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-rw-r--r--builtin/unpack-objects.c568
1 files changed, 568 insertions, 0 deletions
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
new file mode 100644
index 0000000..f63973c
--- /dev/null
+++ b/builtin/unpack-objects.c
@@ -0,0 +1,568 @@
+#include "builtin.h"
+#include "cache.h"
+#include "object.h"
+#include "delta.h"
+#include "pack.h"
+#include "blob.h"
+#include "commit.h"
+#include "tag.h"
+#include "tree.h"
+#include "tree-walk.h"
+#include "progress.h"
+#include "decorate.h"
+#include "fsck.h"
+
+static int dry_run, quiet, recover, has_errors, strict;
+static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict] < pack-file";
+
+/* We always read in 4kB chunks. */
+static unsigned char buffer[4096];
+static unsigned int offset, len;
+static off_t consumed_bytes;
+static git_SHA_CTX ctx;
+
+/*
+ * When running under --strict mode, objects whose reachability are
+ * suspect are kept in core without getting written in the object
+ * store.
+ */
+struct obj_buffer {
+ char *buffer;
+ unsigned long size;
+};
+
+static struct decoration obj_decorate;
+
+static struct obj_buffer *lookup_object_buffer(struct object *base)
+{
+ return lookup_decoration(&obj_decorate, base);
+}
+
+static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
+{
+ struct obj_buffer *obj;
+ obj = xcalloc(1, sizeof(struct obj_buffer));
+ obj->buffer = buffer;
+ obj->size = size;
+ if (add_decoration(&obj_decorate, object, obj))
+ die("object %s tried to add buffer twice!", sha1_to_hex(object->sha1));
+}
+
+/*
+ * Make sure at least "min" bytes are available in the buffer, and
+ * return the pointer to the buffer.
+ */
+static void *fill(int min)
+{
+ if (min <= len)
+ return buffer + offset;
+ if (min > sizeof(buffer))
+ die("cannot fill %d bytes", min);
+ if (offset) {
+ git_SHA1_Update(&ctx, buffer, offset);
+ memmove(buffer, buffer + offset, len);
+ offset = 0;
+ }
+ do {
+ ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
+ if (ret <= 0) {
+ if (!ret)
+ die("early EOF");
+ die_errno("read error on input");
+ }
+ len += ret;
+ } while (len < min);
+ return buffer;
+}
+
+static void use(int bytes)
+{
+ if (bytes > len)
+ die("used more bytes than were available");
+ len -= bytes;
+ offset += bytes;
+
+ /* make sure off_t is sufficiently large not to wrap */
+ if (signed_add_overflows(consumed_bytes, bytes))
+ die("pack too large for current definition of off_t");
+ consumed_bytes += bytes;
+}
+
+static void *get_data(unsigned long size)
+{
+ z_stream stream;
+ void *buf = xmalloc(size);
+
+ memset(&stream, 0, sizeof(stream));
+
+ stream.next_out = buf;
+ stream.avail_out = size;
+ stream.next_in = fill(1);
+ stream.avail_in = len;
+ git_inflate_init(&stream);
+
+ for (;;) {
+ int ret = git_inflate(&stream, 0);
+ use(len - stream.avail_in);
+ if (stream.total_out == size && ret == Z_STREAM_END)
+ break;
+ if (ret != Z_OK) {
+ error("inflate returned %d\n", ret);
+ free(buf);
+ buf = NULL;
+ if (!recover)
+ exit(1);
+ has_errors = 1;
+ break;
+ }
+ stream.next_in = fill(1);
+ stream.avail_in = len;
+ }
+ git_inflate_end(&stream);
+ return buf;
+}
+
+struct delta_info {
+ unsigned char base_sha1[20];
+ unsigned nr;
+ off_t base_offset;
+ unsigned long size;
+ void *delta;
+ struct delta_info *next;
+};
+
+static struct delta_info *delta_list;
+
+static void add_delta_to_list(unsigned nr, unsigned const char *base_sha1,
+ off_t base_offset,
+ void *delta, unsigned long size)
+{
+ struct delta_info *info = xmalloc(sizeof(*info));
+
+ hashcpy(info->base_sha1, base_sha1);
+ info->base_offset = base_offset;
+ info->size = size;
+ info->delta = delta;
+ info->nr = nr;
+ info->next = delta_list;
+ delta_list = info;
+}
+
+struct obj_info {
+ off_t offset;
+ unsigned char sha1[20];
+ struct object *obj;
+};
+
+#define FLAG_OPEN (1u<<20)
+#define FLAG_WRITTEN (1u<<21)
+
+static struct obj_info *obj_list;
+static unsigned nr_objects;
+
+/*
+ * Called only from check_object() after it verified this object
+ * is Ok.
+ */
+static void write_cached_object(struct object *obj)
+{
+ unsigned char sha1[20];
+ struct obj_buffer *obj_buf = lookup_object_buffer(obj);
+ if (write_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), sha1) < 0)
+ die("failed to write object %s", sha1_to_hex(obj->sha1));
+ obj->flags |= FLAG_WRITTEN;
+}
+
+/*
+ * At the very end of the processing, write_rest() scans the objects
+ * that have reachability requirements and calls this function.
+ * Verify its reachability and validity recursively and write it out.
+ */
+static int check_object(struct object *obj, int type, void *data)
+{
+ if (!obj)
+ return 1;
+
+ if (obj->flags & FLAG_WRITTEN)
+ return 0;
+
+ if (type != OBJ_ANY && obj->type != type)
+ die("object type mismatch");
+
+ if (!(obj->flags & FLAG_OPEN)) {
+ unsigned long size;
+ int type = sha1_object_info(obj->sha1, &size);
+ if (type != obj->type || type <= 0)
+ die("object of unexpected type");
+ obj->flags |= FLAG_WRITTEN;
+ return 0;
+ }
+
+ if (fsck_object(obj, 1, fsck_error_function))
+ die("Error in object");
+ if (fsck_walk(obj, check_object, NULL))
+ die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
+ write_cached_object(obj);
+ return 0;
+}
+
+static void write_rest(void)
+{
+ unsigned i;
+ for (i = 0; i < nr_objects; i++) {
+ if (obj_list[i].obj)
+ check_object(obj_list[i].obj, OBJ_ANY, NULL);
+ }
+}
+
+static void added_object(unsigned nr, enum object_type type,
+ void *data, unsigned long size);
+
+/*
+ * Write out nr-th object from the list, now we know the contents
+ * of it. Under --strict, this buffers structured objects in-core,
+ * to be checked at the end.
+ */
+static void write_object(unsigned nr, enum object_type type,
+ void *buf, unsigned long size)
+{
+ if (!strict) {
+ if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
+ die("failed to write object");
+ added_object(nr, type, buf, size);
+ free(buf);
+ obj_list[nr].obj = NULL;
+ } else if (type == OBJ_BLOB) {
+ struct blob *blob;
+ if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
+ die("failed to write object");
+ added_object(nr, type, buf, size);
+ free(buf);
+
+ blob = lookup_blob(obj_list[nr].sha1);
+ if (blob)
+ blob->object.flags |= FLAG_WRITTEN;
+ else
+ die("invalid blob object");
+ obj_list[nr].obj = NULL;
+ } else {
+ struct object *obj;
+ int eaten;
+ hash_sha1_file(buf, size, typename(type), obj_list[nr].sha1);
+ added_object(nr, type, buf, size);
+ obj = parse_object_buffer(obj_list[nr].sha1, type, size, buf, &eaten);
+ if (!obj)
+ die("invalid %s", typename(type));
+ add_object_buffer(obj, buf, size);
+ obj->flags |= FLAG_OPEN;
+ obj_list[nr].obj = obj;
+ }
+}
+
+static void resolve_delta(unsigned nr, enum object_type type,
+ void *base, unsigned long base_size,
+ void *delta, unsigned long delta_size)
+{
+ void *result;
+ unsigned long result_size;
+
+ result = patch_delta(base, base_size,
+ delta, delta_size,
+ &result_size);
+ if (!result)
+ die("failed to apply delta");
+ free(delta);
+ write_object(nr, type, result, result_size);
+}
+
+/*
+ * We now know the contents of an object (which is nr-th in the pack);
+ * resolve all the deltified objects that are based on it.
+ */
+static void added_object(unsigned nr, enum object_type type,
+ void *data, unsigned long size)
+{
+ struct delta_info **p = &delta_list;
+ struct delta_info *info;
+
+ while ((info = *p) != NULL) {
+ if (!hashcmp(info->base_sha1, obj_list[nr].sha1) ||
+ info->base_offset == obj_list[nr].offset) {
+ *p = info->next;
+ p = &delta_list;
+ resolve_delta(info->nr, type, data, size,
+ info->delta, info->size);
+ free(info);
+ continue;
+ }
+ p = &info->next;
+ }
+}
+
+static void unpack_non_delta_entry(enum object_type type, unsigned long size,
+ unsigned nr)
+{
+ void *buf = get_data(size);
+
+ if (!dry_run && buf)
+ write_object(nr, type, buf, size);
+ else
+ free(buf);
+}
+
+static int resolve_against_held(unsigned nr, const unsigned char *base,
+ void *delta_data, unsigned long delta_size)
+{
+ struct object *obj;
+ struct obj_buffer *obj_buffer;
+ obj = lookup_object(base);
+ if (!obj)
+ return 0;
+ obj_buffer = lookup_object_buffer(obj);
+ if (!obj_buffer)
+ return 0;
+ resolve_delta(nr, obj->type, obj_buffer->buffer,
+ obj_buffer->size, delta_data, delta_size);
+ return 1;
+}
+
+static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
+ unsigned nr)
+{
+ void *delta_data, *base;
+ unsigned long base_size;
+ unsigned char base_sha1[20];
+
+ if (type == OBJ_REF_DELTA) {
+ hashcpy(base_sha1, fill(20));
+ use(20);
+ delta_data = get_data(delta_size);
+ if (dry_run || !delta_data) {
+ free(delta_data);
+ return;
+ }
+ if (has_sha1_file(base_sha1))
+ ; /* Ok we have this one */
+ else if (resolve_against_held(nr, base_sha1,
+ delta_data, delta_size))
+ return; /* we are done */
+ else {
+ /* cannot resolve yet --- queue it */
+ hashcpy(obj_list[nr].sha1, null_sha1);
+ add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
+ return;
+ }
+ } else {
+ unsigned base_found = 0;
+ unsigned char *pack, c;
+ off_t base_offset;
+ unsigned lo, mid, hi;
+
+ pack = fill(1);
+ c = *pack;
+ use(1);
+ base_offset = c & 127;
+ while (c & 128) {
+ base_offset += 1;
+ if (!base_offset || MSB(base_offset, 7))
+ die("offset value overflow for delta base object");
+ pack = fill(1);
+ c = *pack;
+ use(1);
+ base_offset = (base_offset << 7) + (c & 127);
+ }
+ base_offset = obj_list[nr].offset - base_offset;
+ if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
+ die("offset value out of bound for delta base object");
+
+ delta_data = get_data(delta_size);
+ if (dry_run || !delta_data) {
+ free(delta_data);
+ return;
+ }
+ lo = 0;
+ hi = nr;
+ while (lo < hi) {
+ mid = (lo + hi)/2;
+ if (base_offset < obj_list[mid].offset) {
+ hi = mid;
+ } else if (base_offset > obj_list[mid].offset) {
+ lo = mid + 1;
+ } else {
+ hashcpy(base_sha1, obj_list[mid].sha1);
+ base_found = !is_null_sha1(base_sha1);
+ break;
+ }
+ }
+ if (!base_found) {
+ /*
+ * The delta base object is itself a delta that
+ * has not been resolved yet.
+ */
+ hashcpy(obj_list[nr].sha1, null_sha1);
+ add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
+ return;
+ }
+ }
+
+ if (resolve_against_held(nr, base_sha1, delta_data, delta_size))
+ return;
+
+ base = read_sha1_file(base_sha1, &type, &base_size);
+ if (!base) {
+ error("failed to read delta-pack base object %s",
+ sha1_to_hex(base_sha1));
+ if (!recover)
+ exit(1);
+ has_errors = 1;
+ return;
+ }
+ resolve_delta(nr, type, base, base_size, delta_data, delta_size);
+ free(base);
+}
+
+static void unpack_one(unsigned nr)
+{
+ unsigned shift;
+ unsigned char *pack;
+ unsigned long size, c;
+ enum object_type type;
+
+ obj_list[nr].offset = consumed_bytes;
+
+ pack = fill(1);
+ c = *pack;
+ use(1);
+ type = (c >> 4) & 7;
+ size = (c & 15);
+ shift = 4;
+ while (c & 0x80) {
+ pack = fill(1);
+ c = *pack;
+ use(1);
+ size += (c & 0x7f) << shift;
+ shift += 7;
+ }
+
+ switch (type) {
+ case OBJ_COMMIT:
+ case OBJ_TREE:
+ case OBJ_BLOB:
+ case OBJ_TAG:
+ unpack_non_delta_entry(type, size, nr);
+ return;
+ case OBJ_REF_DELTA:
+ case OBJ_OFS_DELTA:
+ unpack_delta_entry(type, size, nr);
+ return;
+ default:
+ error("bad object type %d", type);
+ has_errors = 1;
+ if (recover)
+ return;
+ exit(1);
+ }
+}
+
+static void unpack_all(void)
+{
+ int i;
+ struct progress *progress = NULL;
+ struct pack_header *hdr = fill(sizeof(struct pack_header));
+
+ nr_objects = ntohl(hdr->hdr_entries);
+
+ if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
+ die("bad pack file");
+ if (!pack_version_ok(hdr->hdr_version))
+ die("unknown pack file version %"PRIu32,
+ ntohl(hdr->hdr_version));
+ use(sizeof(struct pack_header));
+
+ if (!quiet)
+ progress = start_progress("Unpacking objects", nr_objects);
+ obj_list = xcalloc(nr_objects, sizeof(*obj_list));
+ for (i = 0; i < nr_objects; i++) {
+ unpack_one(i);
+ display_progress(progress, i + 1);
+ }
+ stop_progress(&progress);
+
+ if (delta_list)
+ die("unresolved deltas left after unpacking");
+}
+
+int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
+{
+ int i;
+ unsigned char sha1[20];
+
+ read_replace_refs = 0;
+
+ git_config(git_default_config, NULL);
+
+ quiet = !isatty(2);
+
+ for (i = 1 ; i < argc; i++) {
+ const char *arg = argv[i];
+
+ if (*arg == '-') {
+ if (!strcmp(arg, "-n")) {
+ dry_run = 1;
+ continue;
+ }
+ if (!strcmp(arg, "-q")) {
+ quiet = 1;
+ continue;
+ }
+ if (!strcmp(arg, "-r")) {
+ recover = 1;
+ continue;
+ }
+ if (!strcmp(arg, "--strict")) {
+ strict = 1;
+ continue;
+ }
+ if (!prefixcmp(arg, "--pack_header=")) {
+ struct pack_header *hdr;
+ char *c;
+
+ hdr = (struct pack_header *)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);
+ len = sizeof(*hdr);
+ continue;
+ }
+ usage(unpack_usage);
+ }
+
+ /* We don't take any non-flag arguments now.. Maybe some day */
+ usage(unpack_usage);
+ }
+ git_SHA1_Init(&ctx);
+ unpack_all();
+ git_SHA1_Update(&ctx, buffer, offset);
+ git_SHA1_Final(sha1, &ctx);
+ if (strict)
+ write_rest();
+ if (hashcmp(fill(20), sha1))
+ die("final sha1 did not match");
+ use(20);
+
+ /* Write the last part of the buffer to stdout */
+ while (len) {
+ int ret = xwrite(1, buffer + offset, len);
+ if (ret <= 0)
+ break;
+ len -= ret;
+ offset += ret;
+ }
+
+ /* All done */
+ return has_errors;
+}