Changeset 782 for git/branches/dmik/sha1_file.c

Timestamp:

Jun 23, 2014, 9:45:51 PM (11 years ago)

Author:

dmik

Message:

git: Merge version 2.0.0 from vendor to dmik branch.

Location:

git/branches/dmik

Files:

• . (modified) (1 prop)
• sha1_file.c (modified) (60 diffs)

git/branches/dmik/sha1_file.c ¶

@@ -8 +8 @@
  */
 #include "cache.h"
+#include "string-list.h"
 #include "delta.h"
 #include "pack.h"
@@ -20 +21 @@
 #include "sha1-lookup.h"
 #include "bulk-checkin.h"
+#include "streaming.h"
+#include "dir.h"
 
 #ifndef O_NOATIME
@@ -33 +36 @@
 
 const unsigned char null_sha1[20];
+
+static const char *no_log_pack_access = "no_log_pack_access";
+static const char *log_pack_access;
 
 /*
@@ -55 +61 @@
 };
 
+/*
+ * A pointer to the last packed_git in which an object was found.
+ * When an object is sought, we look in this packfile first, because
+ * objects that are looked up at similar times are often in the same
+ * packfile as one another.
+ */
 static struct packed_git *last_found_pack;
 
@@ -100 +112 @@
 }
 
-int safe_create_leading_directories(char *path)
-{
-        char *pos = path + offset_1st_component(path);
-        struct stat st;
-
-        while (pos) {
-                pos = strchr(pos, '/');
-                if (!pos)
+enum scld_error safe_create_leading_directories(char *path)
+{
+        char *next_component = path + offset_1st_component(path);
+        enum scld_error ret = SCLD_OK;
+
+        while (ret == SCLD_OK && next_component) {
+                struct stat st;
+                char *slash = next_component, slash_character;
+
+                while (*slash && !is_dir_sep(*slash))
+                        slash++;
+
+                if (!*slash)
                         break;
-                while (*++pos == '/')
-                        ;
-                if (!*pos)
+
+                next_component = slash + 1;
+                while (is_dir_sep(*next_component))
+                        next_component++;
+                if (!*next_component)
                         break;
-                *--pos = '\0';
+
+                slash_character = *slash;
+                *slash = '\0';
                 if (!stat(path, &st)) {
                         /* path exists */
-                        if (!S_ISDIR(st.st_mode)) {
-                                *pos = '/';
-                                return -3;
-                        }
-                }
-                else if (mkdir(path, 0777)) {
-                        *pos = '/';
-                        return -1;
-                }
-                else if (adjust_shared_perm(path)) {
-                        *pos = '/';
-                        return -2;
-                }
-                *pos++ = '/';
-        }
-        return 0;
-}
-
-int safe_create_leading_directories_const(const char *path)
+                        if (!S_ISDIR(st.st_mode))
+                                ret = SCLD_EXISTS;
+                } else if (mkdir(path, 0777)) {
+                        if (errno == EEXIST &&
+                            !stat(path, &st) && S_ISDIR(st.st_mode))
+                                ; /* somebody created it since we checked */
+                        else if (errno == ENOENT)
+                                /*
+                                 * Either mkdir() failed because
+                                 * somebody just pruned the containing
+                                 * directory, or stat() failed because
+                                 * the file that was in our way was
+                                 * just removed.  Either way, inform
+                                 * the caller that it might be worth
+                                 * trying again:
+                                 */
+                                ret = SCLD_VANISHED;
+                        else
+                                ret = SCLD_FAILED;
+                } else if (adjust_shared_perm(path)) {
+                        ret = SCLD_PERMS;
+                }
+                *slash = slash_character;
+        }
+        return ret;
+}
+
+enum scld_error safe_create_leading_directories_const(const char *path)
 {
         /* path points to cache entries, so xstrdup before messing with it */
         char *buf = xstrdup(path);
-        int result = safe_create_leading_directories(buf);
+        enum scld_error result = safe_create_leading_directories(buf);
         free(buf);
         return result;
@@ -155 +185 @@
 }
 
-/*
- * NOTE! This returns a statically allocated buffer, so you have to be
- * careful about using it. Do an "xstrdup()" if you need to save the
- * filename.
- *
- * Also note that this returns the location for creating.  Reading
- * SHA1 file can happen from any alternate directory listed in the
- * DB_ENVIRONMENT environment variable if it is not found in
- * the primary object database.
- */
-char *sha1_file_name(const unsigned char *sha1)
+const char *sha1_file_name(const unsigned char *sha1)
 {
         static char buf[PATH_MAX];
@@ -185 +205 @@
 }
 
+/*
+ * Return the name of the pack or index file with the specified sha1
+ * in its filename.  *base and *name are scratch space that must be
+ * provided by the caller.  which should be "pack" or "idx".
+ */
 static char *sha1_get_pack_name(const unsigned char *sha1,
                                 char **name, char **base, const char *which)
@@ -228 +253 @@
 struct alternate_object_database *alt_odb_list;
 static struct alternate_object_database **alt_odb_tail;
-
-static void read_info_alternates(const char * alternates, int depth);
-static int git_open_noatime(const char *name);
 
 /*
@@ -247 +269 @@
  * terminating NUL.
  */
-static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
+static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth)
 {
         const char *objdir = get_object_directory();
@@ -259 +281 @@
                 strbuf_addch(&pathbuf, '/');
         }
-        strbuf_add(&pathbuf, entry, len);
+        strbuf_addstr(&pathbuf, entry);
 
         normalize_path_copy(pathbuf.buf, pathbuf.buf);
@@ -299 +321 @@
                 }
         }
-        if (!memcmp(ent->base, objdir, pfxlen)) {
+        if (!strcmp(ent->base, objdir)) {
                 free(ent);
                 return -1;
@@ -317 +339 @@
 }
 
-static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
+static void link_alt_odb_entries(const char *alt, int len, int sep,
                                  const char *relative_base, int depth)
 {
-        const char *cp, *last;
+        struct string_list entries = STRING_LIST_INIT_NODUP;
+        char *alt_copy;
+        int i;
 
         if (depth > 5) {
@@ -328 +352 @@
         }
 
-        last = alt;
-        while (last < ep) {
-                cp = last;
-                if (cp < ep && *cp == '#') {
-                        while (cp < ep && *cp != sep)
-                                cp++;
-                        last = cp + 1;
+        alt_copy = xmemdupz(alt, len);
+        string_list_split_in_place(&entries, alt_copy, sep, -1);
+        for (i = 0; i < entries.nr; i++) {
+                const char *entry = entries.items[i].string;
+                if (entry[0] == '\0' || entry[0] == '#')
                         continue;
-                }
-                while (cp < ep && *cp != sep)
-                        cp++;
-                if (last != cp) {
-                        if (!is_absolute_path(last) && depth) {
-                                error("%s: ignoring relative alternate object store %s",
-                                                relative_base, last);
-                        } else {
-                                link_alt_odb_entry(last, cp - last,
-                                                relative_base, depth);
-                        }
-                }
-                while (cp < ep && *cp == sep)
-                        cp++;
-                last = cp;
-        }
-}
-
-static void read_info_alternates(const char * relative_base, int depth)
+                if (!is_absolute_path(entry) && depth) {
+                        error("%s: ignoring relative alternate object store %s",
+                                        relative_base, entry);
+                } else {
+                        link_alt_odb_entry(entry, relative_base, depth);
+                }
+        }
+        string_list_clear(&entries, 0);
+        free(alt_copy);
+}
+
+void read_info_alternates(const char * relative_base, int depth)
 {
         char *map;
@@ -378 +393 @@
         close(fd);
 
-        link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
+        link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
 
         munmap(map, mapsz);
@@ -392 +407 @@
                 die("could not close alternates file");
         if (alt_odb_tail)
-                link_alt_odb_entries(alt, alt + strlen(alt), '\n', NULL, 0);
+                link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
 }
 
@@ -416 +431 @@
 
         alt_odb_tail = &alt_odb_list;
-        link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
+        link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
 
         read_info_alternates(get_object_directory(), 0);
@@ -423 +438 @@
 static int has_loose_object_local(const unsigned char *sha1)
 {
-        char *name = sha1_file_name(sha1);
-        return !access(name, F_OK);
+        return !access(sha1_file_name(sha1), F_OK);
 }
 
@@ -476 +490 @@
 }
 
-static int check_packed_git_idx(const char *path,  struct packed_git *p)
+/*
+ * Open and mmap the index file at path, perform a couple of
+ * consistency checks, then record its information to p.  Return 0 on
+ * success.
+ */
+static int check_packed_git_idx(const char *path, struct packed_git *p)
 {
         void *idx_map;
@@ -612 +631 @@
 }
 
-static int unuse_one_window(struct packed_git *current, int keep_fd)
+static int unuse_one_window(struct packed_git *current)
 {
         struct packed_git *p, *lru_p = NULL;
@@ -626 +645 @@
                 if (lru_l)
                         lru_l->next = lru_w->next;
-                else {
+                else
                         lru_p->windows = lru_w->next;
-                        if (!lru_p->windows && lru_p->pack_fd != -1
-                                && lru_p->pack_fd != keep_fd) {
-                                close(lru_p->pack_fd);
-                                pack_open_fds--;
-                                lru_p->pack_fd = -1;
-                        }
-                }
                 free(lru_w);
                 pack_open_windows--;
@@ -642 +654 @@
 }
 
-void release_pack_memory(size_t need, int fd)
+void release_pack_memory(size_t need)
 {
         size_t cur = pack_mapped;
-        while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
+        while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
                 ; /* nothing */
 }
@@ -656 +668 @@
                 if (!length)
                         return NULL;
-                release_pack_memory(length, fd);
+                release_pack_memory(length);
                 ret = mmap(start, length, prot, flags, fd, offset);
                 if (ret == MAP_FAILED)
@@ -680 +692 @@
 }
 
+/*
+ * The LRU pack is the one with the oldest MRU window, preferring packs
+ * with no used windows, or the oldest mtime if it has no windows allocated.
+ */
+static void find_lru_pack(struct packed_git *p, struct packed_git **lru_p, struct pack_window **mru_w, int *accept_windows_inuse)
+{
+        struct pack_window *w, *this_mru_w;
+        int has_windows_inuse = 0;
+
+        /*
+         * Reject this pack if it has windows and the previously selected
+         * one does not.  If this pack does not have windows, reject
+         * it if the pack file is newer than the previously selected one.
+         */
+        if (*lru_p && !*mru_w && (p->windows || p->mtime > (*lru_p)->mtime))
+                return;
+
+        for (w = this_mru_w = p->windows; w; w = w->next) {
+                /*
+                 * Reject this pack if any of its windows are in use,
+                 * but the previously selected pack did not have any
+                 * inuse windows.  Otherwise, record that this pack
+                 * has windows in use.
+                 */
+                if (w->inuse_cnt) {
+                        if (*accept_windows_inuse)
+                                has_windows_inuse = 1;
+                        else
+                                return;
+                }
+
+                if (w->last_used > this_mru_w->last_used)
+                        this_mru_w = w;
+
+                /*
+                 * Reject this pack if it has windows that have been
+                 * used more recently than the previously selected pack.
+                 * If the previously selected pack had windows inuse and
+                 * we have not encountered a window in this pack that is
+                 * inuse, skip this check since we prefer a pack with no
+                 * inuse windows to one that has inuse windows.
+                 */
+                if (*mru_w && *accept_windows_inuse == has_windows_inuse &&
+                    this_mru_w->last_used > (*mru_w)->last_used)
+                        return;
+        }
+
+        /*
+         * Select this pack.
+         */
+        *mru_w = this_mru_w;
+        *lru_p = p;
+        *accept_windows_inuse = has_windows_inuse;
+}
+
+static int close_one_pack(void)
+{
+        struct packed_git *p, *lru_p = NULL;
+        struct pack_window *mru_w = NULL;
+        int accept_windows_inuse = 1;
+
+        for (p = packed_git; p; p = p->next) {
+                if (p->pack_fd == -1)
+                        continue;
+                find_lru_pack(p, &lru_p, &mru_w, &accept_windows_inuse);
+        }
+
+        if (lru_p) {
+                close(lru_p->pack_fd);
+                pack_open_fds--;
+                lru_p->pack_fd = -1;
+                return 1;
+        }
+
+        return 0;
+}
+
 void unuse_pack(struct pack_window **w_cursor)
 {
@@ -702 +791 @@
  * the resulting file might be different even if its name would be the
  * same.  It is best to close any reference to the old pack before it is
- * replaced on disk.  Of course no index pointers nor windows for given pack
+ * replaced on disk.  Of course no index pointers or windows for given pack
  * must subsist at this point.  If ever objects from this pack are requested
  * again, the new version of the pack will be reinitialized through
@@ -732 +821 @@
 }
 
+static unsigned int get_max_fd_limit(void)
+{
+#ifdef RLIMIT_NOFILE
+        {
+                struct rlimit lim;
+
+                if (!getrlimit(RLIMIT_NOFILE, &lim))
+                        return lim.rlim_cur;
+        }
+#endif
+
+#ifdef _SC_OPEN_MAX
+        {
+                long open_max = sysconf(_SC_OPEN_MAX);
+                if (0 < open_max)
+                        return open_max;
+                /*
+                 * Otherwise, we got -1 for one of the two
+                 * reasons:
+                 *
+                 * (1) sysconf() did not understand _SC_OPEN_MAX
+                 *     and signaled an error with -1; or
+                 * (2) sysconf() said there is no limit.
+                 *
+                 * We _could_ clear errno before calling sysconf() to
+                 * tell these two cases apart and return a huge number
+                 * in the latter case to let the caller cap it to a
+                 * value that is not so selfish, but letting the
+                 * fallback OPEN_MAX codepath take care of these cases
+                 * is a lot simpler.
+                 */
+        }
+#endif
+
+#ifdef OPEN_MAX
+        return OPEN_MAX;
+#else
+        return 1; /* see the caller ;-) */
+#endif
+}
+
 /*
  * Do not call this directly as this leaks p->pack_fd on error return;
@@ -748 +878 @@
 
         if (!pack_max_fds) {
-                struct rlimit lim;
-                unsigned int max_fds;
-
-                if (getrlimit(RLIMIT_NOFILE, &lim))
-                        die_errno("cannot get RLIMIT_NOFILE");
-
-                max_fds = lim.rlim_cur;
+                unsigned int max_fds = get_max_fd_limit();
 
                 /* Save 3 for stdin/stdout/stderr, 22 for work */
@@ -763 +887 @@
         }
 
-        while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
+        while (pack_max_fds <= pack_open_fds && close_one_pack())
                 ; /* nothing */
 
@@ -879 +1003 @@
                         pack_mapped += win->len;
                         while (packed_git_limit < pack_mapped
-                                && unuse_one_window(p, p->pack_fd))
+                                && unuse_one_window(p))
                                 ; /* nothing */
                         win->base = xmmap(NULL, win->len,
@@ -925 +1049 @@
 static void try_to_free_pack_memory(size_t size)
 {
-        release_pack_memory(size, -1);
+        release_pack_memory(size);
 }
 
@@ -995 +1119 @@
 }
 
+void (*report_garbage)(const char *desc, const char *path);
+
+static void report_helper(const struct string_list *list,
+                          int seen_bits, int first, int last)
+{
+        const char *msg;
+        switch (seen_bits) {
+        case 0:
+                msg = "no corresponding .idx or .pack";
+                break;
+        case 1:
+                msg = "no corresponding .idx";
+                break;
+        case 2:
+                msg = "no corresponding .pack";
+                break;
+        default:
+                return;
+        }
+        for (; first < last; first++)
+                report_garbage(msg, list->items[first].string);
+}
+
+static void report_pack_garbage(struct string_list *list)
+{
+        int i, baselen = -1, first = 0, seen_bits = 0;
+
+        if (!report_garbage)
+                return;
+
+        sort_string_list(list);
+
+        for (i = 0; i < list->nr; i++) {
+                const char *path = list->items[i].string;
+                if (baselen != -1 &&
+                    strncmp(path, list->items[first].string, baselen)) {
+                        report_helper(list, seen_bits, first, i);
+                        baselen = -1;
+                        seen_bits = 0;
+                }
+                if (baselen == -1) {
+                        const char *dot = strrchr(path, '.');
+                        if (!dot) {
+                                report_garbage("garbage found", path);
+                                continue;
+                        }
+                        baselen = dot - path + 1;
+                        first = i;
+                }
+                if (!strcmp(path + baselen, "pack"))
+                        seen_bits |= 1;
+                else if (!strcmp(path + baselen, "idx"))
+                        seen_bits |= 2;
+        }
+        report_helper(list, seen_bits, first, list->nr);
+}
+
 static void prepare_packed_git_one(char *objdir, int local)
 {
@@ -1004 +1185 @@
         DIR *dir;
         struct dirent *de;
+        struct string_list garbage = STRING_LIST_INIT_DUP;
 
         sprintf(path, "%s/pack", objdir);
@@ -1019 +1201 @@
                 struct packed_git *p;
 
-                if (!has_extension(de->d_name, ".idx"))
+                if (len + namelen + 1 > sizeof(path)) {
+                        if (report_garbage) {
+                                struct strbuf sb = STRBUF_INIT;
+                                strbuf_addf(&sb, "%.*s/%s", len - 1, path, de->d_name);
+                                report_garbage("path too long", sb.buf);
+                                strbuf_release(&sb);
+                        }
                         continue;
-
-                if (len + namelen + 1 > sizeof(path))
+                }
+
+                if (is_dot_or_dotdot(de->d_name))
                         continue;
 
-                /* Don't reopen a pack we already have. */
                 strcpy(path + len, de->d_name);
-                for (p = packed_git; p; p = p->next) {
-                        if (!memcmp(path, p->pack_name, len + namelen - 4))
-                                break;
-                }
-                if (p)
+
+                if (has_extension(de->d_name, ".idx")) {
+                        /* Don't reopen a pack we already have. */
+                        for (p = packed_git; p; p = p->next) {
+                                if (!memcmp(path, p->pack_name, len + namelen - 4))
+                                        break;
+                        }
+                        if (p == NULL &&
+                            /*
+                             * See if it really is a valid .idx file with
+                             * corresponding .pack file that we can map.
+                             */
+                            (p = add_packed_git(path, len + namelen, local)) != NULL)
+                                install_packed_git(p);
+                }
+
+                if (!report_garbage)
                         continue;
-                /* See if it really is a valid .idx file with corresponding
-                 * .pack file that we can map.
-                 */
-                p = add_packed_git(path, len + namelen, local);
-                if (!p)
-                        continue;
-                install_packed_git(p);
+
+                if (has_extension(de->d_name, ".idx") ||
+                    has_extension(de->d_name, ".pack") ||
+                    has_extension(de->d_name, ".bitmap") ||
+                    has_extension(de->d_name, ".keep"))
+                        string_list_append(&garbage, path);
+                else
+                        report_garbage("garbage found", path);
         }
         closedir(dir);
+        report_pack_garbage(&garbage);
+        string_list_clear(&garbage, 0);
 }
 
@@ -1118 +1321 @@
 void reprepare_packed_git(void)
 {
-        discard_revindex();
         prepare_packed_git_run_once = 0;
         prepare_packed_git();
@@ -1147 +1349 @@
 }
 
-int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
+/*
+ * With an in-core object data in "map", rehash it to make sure the
+ * object name actually matches "sha1" to detect object corruption.
+ * With "map" == NULL, try reading the object named with "sha1" using
+ * the streaming interface and rehash it to do the same.
+ */
+int check_sha1_signature(const unsigned char *sha1, void *map,
+                         unsigned long size, const char *type)
 {
         unsigned char real_sha1[20];
-        hash_sha1_file(map, size, type, real_sha1);
+        enum object_type obj_type;
+        struct git_istream *st;
+        git_SHA_CTX c;
+        char hdr[32];
+        int hdrlen;
+
+        if (map) {
+                hash_sha1_file(map, size, type, real_sha1);
+                return hashcmp(sha1, real_sha1) ? -1 : 0;
+        }
+
+        st = open_istream(sha1, &obj_type, &size, NULL);
+        if (!st)
+                return -1;
+
+        /* Generate the header */
+        hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
+
+        /* Sha1.. */
+        git_SHA1_Init(&c);
+        git_SHA1_Update(&c, hdr, hdrlen);
+        for (;;) {
+                char buf[1024 * 16];
+                ssize_t readlen = read_istream(st, buf, sizeof(buf));
+
+                if (readlen < 0) {
+                        close_istream(st);
+                        return -1;
+                }
+                if (!readlen)
+                        break;
+                git_SHA1_Update(&c, buf, readlen);
+        }
+        git_SHA1_Final(real_sha1, &c);
+        close_istream(st);
         return hashcmp(sha1, real_sha1) ? -1 : 0;
 }
 
-static int git_open_noatime(const char *name)
+int git_open_noatime(const char *name)
 {
         static int sha1_file_open_flag = O_NOATIME;
@@ -1173 +1416 @@
 }
 
-static int open_sha1_file(const unsigned char *sha1)
-{
-        int fd;
-        char *name = sha1_file_name(sha1);
+static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
+{
         struct alternate_object_database *alt;
 
-        fd = git_open_noatime(name);
-        if (fd >= 0)
-                return fd;
+        if (!lstat(sha1_file_name(sha1), st))
+                return 0;
 
         prepare_alt_odb();
         errno = ENOENT;
         for (alt = alt_odb_list; alt; alt = alt->next) {
-                name = alt->name;
-                fill_sha1_path(name, sha1);
+                fill_sha1_path(alt->name, sha1);
+                if (!lstat(alt->base, st))
+                        return 0;
+        }
+
+        return -1;
+}
+
+static int open_sha1_file(const unsigned char *sha1)
+{
+        int fd;
+        struct alternate_object_database *alt;
+
+        fd = git_open_noatime(sha1_file_name(sha1));
+        if (fd >= 0)
+                return fd;
+
+        prepare_alt_odb();
+        errno = ENOENT;
+        for (alt = alt_odb_list; alt; alt = alt->next) {
+                fill_sha1_path(alt->name, sha1);
                 fd = git_open_noatime(alt->base);
                 if (fd >= 0)
@@ -1217 +1476 @@
         }
         return map;
-}
-
-/*
- * There used to be a second loose object header format which
- * was meant to mimic the in-pack format, allowing for direct
- * copy of the object data.  This format turned up not to be
- * really worth it and we no longer write loose objects in that
- * format.
- */
-static int experimental_loose_object(unsigned char *map)
-{
-        unsigned int word;
-
-        /*
-         * We must determine if the buffer contains the standard
-         * zlib-deflated stream or the experimental format based
-         * on the in-pack object format. Compare the header byte
-         * for each format:
-         *
-         * RFC1950 zlib w/ deflate : 0www1000 : 0 <= www <= 7
-         * Experimental pack-based : Stttssss : ttt = 1,2,3,4
-         *
-         * If bit 7 is clear and bits 0-3 equal 8, the buffer MUST be
-         * in standard loose-object format, UNLESS it is a Git-pack
-         * format object *exactly* 8 bytes in size when inflated.
-         *
-         * However, RFC1950 also specifies that the 1st 16-bit word
-         * must be divisible by 31 - this checksum tells us our buffer
-         * is in the standard format, giving a false positive only if
-         * the 1st word of the Git-pack format object happens to be
-         * divisible by 31, ie:
-         *      ((byte0 * 256) + byte1) % 31 = 0
-         *   =>        0ttt10000www1000 % 31 = 0
-         *
-         * As it happens, this case can only arise for www=3 & ttt=1
-         * - ie, a Commit object, which would have to be 8 bytes in
-         * size. As no Commit can be that small, we find that the
-         * combination of these two criteria (bitmask & checksum)
-         * can always correctly determine the buffer format.
-         */
-        word = (map[0] << 8) + map[1];
-        if ((map[0] & 0x8F) == 0x08 && !(word % 31))
-                return 0;
-        else
-                return 1;
 }
 
@@ -1291 +1505 @@
 int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 {
-        unsigned long size, used;
-        static const char valid_loose_object_type[8] = {
-                0, /* OBJ_EXT */
-                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
-                0, /* "delta" and others are invalid in a loose object */
-        };
-        enum object_type type;
-
         /* Get the data stream */
         memset(stream, 0, sizeof(*stream));
@@ -1306 +1512 @@
         stream->avail_out = bufsiz;
 
-        if (experimental_loose_object(map)) {
-                /*
-                 * The old experimental format we no longer produce;
-                 * we can still read it.
-                 */
-                used = unpack_object_header_buffer(map, mapsize, &type, &size);
-                if (!used || !valid_loose_object_type[type])
-                        return -1;
-                map += used;
-                mapsize -= used;
-
-                /* Set up the stream for the rest.. */
-                stream->next_in = map;
-                stream->avail_in = mapsize;
-                git_inflate_init(stream);
-
-                /* And generate the fake traditional header */
-                stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
-                                                 typename(type), size);
-                return 0;
-        }
         git_inflate_init(stream);
         return git_inflate(stream, 0);
@@ -1518 +1703 @@
 }
 
-/* forward declaration for a mutually recursive function */
-static int packed_object_info(struct packed_git *p, off_t offset,
-                              unsigned long *sizep, int *rtype);
-
-static int packed_delta_info(struct packed_git *p,
-                             struct pack_window **w_curs,
-                             off_t curpos,
-                             enum object_type type,
-                             off_t obj_offset,
-                             unsigned long *sizep)
-{
-        off_t base_offset;
-
-        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
-        if (!base_offset)
-                return OBJ_BAD;
-        type = packed_object_info(p, base_offset, NULL, NULL);
-        if (type <= OBJ_NONE) {
+/*
+ * Like get_delta_base above, but we return the sha1 instead of the pack
+ * offset. This means it is cheaper for REF deltas (we do not have to do
+ * the final object lookup), but more expensive for OFS deltas (we
+ * have to load the revidx to convert the offset back into a sha1).
+ */
+static const unsigned char *get_delta_base_sha1(struct packed_git *p,
+                                                struct pack_window **w_curs,
+                                                off_t curpos,
+                                                enum object_type type,
+                                                off_t delta_obj_offset)
+{
+        if (type == OBJ_REF_DELTA) {
+                unsigned char *base = use_pack(p, w_curs, curpos, NULL);
+                return base;
+        } else if (type == OBJ_OFS_DELTA) {
                 struct revindex_entry *revidx;
-                const unsigned char *base_sha1;
+                off_t base_offset = get_delta_base(p, w_curs, &curpos,
+                                                   type, delta_obj_offset);
+
+                if (!base_offset)
+                        return NULL;
+
                 revidx = find_pack_revindex(p, base_offset);
                 if (!revidx)
-                        return OBJ_BAD;
-                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
-                mark_bad_packed_object(p, base_sha1);
-                type = sha1_object_info(base_sha1, NULL);
-                if (type <= OBJ_NONE)
-                        return OBJ_BAD;
-        }
-
-        /* We choose to only get the type of the base object and
-         * ignore potentially corrupt pack file that expects the delta
-         * based on a base with a wrong size.  This saves tons of
-         * inflate() calls.
-         */
-        if (sizep) {
-                *sizep = get_size_from_delta(p, w_curs, curpos);
-                if (*sizep == 0)
-                        type = OBJ_BAD;
-        }
-
-        return type;
+                        return NULL;
+
+                return nth_packed_object_sha1(p, revidx->nr);
+        } else
+                return NULL;
 }
 
@@ -1588 +1761 @@
 }
 
-static int packed_object_info(struct packed_git *p, off_t obj_offset,
-                              unsigned long *sizep, int *rtype)
-{
-        struct pack_window *w_curs = NULL;
-        unsigned long size;
-        off_t curpos = obj_offset;
-        enum object_type type;
-
-        type = unpack_object_header(p, &w_curs, &curpos, &size);
-        if (rtype)
-                *rtype = type; /* representation type */
+static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
+{
+        int type;
+        struct revindex_entry *revidx;
+        const unsigned char *sha1;
+        revidx = find_pack_revindex(p, obj_offset);
+        if (!revidx)
+                return OBJ_BAD;
+        sha1 = nth_packed_object_sha1(p, revidx->nr);
+        mark_bad_packed_object(p, sha1);
+        type = sha1_object_info(sha1, NULL);
+        if (type <= OBJ_NONE)
+                return OBJ_BAD;
+        return type;
+}
+
+#define POI_STACK_PREALLOC 64
+
+static enum object_type packed_to_object_type(struct packed_git *p,
+                                              off_t obj_offset,
+                                              enum object_type type,
+                                              struct pack_window **w_curs,
+                                              off_t curpos)
+{
+        off_t small_poi_stack[POI_STACK_PREALLOC];
+        off_t *poi_stack = small_poi_stack;
+        int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
+
+        while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
+                off_t base_offset;
+                unsigned long size;
+                /* Push the object we're going to leave behind */
+                if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
+                        poi_stack_alloc = alloc_nr(poi_stack_nr);
+                        poi_stack = xmalloc(sizeof(off_t)*poi_stack_alloc);
+                        memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
+                } else {
+                        ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
+                }
+                poi_stack[poi_stack_nr++] = obj_offset;
+                /* If parsing the base offset fails, just unwind */
+                base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
+                if (!base_offset)
+                        goto unwind;
+                curpos = obj_offset = base_offset;
+                type = unpack_object_header(p, w_curs, &curpos, &size);
+                if (type <= OBJ_NONE) {
+                        /* If getting the base itself fails, we first
+                         * retry the base, otherwise unwind */
+                        type = retry_bad_packed_offset(p, base_offset);
+                        if (type > OBJ_NONE)
+                                goto out;
+                        goto unwind;
+                }
+        }
 
         switch (type) {
-        case OBJ_OFS_DELTA:
-        case OBJ_REF_DELTA:
-                type = packed_delta_info(p, &w_curs, curpos,
-                                         type, obj_offset, sizep);
-                break;
+        case OBJ_BAD:
         case OBJ_COMMIT:
         case OBJ_TREE:
         case OBJ_BLOB:
         case OBJ_TAG:
-                if (sizep)
-                        *sizep = size;
                 break;
         default:
@@ -1618 +1829 @@
                 type = OBJ_BAD;
         }
+
+out:
+        if (poi_stack != small_poi_stack)
+                free(poi_stack);
+        return type;
+
+unwind:
+        while (poi_stack_nr) {
+                obj_offset = poi_stack[--poi_stack_nr];
+                type = retry_bad_packed_offset(p, obj_offset);
+                if (type > OBJ_NONE)
+                        goto out;
+        }
+        type = OBJ_BAD;
+        goto out;
+}
+
+static int packed_object_info(struct packed_git *p, off_t obj_offset,
+                              struct object_info *oi)
+{
+        struct pack_window *w_curs = NULL;
+        unsigned long size;
+        off_t curpos = obj_offset;
+        enum object_type type;
+
+        /*
+         * We always get the representation type, but only convert it to
+         * a "real" type later if the caller is interested.
+         */
+        type = unpack_object_header(p, &w_curs, &curpos, &size);
+
+        if (oi->sizep) {
+                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
+                        off_t tmp_pos = curpos;
+                        off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
+                                                           type, obj_offset);
+                        if (!base_offset) {
+                                type = OBJ_BAD;
+                                goto out;
+                        }
+                        *oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
+                        if (*oi->sizep == 0) {
+                                type = OBJ_BAD;
+                                goto out;
+                        }
+                } else {
+                        *oi->sizep = size;
+                }
+        }
+
+        if (oi->disk_sizep) {
+                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
+                *oi->disk_sizep = revidx[1].offset - obj_offset;
+        }
+
+        if (oi->typep) {
+                *oi->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
+                if (*oi->typep < 0) {
+                        type = OBJ_BAD;
+                        goto out;
+                }
+        }
+
+        if (oi->delta_base_sha1) {
+                if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
+                        const unsigned char *base;
+
+                        base = get_delta_base_sha1(p, &w_curs, curpos,
+                                                   type, obj_offset);
+                        if (!base) {
+                                type = OBJ_BAD;
+                                goto out;
+                        }
+
+                        hashcpy(oi->delta_base_sha1, base);
+                } else
+                        hashclr(oi->delta_base_sha1);
+        }
+
+out:
         unuse_pack(&w_curs);
         return type;
@@ -1681 +1972 @@
 }
 
+static struct delta_base_cache_entry *
+get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
+{
+        unsigned long hash = pack_entry_hash(p, base_offset);
+        return delta_base_cache + hash;
+}
+
+static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
+                                     struct packed_git *p, off_t base_offset)
+{
+        return (ent->data && ent->p == p && ent->base_offset == base_offset);
+}
+
 static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
 {
-        unsigned long hash = pack_entry_hash(p, base_offset);
-        struct delta_base_cache_entry *ent = delta_base_cache + hash;
-        return (ent->data && ent->p == p && ent->base_offset == base_offset);
+        struct delta_base_cache_entry *ent;
+        ent = get_delta_base_cache_entry(p, base_offset);
+        return eq_delta_base_cache_entry(ent, p, base_offset);
+}
+
+static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
+{
+        ent->data = NULL;
+        ent->lru.next->prev = ent->lru.prev;
+        ent->lru.prev->next = ent->lru.next;
+        delta_base_cached -= ent->size;
 }
 
@@ -1691 +2003 @@
         unsigned long *base_size, enum object_type *type, int keep_cache)
 {
+        struct delta_base_cache_entry *ent;
         void *ret;
-        unsigned long hash = pack_entry_hash(p, base_offset);
-        struct delta_base_cache_entry *ent = delta_base_cache + hash;
+
+        ent = get_delta_base_cache_entry(p, base_offset);
+
+        if (!eq_delta_base_cache_entry(ent, p, base_offset))
+                return unpack_entry(p, base_offset, type, base_size);
 
         ret = ent->data;
-        if (!ret || ent->p != p || ent->base_offset != base_offset)
-                return unpack_entry(p, base_offset, type, base_size);
-
-        if (!keep_cache) {
-                ent->data = NULL;
-                ent->lru.next->prev = ent->lru.prev;
-                ent->lru.prev->next = ent->lru.next;
-                delta_base_cached -= ent->size;
-        } else {
+
+        if (!keep_cache)
+                clear_delta_base_cache_entry(ent);
+        else
                 ret = xmemdupz(ent->data, ent->size);
-        }
         *type = ent->type;
         *base_size = ent->size;
@@ -1770 +2080 @@
                          unsigned long *size);
 
-static void *unpack_delta_entry(struct packed_git *p,
-                                struct pack_window **w_curs,
-                                off_t curpos,
-                                unsigned long delta_size,
-                                off_t obj_offset,
-                                enum object_type *type,
-                                unsigned long *sizep)
-{
-        void *delta_data, *result, *base;
-        unsigned long base_size;
-        off_t base_offset;
-
-        base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
-        if (!base_offset) {
-                error("failed to validate delta base reference "
-                      "at offset %"PRIuMAX" from %s",
-                      (uintmax_t)curpos, p->pack_name);
-                return NULL;
-        }
-        unuse_pack(w_curs);
-        base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
-        if (!base) {
-                /*
-                 * We're probably in deep shit, but let's try to fetch
-                 * the required base anyway from another pack or loose.
-                 * This is costly but should happen only in the presence
-                 * of a corrupted pack, and is better than failing outright.
-                 */
-                struct revindex_entry *revidx;
-                const unsigned char *base_sha1;
-                revidx = find_pack_revindex(p, base_offset);
-                if (!revidx)
-                        return NULL;
-                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
-                error("failed to read delta base object %s"
-                      " at offset %"PRIuMAX" from %s",
-                      sha1_to_hex(base_sha1), (uintmax_t)base_offset,
-                      p->pack_name);
-                mark_bad_packed_object(p, base_sha1);
-                base = read_object(base_sha1, type, &base_size);
-                if (!base)
-                        return NULL;
-        }
-
-        delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
-        if (!delta_data) {
-                error("failed to unpack compressed delta "
-                      "at offset %"PRIuMAX" from %s",
-                      (uintmax_t)curpos, p->pack_name);
-                free(base);
-                return NULL;
-        }
-        result = patch_delta(base, base_size,
-                             delta_data, delta_size,
-                             sizep);
-        if (!result)
-                die("failed to apply delta");
-        free(delta_data);
-        add_delta_base_cache(p, base_offset, base, base_size, *type);
-        return result;
-}
-
 static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
 {
         static FILE *log_file;
+
+        if (!log_pack_access)
+                log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
+        if (!log_pack_access)
+                log_pack_access = no_log_pack_access;
+        if (log_pack_access == no_log_pack_access)
+                return;
 
         if (!log_file) {
@@ -1841 +2096 @@
                         error("cannot open pack access log '%s' for writing: %s",
                               log_pack_access, strerror(errno));
-                        log_pack_access = NULL;
+                        log_pack_access = no_log_pack_access;
                         return;
                 }
@@ -1852 +2107 @@
 int do_check_packed_object_crc;
 
+#define UNPACK_ENTRY_STACK_PREALLOC 64
+struct unpack_entry_stack_ent {
+        off_t obj_offset;
+        off_t curpos;
+        unsigned long size;
+};
+
 void *unpack_entry(struct packed_git *p, off_t obj_offset,
-                   enum object_type *type, unsigned long *sizep)
+                   enum object_type *final_type, unsigned long *final_size)
 {
         struct pack_window *w_curs = NULL;
         off_t curpos = obj_offset;
-        void *data;
-
-        if (log_pack_access)
+        void *data = NULL;
+        unsigned long size;
+        enum object_type type;
+        struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
+        struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
+        int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
+        int base_from_cache = 0;
+
+        if (log_pack_access != no_log_pack_access)
                 write_pack_access_log(p, obj_offset);
 
-        if (do_check_packed_object_crc && p->index_version > 1) {
-                struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
-                unsigned long len = revidx[1].offset - obj_offset;
-                if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
-                        const unsigned char *sha1 =
-                                nth_packed_object_sha1(p, revidx->nr);
-                        error("bad packed object CRC for %s",
-                              sha1_to_hex(sha1));
-                        mark_bad_packed_object(p, sha1);
-                        unuse_pack(&w_curs);
-                        return NULL;
-                }
-        }
-
-        *type = unpack_object_header(p, &w_curs, &curpos, sizep);
-        switch (*type) {
+        /* PHASE 1: drill down to the innermost base object */
+        for (;;) {
+                off_t base_offset;
+                int i;
+                struct delta_base_cache_entry *ent;
+
+                ent = get_delta_base_cache_entry(p, curpos);
+                if (eq_delta_base_cache_entry(ent, p, curpos)) {
+                        type = ent->type;
+                        data = ent->data;
+                        size = ent->size;
+                        clear_delta_base_cache_entry(ent);
+                        base_from_cache = 1;
+                        break;
+                }
+
+                if (do_check_packed_object_crc && p->index_version > 1) {
+                        struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
+                        unsigned long len = revidx[1].offset - obj_offset;
+                        if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
+                                const unsigned char *sha1 =
+                                        nth_packed_object_sha1(p, revidx->nr);
+                                error("bad packed object CRC for %s",
+                                      sha1_to_hex(sha1));
+                                mark_bad_packed_object(p, sha1);
+                                unuse_pack(&w_curs);
+                                return NULL;
+                        }
+                }
+
+                type = unpack_object_header(p, &w_curs, &curpos, &size);
+                if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
+                        break;
+
+                base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
+                if (!base_offset) {
+                        error("failed to validate delta base reference "
+                              "at offset %"PRIuMAX" from %s",
+                              (uintmax_t)curpos, p->pack_name);
+                        /* bail to phase 2, in hopes of recovery */
+                        data = NULL;
+                        break;
+                }
+
+                /* push object, proceed to base */
+                if (delta_stack_nr >= delta_stack_alloc
+                    && delta_stack == small_delta_stack) {
+                        delta_stack_alloc = alloc_nr(delta_stack_nr);
+                        delta_stack = xmalloc(sizeof(*delta_stack)*delta_stack_alloc);
+                        memcpy(delta_stack, small_delta_stack,
+                               sizeof(*delta_stack)*delta_stack_nr);
+                } else {
+                        ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
+                }
+                i = delta_stack_nr++;
+                delta_stack[i].obj_offset = obj_offset;
+                delta_stack[i].curpos = curpos;
+                delta_stack[i].size = size;
+
+                curpos = obj_offset = base_offset;
+        }
+
+        /* PHASE 2: handle the base */
+        switch (type) {
         case OBJ_OFS_DELTA:
         case OBJ_REF_DELTA:
-                data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
-                                          obj_offset, type, sizep);
+                if (data)
+                        die("BUG in unpack_entry: left loop at a valid delta");
                 break;
         case OBJ_COMMIT:
@@ -1887 +2203 @@
         case OBJ_BLOB:
         case OBJ_TAG:
-                data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
+                if (!base_from_cache)
+                        data = unpack_compressed_entry(p, &w_curs, curpos, size);
                 break;
         default:
                 data = NULL;
                 error("unknown object type %i at offset %"PRIuMAX" in %s",
-                      *type, (uintmax_t)obj_offset, p->pack_name);
-        }
+                      type, (uintmax_t)obj_offset, p->pack_name);
+        }
+
+        /* PHASE 3: apply deltas in order */
+
+        /* invariants:
+         *   'data' holds the base data, or NULL if there was corruption
+         */
+        while (delta_stack_nr) {
+                void *delta_data;
+                void *base = data;
+                unsigned long delta_size, base_size = size;
+                int i;
+
+                data = NULL;
+
+                if (base)
+                        add_delta_base_cache(p, obj_offset, base, base_size, type);
+
+                if (!base) {
+                        /*
+                         * We're probably in deep shit, but let's try to fetch
+                         * the required base anyway from another pack or loose.
+                         * This is costly but should happen only in the presence
+                         * of a corrupted pack, and is better than failing outright.
+                         */
+                        struct revindex_entry *revidx;
+                        const unsigned char *base_sha1;
+                        revidx = find_pack_revindex(p, obj_offset);
+                        if (revidx) {
+                                base_sha1 = nth_packed_object_sha1(p, revidx->nr);
+                                error("failed to read delta base object %s"
+                                      " at offset %"PRIuMAX" from %s",
+                                      sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
+                                      p->pack_name);
+                                mark_bad_packed_object(p, base_sha1);
+                                base = read_object(base_sha1, &type, &base_size);
+                        }
+                }
+
+                i = --delta_stack_nr;
+                obj_offset = delta_stack[i].obj_offset;
+                curpos = delta_stack[i].curpos;
+                delta_size = delta_stack[i].size;
+
+                if (!base)
+                        continue;
+
+                delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
+
+                if (!delta_data) {
+                        error("failed to unpack compressed delta "
+                              "at offset %"PRIuMAX" from %s",
+                              (uintmax_t)curpos, p->pack_name);
+                        data = NULL;
+                        continue;
+                }
+
+                data = patch_delta(base, base_size,
+                                   delta_data, delta_size,
+                                   &size);
+
+                /*
+                 * We could not apply the delta; warn the user, but keep going.
+                 * Our failure will be noticed either in the next iteration of
+                 * the loop, or if this is the final delta, in the caller when
+                 * we return NULL. Those code paths will take care of making
+                 * a more explicit warning and retrying with another copy of
+                 * the object.
+                 */
+                if (!data)
+                        error("failed to apply delta");
+
+                free(delta_data);
+        }
+
+        *final_type = type;
+        *final_size = size;
+
         unuse_pack(&w_curs);
+
+        if (delta_stack != small_delta_stack)
+                free(delta_stack);
+
         return data;
 }
@@ -2054 +2452 @@
 }
 
+/*
+ * Iff a pack file contains the object named by sha1, return true and
+ * store its location to e.
+ */
 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 {
@@ -2066 +2468 @@
 
         for (p = packed_git; p; p = p->next) {
-                if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
-                        continue;
-
-                last_found_pack = p;
-                return 1;
+                if (p == last_found_pack)
+                        continue; /* we already checked this one */
+
+                if (fill_pack_entry(sha1, e, p)) {
+                        last_found_pack = p;
+                        return 1;
+                }
         }
         return 0;
@@ -2088 +2492 @@
 }
 
-static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
+static int sha1_loose_object_info(const unsigned char *sha1,
+                                  struct object_info *oi)
 {
         int status;
@@ -2096 +2501 @@
         char hdr[32];
 
+        if (oi->delta_base_sha1)
+                hashclr(oi->delta_base_sha1);
+
+        /*
+         * If we don't care about type or size, then we don't
+         * need to look inside the object at all. Note that we
+         * do not optimize out the stat call, even if the
+         * caller doesn't care about the disk-size, since our
+         * return value implicitly indicates whether the
+         * object even exists.
+         */
+        if (!oi->typep && !oi->sizep) {
+                struct stat st;
+                if (stat_sha1_file(sha1, &st) < 0)
+                        return -1;
+                if (oi->disk_sizep)
+                        *oi->disk_sizep = st.st_size;
+                return 0;
+        }
+
         map = map_sha1_file(sha1, &mapsize);
         if (!map)
-                return error("unable to find %s", sha1_to_hex(sha1));
+                return -1;
+        if (oi->disk_sizep)
+                *oi->disk_sizep = mapsize;
         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
                 status = error("unable to unpack %s header",
@@ -2104 +2531 @@
         else if ((status = parse_sha1_header(hdr, &size)) < 0)
                 status = error("unable to parse %s header", sha1_to_hex(sha1));
-        else if (sizep)
-                *sizep = size;
+        else if (oi->sizep)
+                *oi->sizep = size;
         git_inflate_end(&stream);
         munmap(map, mapsize);
-        return status;
-}
-
-/* returns enum object_type or negative */
-int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
+        if (oi->typep)
+                *oi->typep = status;
+        return 0;
+}
+
+int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi, unsigned flags)
 {
         struct cached_object *co;
         struct pack_entry e;
-        int status, rtype;
-
-        co = find_cached_object(sha1);
+        int rtype;
+        const unsigned char *real = lookup_replace_object_extended(sha1, flags);
+
+        co = find_cached_object(real);
         if (co) {
+                if (oi->typep)
+                        *(oi->typep) = co->type;
                 if (oi->sizep)
                         *(oi->sizep) = co->size;
+                if (oi->disk_sizep)
+                        *(oi->disk_sizep) = 0;
+                if (oi->delta_base_sha1)
+                        hashclr(oi->delta_base_sha1);
                 oi->whence = OI_CACHED;
-                return co->type;
-        }
-
-        if (!find_pack_entry(sha1, &e)) {
+                return 0;
+        }
+
+        if (!find_pack_entry(real, &e)) {
                 /* Most likely it's a loose object. */
-                status = sha1_loose_object_info(sha1, oi->sizep);
-                if (status >= 0) {
+                if (!sha1_loose_object_info(real, oi)) {
                         oi->whence = OI_LOOSE;
-                        return status;
+                        return 0;
                 }
 
                 /* Not a loose object; someone else may have just packed it. */
                 reprepare_packed_git();
-                if (!find_pack_entry(sha1, &e))
-                        return status;
-        }
-
-        status = packed_object_info(e.p, e.offset, oi->sizep, &rtype);
-        if (status < 0) {
-                mark_bad_packed_object(e.p, sha1);
-                status = sha1_object_info_extended(sha1, oi);
+                if (!find_pack_entry(real, &e))
+                        return -1;
+        }
+
+        rtype = packed_object_info(e.p, e.offset, oi);
+        if (rtype < 0) {
+                mark_bad_packed_object(e.p, real);
+                return sha1_object_info_extended(real, oi, 0);
         } else if (in_delta_base_cache(e.p, e.offset)) {
                 oi->whence = OI_DBCACHED;
@@ -2154 +2588 @@
         }
 
-        return status;
-}
-
+        return 0;
+}
+
+/* returns enum object_type or negative */
 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 {
-        struct object_info oi;
-
+        enum object_type type;
+        struct object_info oi = {NULL};
+
+        oi.typep = &type;
         oi.sizep = sizep;
-        return sha1_object_info_extended(sha1, &oi);
+        if (sha1_object_info_extended(sha1, &oi, LOOKUP_REPLACE_OBJECT) < 0)
+                return -1;
+        return type;
 }
 
@@ -2197 +2636 @@
         if (has_sha1_file(sha1) || find_cached_object(sha1))
                 return 0;
-        if (cached_object_alloc <= cached_object_nr) {
-                cached_object_alloc = alloc_nr(cached_object_alloc);
-                cached_objects = xrealloc(cached_objects,
-                                          sizeof(*cached_objects) *
-                                          cached_object_alloc);
-        }
+        ALLOC_GROW(cached_objects, cached_object_nr + 1, cached_object_alloc);
         co = &cached_objects[cached_object_nr++];
         co->size = len;
@@ -2250 +2684 @@
 {
         void *data;
-        char *path;
         const struct packed_git *p;
-        const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
-                ? lookup_replace_object(sha1) : sha1;
+        const unsigned char *repl = lookup_replace_object_extended(sha1, flag);
 
         errno = 0;
@@ -2269 +2701 @@
 
         if (has_loose_object(repl)) {
-                path = sha1_file_name(sha1);
+                const char *path = sha1_file_name(sha1);
+
                 die("loose object %s (stored in %s) is corrupt",
                     sha1_to_hex(repl), path);
@@ -2380 +2813 @@
         if (ret) {
                 if (ret != EEXIST) {
-                        return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
+                        return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
                 }
                 /* FIXME!!! Collision check here ? */
@@ -2447 +2880 @@
                 memcpy(buffer, filename, dirlen);
                 buffer[dirlen-1] = 0;
-                if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
+                if (mkdir(buffer, 0777) && errno != EEXIST)
+                        return -1;
+                if (adjust_shared_perm(buffer))
                         return -1;
 
@@ -2465 +2900 @@
         git_SHA_CTX c;
         unsigned char parano_sha1[20];
-        char *filename;
         static char tmp_file[PATH_MAX];
-
-        filename = sha1_file_name(sha1);
+        const char *filename = sha1_file_name(sha1);
+
         fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
         if (fd < 0) {
                 if (errno == EACCES)
-                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
+                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
                 else
-                        return error("unable to create temporary sha1 filename %s: %s\n", tmp_file, strerror(errno));
+                        return error("unable to create temporary file: %s", strerror(errno));
         }
 
@@ -2585 +3019 @@
         if (find_pack_entry(sha1, &e))
                 return 1;
-        return has_loose_object(sha1);
+        if (has_loose_object(sha1))
+                return 1;
+        reprepare_packed_git();
+        return find_pack_entry(sha1, &e);
 }