t: translate SIGINT to an exit
[gitweb.git] / sha1_file.c
index 263cf71c27fa81f60da5a8688d899b66b1967d23..69a60ec88bad190f885cd89a93573236a88ddbd9 100644 (file)
@@ -8,6 +8,7 @@
  */
 #include "cache.h"
 #include "string-list.h"
+#include "lockfile.h"
 #include "delta.h"
 #include "pack.h"
 #include "blob.h"
@@ -21,6 +22,7 @@
 #include "sha1-lookup.h"
 #include "bulk-checkin.h"
 #include "streaming.h"
+#include "dir.h"
 
 #ifndef O_NOATIME
 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
@@ -56,6 +58,12 @@ static struct cached_object empty_tree = {
        0
 };
 
+/*
+ * 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;
 
 static struct cached_object *find_cached_object(const unsigned char *sha1)
@@ -101,45 +109,63 @@ int mkdir_in_gitdir(const char *path)
        return adjust_shared_perm(path);
 }
 
-int safe_create_leading_directories(char *path)
+enum scld_error safe_create_leading_directories(char *path)
 {
-       char *pos = path + offset_1st_component(path);
-       struct stat st;
+       char *next_component = path + offset_1st_component(path);
+       enum scld_error ret = SCLD_OK;
 
-       while (pos) {
-               pos = strchr(pos, '/');
-               if (!pos)
+       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;
+                       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;
                }
-               *pos++ = '/';
+               *slash = slash_character;
        }
-       return 0;
+       return ret;
 }
 
-int safe_create_leading_directories_const(const char *path)
+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;
 }
@@ -156,17 +182,7 @@ static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
        }
 }
 
-/*
- * 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];
        const char *objdir;
@@ -186,6 +202,11 @@ char *sha1_file_name(const unsigned char *sha1)
        return buf;
 }
 
+/*
+ * 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)
 {
@@ -230,8 +251,6 @@ char *sha1_pack_index_name(const unsigned char *sha1)
 struct alternate_object_database *alt_odb_list;
 static struct alternate_object_database **alt_odb_tail;
 
-static int git_open_noatime(const char *name);
-
 /*
  * Prepare alternate object database registry.
  *
@@ -247,9 +266,9 @@ static int git_open_noatime(const char *name);
  * SHA1, an extra slash for the first level indirection, and the
  * terminating NUL.
  */
-static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth)
+static int link_alt_odb_entry(const char *entry, const char *relative_base,
+       int depth, const char *normalized_objdir)
 {
-       const char *objdir = get_object_directory();
        struct alternate_object_database *ent;
        struct alternate_object_database *alt;
        int pfxlen, entlen;
@@ -294,12 +313,13 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base, int
         * thing twice, or object directory itself.
         */
        for (alt = alt_odb_list; alt; alt = alt->next) {
-               if (!memcmp(ent->base, alt->base, pfxlen)) {
+               if (pfxlen == alt->name - alt->base - 1 &&
+                   !memcmp(ent->base, alt->base, pfxlen)) {
                        free(ent);
                        return -1;
                }
        }
-       if (!strcmp(ent->base, objdir)) {
+       if (!strcmp_icase(ent->base, normalized_objdir)) {
                free(ent);
                return -1;
        }
@@ -323,6 +343,7 @@ static void link_alt_odb_entries(const char *alt, int len, int sep,
        struct string_list entries = STRING_LIST_INIT_NODUP;
        char *alt_copy;
        int i;
+       struct strbuf objdirbuf = STRBUF_INIT;
 
        if (depth > 5) {
                error("%s: ignoring alternate object stores, nesting too deep.",
@@ -330,6 +351,9 @@ static void link_alt_odb_entries(const char *alt, int len, int sep,
                return;
        }
 
+       strbuf_add_absolute_path(&objdirbuf, get_object_directory());
+       normalize_path_copy(objdirbuf.buf, objdirbuf.buf);
+
        alt_copy = xmemdupz(alt, len);
        string_list_split_in_place(&entries, alt_copy, sep, -1);
        for (i = 0; i < entries.nr; i++) {
@@ -340,11 +364,12 @@ static void link_alt_odb_entries(const char *alt, int len, int sep,
                        error("%s: ignoring relative alternate object store %s",
                                        relative_base, entry);
                } else {
-                       link_alt_odb_entry(entry, relative_base, depth);
+                       link_alt_odb_entry(entry, relative_base, depth, objdirbuf.buf);
                }
        }
        string_list_clear(&entries, 0);
        free(alt_copy);
+       strbuf_release(&objdirbuf);
 }
 
 void read_info_alternates(const char * relative_base, int depth)
@@ -388,14 +413,18 @@ void add_to_alternates_file(const char *reference)
                link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
 }
 
-void foreach_alt_odb(alt_odb_fn fn, void *cb)
+int foreach_alt_odb(alt_odb_fn fn, void *cb)
 {
        struct alternate_object_database *ent;
+       int r = 0;
 
        prepare_alt_odb();
-       for (ent = alt_odb_list; ent; ent = ent->next)
-               if (fn(ent, cb))
-                       return;
+       for (ent = alt_odb_list; ent; ent = ent->next) {
+               r = fn(ent, cb);
+               if (r)
+                       break;
+       }
+       return r;
 }
 
 void prepare_alt_odb(void)
@@ -414,28 +443,53 @@ void prepare_alt_odb(void)
        read_info_alternates(get_object_directory(), 0);
 }
 
-static int has_loose_object_local(const unsigned char *sha1)
+static int freshen_file(const char *fn)
 {
-       char *name = sha1_file_name(sha1);
-       return !access(name, F_OK);
+       struct utimbuf t;
+       t.actime = t.modtime = time(NULL);
+       return !utime(fn, &t);
 }
 
-int has_loose_object_nonlocal(const unsigned char *sha1)
+static int check_and_freshen_file(const char *fn, int freshen)
+{
+       if (access(fn, F_OK))
+               return 0;
+       if (freshen && freshen_file(fn))
+               return 0;
+       return 1;
+}
+
+static int check_and_freshen_local(const unsigned char *sha1, int freshen)
+{
+       return check_and_freshen_file(sha1_file_name(sha1), freshen);
+}
+
+static int check_and_freshen_nonlocal(const unsigned char *sha1, int freshen)
 {
        struct alternate_object_database *alt;
        prepare_alt_odb();
        for (alt = alt_odb_list; alt; alt = alt->next) {
                fill_sha1_path(alt->name, sha1);
-               if (!access(alt->base, F_OK))
+               if (check_and_freshen_file(alt->base, freshen))
                        return 1;
        }
        return 0;
 }
 
+static int check_and_freshen(const unsigned char *sha1, int freshen)
+{
+       return check_and_freshen_local(sha1, freshen) ||
+              check_and_freshen_nonlocal(sha1, freshen);
+}
+
+int has_loose_object_nonlocal(const unsigned char *sha1)
+{
+       return check_and_freshen_nonlocal(sha1, 0);
+}
+
 static int has_loose_object(const unsigned char *sha1)
 {
-       return has_loose_object_local(sha1) ||
-              has_loose_object_nonlocal(sha1);
+       return check_and_freshen(sha1, 0);
 }
 
 static unsigned int pack_used_ctr;
@@ -469,7 +523,12 @@ void pack_report(void)
                sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
 }
 
-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;
        struct pack_idx_header *hdr;
@@ -605,7 +664,7 @@ static void scan_windows(struct packed_git *p,
        }
 }
 
-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;
        struct pack_window *lru_w = NULL, *lru_l = NULL;
@@ -619,15 +678,8 @@ static int unuse_one_window(struct packed_git *current, int keep_fd)
                pack_mapped -= lru_w->len;
                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--;
                return 1;
@@ -635,21 +687,37 @@ static int unuse_one_window(struct packed_git *current, int keep_fd)
        return 0;
 }
 
-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 */
 }
 
+static void mmap_limit_check(size_t length)
+{
+       static size_t limit = 0;
+       if (!limit) {
+               limit = git_env_ulong("GIT_MMAP_LIMIT", 0);
+               if (!limit)
+                       limit = SIZE_MAX;
+       }
+       if (length > limit)
+               die("attempting to mmap %"PRIuMAX" over limit %"PRIuMAX,
+                   (uintmax_t)length, (uintmax_t)limit);
+}
+
 void *xmmap(void *start, size_t length,
        int prot, int flags, int fd, off_t offset)
 {
-       void *ret = mmap(start, length, prot, flags, fd, offset);
+       void *ret;
+
+       mmap_limit_check(length);
+       ret = mmap(start, length, prot, flags, fd, offset);
        if (ret == MAP_FAILED) {
                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)
                        die_errno("Out of memory? mmap failed");
@@ -772,7 +840,7 @@ void close_pack_index(struct packed_git *p)
  * contain the same set of objects as an existing one.  In that case
  * 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
  * reprepare_packed_git().
@@ -805,15 +873,38 @@ void free_pack_by_name(const char *pack_name)
 static unsigned int get_max_fd_limit(void)
 {
 #ifdef RLIMIT_NOFILE
-       struct rlimit lim;
+       {
+               struct rlimit lim;
+
+               if (!getrlimit(RLIMIT_NOFILE, &lim))
+                       return lim.rlim_cur;
+       }
+#endif
 
-       if (getrlimit(RLIMIT_NOFILE, &lim))
-               die_errno("cannot get RLIMIT_NOFILE");
+#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
 
-       return lim.rlim_cur;
-#elif defined(_SC_OPEN_MAX)
-       return sysconf(_SC_OPEN_MAX);
-#elif defined(OPEN_MAX)
+#ifdef OPEN_MAX
        return OPEN_MAX;
 #else
        return 1; /* see the caller ;-) */
@@ -961,7 +1052,7 @@ unsigned char *use_pack(struct packed_git *p,
                        win->len = (size_t)len;
                        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,
                                PROT_READ, MAP_PRIVATE,
@@ -1007,7 +1098,7 @@ static struct packed_git *alloc_packed_git(int extra)
 
 static void try_to_free_pack_memory(size_t size)
 {
-       release_pack_memory(size, -1);
+       release_pack_memory(size);
 }
 
 struct packed_git *add_packed_git(const char *path, int path_len, int local)
@@ -1077,53 +1168,127 @@ void install_packed_git(struct packed_git *pack)
        packed_git = pack;
 }
 
+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;
+
+       string_list_sort(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)
 {
-       /* Ensure that this buffer is large enough so that we can
-          append "/pack/" without clobbering the stack even if
-          strlen(objdir) were PATH_MAX.  */
-       char path[PATH_MAX + 1 + 4 + 1 + 1];
-       int len;
+       struct strbuf path = STRBUF_INIT;
+       size_t dirnamelen;
        DIR *dir;
        struct dirent *de;
+       struct string_list garbage = STRING_LIST_INIT_DUP;
 
-       sprintf(path, "%s/pack", objdir);
-       len = strlen(path);
-       dir = opendir(path);
+       strbuf_addstr(&path, objdir);
+       strbuf_addstr(&path, "/pack");
+       dir = opendir(path.buf);
        if (!dir) {
                if (errno != ENOENT)
                        error("unable to open object pack directory: %s: %s",
-                             path, strerror(errno));
+                             path.buf, strerror(errno));
+               strbuf_release(&path);
                return;
        }
-       path[len++] = '/';
+       strbuf_addch(&path, '/');
+       dirnamelen = path.len;
        while ((de = readdir(dir)) != NULL) {
-               int namelen = strlen(de->d_name);
                struct packed_git *p;
+               size_t base_len;
 
-               if (!has_extension(de->d_name, ".idx"))
-                       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;
+               strbuf_setlen(&path, dirnamelen);
+               strbuf_addstr(&path, de->d_name);
+
+               base_len = path.len;
+               if (strip_suffix_mem(path.buf, &base_len, ".idx")) {
+                       /* Don't reopen a pack we already have. */
+                       for (p = packed_git; p; p = p->next) {
+                               size_t len;
+                               if (strip_suffix(p->pack_name, ".pack", &len) &&
+                                   len == base_len &&
+                                   !memcmp(p->pack_name, path.buf, len))
+                                       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.buf, path.len, local)) != NULL)
+                               install_packed_git(p);
                }
-               if (p)
-                       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)
+
+               if (!report_garbage)
                        continue;
-               install_packed_git(p);
+
+               if (ends_with(de->d_name, ".idx") ||
+                   ends_with(de->d_name, ".pack") ||
+                   ends_with(de->d_name, ".bitmap") ||
+                   ends_with(de->d_name, ".keep"))
+                       string_list_append(&garbage, path.buf);
+               else
+                       report_garbage("garbage found", path.buf);
        }
        closedir(dir);
+       report_pack_garbage(&garbage);
+       string_list_clear(&garbage, 0);
+       strbuf_release(&path);
 }
 
 static int sort_pack(const void *a_, const void *b_)
@@ -1200,7 +1365,6 @@ void prepare_packed_git(void)
 
 void reprepare_packed_git(void)
 {
-       discard_revindex();
        prepare_packed_git_run_once = 0;
        prepare_packed_git();
 }
@@ -1264,6 +1428,10 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
                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);
@@ -1273,7 +1441,7 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
        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;
 
@@ -1292,25 +1460,45 @@ static int git_open_noatime(const char *name)
        }
 }
 
+static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
+{
+       struct alternate_object_database *alt;
+
+       if (!lstat(sha1_file_name(sha1), st))
+               return 0;
+
+       prepare_alt_odb();
+       errno = ENOENT;
+       for (alt = alt_odb_list; alt; alt = alt->next) {
+               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;
-       char *name = sha1_file_name(sha1);
        struct alternate_object_database *alt;
+       int most_interesting_errno;
 
-       fd = git_open_noatime(name);
+       fd = git_open_noatime(sha1_file_name(sha1));
        if (fd >= 0)
                return fd;
+       most_interesting_errno = errno;
 
        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);
                fd = git_open_noatime(alt->base);
                if (fd >= 0)
                        return fd;
+               if (most_interesting_errno == ENOENT)
+                       most_interesting_errno = errno;
        }
+       errno = most_interesting_errno;
        return -1;
 }
 
@@ -1338,51 +1526,6 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
        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;
-}
-
 unsigned long unpack_object_header_buffer(const unsigned char *buf,
                unsigned long len, enum object_type *type, unsigned long *sizep)
 {
@@ -1410,14 +1553,6 @@ unsigned long unpack_object_header_buffer(const unsigned char *buf,
 
 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));
        stream->next_in = map;
@@ -1425,27 +1560,6 @@ int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long ma
        stream->next_out = buffer;
        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);
 }
@@ -1637,48 +1751,36 @@ static off_t get_delta_base(struct packed_git *p,
        return base_offset;
 }
 
-/* forward declaration for a mutually recursive function */
-static int packed_object_info(struct packed_git *p, off_t offset,
-                             unsigned long *sizep, int *rtype);
+/*
+ * 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;
+               off_t base_offset = get_delta_base(p, w_curs, &curpos,
+                                                  type, delta_obj_offset);
 
-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;
+               if (!base_offset)
+                       return NULL;
 
-       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) {
-               struct revindex_entry *revidx;
-               const unsigned char *base_sha1;
                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 NULL;
 
-       return type;
+               return nth_packed_object_sha1(p, revidx->nr);
+       } else
+               return NULL;
 }
 
 int unpack_object_header(struct packed_git *p,
@@ -1707,36 +1809,154 @@ int unpack_object_header(struct packed_git *p,
        return type;
 }
 
-static int packed_object_info(struct packed_git *p, off_t obj_offset,
-                             unsigned long *sizep, int *rtype)
+static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
 {
-       struct pack_window *w_curs = NULL;
-       unsigned long size;
-       off_t curpos = obj_offset;
-       enum object_type type;
+       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;
+}
 
-       type = unpack_object_header(p, &w_curs, &curpos, &size);
-       if (rtype)
-               *rtype = type; /* representation 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:
                error("unknown object type %i at offset %"PRIuMAX" in %s",
                      type, (uintmax_t)obj_offset, p->pack_name);
                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;
 }
@@ -1750,7 +1970,9 @@ static void *unpack_compressed_entry(struct packed_git *p,
        git_zstream stream;
        unsigned char *buffer, *in;
 
-       buffer = xmallocz(size);
+       buffer = xmallocz_gently(size);
+       if (!buffer)
+               return NULL;
        memset(&stream, 0, sizeof(stream));
        stream.next_out = buffer;
        stream.avail_out = size + 1;
@@ -1800,32 +2022,51 @@ static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
        return hash % MAX_DELTA_CACHE;
 }
 
-static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
+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);
-       struct delta_base_cache_entry *ent = delta_base_cache + hash;
+       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)
+{
+       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;
+}
+
 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
        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;
 
-       ret = ent->data;
-       if (!ret || ent->p != p || ent->base_offset != base_offset)
+       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);
 
-       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 {
+       ret = ent->data;
+
+       if (!keep_cache)
+               clear_delta_base_cache_entry(ent);
+       else
                ret = xmemdupz(ent->data, ent->size);
-       }
        *type = ent->type;
        *base_size = ent->size;
        return ret;
@@ -1889,131 +2130,200 @@ static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
 static void *read_object(const unsigned char *sha1, enum object_type *type,
                         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_file) {
-               log_file = fopen(log_pack_access, "w");
-               if (!log_file) {
-                       error("cannot open pack access log '%s' for writing: %s",
-                             log_pack_access, strerror(errno));
-                       log_pack_access = NULL;
-                       return;
-               }
-       }
-       fprintf(log_file, "%s %"PRIuMAX"\n",
-               p->pack_name, (uintmax_t)obj_offset);
-       fflush(log_file);
+       static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
+       trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
+                        p->pack_name, (uintmax_t)obj_offset);
 }
 
 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;
+       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)
-               write_pack_access_log(p, obj_offset);
+       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;
+       /* 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;
        }
 
-       *type = unpack_object_header(p, &w_curs, &curpos, sizep);
-       switch (*type) {
+       /* 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:
        case OBJ_TREE:
        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;
 }
 
@@ -2173,6 +2483,10 @@ static int fill_pack_entry(const unsigned char *sha1,
        return 1;
 }
 
+/*
+ * 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)
 {
        struct packed_git *p;
@@ -2185,11 +2499,13 @@ static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
                return 1;
 
        for (p = packed_git; p; p = p->next) {
-               if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
-                       continue;
+               if (p == last_found_pack)
+                       continue; /* we already checked this one */
 
-               last_found_pack = p;
-               return 1;
+               if (fill_pack_entry(sha1, e, p)) {
+                       last_found_pack = p;
+                       return 1;
+               }
        }
        return 0;
 }
@@ -2207,7 +2523,8 @@ struct packed_git *find_sha1_pack(const unsigned char *sha1,
 
 }
 
-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;
        unsigned long mapsize, size;
@@ -2215,54 +2532,83 @@ static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *size
        git_zstream stream;
        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",
                               sha1_to_hex(sha1));
        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;
+       if (oi->typep)
+               *oi->typep = status;
+       return 0;
 }
 
-/* returns enum object_type or negative */
-int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
+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;
+       int rtype;
+       const unsigned char *real = lookup_replace_object_extended(sha1, flags);
 
-       co = find_cached_object(sha1);
+       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;
+               return 0;
        }
 
-       if (!find_pack_entry(sha1, &e)) {
+       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;
+               if (!find_pack_entry(real, &e))
+                       return -1;
        }
 
-       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);
+       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;
        } else {
@@ -2273,15 +2619,20 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
                                         rtype == OBJ_OFS_DELTA);
        }
 
-       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;
 }
 
 static void *read_packed_sha1(const unsigned char *sha1,
@@ -2316,12 +2667,7 @@ int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
        hash_sha1_file(buf, len, typename(type), sha1);
        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;
        co->type = type;
@@ -2369,10 +2715,8 @@ void *read_sha1_file_extended(const unsigned char *sha1,
                              unsigned flag)
 {
        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;
        data = read_object(repl, type, size);
@@ -2388,7 +2732,8 @@ void *read_sha1_file_extended(const unsigned char *sha1,
                    sha1_to_hex(repl), sha1_to_hex(sha1));
 
        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);
        }
@@ -2566,7 +2911,9 @@ static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
                /* Make sure the directory exists */
                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;
 
                /* Try again */
@@ -2584,10 +2931,9 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
        git_zstream stream;
        git_SHA_CTX c;
        unsigned char parano_sha1[20];
-       char *filename;
        static char tmp_file[PATH_MAX];
+       const char *filename = sha1_file_name(sha1);
 
-       filename = sha1_file_name(sha1);
        fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
        if (fd < 0) {
                if (errno == EACCES)
@@ -2646,6 +2992,17 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
        return move_temp_to_file(tmp_file, filename);
 }
 
+static int freshen_loose_object(const unsigned char *sha1)
+{
+       return check_and_freshen(sha1, 1);
+}
+
+static int freshen_packed_object(const unsigned char *sha1)
+{
+       struct pack_entry e;
+       return find_pack_entry(sha1, &e) && freshen_file(e.p->pack_name);
+}
+
 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 {
        unsigned char sha1[20];
@@ -2658,7 +3015,7 @@ int write_sha1_file(const void *buf, unsigned long len, const char *type, unsign
        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
        if (returnsha1)
                hashcpy(returnsha1, sha1);
-       if (has_sha1_file(sha1))
+       if (freshen_loose_object(sha1) || freshen_packed_object(sha1))
                return 0;
        return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
 }
@@ -2704,7 +3061,10 @@ int has_sha1_file(const unsigned char *sha1)
 
        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);
 }
 
 static void check_tree(const void *buf, size_t size)
@@ -2774,6 +3134,29 @@ static int index_mem(unsigned char *sha1, void *buf, size_t size,
        return ret;
 }
 
+static int index_stream_convert_blob(unsigned char *sha1, int fd,
+                                    const char *path, unsigned flags)
+{
+       int ret;
+       const int write_object = flags & HASH_WRITE_OBJECT;
+       struct strbuf sbuf = STRBUF_INIT;
+
+       assert(path);
+       assert(would_convert_to_git_filter_fd(path));
+
+       convert_to_git_filter_fd(path, fd, &sbuf,
+                                write_object ? safe_crlf : SAFE_CRLF_FALSE);
+
+       if (write_object)
+               ret = write_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
+                                     sha1);
+       else
+               ret = hash_sha1_file(sbuf.buf, sbuf.len, typename(OBJ_BLOB),
+                                    sha1);
+       strbuf_release(&sbuf);
+       return ret;
+}
+
 static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
                      const char *path, unsigned flags)
 {
@@ -2839,15 +3222,22 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st,
             enum object_type type, const char *path, unsigned flags)
 {
        int ret;
-       size_t size = xsize_t(st->st_size);
 
-       if (!S_ISREG(st->st_mode))
+       /*
+        * Call xsize_t() only when needed to avoid potentially unnecessary
+        * die() for large files.
+        */
+       if (type == OBJ_BLOB && path && would_convert_to_git_filter_fd(path))
+               ret = index_stream_convert_blob(sha1, fd, path, flags);
+       else if (!S_ISREG(st->st_mode))
                ret = index_pipe(sha1, fd, type, path, flags);
-       else if (size <= big_file_threshold || type != OBJ_BLOB ||
-                (path && would_convert_to_git(path, NULL, 0, 0)))
-               ret = index_core(sha1, fd, size, type, path, flags);
+       else if (st->st_size <= big_file_threshold || type != OBJ_BLOB ||
+                (path && would_convert_to_git(path)))
+               ret = index_core(sha1, fd, xsize_t(st->st_size), type, path,
+                                flags);
        else
-               ret = index_stream(sha1, fd, size, type, path, flags);
+               ret = index_stream(sha1, fd, xsize_t(st->st_size), type, path,
+                                  flags);
        close(fd);
        return ret;
 }
@@ -2912,3 +3302,167 @@ void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
                die("%s is not a valid '%s' object", sha1_to_hex(sha1),
                    typename(expect));
 }
+
+static int for_each_file_in_obj_subdir(int subdir_nr,
+                                      struct strbuf *path,
+                                      each_loose_object_fn obj_cb,
+                                      each_loose_cruft_fn cruft_cb,
+                                      each_loose_subdir_fn subdir_cb,
+                                      void *data)
+{
+       size_t baselen = path->len;
+       DIR *dir = opendir(path->buf);
+       struct dirent *de;
+       int r = 0;
+
+       if (!dir) {
+               if (errno == ENOENT)
+                       return 0;
+               return error("unable to open %s: %s", path->buf, strerror(errno));
+       }
+
+       while ((de = readdir(dir))) {
+               if (is_dot_or_dotdot(de->d_name))
+                       continue;
+
+               strbuf_setlen(path, baselen);
+               strbuf_addf(path, "/%s", de->d_name);
+
+               if (strlen(de->d_name) == 38)  {
+                       char hex[41];
+                       unsigned char sha1[20];
+
+                       snprintf(hex, sizeof(hex), "%02x%s",
+                                subdir_nr, de->d_name);
+                       if (!get_sha1_hex(hex, sha1)) {
+                               if (obj_cb) {
+                                       r = obj_cb(sha1, path->buf, data);
+                                       if (r)
+                                               break;
+                               }
+                               continue;
+                       }
+               }
+
+               if (cruft_cb) {
+                       r = cruft_cb(de->d_name, path->buf, data);
+                       if (r)
+                               break;
+               }
+       }
+       strbuf_setlen(path, baselen);
+
+       if (!r && subdir_cb)
+               r = subdir_cb(subdir_nr, path->buf, data);
+
+       closedir(dir);
+       return r;
+}
+
+int for_each_loose_file_in_objdir_buf(struct strbuf *path,
+                           each_loose_object_fn obj_cb,
+                           each_loose_cruft_fn cruft_cb,
+                           each_loose_subdir_fn subdir_cb,
+                           void *data)
+{
+       size_t baselen = path->len;
+       int r = 0;
+       int i;
+
+       for (i = 0; i < 256; i++) {
+               strbuf_addf(path, "/%02x", i);
+               r = for_each_file_in_obj_subdir(i, path, obj_cb, cruft_cb,
+                                               subdir_cb, data);
+               strbuf_setlen(path, baselen);
+               if (r)
+                       break;
+       }
+
+       return r;
+}
+
+int for_each_loose_file_in_objdir(const char *path,
+                                 each_loose_object_fn obj_cb,
+                                 each_loose_cruft_fn cruft_cb,
+                                 each_loose_subdir_fn subdir_cb,
+                                 void *data)
+{
+       struct strbuf buf = STRBUF_INIT;
+       int r;
+
+       strbuf_addstr(&buf, path);
+       r = for_each_loose_file_in_objdir_buf(&buf, obj_cb, cruft_cb,
+                                             subdir_cb, data);
+       strbuf_release(&buf);
+
+       return r;
+}
+
+struct loose_alt_odb_data {
+       each_loose_object_fn *cb;
+       void *data;
+};
+
+static int loose_from_alt_odb(struct alternate_object_database *alt,
+                             void *vdata)
+{
+       struct loose_alt_odb_data *data = vdata;
+       struct strbuf buf = STRBUF_INIT;
+       int r;
+
+       /* copy base not including trailing '/' */
+       strbuf_add(&buf, alt->base, alt->name - alt->base - 1);
+       r = for_each_loose_file_in_objdir_buf(&buf,
+                                             data->cb, NULL, NULL,
+                                             data->data);
+       strbuf_release(&buf);
+       return r;
+}
+
+int for_each_loose_object(each_loose_object_fn cb, void *data)
+{
+       struct loose_alt_odb_data alt;
+       int r;
+
+       r = for_each_loose_file_in_objdir(get_object_directory(),
+                                         cb, NULL, NULL, data);
+       if (r)
+               return r;
+
+       alt.cb = cb;
+       alt.data = data;
+       return foreach_alt_odb(loose_from_alt_odb, &alt);
+}
+
+static int for_each_object_in_pack(struct packed_git *p, each_packed_object_fn cb, void *data)
+{
+       uint32_t i;
+       int r = 0;
+
+       for (i = 0; i < p->num_objects; i++) {
+               const unsigned char *sha1 = nth_packed_object_sha1(p, i);
+
+               if (!sha1)
+                       return error("unable to get sha1 of object %u in %s",
+                                    i, p->pack_name);
+
+               r = cb(sha1, p, i, data);
+               if (r)
+                       break;
+       }
+       return r;
+}
+
+int for_each_packed_object(each_packed_object_fn cb, void *data)
+{
+       struct packed_git *p;
+       int r = 0;
+
+       prepare_packed_git();
+       for (p = packed_git; p; p = p->next) {
+               r = for_each_object_in_pack(p, cb, data);
+               if (r)
+                       break;
+       }
+       return r;
+}