
+       int ret, save_errno;
+
+       /* Sanity check: */
+       assert(*path);
+
+retry_fn:
+       ret = fn(path, cb);
+       save_errno = errno;
+       if (!ret)
+               goto out;
+
+       if (errno == EISDIR && remove_directories_remaining-- > 0) {
+               /*
+                * A directory is in the way. Maybe it is empty; try
+                * to remove it:
+                */
+               if (!path_copy.len)
+                       strbuf_addstr(&path_copy, path);
+
+               if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
+                       goto retry_fn;
+       } else if (errno == ENOENT && create_directories_remaining-- > 0) {
+               /*
+                * Maybe the containing directory didn't exist, or
+                * maybe it was just deleted by a process that is
+                * racing with us to clean up empty directories. Try
+                * to create it:
+                */
+               enum scld_error scld_result;
+
+               if (!path_copy.len)
+                       strbuf_addstr(&path_copy, path);
+
+               do {
+                       scld_result = safe_create_leading_directories(path_copy.buf);
+                       if (scld_result == SCLD_OK)
+                               goto retry_fn;
+               } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
+       }
+
+out:
+       strbuf_release(&path_copy);
+       errno = save_errno;
+       return ret;
+}
+
 static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 {
        int i;
@@ -593,7 +667,7 @@ static int freshen_file(const char *fn)
  * either does not exist on disk, or has a stale mtime and may be subject to
  * pruning).
  */
-static int check_and_freshen_file(const char *fn, int freshen)
+int check_and_freshen_file(const char *fn, int freshen)
 {
        if (access(fn, F_OK))
                return 0;
@@ -1630,39 +1704,54 @@ int git_open_cloexec(const char *name, int flags)
        return fd;
 }
 
-static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
+/*
+ * Find "sha1" as a loose object in the local repository or in an alternate.
+ * Returns 0 on success, negative on failure.
+ *
+ * The "path" out-parameter will give the path of the object we found (if any).
+ * Note that it may point to static storage and is only valid until another
+ * call to sha1_file_name(), etc.
+ */
+static int stat_sha1_file(const unsigned char *sha1, struct stat *st,
+                         const char **path)
 {
        struct alternate_object_database *alt;
 
-       if (!lstat(sha1_file_name(sha1), st))
+       *path = sha1_file_name(sha1);
+       if (!lstat(*path, st))
                return 0;
 
        prepare_alt_odb();
        errno = ENOENT;
        for (alt = alt_odb_list; alt; alt = alt->next) {
-               const char *path = alt_sha1_path(alt, sha1);
-               if (!lstat(path, st))
+               *path = alt_sha1_path(alt, sha1);
+               if (!lstat(*path, st))
                        return 0;
        }
 
        return -1;
 }
 
-static int open_sha1_file(const unsigned char *sha1)
+/*
+ * Like stat_sha1_file(), but actually open the object and return the
+ * descriptor. See the caveats on the "path" parameter above.
+ */
+static int open_sha1_file(const unsigned char *sha1, const char **path)
 {
        int fd;
        struct alternate_object_database *alt;
        int most_interesting_errno;
 
-       fd = git_open(sha1_file_name(sha1));
+       *path = sha1_file_name(sha1);
+       fd = git_open(*path);
        if (fd >= 0)
                return fd;
        most_interesting_errno = errno;
 
        prepare_alt_odb();
        for (alt = alt_odb_list; alt; alt = alt->next) {
-               const char *path = alt_sha1_path(alt, sha1);
-               fd = git_open(path);
+               *path = alt_sha1_path(alt, sha1);
+               fd = git_open(*path);
                if (fd >= 0)
                        return fd;
                if (most_interesting_errno == ENOENT)
@@ -1672,12 +1761,21 @@ static int open_sha1_file(const unsigned char *sha1)
        return -1;
 }
 
-void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+/*
+ * Map the loose object at "path" if it is not NULL, or the path found by
+ * searching for a loose object named "sha1".
+ */
+static void *map_sha1_file_1(const char *path,
+                            const unsigned char *sha1,
+                            unsigned long *size)
 {
        void *map;
        int fd;
 
-       fd = open_sha1_file(sha1);
+       if (path)
+               fd = git_open(path);
+       else
+               fd = open_sha1_file(sha1, &path);
        map = NULL;
        if (fd >= 0) {
                struct stat st;
@@ -1686,7 +1784,7 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
                        *size = xsize_t(st.st_size);
                        if (!*size) {
                                /* mmap() is forbidden on empty files */
-                               error("object file %s is empty", sha1_file_name(sha1));
+                               error("object file %s is empty", path);
                                return NULL;
                        }
                        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
@@ -1696,6 +1794,11 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
        return map;
 }
 
+void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+{
+       return map_sha1_file_1(NULL, sha1, size);
+}
+
 unsigned long unpack_object_header_buffer(const unsigned char *buf,
                unsigned long len, enum object_type *type, unsigned long *sizep)
 {
@@ -2342,11 +2445,10 @@ static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
 
 void clear_delta_base_cache(void)
 {
-       struct hashmap_iter iter;
-       struct delta_base_cache_entry *entry;
-       for (entry = hashmap_iter_first(&delta_base_cache, &iter);
-            entry;
-            entry = hashmap_iter_next(&iter)) {
+       struct list_head *lru, *tmp;
+       list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
+               struct delta_base_cache_entry *entry =
+                       list_entry(lru, struct delta_base_cache_entry, lru);
                release_delta_base_cache(entry);
        }
 }
@@ -2504,6 +2606,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
        while (delta_stack_nr) {
                void *delta_data;
                void *base = data;
+               void *external_base = NULL;
                unsigned long delta_size, base_size = size;
                int i;
 
@@ -2530,6 +2633,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
                                      p->pack_name);
                                mark_bad_packed_object(p, base_sha1);
                                base = read_object(base_sha1, &type, &base_size);
+                               external_base = base;
                        }
                }
 
@@ -2548,6 +2652,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
                              "at offset %"PRIuMAX" from %s",
                              (uintmax_t)curpos, p->pack_name);
                        data = NULL;
+                       free(external_base);
                        continue;
                }
 
@@ -2567,6 +2672,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
                        error("failed to apply delta");
 
                free(delta_data);
+               free(external_base);
        }
 
        *final_type = type;
@@ -2600,6 +2706,17 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
        }
 }
 
+const struct object_id *nth_packed_object_oid(struct object_id *oid,
+                                             struct packed_git *p,
+                                             uint32_t n)
+{
+       const unsigned char *hash = nth_packed_object_sha1(p, n);
+       if (!hash)
+               return NULL;
+       hashcpy(oid->hash, hash);
+       return oid;
+}
+
 void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
 {
        const unsigned char *ptr = vptr;
@@ -2806,8 +2923,9 @@ static int sha1_loose_object_info(const unsigned char *sha1,
         * object even exists.
         */
        if (!oi->typep && !oi->typename && !oi->sizep) {
+               const char *path;
                struct stat st;
-               if (stat_sha1_file(sha1, &st) < 0)
+               if (stat_sha1_file(sha1, &st, &path) < 0)
                        return -1;
                if (oi->disk_sizep)
                        *oi->disk_sizep = st.st_size;
@@ -3003,6 +3121,8 @@ void *read_sha1_file_extended(const unsigned char *sha1,
 {
        void *data;
        const struct packed_git *p;
+       const char *path;
+       struct stat st;
        const unsigned char *repl = lookup_replace_object_extended(sha1, flag);
 
        errno = 0;
@@ -3018,12 +3138,9 @@ void *read_sha1_file_extended(const unsigned char *sha1,
                die("replacement %s not found for %s",
                    sha1_to_hex(repl), sha1_to_hex(sha1));
 
-       if (has_loose_object(repl)) {
-               const char *path = sha1_file_name(sha1);
-
+       if (!stat_sha1_file(repl, &st, &path))
                die("loose object %s (stored in %s) is corrupt",
                    sha1_to_hex(repl), path);
-       }
 
        if ((p = has_packed_and_bad(repl)) != NULL)
                die("packed object %s (stored in %s) is corrupt",
@@ -3646,15 +3763,15 @@ static int for_each_file_in_obj_subdir(int subdir_nr,
                strbuf_setlen(path, baselen);
                strbuf_addf(path, "/%s", de->d_name);
 
-               if (strlen(de->d_name) == 38)  {
-                       char hex[41];
-                       unsigned char sha1[20];
+               if (strlen(de->d_name) == GIT_SHA1_HEXSZ - 2)  {
+                       char hex[GIT_SHA1_HEXSZ+1];
+                       struct object_id oid;
 
                        snprintf(hex, sizeof(hex), "%02x%s",
                                 subdir_nr, de->d_name);
-                       if (!get_sha1_hex(hex, sha1)) {
+                       if (!get_oid_hex(hex, &oid)) {
                                if (obj_cb) {
-                                       r = obj_cb(sha1, path->buf, data);
+                                       r = obj_cb(&oid, path->buf, data);
                                        if (r)
                                                break;
                                }
@@ -3760,13 +3877,13 @@ static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn c
        int r = 0;
 
        for (i = 0; i < p->num_objects; i++) {
-               const unsigned char *sha1 = nth_packed_object_sha1(p, i);
+               struct object_id oid;
 
-               if (!sha1)
+               if (!nth_packed_object_oid(&oid, p, i))
                        return error("unable to get sha1 of object %u in %s",
                                     i, p->pack_name);
 
-               r = cb(sha1, p, i, data);
+               r = cb(&oid, p, i, data);
                if (r)
                        break;
        }
@@ -3793,3 +3910,122 @@ int for_each_packed_object(each_packed_object_fn cb, void *data, unsigned flags)
        }
        return r ? r : pack_errors;
 }
+
+static int check_stream_sha1(git_zstream *stream,
+                            const char *hdr,
+                            unsigned long size,
+                            const char *path,
+                            const unsigned char *expected_sha1)
+{
+       git_SHA_CTX c;
+       unsigned char real_sha1[GIT_SHA1_RAWSZ];
+       unsigned char buf[4096];
+       unsigned long total_read;
+       int status = Z_OK;
+
+       git_SHA1_Init(&c);
+       git_SHA1_Update(&c, hdr, stream->total_out);
+
+       /*
+        * We already read some bytes into hdr, but the ones up to the NUL
+        * do not count against the object's content size.
+        */
+       total_read = stream->total_out - strlen(hdr) - 1;
+
+       /*
+        * This size comparison must be "<=" to read the final zlib packets;
+        * see the comment in unpack_sha1_rest for details.
+        */
+       while (total_read <= size &&
+              (status == Z_OK || status == Z_BUF_ERROR)) {
+               stream->next_out = buf;
+               stream->avail_out = sizeof(buf);
+               if (size - total_read < stream->avail_out)
+                       stream->avail_out = size - total_read;
+               status = git_inflate(stream, Z_FINISH);
+               git_SHA1_Update(&c, buf, stream->next_out - buf);
+               total_read += stream->next_out - buf;
+       }
+       git_inflate_end(stream);
+
+       if (status != Z_STREAM_END) {
+               error("corrupt loose object '%s'", sha1_to_hex(expected_sha1));
+               return -1;
+       }
+       if (stream->avail_in) {
+               error("garbage at end of loose object '%s'",
+                     sha1_to_hex(expected_sha1));
+               return -1;
+       }
+
+       git_SHA1_Final(real_sha1, &c);
+       if (hashcmp(expected_sha1, real_sha1)) {
+               error("sha1 mismatch for %s (expected %s)", path,
+                     sha1_to_hex(expected_sha1));
+               return -1;
+       }
+
+       return 0;
+}
+
+int read_loose_object(const char *path,
+                     const unsigned char *expected_sha1,
+                     enum object_type *type,
+                     unsigned long *size,
+                     void **contents)
+{
+       int ret = -1;
+       int fd = -1;
+       void *map = NULL;
+       unsigned long mapsize;
+       git_zstream stream;
+       char hdr[32];
+
+       *contents = NULL;
+
+       map = map_sha1_file_1(path, NULL, &mapsize);
+       if (!map) {
+               error_errno("unable to mmap %s", path);
+               goto out;
+       }
+
+       if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0) {
+               error("unable to unpack header of %s", path);
+               goto out;
+       }
+
+       *type = parse_sha1_header(hdr, size);
+       if (*type < 0) {
+               error("unable to parse header of %s", path);
+               git_inflate_end(&stream);
+               goto out;
+       }
+
+       if (*type == OBJ_BLOB) {
+               if (check_stream_sha1(&stream, hdr, *size, path, expected_sha1) < 0)
+                       goto out;
+       } else {
+               *contents = unpack_sha1_rest(&stream, hdr, *size, expected_sha1);
+               if (!*contents) {
+                       error("unable to unpack contents of %s", path);
+                       git_inflate_end(&stream);
+                       goto out;
+               }
+               if (check_sha1_signature(expected_sha1, *contents,
+                                        *size, typename(*type))) {
+                       error("sha1 mismatch for %s (expected %s)", path,
+                             sha1_to_hex(expected_sha1));
+                       free(*contents);
+                       goto out;
+               }
+       }
+
+       ret = 0; /* everything checks out */
+
+out:
+       if (map)
+               munmap(map, mapsize);
+       if (fd >= 0)
+               close(fd);
+       return ret;
+}