git_open(): untangle possible NOATIME and CLOEXEC interactions
[gitweb.git] / sha1_file.c
index f7054d3d32e2daf28e207918923fad308ff83896..dfbf398183d5b9593b56c27b8cf5011d0ddd5e84 100644 (file)
@@ -23,6 +23,9 @@
 #include "bulk-checkin.h"
 #include "streaming.h"
 #include "dir.h"
+#include "mru.h"
+#include "list.h"
+#include "mergesort.h"
 
 #ifndef O_NOATIME
 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
 static inline uintmax_t sz_fmt(size_t s) { return s; }
 
 const unsigned char null_sha1[20];
+const struct object_id null_oid;
+const struct object_id empty_tree_oid = {
+       EMPTY_TREE_SHA1_BIN_LITERAL
+};
+const struct object_id empty_blob_oid = {
+       EMPTY_BLOB_SHA1_BIN_LITERAL
+};
 
 /*
  * This is meant to hold a *small* number of objects that you would
@@ -58,14 +68,6 @@ 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)
 {
        int i;
@@ -170,36 +172,42 @@ enum scld_error safe_create_leading_directories_const(const char *path)
        return result;
 }
 
-static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
+static void fill_sha1_path(struct strbuf *buf, const unsigned char *sha1)
 {
        int i;
        for (i = 0; i < 20; i++) {
                static char hex[] = "0123456789abcdef";
                unsigned int val = sha1[i];
-               char *pos = pathbuf + i*2 + (i > 0);
-               *pos++ = hex[val >> 4];
-               *pos = hex[val & 0xf];
+               strbuf_addch(buf, hex[val >> 4]);
+               strbuf_addch(buf, hex[val & 0xf]);
+               if (!i)
+                       strbuf_addch(buf, '/');
        }
 }
 
 const char *sha1_file_name(const unsigned char *sha1)
 {
-       static char buf[PATH_MAX];
-       const char *objdir;
-       int len;
+       static struct strbuf buf = STRBUF_INIT;
+
+       strbuf_reset(&buf);
+       strbuf_addf(&buf, "%s/", get_object_directory());
 
-       objdir = get_object_directory();
-       len = strlen(objdir);
+       fill_sha1_path(&buf, sha1);
+       return buf.buf;
+}
 
-       /* '/' + sha1(2) + '/' + sha1(38) + '\0' */
-       if (len + 43 > PATH_MAX)
-               die("insanely long object directory %s", objdir);
-       memcpy(buf, objdir, len);
-       buf[len] = '/';
-       buf[len+3] = '/';
-       buf[len+42] = '\0';
-       fill_sha1_path(buf + len + 1, sha1);
-       return buf;
+struct strbuf *alt_scratch_buf(struct alternate_object_database *alt)
+{
+       strbuf_setlen(&alt->scratch, alt->base_len);
+       return &alt->scratch;
+}
+
+static const char *alt_sha1_path(struct alternate_object_database *alt,
+                                const unsigned char *sha1)
+{
+       struct strbuf *buf = alt_scratch_buf(alt);
+       fill_sha1_path(buf, sha1);
+       return buf->buf;
 }
 
 /*
@@ -208,49 +216,59 @@ const char *sha1_file_name(const unsigned char *sha1)
  * 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)
+                               struct strbuf *buf,
+                               const char *which)
 {
-       static const char hex[] = "0123456789abcdef";
-       char *buf;
-       int i;
-
-       if (!*base) {
-               const char *sha1_file_directory = get_object_directory();
-               int len = strlen(sha1_file_directory);
-               *base = xmalloc(len + 60);
-               sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
-                       sha1_file_directory, which);
-               *name = *base + len + 11;
-       }
-
-       buf = *name;
-
-       for (i = 0; i < 20; i++) {
-               unsigned int val = *sha1++;
-               *buf++ = hex[val >> 4];
-               *buf++ = hex[val & 0xf];
-       }
-
-       return *base;
+       strbuf_reset(buf);
+       strbuf_addf(buf, "%s/pack/pack-%s.%s", get_object_directory(),
+                   sha1_to_hex(sha1), which);
+       return buf->buf;
 }
 
 char *sha1_pack_name(const unsigned char *sha1)
 {
-       static char *name, *base;
-
-       return sha1_get_pack_name(sha1, &name, &base, "pack");
+       static struct strbuf buf = STRBUF_INIT;
+       return sha1_get_pack_name(sha1, &buf, "pack");
 }
 
 char *sha1_pack_index_name(const unsigned char *sha1)
 {
-       static char *name, *base;
-
-       return sha1_get_pack_name(sha1, &name, &base, "idx");
+       static struct strbuf buf = STRBUF_INIT;
+       return sha1_get_pack_name(sha1, &buf, "idx");
 }
 
 struct alternate_object_database *alt_odb_list;
 static struct alternate_object_database **alt_odb_tail;
 
+/*
+ * Return non-zero iff the path is usable as an alternate object database.
+ */
+static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir)
+{
+       struct alternate_object_database *alt;
+
+       /* Detect cases where alternate disappeared */
+       if (!is_directory(path->buf)) {
+               error("object directory %s does not exist; "
+                     "check .git/objects/info/alternates.",
+                     path->buf);
+               return 0;
+       }
+
+       /*
+        * Prevent the common mistake of listing the same
+        * thing twice, or object directory itself.
+        */
+       for (alt = alt_odb_list; alt; alt = alt->next) {
+               if (!fspathcmp(path->buf, alt->path))
+                       return 0;
+       }
+       if (!fspathcmp(path->buf, normalized_objdir))
+               return 0;
+
+       return 1;
+}
+
 /*
  * Prepare alternate object database registry.
  *
@@ -270,8 +288,6 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
        int depth, const char *normalized_objdir)
 {
        struct alternate_object_database *ent;
-       struct alternate_object_database *alt;
-       int pfxlen, entlen;
        struct strbuf pathbuf = STRBUF_INIT;
 
        if (!is_absolute_path(entry) && relative_base) {
@@ -280,49 +296,26 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
        }
        strbuf_addstr(&pathbuf, entry);
 
-       normalize_path_copy(pathbuf.buf, pathbuf.buf);
-
-       pfxlen = strlen(pathbuf.buf);
+       if (strbuf_normalize_path(&pathbuf) < 0) {
+               error("unable to normalize alternate object path: %s",
+                     pathbuf.buf);
+               strbuf_release(&pathbuf);
+               return -1;
+       }
 
        /*
         * The trailing slash after the directory name is given by
         * this function at the end. Remove duplicates.
         */
-       while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
-               pfxlen -= 1;
-
-       entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
-       ent = xmalloc(sizeof(*ent) + entlen);
-       memcpy(ent->base, pathbuf.buf, pfxlen);
-       strbuf_release(&pathbuf);
+       while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/')
+               strbuf_setlen(&pathbuf, pathbuf.len - 1);
 
-       ent->name = ent->base + pfxlen + 1;
-       ent->base[pfxlen + 3] = '/';
-       ent->base[pfxlen] = ent->base[entlen-1] = 0;
-
-       /* Detect cases where alternate disappeared */
-       if (!is_directory(ent->base)) {
-               error("object directory %s does not exist; "
-                     "check .git/objects/info/alternates.",
-                     ent->base);
-               free(ent);
+       if (!alt_odb_usable(&pathbuf, normalized_objdir)) {
+               strbuf_release(&pathbuf);
                return -1;
        }
 
-       /* Prevent the common mistake of listing the same
-        * thing twice, or object directory itself.
-        */
-       for (alt = alt_odb_list; alt; alt = alt->next) {
-               if (pfxlen == alt->name - alt->base - 1 &&
-                   !memcmp(ent->base, alt->base, pfxlen)) {
-                       free(ent);
-                       return -1;
-               }
-       }
-       if (!strcmp_icase(ent->base, normalized_objdir)) {
-               free(ent);
-               return -1;
-       }
+       ent = alloc_alt_odb(pathbuf.buf);
 
        /* add the alternate entry */
        *alt_odb_tail = ent;
@@ -330,10 +323,9 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base,
        ent->next = NULL;
 
        /* recursively add alternates */
-       read_info_alternates(ent->base, depth + 1);
-
-       ent->base[pfxlen] = '/';
+       read_info_alternates(pathbuf.buf, depth + 1);
 
+       strbuf_release(&pathbuf);
        return 0;
 }
 
@@ -352,7 +344,9 @@ static void link_alt_odb_entries(const char *alt, int len, int sep,
        }
 
        strbuf_add_absolute_path(&objdirbuf, get_object_directory());
-       normalize_path_copy(objdirbuf.buf, objdirbuf.buf);
+       if (strbuf_normalize_path(&objdirbuf) < 0)
+               die("unable to normalize object directory: %s",
+                   objdirbuf.buf);
 
        alt_copy = xmemdupz(alt, len);
        string_list_split_in_place(&entries, alt_copy, sep, -1);
@@ -360,12 +354,7 @@ static void link_alt_odb_entries(const char *alt, int len, int sep,
                const char *entry = entries.items[i].string;
                if (entry[0] == '\0' || entry[0] == '#')
                        continue;
-               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, objdirbuf.buf);
-               }
+               link_alt_odb_entry(entry, relative_base, depth, objdirbuf.buf);
        }
        string_list_clear(&entries, 0);
        free(alt_copy);
@@ -381,7 +370,7 @@ void read_info_alternates(const char * relative_base, int depth)
        int fd;
 
        path = xstrfmt("%s/info/alternates", relative_base);
-       fd = git_open_noatime(path);
+       fd = git_open(path);
        free(path);
        if (fd < 0)
                return;
@@ -398,16 +387,148 @@ void read_info_alternates(const char * relative_base, int depth)
        munmap(map, mapsz);
 }
 
+struct alternate_object_database *alloc_alt_odb(const char *dir)
+{
+       struct alternate_object_database *ent;
+
+       FLEX_ALLOC_STR(ent, path, dir);
+       strbuf_init(&ent->scratch, 0);
+       strbuf_addf(&ent->scratch, "%s/", dir);
+       ent->base_len = ent->scratch.len;
+
+       return ent;
+}
+
 void add_to_alternates_file(const char *reference)
 {
        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
-       int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
-       const char *alt = mkpath("%s\n", reference);
-       write_or_die(fd, alt, strlen(alt));
-       if (commit_lock_file(lock))
-               die("could not close alternates file");
-       if (alt_odb_tail)
-               link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
+       char *alts = git_pathdup("objects/info/alternates");
+       FILE *in, *out;
+
+       hold_lock_file_for_update(lock, alts, LOCK_DIE_ON_ERROR);
+       out = fdopen_lock_file(lock, "w");
+       if (!out)
+               die_errno("unable to fdopen alternates lockfile");
+
+       in = fopen(alts, "r");
+       if (in) {
+               struct strbuf line = STRBUF_INIT;
+               int found = 0;
+
+               while (strbuf_getline(&line, in) != EOF) {
+                       if (!strcmp(reference, line.buf)) {
+                               found = 1;
+                               break;
+                       }
+                       fprintf_or_die(out, "%s\n", line.buf);
+               }
+
+               strbuf_release(&line);
+               fclose(in);
+
+               if (found) {
+                       rollback_lock_file(lock);
+                       lock = NULL;
+               }
+       }
+       else if (errno != ENOENT)
+               die_errno("unable to read alternates file");
+
+       if (lock) {
+               fprintf_or_die(out, "%s\n", reference);
+               if (commit_lock_file(lock))
+                       die_errno("unable to move new alternates file into place");
+               if (alt_odb_tail)
+                       link_alt_odb_entries(reference, strlen(reference), '\n', NULL, 0);
+       }
+       free(alts);
+}
+
+void add_to_alternates_memory(const char *reference)
+{
+       /*
+        * Make sure alternates are initialized, or else our entry may be
+        * overwritten when they are.
+        */
+       prepare_alt_odb();
+
+       link_alt_odb_entries(reference, strlen(reference), '\n', NULL, 0);
+}
+
+/*
+ * Compute the exact path an alternate is at and returns it. In case of
+ * error NULL is returned and the human readable error is added to `err`
+ * `path` may be relative and should point to $GITDIR.
+ * `err` must not be null.
+ */
+char *compute_alternate_path(const char *path, struct strbuf *err)
+{
+       char *ref_git = NULL;
+       const char *repo, *ref_git_s;
+       int seen_error = 0;
+
+       ref_git_s = real_path_if_valid(path);
+       if (!ref_git_s) {
+               seen_error = 1;
+               strbuf_addf(err, _("path '%s' does not exist"), path);
+               goto out;
+       } else
+               /*
+                * Beware: read_gitfile(), real_path() and mkpath()
+                * return static buffer
+                */
+               ref_git = xstrdup(ref_git_s);
+
+       repo = read_gitfile(ref_git);
+       if (!repo)
+               repo = read_gitfile(mkpath("%s/.git", ref_git));
+       if (repo) {
+               free(ref_git);
+               ref_git = xstrdup(repo);
+       }
+
+       if (!repo && is_directory(mkpath("%s/.git/objects", ref_git))) {
+               char *ref_git_git = mkpathdup("%s/.git", ref_git);
+               free(ref_git);
+               ref_git = ref_git_git;
+       } else if (!is_directory(mkpath("%s/objects", ref_git))) {
+               struct strbuf sb = STRBUF_INIT;
+               seen_error = 1;
+               if (get_common_dir(&sb, ref_git)) {
+                       strbuf_addf(err,
+                                   _("reference repository '%s' as a linked "
+                                     "checkout is not supported yet."),
+                                   path);
+                       goto out;
+               }
+
+               strbuf_addf(err, _("reference repository '%s' is not a "
+                                       "local repository."), path);
+               goto out;
+       }
+
+       if (!access(mkpath("%s/shallow", ref_git), F_OK)) {
+               strbuf_addf(err, _("reference repository '%s' is shallow"),
+                           path);
+               seen_error = 1;
+               goto out;
+       }
+
+       if (!access(mkpath("%s/info/grafts", ref_git), F_OK)) {
+               strbuf_addf(err,
+                           _("reference repository '%s' is grafted"),
+                           path);
+               seen_error = 1;
+               goto out;
+       }
+
+out:
+       if (seen_error) {
+               free(ref_git);
+               ref_git = NULL;
+       }
+
+       return ref_git;
 }
 
 int foreach_alt_odb(alt_odb_fn fn, void *cb)
@@ -474,8 +595,8 @@ 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 (check_and_freshen_file(alt->base, freshen))
+               const char *path = alt_sha1_path(alt, sha1);
+               if (check_and_freshen_file(path, freshen))
                        return 1;
        }
        return 0;
@@ -507,6 +628,9 @@ static size_t peak_pack_mapped;
 static size_t pack_mapped;
 struct packed_git *packed_git;
 
+static struct mru packed_git_mru_storage;
+struct mru *packed_git_mru = &packed_git_mru_storage;
+
 void pack_report(void)
 {
        fprintf(stderr,
@@ -539,7 +663,7 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
        struct pack_idx_header *hdr;
        size_t idx_size;
        uint32_t version, nr, i, *index;
-       int fd = git_open_noatime(path);
+       int fd = git_open(path);
        struct stat st;
 
        if (fd < 0)
@@ -638,13 +762,15 @@ static int check_packed_git_idx(const char *path, struct packed_git *p)
 int open_pack_index(struct packed_git *p)
 {
        char *idx_name;
+       size_t len;
        int ret;
 
        if (p->index_data)
                return 0;
 
-       idx_name = xstrdup(p->pack_name);
-       strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
+       if (!strip_suffix(p->pack_name, ".pack", &len))
+               die("BUG: pack_name does not end in .pack");
+       idx_name = xstrfmt("%.*s.idx", (int)len, p->pack_name);
        ret = check_packed_git_idx(idx_name, p);
        free(idx_name);
        return ret;
@@ -753,6 +879,37 @@ void close_pack_windows(struct packed_git *p)
        }
 }
 
+static int close_pack_fd(struct packed_git *p)
+{
+       if (p->pack_fd < 0)
+               return 0;
+
+       close(p->pack_fd);
+       pack_open_fds--;
+       p->pack_fd = -1;
+
+       return 1;
+}
+
+static void close_pack(struct packed_git *p)
+{
+       close_pack_windows(p);
+       close_pack_fd(p);
+       close_pack_index(p);
+}
+
+void close_all_packs(void)
+{
+       struct packed_git *p;
+
+       for (p = packed_git; p; p = p->next)
+               if (p->do_not_close)
+                       die("BUG: want to close pack marked 'do-not-close'");
+               else
+                       close_pack(p);
+}
+
+
 /*
  * 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.
@@ -820,12 +977,8 @@ static int close_one_pack(void)
                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;
-       }
+       if (lru_p)
+               return close_pack_fd(lru_p);
 
        return 0;
 }
@@ -847,41 +1000,6 @@ void close_pack_index(struct packed_git *p)
        }
 }
 
-/*
- * This is used by git-repack in case a newly created pack happens to
- * 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 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().
- */
-void free_pack_by_name(const char *pack_name)
-{
-       struct packed_git *p, **pp = &packed_git;
-
-       while (*pp) {
-               p = *pp;
-               if (strcmp(pack_name, p->pack_name) == 0) {
-                       clear_delta_base_cache();
-                       close_pack_windows(p);
-                       if (p->pack_fd != -1) {
-                               close(p->pack_fd);
-                               pack_open_fds--;
-                       }
-                       close_pack_index(p);
-                       free(p->bad_object_sha1);
-                       *pp = p->next;
-                       if (last_found_pack == p)
-                               last_found_pack = NULL;
-                       free(p);
-                       return;
-               }
-               pp = &p->next;
-       }
-}
-
 static unsigned int get_max_fd_limit(void)
 {
 #ifdef RLIMIT_NOFILE
@@ -951,7 +1069,7 @@ static int open_packed_git_1(struct packed_git *p)
        while (pack_max_fds <= pack_open_fds && close_one_pack())
                ; /* nothing */
 
-       p->pack_fd = git_open_noatime(p->pack_name);
+       p->pack_fd = git_open(p->pack_name);
        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
                return -1;
        pack_open_fds++;
@@ -1004,11 +1122,7 @@ static int open_packed_git(struct packed_git *p)
 {
        if (!open_packed_git_1(p))
                return 0;
-       if (p->pack_fd != -1) {
-               close(p->pack_fd);
-               pack_open_fds--;
-               p->pack_fd = -1;
-       }
+       close_pack_fd(p);
        return -1;
 }
 
@@ -1041,6 +1155,8 @@ unsigned char *use_pack(struct packed_git *p,
                die("packfile %s cannot be accessed", p->pack_name);
        if (offset > (p->pack_size - 20))
                die("offset beyond end of packfile (truncated pack?)");
+       if (offset < 0)
+               die(_("offset before end of packfile (broken .idx?)"));
 
        if (!win || !in_window(win, offset)) {
                if (win)
@@ -1070,15 +1186,11 @@ unsigned char *use_pack(struct packed_git *p,
                                PROT_READ, MAP_PRIVATE,
                                p->pack_fd, win->offset);
                        if (win->base == MAP_FAILED)
-                               die("packfile %s cannot be mapped: %s",
-                                       p->pack_name,
-                                       strerror(errno));
+                               die_errno("packfile %s cannot be mapped",
+                                         p->pack_name);
                        if (!win->offset && win->len == p->pack_size
-                               && !p->do_not_close) {
-                               close(p->pack_fd);
-                               pack_open_fds--;
-                               p->pack_fd = -1;
-                       }
+                               && !p->do_not_close)
+                               close_pack_fd(p);
                        pack_mmap_calls++;
                        pack_open_windows++;
                        if (pack_mapped > peak_pack_mapped)
@@ -1102,7 +1214,7 @@ unsigned char *use_pack(struct packed_git *p,
 
 static struct packed_git *alloc_packed_git(int extra)
 {
-       struct packed_git *p = xmalloc(sizeof(*p) + extra);
+       struct packed_git *p = xmalloc(st_add(sizeof(*p), extra));
        memset(p, 0, sizeof(*p));
        p->pack_fd = -1;
        return p;
@@ -1113,11 +1225,12 @@ static void try_to_free_pack_memory(size_t size)
        release_pack_memory(size);
 }
 
-struct packed_git *add_packed_git(const char *path, int path_len, int local)
+struct packed_git *add_packed_git(const char *path, size_t path_len, int local)
 {
        static int have_set_try_to_free_routine;
        struct stat st;
-       struct packed_git *p = alloc_packed_git(path_len + 2);
+       size_t alloc;
+       struct packed_git *p;
 
        if (!have_set_try_to_free_routine) {
                have_set_try_to_free_routine = 1;
@@ -1128,18 +1241,22 @@ struct packed_git *add_packed_git(const char *path, int path_len, int local)
         * Make sure a corresponding .pack file exists and that
         * the index looks sane.
         */
-       path_len -= strlen(".idx");
-       if (path_len < 1) {
-               free(p);
+       if (!strip_suffix_mem(path, &path_len, ".idx"))
                return NULL;
-       }
+
+       /*
+        * ".pack" is long enough to hold any suffix we're adding (and
+        * the use xsnprintf double-checks that)
+        */
+       alloc = st_add3(path_len, strlen(".pack"), 1);
+       p = alloc_packed_git(alloc);
        memcpy(p->pack_name, path, path_len);
 
-       strcpy(p->pack_name + path_len, ".keep");
+       xsnprintf(p->pack_name + path_len, alloc - path_len, ".keep");
        if (!access(p->pack_name, F_OK))
                p->pack_keep = 1;
 
-       strcpy(p->pack_name + path_len, ".pack");
+       xsnprintf(p->pack_name + path_len, alloc - path_len, ".pack");
        if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
                free(p);
                return NULL;
@@ -1159,9 +1276,10 @@ struct packed_git *add_packed_git(const char *path, int path_len, int local)
 struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
 {
        const char *path = sha1_pack_name(sha1);
-       struct packed_git *p = alloc_packed_git(strlen(path) + 1);
+       size_t alloc = st_add(strlen(path), 1);
+       struct packed_git *p = alloc_packed_git(alloc);
 
-       strcpy(p->pack_name, path);
+       memcpy(p->pack_name, path, alloc); /* includes NUL */
        hashcpy(p->sha1, sha1);
        if (check_packed_git_idx(idx_path, p)) {
                free(p);
@@ -1180,27 +1298,16 @@ void install_packed_git(struct packed_git *pack)
        packed_git = pack;
 }
 
-void (*report_garbage)(const char *desc, const char *path);
+void (*report_garbage)(unsigned seen_bits, 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:
+       if (seen_bits == (PACKDIR_FILE_PACK|PACKDIR_FILE_IDX))
                return;
-       }
+
        for (; first < last; first++)
-               report_garbage(msg, list->items[first].string);
+               report_garbage(seen_bits, list->items[first].string);
 }
 
 static void report_pack_garbage(struct string_list *list)
@@ -1223,7 +1330,7 @@ static void report_pack_garbage(struct string_list *list)
                if (baselen == -1) {
                        const char *dot = strrchr(path, '.');
                        if (!dot) {
-                               report_garbage("garbage found", path);
+                               report_garbage(PACKDIR_FILE_GARBAGE, path);
                                continue;
                        }
                        baselen = dot - path + 1;
@@ -1250,8 +1357,8 @@ static void prepare_packed_git_one(char *objdir, int local)
        dir = opendir(path.buf);
        if (!dir) {
                if (errno != ENOENT)
-                       error("unable to open object pack directory: %s: %s",
-                             path.buf, strerror(errno));
+                       error_errno("unable to open object pack directory: %s",
+                                   path.buf);
                strbuf_release(&path);
                return;
        }
@@ -1295,7 +1402,7 @@ static void prepare_packed_git_one(char *objdir, int local)
                    ends_with(de->d_name, ".keep"))
                        string_list_append(&garbage, path.buf);
                else
-                       report_garbage("garbage found", path.buf);
+                       report_garbage(PACKDIR_FILE_GARBAGE, path.buf);
        }
        closedir(dir);
        report_pack_garbage(&garbage);
@@ -1303,10 +1410,20 @@ static void prepare_packed_git_one(char *objdir, int local)
        strbuf_release(&path);
 }
 
+static void *get_next_packed_git(const void *p)
+{
+       return ((const struct packed_git *)p)->next;
+}
+
+static void set_next_packed_git(void *p, void *next)
+{
+       ((struct packed_git *)p)->next = next;
+}
+
 static int sort_pack(const void *a_, const void *b_)
 {
-       struct packed_git *a = *((struct packed_git **)a_);
-       struct packed_git *b = *((struct packed_git **)b_);
+       const struct packed_git *a = a_;
+       const struct packed_git *b = b_;
        int st;
 
        /*
@@ -1333,28 +1450,17 @@ static int sort_pack(const void *a_, const void *b_)
 
 static void rearrange_packed_git(void)
 {
-       struct packed_git **ary, *p;
-       int i, n;
-
-       for (n = 0, p = packed_git; p; p = p->next)
-               n++;
-       if (n < 2)
-               return;
-
-       /* prepare an array of packed_git for easier sorting */
-       ary = xcalloc(n, sizeof(struct packed_git *));
-       for (n = 0, p = packed_git; p; p = p->next)
-               ary[n++] = p;
-
-       qsort(ary, n, sizeof(struct packed_git *), sort_pack);
+       packed_git = llist_mergesort(packed_git, get_next_packed_git,
+                                    set_next_packed_git, sort_pack);
+}
 
-       /* link them back again */
-       for (i = 0; i < n - 1; i++)
-               ary[i]->next = ary[i + 1];
-       ary[n - 1]->next = NULL;
-       packed_git = ary[0];
+static void prepare_packed_git_mru(void)
+{
+       struct packed_git *p;
 
-       free(ary);
+       mru_clear(packed_git_mru);
+       for (p = packed_git; p; p = p->next)
+               mru_append(packed_git_mru, p);
 }
 
 static int prepare_packed_git_run_once = 0;
@@ -1366,12 +1472,10 @@ void prepare_packed_git(void)
                return;
        prepare_packed_git_one(get_object_directory(), 1);
        prepare_alt_odb();
-       for (alt = alt_odb_list; alt; alt = alt->next) {
-               alt->name[-1] = 0;
-               prepare_packed_git_one(alt->base, 0);
-               alt->name[-1] = '/';
-       }
+       for (alt = alt_odb_list; alt; alt = alt->next)
+               prepare_packed_git_one(alt->path, 0);
        rearrange_packed_git();
+       prepare_packed_git_mru();
        prepare_packed_git_run_once = 1;
 }
 
@@ -1386,10 +1490,12 @@ static void mark_bad_packed_object(struct packed_git *p,
 {
        unsigned i;
        for (i = 0; i < p->num_bad_objects; i++)
-               if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
+               if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
                        return;
-       p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
-       hashcpy(p->bad_object_sha1 + 20 * p->num_bad_objects, sha1);
+       p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
+                                     st_mult(GIT_SHA1_RAWSZ,
+                                             st_add(p->num_bad_objects, 1)));
+       hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
        p->num_bad_objects++;
 }
 
@@ -1431,7 +1537,7 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
                return -1;
 
        /* Generate the header */
-       hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
+       hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(obj_type), size) + 1;
 
        /* Sha1.. */
        git_SHA1_Init(&c);
@@ -1453,26 +1559,30 @@ int check_sha1_signature(const unsigned char *sha1, void *map,
        return hashcmp(sha1, real_sha1) ? -1 : 0;
 }
 
-int git_open_noatime(const char *name)
+int git_open_cloexec(const char *name, int flags)
 {
-       static int sha1_file_open_flag = O_NOATIME;
-
-       for (;;) {
-               int fd;
+       static int cloexec = O_CLOEXEC;
+       int fd = open(name, flags | cloexec);
 
-               errno = 0;
-               fd = open(name, O_RDONLY | sha1_file_open_flag);
-               if (fd >= 0)
-                       return fd;
+       if ((cloexec & O_CLOEXEC) && fd < 0 && errno == EINVAL) {
+               /* Try again w/o O_CLOEXEC: the kernel might not support it */
+               cloexec &= ~O_CLOEXEC;
+               fd = open(name, flags | cloexec);
+       }
+       return fd;
+}
 
-               /* Might the failure be due to O_NOATIME? */
-               if (errno != ENOENT && sha1_file_open_flag) {
-                       sha1_file_open_flag = 0;
-                       continue;
-               }
+int git_open(const char *name)
+{
+       static int noatime = O_NOATIME;
+       int fd = git_open_cloexec(name, O_RDONLY);
 
-               return -1;
+       if (0 <= fd && (noatime & O_NOATIME)) {
+               int flags = fcntl(fd, F_GETFL);
+               if (fcntl(fd, F_SETFL, flags | noatime))
+                       noatime = 0;
        }
+       return fd;
 }
 
 static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
@@ -1485,8 +1595,8 @@ static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
        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))
+               const char *path = alt_sha1_path(alt, sha1);
+               if (!lstat(path, st))
                        return 0;
        }
 
@@ -1499,15 +1609,15 @@ static int open_sha1_file(const unsigned char *sha1)
        struct alternate_object_database *alt;
        int most_interesting_errno;
 
-       fd = git_open_noatime(sha1_file_name(sha1));
+       fd = git_open(sha1_file_name(sha1));
        if (fd >= 0)
                return fd;
        most_interesting_errno = errno;
 
        prepare_alt_odb();
        for (alt = alt_odb_list; alt; alt = alt->next) {
-               fill_sha1_path(alt->name, sha1);
-               fd = git_open_noatime(alt->base);
+               const char *path = alt_sha1_path(alt, sha1);
+               fd = git_open(path);
                if (fd >= 0)
                        return fd;
                if (most_interesting_errno == ENOENT)
@@ -1708,7 +1818,7 @@ static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
                strbuf_add(oi->typename, type_buf, type_len);
        /*
         * Set type to 0 if its an unknown object and
-        * we're obtaining the type using '--allow-unkown-type'
+        * we're obtaining the type using '--allow-unknown-type'
         * option.
         */
        if ((flags & LOOKUP_UNKNOWN_OBJECT) && (type < 0))
@@ -1746,11 +1856,9 @@ static int parse_sha1_header_extended(const char *hdr, struct object_info *oi,
 
 int parse_sha1_header(const char *hdr, unsigned long *sizep)
 {
-       struct object_info oi;
+       struct object_info oi = OBJECT_INFO_INIT;
 
        oi.sizep = sizep;
-       oi.typename = NULL;
-       oi.typep = NULL;
        return parse_sha1_header_extended(hdr, &oi, LOOKUP_REPLACE_OBJECT);
 }
 
@@ -1937,7 +2045,7 @@ static enum object_type packed_to_object_type(struct packed_git *p,
                /* 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);
+                       ALLOC_ARRAY(poi_stack, 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);
@@ -1988,8 +2096,8 @@ static enum object_type packed_to_object_type(struct packed_git *p,
        goto out;
 }
 
-static int packed_object_info(struct packed_git *p, off_t obj_offset,
-                             struct object_info *oi)
+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;
@@ -2089,136 +2197,142 @@ static void *unpack_compressed_entry(struct packed_git *p,
        return buffer;
 }
 
-#define MAX_DELTA_CACHE (256)
-
+static struct hashmap delta_base_cache;
 static size_t delta_base_cached;
 
-static struct delta_base_cache_lru_list {
-       struct delta_base_cache_lru_list *prev;
-       struct delta_base_cache_lru_list *next;
-} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
+static LIST_HEAD(delta_base_cache_lru);
 
-static struct delta_base_cache_entry {
-       struct delta_base_cache_lru_list lru;
-       void *data;
+struct delta_base_cache_key {
        struct packed_git *p;
        off_t base_offset;
+};
+
+struct delta_base_cache_entry {
+       struct hashmap hash;
+       struct delta_base_cache_key key;
+       struct list_head lru;
+       void *data;
        unsigned long size;
        enum object_type type;
-} delta_base_cache[MAX_DELTA_CACHE];
+};
 
-static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
+static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
 {
-       unsigned long hash;
+       unsigned int hash;
 
-       hash = (unsigned long)p + (unsigned long)base_offset;
+       hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
        hash += (hash >> 8) + (hash >> 16);
-       return hash % MAX_DELTA_CACHE;
+       return hash;
 }
 
 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;
+       struct hashmap_entry entry;
+       struct delta_base_cache_key key;
+
+       if (!delta_base_cache.cmpfn)
+               return NULL;
+
+       hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
+       key.p = p;
+       key.base_offset = base_offset;
+       return hashmap_get(&delta_base_cache, &entry, &key);
+}
+
+static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
+                                  const struct delta_base_cache_key *b)
+{
+       return a->p == b->p && a->base_offset == b->base_offset;
 }
 
-static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
-                                    struct packed_git *p, off_t base_offset)
+static int delta_base_cache_hash_cmp(const void *va, const void *vb,
+                                    const void *vkey)
 {
-       return (ent->data && ent->p == p && ent->base_offset == base_offset);
+       const struct delta_base_cache_entry *a = va, *b = vb;
+       const struct delta_base_cache_key *key = vkey;
+       if (key)
+               return !delta_base_cache_key_eq(&a->key, key);
+       else
+               return !delta_base_cache_key_eq(&a->key, &b->key);
 }
 
 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);
+       return !!get_delta_base_cache_entry(p, base_offset);
 }
 
-static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
+/*
+ * Remove the entry from the cache, but do _not_ free the associated
+ * entry data. The caller takes ownership of the "data" buffer, and
+ * should copy out any fields it wants before detaching.
+ */
+static void detach_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;
+       hashmap_remove(&delta_base_cache, ent, &ent->key);
+       list_del(&ent->lru);
        delta_base_cached -= ent->size;
+       free(ent);
 }
 
 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)
+       unsigned long *base_size, enum object_type *type)
 {
        struct delta_base_cache_entry *ent;
-       void *ret;
 
        ent = get_delta_base_cache_entry(p, base_offset);
-
-       if (!eq_delta_base_cache_entry(ent, p, base_offset))
+       if (!ent)
                return unpack_entry(p, base_offset, type, base_size);
 
-       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;
+       return xmemdupz(ent->data, ent->size);
 }
 
 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
 {
-       if (ent->data) {
-               free(ent->data);
-               ent->data = NULL;
-               ent->lru.next->prev = ent->lru.prev;
-               ent->lru.prev->next = ent->lru.next;
-               delta_base_cached -= ent->size;
-       }
+       free(ent->data);
+       detach_delta_base_cache_entry(ent);
 }
 
 void clear_delta_base_cache(void)
 {
-       unsigned long p;
-       for (p = 0; p < MAX_DELTA_CACHE; p++)
-               release_delta_base_cache(&delta_base_cache[p]);
+       struct hashmap_iter iter;
+       struct delta_base_cache_entry *entry;
+       for (entry = hashmap_iter_first(&delta_base_cache, &iter);
+            entry;
+            entry = hashmap_iter_next(&iter)) {
+               release_delta_base_cache(entry);
+       }
 }
 
 static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
        void *base, unsigned long base_size, enum object_type type)
 {
-       unsigned long hash = pack_entry_hash(p, base_offset);
-       struct delta_base_cache_entry *ent = delta_base_cache + hash;
-       struct delta_base_cache_lru_list *lru;
+       struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
+       struct list_head *lru, *tmp;
 
-       release_delta_base_cache(ent);
        delta_base_cached += base_size;
 
-       for (lru = delta_base_cache_lru.next;
-            delta_base_cached > delta_base_cache_limit
-            && lru != &delta_base_cache_lru;
-            lru = lru->next) {
-               struct delta_base_cache_entry *f = (void *)lru;
-               if (f->type == OBJ_BLOB)
-                       release_delta_base_cache(f);
-       }
-       for (lru = delta_base_cache_lru.next;
-            delta_base_cached > delta_base_cache_limit
-            && lru != &delta_base_cache_lru;
-            lru = lru->next) {
-               struct delta_base_cache_entry *f = (void *)lru;
+       list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
+               struct delta_base_cache_entry *f =
+                       list_entry(lru, struct delta_base_cache_entry, lru);
+               if (delta_base_cached <= delta_base_cache_limit)
+                       break;
                release_delta_base_cache(f);
        }
 
-       ent->p = p;
-       ent->base_offset = base_offset;
+       ent->key.p = p;
+       ent->key.base_offset = base_offset;
        ent->type = type;
        ent->data = base;
        ent->size = base_size;
-       ent->lru.next = &delta_base_cache_lru;
-       ent->lru.prev = delta_base_cache_lru.prev;
-       delta_base_cache_lru.prev->next = &ent->lru;
-       delta_base_cache_lru.prev = &ent->lru;
+       list_add_tail(&ent->lru, &delta_base_cache_lru);
+
+       if (!delta_base_cache.cmpfn)
+               hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, 0);
+       hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
+       hashmap_add(&delta_base_cache, ent);
 }
 
 static void *read_object(const unsigned char *sha1, enum object_type *type,
@@ -2262,18 +2376,18 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
                struct delta_base_cache_entry *ent;
 
                ent = get_delta_base_cache_entry(p, curpos);
-               if (eq_delta_base_cache_entry(ent, p, curpos)) {
+               if (ent) {
                        type = ent->type;
                        data = ent->data;
                        size = ent->size;
-                       clear_delta_base_cache_entry(ent);
+                       detach_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;
+                       off_t 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);
@@ -2303,7 +2417,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
                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);
+                       ALLOC_ARRAY(delta_stack, delta_stack_alloc);
                        memcpy(delta_stack, small_delta_stack,
                               sizeof(*delta_stack)*delta_stack_nr);
                } else {
@@ -2322,7 +2436,7 @@ void *unpack_entry(struct packed_git *p, off_t obj_offset,
        case OBJ_OFS_DELTA:
        case OBJ_REF_DELTA:
                if (data)
-                       die("BUG in unpack_entry: left loop at a valid delta");
+                       die("BUG: unpack_entry: left loop at a valid delta");
                break;
        case OBJ_COMMIT:
        case OBJ_TREE:
@@ -2441,6 +2555,20 @@ const unsigned char *nth_packed_object_sha1(struct packed_git *p,
        }
 }
 
+void check_pack_index_ptr(const struct packed_git *p, const void *vptr)
+{
+       const unsigned char *ptr = vptr;
+       const unsigned char *start = p->index_data;
+       const unsigned char *end = start + p->index_size;
+       if (ptr < start)
+               die(_("offset before start of pack index for %s (corrupt index?)"),
+                   p->pack_name);
+       /* No need to check for underflow; .idx files must be at least 8 bytes */
+       if (ptr >= end - 8)
+               die(_("offset beyond end of pack index for %s (truncated index?)"),
+                   p->pack_name);
+}
+
 off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
 {
        const unsigned char *index = p->index_data;
@@ -2454,6 +2582,7 @@ off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
                if (!(off & 0x80000000))
                        return off;
                index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
+               check_pack_index_ptr(p, index);
                return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
                                   ntohl(*((uint32_t *)(index + 4)));
        }
@@ -2581,21 +2710,15 @@ static int fill_pack_entry(const unsigned char *sha1,
  */
 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
 {
-       struct packed_git *p;
+       struct mru_entry *p;
 
        prepare_packed_git();
        if (!packed_git)
                return 0;
 
-       if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
-               return 1;
-
-       for (p = packed_git; p; p = p->next) {
-               if (p == last_found_pack)
-                       continue; /* we already checked this one */
-
-               if (fill_pack_entry(sha1, e, p)) {
-                       last_found_pack = p;
+       for (p = packed_git_mru->head; p; p = p->next) {
+               if (fill_pack_entry(sha1, e, p->item)) {
+                       mru_mark(packed_git_mru, p);
                        return 1;
                }
        }
@@ -2745,7 +2868,7 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi,
 int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
 {
        enum object_type type;
-       struct object_info oi = {NULL};
+       struct object_info oi = OBJECT_INFO_INIT;
 
        oi.typep = &type;
        oi.sizep = sizep;
@@ -2762,7 +2885,7 @@ static void *read_packed_sha1(const unsigned char *sha1,
 
        if (!find_pack_entry(sha1, &e))
                return NULL;
-       data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
+       data = cache_or_unpack_entry(e.p, e.offset, size, type);
        if (!data) {
                /*
                 * We're probably in deep shit, but let's try to fetch
@@ -2919,7 +3042,7 @@ static void write_sha1_file_prepare(const void *buf, unsigned long len,
        git_SHA_CTX c;
 
        /* Generate the header */
-       *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
+       *hdrlen = xsnprintf(hdr, *hdrlen, "%s %lu", type, len)+1;
 
        /* Sha1.. */
        git_SHA1_Init(&c);
@@ -2930,11 +3053,8 @@ static void write_sha1_file_prepare(const void *buf, unsigned long len,
 
 /*
  * Move the just written object into its final resting place.
- * NEEDSWORK: this should be renamed to finalize_temp_file() as
- * "moving" is only a part of what it does, when no patch between
- * master to pu changes the call sites of this function.
  */
-int move_temp_to_file(const char *tmpfile, const char *filename)
+int finalize_object_file(const char *tmpfile, const char *filename)
 {
        int ret = 0;
 
@@ -2963,7 +3083,7 @@ int move_temp_to_file(const char *tmpfile, const char *filename)
        unlink_or_warn(tmpfile);
        if (ret) {
                if (ret != EEXIST) {
-                       return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
+                       return error_errno("unable to write sha1 filename %s", filename);
                }
                /* FIXME!!! Collision check here ? */
        }
@@ -2977,7 +3097,7 @@ int move_temp_to_file(const char *tmpfile, const char *filename)
 static int write_buffer(int fd, const void *buf, size_t len)
 {
        if (write_in_full(fd, buf, len) < 0)
-               return error("file write error (%s)", strerror(errno));
+               return error_errno("file write error");
        return 0;
 }
 
@@ -2985,7 +3105,7 @@ int hash_sha1_file(const void *buf, unsigned long len, const char *type,
                    unsigned char *sha1)
 {
        char hdr[32];
-       int hdrlen;
+       int hdrlen = sizeof(hdr);
        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
        return 0;
 }
@@ -3015,29 +3135,31 @@ static inline int directory_size(const char *filename)
  * We want to avoid cross-directory filename renames, because those
  * can have problems on various filesystems (FAT, NFS, Coda).
  */
-static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
+static int create_tmpfile(struct strbuf *tmp, const char *filename)
 {
        int fd, dirlen = directory_size(filename);
 
-       if (dirlen + 20 > bufsiz) {
-               errno = ENAMETOOLONG;
-               return -1;
-       }
-       memcpy(buffer, filename, dirlen);
-       strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
-       fd = git_mkstemp_mode(buffer, 0444);
+       strbuf_reset(tmp);
+       strbuf_add(tmp, filename, dirlen);
+       strbuf_addstr(tmp, "tmp_obj_XXXXXX");
+       fd = git_mkstemp_mode(tmp->buf, 0444);
        if (fd < 0 && dirlen && errno == ENOENT) {
-               /* Make sure the directory exists */
-               memcpy(buffer, filename, dirlen);
-               buffer[dirlen-1] = 0;
-               if (mkdir(buffer, 0777) && errno != EEXIST)
+               /*
+                * Make sure the directory exists; note that the contents
+                * of the buffer are undefined after mkstemp returns an
+                * error, so we have to rewrite the whole buffer from
+                * scratch.
+                */
+               strbuf_reset(tmp);
+               strbuf_add(tmp, filename, dirlen - 1);
+               if (mkdir(tmp->buf, 0777) && errno != EEXIST)
                        return -1;
-               if (adjust_shared_perm(buffer))
+               if (adjust_shared_perm(tmp->buf))
                        return -1;
 
                /* Try again */
-               strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
-               fd = git_mkstemp_mode(buffer, 0444);
+               strbuf_addstr(tmp, "/tmp_obj_XXXXXX");
+               fd = git_mkstemp_mode(tmp->buf, 0444);
        }
        return fd;
 }
@@ -3050,15 +3172,15 @@ 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];
-       static char tmp_file[PATH_MAX];
+       static struct strbuf tmp_file = STRBUF_INIT;
        const char *filename = sha1_file_name(sha1);
 
-       fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
+       fd = create_tmpfile(&tmp_file, filename);
        if (fd < 0) {
                if (errno == EACCES)
                        return error("insufficient permission for adding an object to repository database %s", get_object_directory());
                else
-                       return error("unable to create temporary file: %s", strerror(errno));
+                       return error_errno("unable to create temporary file");
        }
 
        /* Set it up */
@@ -3102,12 +3224,11 @@ static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
                struct utimbuf utb;
                utb.actime = mtime;
                utb.modtime = mtime;
-               if (utime(tmp_file, &utb) < 0)
-                       warning("failed utime() on %s: %s",
-                               tmp_file, strerror(errno));
+               if (utime(tmp_file.buf, &utb) < 0)
+                       warning_errno("failed utime() on %s", tmp_file.buf);
        }
 
-       return move_temp_to_file(tmp_file, filename);
+       return finalize_object_file(tmp_file.buf, filename);
 }
 
 static int freshen_loose_object(const unsigned char *sha1)
@@ -3131,7 +3252,7 @@ static int freshen_packed_object(const unsigned char *sha1)
 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *sha1)
 {
        char hdr[32];
-       int hdrlen;
+       int hdrlen = sizeof(hdr);
 
        /* Normally if we have it in the pack then we do not bother writing
         * it out into .git/objects/??/?{38} file.
@@ -3149,7 +3270,8 @@ int hash_sha1_file_literally(const void *buf, unsigned long len, const char *typ
        int hdrlen, status = 0;
 
        /* type string, SP, %lu of the length plus NUL must fit this */
-       header = xmalloc(strlen(type) + 32);
+       hdrlen = strlen(type) + 32;
+       header = xmalloc(hdrlen);
        write_sha1_file_prepare(buf, len, type, sha1, header, &hdrlen);
 
        if (!(flags & HASH_WRITE_OBJECT))
@@ -3177,7 +3299,7 @@ int force_object_loose(const unsigned char *sha1, time_t mtime)
        buf = read_packed_sha1(sha1, &type, &len);
        if (!buf)
                return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
-       hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
+       hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %lu", typename(type), len) + 1;
        ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
        free(buf);
 
@@ -3212,6 +3334,11 @@ int has_sha1_file_with_flags(const unsigned char *sha1, int flags)
        return find_pack_entry(sha1, &e);
 }
 
+int has_object_file(const struct object_id *oid)
+{
+       return has_sha1_file(oid->hash);
+}
+
 static void check_tree(const void *buf, size_t size)
 {
        struct tree_desc desc;
@@ -3331,7 +3458,7 @@ static int index_core(unsigned char *sha1, int fd, size_t size,
                if (size == read_in_full(fd, buf, size))
                        ret = index_mem(sha1, buf, size, type, path, flags);
                else
-                       ret = error("short read %s", strerror(errno));
+                       ret = error_errno("short read");
                free(buf);
        } else {
                void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
@@ -3396,18 +3523,14 @@ int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned
        case S_IFREG:
                fd = open(path, O_RDONLY);
                if (fd < 0)
-                       return error("open(\"%s\"): %s", path,
-                                    strerror(errno));
+                       return error_errno("open(\"%s\")", path);
                if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
                        return error("%s: failed to insert into database",
                                     path);
                break;
        case S_IFLNK:
-               if (strbuf_readlink(&sb, path, st->st_size)) {
-                       char *errstr = strerror(errno);
-                       return error("readlink(\"%s\"): %s", path,
-                                    errstr);
-               }
+               if (strbuf_readlink(&sb, path, st->st_size))
+                       return error_errno("readlink(\"%s\")", path);
                if (!(flags & HASH_WRITE_OBJECT))
                        hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
                else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
@@ -3463,7 +3586,7 @@ static int for_each_file_in_obj_subdir(int subdir_nr,
        if (!dir) {
                if (errno == ENOENT)
                        return 0;
-               return error("unable to open %s: %s", path->buf, strerror(errno));
+               return error_errno("unable to open %s", path->buf);
        }
 
        while ((de = readdir(dir))) {
@@ -3495,12 +3618,12 @@ static int for_each_file_in_obj_subdir(int subdir_nr,
                                break;
                }
        }
-       strbuf_setlen(path, baselen);
+       closedir(dir);
 
+       strbuf_setlen(path, baselen);
        if (!r && subdir_cb)
                r = subdir_cb(subdir_nr, path->buf, data);
 
-       closedir(dir);
        return r;
 }
 
@@ -3555,8 +3678,7 @@ static int loose_from_alt_odb(struct alternate_object_database *alt,
        struct strbuf buf = STRBUF_INIT;
        int r;
 
-       /* copy base not including trailing '/' */
-       strbuf_add(&buf, alt->base, alt->name - alt->base - 1);
+       strbuf_addstr(&buf, alt->path);
        r = for_each_loose_file_in_objdir_buf(&buf,
                                              data->cb, NULL, NULL,
                                              data->data);