git-remote: support remotes with a dot in the name
[gitweb.git] / index-pack.c
index e33f60524f240f288df7dc6d398486d1d6e7e5ee..72e0962415d74c856917f6bb56e6fa2fea950c25 100644 (file)
@@ -8,7 +8,7 @@
 #include "tree.h"
 
 static const char index_pack_usage[] =
-"git-index-pack [-o index-file] pack-file";
+"git-index-pack [-v] [-o <index-file>] [{ ---keep | --keep=<msg> }] { <pack-file> | --stdin [--fix-thin] [<pack-file>] }";
 
 struct object_entry
 {
@@ -33,37 +33,83 @@ union delta_base {
 
 struct delta_entry
 {
-       struct object_entry *obj;
        union delta_base base;
+       int obj_no;
 };
 
-static const char *pack_name;
 static struct object_entry *objects;
 static struct delta_entry *deltas;
 static int nr_objects;
 static int nr_deltas;
+static int nr_resolved_deltas;
+
+static int from_stdin;
+static int verbose;
+
+static volatile sig_atomic_t progress_update;
+
+static void progress_interval(int signum)
+{
+       progress_update = 1;
+}
+
+static void setup_progress_signal(void)
+{
+       struct sigaction sa;
+       struct itimerval v;
+
+       memset(&sa, 0, sizeof(sa));
+       sa.sa_handler = progress_interval;
+       sigemptyset(&sa.sa_mask);
+       sa.sa_flags = SA_RESTART;
+       sigaction(SIGALRM, &sa, NULL);
+
+       v.it_interval.tv_sec = 1;
+       v.it_interval.tv_usec = 0;
+       v.it_value = v.it_interval;
+       setitimer(ITIMER_REAL, &v, NULL);
+
+}
+
+static unsigned display_progress(unsigned n, unsigned total, unsigned last_pc)
+{
+       unsigned percent = n * 100 / total;
+       if (percent != last_pc || progress_update) {
+               fprintf(stderr, "%4u%% (%u/%u) done\r", percent, n, total);
+               progress_update = 0;
+       }
+       return percent;
+}
 
 /* We always read in 4kB chunks. */
 static unsigned char input_buffer[4096];
 static unsigned long input_offset, input_len, consumed_bytes;
 static SHA_CTX input_ctx;
-static int input_fd;
+static int input_fd, output_fd, pack_fd;
+
+/* Discard current buffer used content. */
+static void flush(void)
+{
+       if (input_offset) {
+               if (output_fd >= 0)
+                       write_or_die(output_fd, input_buffer, input_offset);
+               SHA1_Update(&input_ctx, input_buffer, input_offset);
+               memmove(input_buffer, input_buffer + input_offset, input_len);
+               input_offset = 0;
+       }
+}
 
 /*
  * Make sure at least "min" bytes are available in the buffer, and
  * return the pointer to the buffer.
  */
-static void * fill(int min)
+static void *fill(int min)
 {
        if (min <= input_len)
                return input_buffer + input_offset;
        if (min > sizeof(input_buffer))
                die("cannot fill %d bytes", min);
-       if (input_offset) {
-               SHA1_Update(&input_ctx, input_buffer, input_offset);
-               memcpy(input_buffer, input_buffer + input_offset, input_len);
-               input_offset = 0;
-       }
+       flush();
        do {
                int ret = xread(input_fd, input_buffer + input_len,
                                sizeof(input_buffer) - input_len);
@@ -86,13 +132,31 @@ static void use(int bytes)
        consumed_bytes += bytes;
 }
 
-static void open_pack_file(void)
+static const char *open_pack_file(const char *pack_name)
 {
-       input_fd = open(pack_name, O_RDONLY);
-       if (input_fd < 0)
-               die("cannot open packfile '%s': %s", pack_name,
-                   strerror(errno));
+       if (from_stdin) {
+               input_fd = 0;
+               if (!pack_name) {
+                       static char tmpfile[PATH_MAX];
+                       snprintf(tmpfile, sizeof(tmpfile),
+                                "%s/pack_XXXXXX", get_object_directory());
+                       output_fd = mkstemp(tmpfile);
+                       pack_name = xstrdup(tmpfile);
+               } else
+                       output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
+               if (output_fd < 0)
+                       die("unable to create %s: %s\n", pack_name, strerror(errno));
+               pack_fd = output_fd;
+       } else {
+               input_fd = open(pack_name, O_RDONLY);
+               if (input_fd < 0)
+                       die("cannot open packfile '%s': %s",
+                           pack_name, strerror(errno));
+               output_fd = -1;
+               pack_fd = input_fd;
+       }
        SHA1_Init(&input_ctx);
+       return pack_name;
 }
 
 static void parse_pack_header(void)
@@ -101,14 +165,12 @@ static void parse_pack_header(void)
 
        /* Header consistency check */
        if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
-               die("packfile '%s' signature mismatch", pack_name);
+               die("pack signature mismatch");
        if (!pack_version_ok(hdr->hdr_version))
-               die("packfile '%s' version %d unsupported",
-                   pack_name, ntohl(hdr->hdr_version));
+               die("pack version %d unsupported", ntohl(hdr->hdr_version));
 
        nr_objects = ntohl(hdr->hdr_entries);
        use(sizeof(struct pack_header));
-       /*fprintf(stderr, "Indexing %d objects\n", nr_objects);*/
 }
 
 static void bad_object(unsigned long offset, const char *format,
@@ -122,8 +184,7 @@ static void bad_object(unsigned long offset, const char *format, ...)
        va_start(params, format);
        vsnprintf(buf, sizeof(buf), format, params);
        va_end(params);
-       die("packfile '%s': bad object at offset %lu: %s",
-           pack_name, offset, buf);
+       die("pack has bad object at offset %lu: %s", offset, buf);
 }
 
 static void *unpack_entry_data(unsigned long offset, unsigned long size)
@@ -205,38 +266,36 @@ static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_
        case OBJ_TAG:
                break;
        default:
-               bad_object(obj->offset, "bad object type %d", obj->type);
+               bad_object(obj->offset, "unknown object type %d", obj->type);
        }
        obj->hdr_size = consumed_bytes - obj->offset;
 
        return unpack_entry_data(obj->offset, obj->size);
 }
 
-static void * get_data_from_pack(struct object_entry *obj)
+static void *get_data_from_pack(struct object_entry *obj)
 {
        unsigned long from = obj[0].offset + obj[0].hdr_size;
        unsigned long len = obj[1].offset - from;
-       unsigned pg_offset = from % getpagesize();
-       unsigned char *map, *data;
+       unsigned char *src, *data;
        z_stream stream;
        int st;
 
-       map = mmap(NULL, len + pg_offset, PROT_READ, MAP_PRIVATE,
-                  input_fd, from - pg_offset);
-       if (map == MAP_FAILED)
-               die("cannot mmap packfile '%s': %s", pack_name, strerror(errno));
+       src = xmalloc(len);
+       if (pread(pack_fd, src, len, from) != len)
+               die("cannot pread pack file: %s", strerror(errno));
        data = xmalloc(obj->size);
        memset(&stream, 0, sizeof(stream));
        stream.next_out = data;
        stream.avail_out = obj->size;
-       stream.next_in = map + pg_offset;
+       stream.next_in = src;
        stream.avail_in = len;
        inflateInit(&stream);
        while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
        inflateEnd(&stream);
        if (st != Z_STREAM_END || stream.total_out != obj->size)
                die("serious inflate inconsistency");
-       munmap(map, len + pg_offset);
+       free(src);
        return data;
 }
 
@@ -261,8 +320,8 @@ static int find_delta(const union delta_base *base)
         return -first-1;
 }
 
-static int find_delta_childs(const union delta_base *base,
-                            int *first_index, int *last_index)
+static int find_delta_children(const union delta_base *base,
+                              int *first_index, int *last_index)
 {
        int first = find_delta(base);
        int last = first;
@@ -304,10 +363,9 @@ static void sha1_object(const void *data, unsigned long size,
        SHA1_Final(sha1, &ctx);
 }
 
-static void resolve_delta(struct delta_entry *delta, void *base_data,
+static void resolve_delta(struct object_entry *delta_obj, void *base_data,
                          unsigned long base_size, enum object_type type)
 {
-       struct object_entry *obj = delta->obj;
        void *delta_data;
        unsigned long delta_size;
        void *result;
@@ -315,29 +373,34 @@ static void resolve_delta(struct delta_entry *delta, void *base_data,
        union delta_base delta_base;
        int j, first, last;
 
-       obj->real_type = type;
-       delta_data = get_data_from_pack(obj);
-       delta_size = obj->size;
+       delta_obj->real_type = type;
+       delta_data = get_data_from_pack(delta_obj);
+       delta_size = delta_obj->size;
        result = patch_delta(base_data, base_size, delta_data, delta_size,
                             &result_size);
        free(delta_data);
        if (!result)
-               bad_object(obj->offset, "failed to apply delta");
-       sha1_object(result, result_size, type, obj->sha1);
-
-       hashcpy(delta_base.sha1, obj->sha1);
-       if (!find_delta_childs(&delta_base, &first, &last)) {
-               for (j = first; j <= last; j++)
-                       if (deltas[j].obj->type == OBJ_REF_DELTA)
-                               resolve_delta(&deltas[j], result, result_size, type);
+               bad_object(delta_obj->offset, "failed to apply delta");
+       sha1_object(result, result_size, type, delta_obj->sha1);
+       nr_resolved_deltas++;
+
+       hashcpy(delta_base.sha1, delta_obj->sha1);
+       if (!find_delta_children(&delta_base, &first, &last)) {
+               for (j = first; j <= last; j++) {
+                       struct object_entry *child = objects + deltas[j].obj_no;
+                       if (child->real_type == OBJ_REF_DELTA)
+                               resolve_delta(child, result, result_size, type);
+               }
        }
 
        memset(&delta_base, 0, sizeof(delta_base));
-       delta_base.offset = obj->offset;
-       if (!find_delta_childs(&delta_base, &first, &last)) {
-               for (j = first; j <= last; j++)
-                       if (deltas[j].obj->type == OBJ_OFS_DELTA)
-                               resolve_delta(&deltas[j], result, result_size, type);
+       delta_base.offset = delta_obj->offset;
+       if (!find_delta_children(&delta_base, &first, &last)) {
+               for (j = first; j <= last; j++) {
+                       struct object_entry *child = objects + deltas[j].obj_no;
+                       if (child->real_type == OBJ_OFS_DELTA)
+                               resolve_delta(child, result, result_size, type);
+               }
        }
 
        free(result);
@@ -353,7 +416,7 @@ static int compare_delta_entry(const void *a, const void *b)
 /* Parse all objects and return the pack content SHA1 hash */
 static void parse_pack_objects(unsigned char *sha1)
 {
-       int i;
+       int i, percent = -1;
        struct delta_entry *delta = deltas;
        void *data;
        struct stat st;
@@ -362,34 +425,43 @@ static void parse_pack_objects(unsigned char *sha1)
         * First pass:
         * - find locations of all objects;
         * - calculate SHA1 of all non-delta objects;
-        * - remember base SHA1 for all deltas.
+        * - remember base (SHA1 or offset) for all deltas.
         */
+       if (verbose)
+               fprintf(stderr, "Indexing %d objects.\n", nr_objects);
        for (i = 0; i < nr_objects; i++) {
                struct object_entry *obj = &objects[i];
                data = unpack_raw_entry(obj, &delta->base);
                obj->real_type = obj->type;
                if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
                        nr_deltas++;
-                       delta->obj = obj;
+                       delta->obj_no = i;
                        delta++;
                } else
                        sha1_object(data, obj->size, obj->type, obj->sha1);
                free(data);
+               if (verbose)
+                       percent = display_progress(i+1, nr_objects, percent);
        }
        objects[i].offset = consumed_bytes;
+       if (verbose)
+               fputc('\n', stderr);
 
        /* Check pack integrity */
-       SHA1_Update(&input_ctx, input_buffer, input_offset);
+       flush();
        SHA1_Final(sha1, &input_ctx);
        if (hashcmp(fill(20), sha1))
-               die("packfile '%s' SHA1 mismatch", pack_name);
+               die("pack is corrupted (SHA1 mismatch)");
        use(20);
 
        /* If input_fd is a file, we should have reached its end now. */
        if (fstat(input_fd, &st))
-               die("cannot fstat packfile '%s': %s", pack_name, strerror(errno));
+               die("cannot fstat packfile: %s", strerror(errno));
        if (S_ISREG(st.st_mode) && st.st_size != consumed_bytes)
-               die("packfile '%s' has junk at the end", pack_name);
+               die("pack has junk at the end");
+
+       if (!nr_deltas)
+               return;
 
        /* Sort deltas by base SHA1/offset for fast searching */
        qsort(deltas, nr_deltas, sizeof(struct delta_entry),
@@ -403,6 +475,8 @@ static void parse_pack_objects(unsigned char *sha1)
         *   recursively checking if the resulting object is used as a base
         *   for some more deltas.
         */
+       if (verbose)
+               fprintf(stderr, "Resolving %d deltas.\n", nr_deltas);
        for (i = 0; i < nr_objects; i++) {
                struct object_entry *obj = &objects[i];
                union delta_base base;
@@ -411,32 +485,179 @@ static void parse_pack_objects(unsigned char *sha1)
                if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
                        continue;
                hashcpy(base.sha1, obj->sha1);
-               ref = !find_delta_childs(&base, &ref_first, &ref_last);
+               ref = !find_delta_children(&base, &ref_first, &ref_last);
                memset(&base, 0, sizeof(base));
                base.offset = obj->offset;
-               ofs = !find_delta_childs(&base, &ofs_first, &ofs_last);
+               ofs = !find_delta_children(&base, &ofs_first, &ofs_last);
                if (!ref && !ofs)
                        continue;
                data = get_data_from_pack(obj);
                if (ref)
-                       for (j = ref_first; j <= ref_last; j++)
-                               if (deltas[j].obj->type == OBJ_REF_DELTA)
-                                       resolve_delta(&deltas[j], data,
+                       for (j = ref_first; j <= ref_last; j++) {
+                               struct object_entry *child = objects + deltas[j].obj_no;
+                               if (child->real_type == OBJ_REF_DELTA)
+                                       resolve_delta(child, data,
                                                      obj->size, obj->type);
+                       }
                if (ofs)
-                       for (j = ofs_first; j <= ofs_last; j++)
-                               if (deltas[j].obj->type == OBJ_OFS_DELTA)
-                                       resolve_delta(&deltas[j], data,
+                       for (j = ofs_first; j <= ofs_last; j++) {
+                               struct object_entry *child = objects + deltas[j].obj_no;
+                               if (child->real_type == OBJ_OFS_DELTA)
+                                       resolve_delta(child, data,
                                                      obj->size, obj->type);
+                       }
                free(data);
+               if (verbose)
+                       percent = display_progress(nr_resolved_deltas,
+                                                  nr_deltas, percent);
        }
+       if (verbose && nr_resolved_deltas == nr_deltas)
+               fputc('\n', stderr);
+}
+
+static int write_compressed(int fd, void *in, unsigned int size)
+{
+       z_stream stream;
+       unsigned long maxsize;
+       void *out;
+
+       memset(&stream, 0, sizeof(stream));
+       deflateInit(&stream, zlib_compression_level);
+       maxsize = deflateBound(&stream, size);
+       out = xmalloc(maxsize);
+
+       /* Compress it */
+       stream.next_in = in;
+       stream.avail_in = size;
+       stream.next_out = out;
+       stream.avail_out = maxsize;
+       while (deflate(&stream, Z_FINISH) == Z_OK);
+       deflateEnd(&stream);
+
+       size = stream.total_out;
+       write_or_die(fd, out, size);
+       free(out);
+       return size;
+}
+
+static void append_obj_to_pack(void *buf,
+                              unsigned long size, enum object_type type)
+{
+       struct object_entry *obj = &objects[nr_objects++];
+       unsigned char header[10];
+       unsigned long s = size;
+       int n = 0;
+       unsigned char c = (type << 4) | (s & 15);
+       s >>= 4;
+       while (s) {
+               header[n++] = c | 0x80;
+               c = s & 0x7f;
+               s >>= 7;
+       }
+       header[n++] = c;
+       write_or_die(output_fd, header, n);
+       obj[1].offset = obj[0].offset + n;
+       obj[1].offset += write_compressed(output_fd, buf, size);
+       sha1_object(buf, size, type, obj->sha1);
+}
+
+static int delta_pos_compare(const void *_a, const void *_b)
+{
+       struct delta_entry *a = *(struct delta_entry **)_a;
+       struct delta_entry *b = *(struct delta_entry **)_b;
+       return a->obj_no - b->obj_no;
+}
+
+static void fix_unresolved_deltas(int nr_unresolved)
+{
+       struct delta_entry **sorted_by_pos;
+       int i, n = 0, percent = -1;
 
-       /* Check for unresolved deltas */
+       /*
+        * Since many unresolved deltas may well be themselves base objects
+        * for more unresolved deltas, we really want to include the
+        * smallest number of base objects that would cover as much delta
+        * as possible by picking the
+        * trunc deltas first, allowing for other deltas to resolve without
+        * additional base objects.  Since most base objects are to be found
+        * before deltas depending on them, a good heuristic is to start
+        * resolving deltas in the same order as their position in the pack.
+        */
+       sorted_by_pos = xmalloc(nr_unresolved * sizeof(*sorted_by_pos));
        for (i = 0; i < nr_deltas; i++) {
-               if (deltas[i].obj->real_type == OBJ_REF_DELTA ||
-                   deltas[i].obj->real_type == OBJ_OFS_DELTA)
-                       die("packfile '%s' has unresolved deltas",  pack_name);
+               if (objects[deltas[i].obj_no].real_type != OBJ_REF_DELTA)
+                       continue;
+               sorted_by_pos[n++] = &deltas[i];
+       }
+       qsort(sorted_by_pos, n, sizeof(*sorted_by_pos), delta_pos_compare);
+
+       for (i = 0; i < n; i++) {
+               struct delta_entry *d = sorted_by_pos[i];
+               void *data;
+               unsigned long size;
+               char type[10];
+               enum object_type obj_type;
+               int j, first, last;
+
+               if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
+                       continue;
+               data = read_sha1_file(d->base.sha1, type, &size);
+               if (!data)
+                       continue;
+               if      (!strcmp(type, blob_type))   obj_type = OBJ_BLOB;
+               else if (!strcmp(type, tree_type))   obj_type = OBJ_TREE;
+               else if (!strcmp(type, commit_type)) obj_type = OBJ_COMMIT;
+               else if (!strcmp(type, tag_type))    obj_type = OBJ_TAG;
+               else die("base object %s is of type '%s'",
+                        sha1_to_hex(d->base.sha1), type);
+
+               find_delta_children(&d->base, &first, &last);
+               for (j = first; j <= last; j++) {
+                       struct object_entry *child = objects + deltas[j].obj_no;
+                       if (child->real_type == OBJ_REF_DELTA)
+                               resolve_delta(child, data, size, obj_type);
+               }
+
+               append_obj_to_pack(data, size, obj_type);
+               free(data);
+               if (verbose)
+                       percent = display_progress(nr_resolved_deltas,
+                                                  nr_deltas, percent);
        }
+       free(sorted_by_pos);
+       if (verbose)
+               fputc('\n', stderr);
+}
+
+static void readjust_pack_header_and_sha1(unsigned char *sha1)
+{
+       struct pack_header hdr;
+       SHA_CTX ctx;
+       int size;
+
+       /* Rewrite pack header with updated object number */
+       if (lseek(output_fd, 0, SEEK_SET) != 0)
+               die("cannot seek back: %s", strerror(errno));
+       if (read_in_full(output_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
+               die("cannot read pack header back: %s", strerror(errno));
+       hdr.hdr_entries = htonl(nr_objects);
+       if (lseek(output_fd, 0, SEEK_SET) != 0)
+               die("cannot seek back: %s", strerror(errno));
+       write_or_die(output_fd, &hdr, sizeof(hdr));
+       if (lseek(output_fd, 0, SEEK_SET) != 0)
+               die("cannot seek back: %s", strerror(errno));
+
+       /* Recompute and store the new pack's SHA1 */
+       SHA1_Init(&ctx);
+       do {
+               unsigned char *buf[4096];
+               size = xread(output_fd, buf, sizeof(buf));
+               if (size < 0)
+                       die("cannot read pack data back: %s", strerror(errno));
+               SHA1_Update(&ctx, buf, size);
+       } while (size > 0);
+       SHA1_Final(sha1, &ctx);
+       write_or_die(output_fd, sha1, 20);
 }
 
 static int sha1_compare(const void *_a, const void *_b)
@@ -450,12 +671,12 @@ static int sha1_compare(const void *_a, const void *_b)
  * On entry *sha1 contains the pack content SHA1 hash, on exit it is
  * the SHA1 hash of sorted object names.
  */
-static void write_index_file(const char *index_name, unsigned char *sha1)
+static const char *write_index_file(const char *index_name, unsigned char *sha1)
 {
        struct sha1file *f;
        struct object_entry **sorted_by_sha, **list, **last;
        unsigned int array[256];
-       int i;
+       int i, fd;
        SHA_CTX ctx;
 
        if (nr_objects) {
@@ -472,8 +693,19 @@ static void write_index_file(const char *index_name, unsigned char *sha1)
        else
                sorted_by_sha = list = last = NULL;
 
-       unlink(index_name);
-       f = sha1create("%s", index_name);
+       if (!index_name) {
+               static char tmpfile[PATH_MAX];
+               snprintf(tmpfile, sizeof(tmpfile),
+                        "%s/index_XXXXXX", get_object_directory());
+               fd = mkstemp(tmpfile);
+               index_name = xstrdup(tmpfile);
+       } else {
+               unlink(index_name);
+               fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
+       }
+       if (fd < 0)
+               die("unable to create %s: %s", index_name, strerror(errno));
+       f = sha1fd(fd, index_name);
 
        /*
         * Write the first-level table (the list is sorted,
@@ -513,20 +745,128 @@ static void write_index_file(const char *index_name, unsigned char *sha1)
        sha1close(f, NULL, 1);
        free(sorted_by_sha);
        SHA1_Final(sha1, &ctx);
+       return index_name;
+}
+
+static void final(const char *final_pack_name, const char *curr_pack_name,
+                 const char *final_index_name, const char *curr_index_name,
+                 const char *keep_name, const char *keep_msg,
+                 unsigned char *sha1)
+{
+       char *report = "pack";
+       char name[PATH_MAX];
+       int err;
+
+       if (!from_stdin) {
+               close(input_fd);
+       } else {
+               err = close(output_fd);
+               if (err)
+                       die("error while closing pack file: %s", strerror(errno));
+               chmod(curr_pack_name, 0444);
+       }
+
+       if (keep_msg) {
+               int keep_fd, keep_msg_len = strlen(keep_msg);
+               if (!keep_name) {
+                       snprintf(name, sizeof(name), "%s/pack/pack-%s.keep",
+                                get_object_directory(), sha1_to_hex(sha1));
+                       keep_name = name;
+               }
+               keep_fd = open(keep_name, O_RDWR|O_CREAT|O_EXCL, 0600);
+               if (keep_fd < 0) {
+                       if (errno != EEXIST)
+                               die("cannot write keep file");
+               } else {
+                       if (keep_msg_len > 0) {
+                               write_or_die(keep_fd, keep_msg, keep_msg_len);
+                               write_or_die(keep_fd, "\n", 1);
+                       }
+                       close(keep_fd);
+                       report = "keep";
+               }
+       }
+
+       if (final_pack_name != curr_pack_name) {
+               if (!final_pack_name) {
+                       snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
+                                get_object_directory(), sha1_to_hex(sha1));
+                       final_pack_name = name;
+               }
+               if (move_temp_to_file(curr_pack_name, final_pack_name))
+                       die("cannot store pack file");
+       }
+
+       chmod(curr_index_name, 0444);
+       if (final_index_name != curr_index_name) {
+               if (!final_index_name) {
+                       snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
+                                get_object_directory(), sha1_to_hex(sha1));
+                       final_index_name = name;
+               }
+               if (move_temp_to_file(curr_index_name, final_index_name))
+                       die("cannot store index file");
+       }
+
+       if (!from_stdin) {
+               printf("%s\n", sha1_to_hex(sha1));
+       } else {
+               char buf[48];
+               int len = snprintf(buf, sizeof(buf), "%s\t%s\n",
+                                  report, sha1_to_hex(sha1));
+               write_or_die(1, buf, len);
+
+               /*
+                * Let's just mimic git-unpack-objects here and write
+                * the last part of the input buffer to stdout.
+                */
+               while (input_len) {
+                       err = xwrite(1, input_buffer + input_offset, input_len);
+                       if (err <= 0)
+                               break;
+                       input_len -= err;
+                       input_offset += err;
+               }
+       }
 }
 
 int main(int argc, char **argv)
 {
-       int i;
-       char *index_name = NULL;
-       char *index_name_buf = NULL;
+       int i, fix_thin_pack = 0;
+       const char *curr_pack, *pack_name = NULL;
+       const char *curr_index, *index_name = NULL;
+       const char *keep_name = NULL, *keep_msg = NULL;
+       char *index_name_buf = NULL, *keep_name_buf = NULL;
        unsigned char sha1[20];
 
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
 
                if (*arg == '-') {
-                       if (!strcmp(arg, "-o")) {
+                       if (!strcmp(arg, "--stdin")) {
+                               from_stdin = 1;
+                       } else if (!strcmp(arg, "--fix-thin")) {
+                               fix_thin_pack = 1;
+                       } else if (!strcmp(arg, "--keep")) {
+                               keep_msg = "";
+                       } else if (!strncmp(arg, "--keep=", 7)) {
+                               keep_msg = arg + 7;
+                       } else if (!strncmp(arg, "--pack_header=", 14)) {
+                               struct pack_header *hdr;
+                               char *c;
+
+                               hdr = (struct pack_header *)input_buffer;
+                               hdr->hdr_signature = htonl(PACK_SIGNATURE);
+                               hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
+                               if (*c != ',')
+                                       die("bad %s", arg);
+                               hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
+                               if (*c)
+                                       die("bad %s", arg);
+                               input_len = sizeof(*hdr);
+                       } else if (!strcmp(arg, "-v")) {
+                               verbose = 1;
+                       } else if (!strcmp(arg, "-o")) {
                                if (index_name || (i+1) >= argc)
                                        usage(index_pack_usage);
                                index_name = argv[++i];
@@ -540,9 +880,11 @@ int main(int argc, char **argv)
                pack_name = arg;
        }
 
-       if (!pack_name)
+       if (!pack_name && !from_stdin)
                usage(index_pack_usage);
-       if (!index_name) {
+       if (fix_thin_pack && !from_stdin)
+               die("--fix-thin cannot be used without --stdin");
+       if (!index_name && pack_name) {
                int len = strlen(pack_name);
                if (!has_extension(pack_name, ".pack"))
                        die("packfile name '%s' does not end with '.pack'",
@@ -552,18 +894,55 @@ int main(int argc, char **argv)
                strcpy(index_name_buf + len - 5, ".idx");
                index_name = index_name_buf;
        }
+       if (keep_msg && !keep_name && pack_name) {
+               int len = strlen(pack_name);
+               if (!has_extension(pack_name, ".pack"))
+                       die("packfile name '%s' does not end with '.pack'",
+                           pack_name);
+               keep_name_buf = xmalloc(len);
+               memcpy(keep_name_buf, pack_name, len - 5);
+               strcpy(keep_name_buf + len - 5, ".keep");
+               keep_name = keep_name_buf;
+       }
 
-       open_pack_file();
+       curr_pack = open_pack_file(pack_name);
        parse_pack_header();
-       objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
-       deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
+       objects = xmalloc((nr_objects + 1) * sizeof(struct object_entry));
+       deltas = xmalloc(nr_objects * sizeof(struct delta_entry));
+       if (verbose)
+               setup_progress_signal();
        parse_pack_objects(sha1);
+       if (nr_deltas != nr_resolved_deltas) {
+               if (fix_thin_pack) {
+                       int nr_unresolved = nr_deltas - nr_resolved_deltas;
+                       int nr_objects_initial = nr_objects;
+                       if (nr_unresolved <= 0)
+                               die("confusion beyond insanity");
+                       objects = xrealloc(objects,
+                                          (nr_objects + nr_unresolved + 1)
+                                          * sizeof(*objects));
+                       fix_unresolved_deltas(nr_unresolved);
+                       if (verbose)
+                               fprintf(stderr, "%d objects were added to complete this thin pack.\n",
+                                       nr_objects - nr_objects_initial);
+                       readjust_pack_header_and_sha1(sha1);
+               }
+               if (nr_deltas != nr_resolved_deltas)
+                       die("pack has %d unresolved deltas",
+                           nr_deltas - nr_resolved_deltas);
+       } else {
+               /* Flush remaining pack final 20-byte SHA1. */
+               flush();
+       }
        free(deltas);
-       write_index_file(index_name, sha1);
+       curr_index = write_index_file(index_name, sha1);
+       final(pack_name, curr_pack,
+               index_name, curr_index,
+               keep_name, keep_msg,
+               sha1);
        free(objects);
        free(index_name_buf);
-
-       printf("%s\n", sha1_to_hex(sha1));
+       free(keep_name_buf);
 
        return 0;
 }