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![Nicolas Pitre](/assets/img/avatar_default.png)
Some applications which invoke unpack-objects or index-pack --stdin may want to examine the pack header to determine the number of objects contained in the pack and use that value to determine which executable to invoke to handle the rest of the pack stream. However if the caller consumes the pack header from the input stream then its no longer available for unpack-objects or index-pack --stdin, both of which need the version and object count to process the stream. This change introduces --pack_header=ver,cnt as a command line option that the caller can supply to indicate it has already consumed the pack header and what version and object count were found in that header. As this option is only meant for low level applications such as receive-pack we are not documenting it at this time. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
417 lines
9 KiB
C
417 lines
9 KiB
C
#include "builtin.h"
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#include "cache.h"
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#include "object.h"
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#include "delta.h"
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#include "pack.h"
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#include "blob.h"
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#include "commit.h"
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#include "tag.h"
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#include "tree.h"
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#include <sys/time.h>
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static int dry_run, quiet, recover, has_errors;
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static const char unpack_usage[] = "git-unpack-objects [-n] [-q] [-r] < pack-file";
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/* We always read in 4kB chunks. */
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static unsigned char buffer[4096];
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static unsigned long offset, len, consumed_bytes;
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static SHA_CTX ctx;
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/*
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* Make sure at least "min" bytes are available in the buffer, and
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* return the pointer to the buffer.
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*/
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static void *fill(int min)
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{
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if (min <= len)
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return buffer + offset;
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if (min > sizeof(buffer))
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die("cannot fill %d bytes", min);
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if (offset) {
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SHA1_Update(&ctx, buffer, offset);
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memmove(buffer, buffer + offset, len);
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offset = 0;
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}
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do {
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int ret = xread(0, buffer + len, sizeof(buffer) - len);
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if (ret <= 0) {
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if (!ret)
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die("early EOF");
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die("read error on input: %s", strerror(errno));
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}
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len += ret;
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} while (len < min);
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return buffer;
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}
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static void use(int bytes)
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{
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if (bytes > len)
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die("used more bytes than were available");
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len -= bytes;
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offset += bytes;
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consumed_bytes += bytes;
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}
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static void *get_data(unsigned long size)
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{
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z_stream stream;
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void *buf = xmalloc(size);
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memset(&stream, 0, sizeof(stream));
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stream.next_out = buf;
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stream.avail_out = size;
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stream.next_in = fill(1);
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stream.avail_in = len;
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inflateInit(&stream);
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for (;;) {
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int ret = inflate(&stream, 0);
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use(len - stream.avail_in);
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if (stream.total_out == size && ret == Z_STREAM_END)
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break;
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if (ret != Z_OK) {
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error("inflate returned %d\n", ret);
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free(buf);
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buf = NULL;
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if (!recover)
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exit(1);
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has_errors = 1;
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break;
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}
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stream.next_in = fill(1);
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stream.avail_in = len;
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}
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inflateEnd(&stream);
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return buf;
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}
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struct delta_info {
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unsigned char base_sha1[20];
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unsigned long base_offset;
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unsigned long size;
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void *delta;
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unsigned nr;
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struct delta_info *next;
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};
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static struct delta_info *delta_list;
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static void add_delta_to_list(unsigned nr, unsigned const char *base_sha1,
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unsigned long base_offset,
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void *delta, unsigned long size)
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{
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struct delta_info *info = xmalloc(sizeof(*info));
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hashcpy(info->base_sha1, base_sha1);
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info->base_offset = base_offset;
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info->size = size;
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info->delta = delta;
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info->nr = nr;
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info->next = delta_list;
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delta_list = info;
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}
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struct obj_info {
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unsigned long offset;
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unsigned char sha1[20];
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};
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static struct obj_info *obj_list;
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static void added_object(unsigned nr, const char *type, void *data,
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unsigned long size);
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static void write_object(unsigned nr, void *buf, unsigned long size,
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const char *type)
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{
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if (write_sha1_file(buf, size, type, obj_list[nr].sha1) < 0)
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die("failed to write object");
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added_object(nr, type, buf, size);
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}
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static void resolve_delta(unsigned nr, const char *type,
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void *base, unsigned long base_size,
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void *delta, unsigned long delta_size)
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{
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void *result;
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unsigned long result_size;
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result = patch_delta(base, base_size,
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delta, delta_size,
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&result_size);
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if (!result)
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die("failed to apply delta");
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free(delta);
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write_object(nr, result, result_size, type);
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free(result);
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}
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static void added_object(unsigned nr, const char *type, void *data,
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unsigned long size)
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{
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struct delta_info **p = &delta_list;
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struct delta_info *info;
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while ((info = *p) != NULL) {
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if (!hashcmp(info->base_sha1, obj_list[nr].sha1) ||
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info->base_offset == obj_list[nr].offset) {
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*p = info->next;
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p = &delta_list;
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resolve_delta(info->nr, type, data, size,
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info->delta, info->size);
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free(info);
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continue;
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}
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p = &info->next;
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}
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}
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static void unpack_non_delta_entry(enum object_type kind, unsigned long size,
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unsigned nr)
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{
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void *buf = get_data(size);
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const char *type;
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switch (kind) {
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case OBJ_COMMIT: type = commit_type; break;
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case OBJ_TREE: type = tree_type; break;
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case OBJ_BLOB: type = blob_type; break;
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case OBJ_TAG: type = tag_type; break;
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default: die("bad type %d", kind);
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}
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if (!dry_run && buf)
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write_object(nr, buf, size, type);
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free(buf);
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}
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static void unpack_delta_entry(enum object_type kind, unsigned long delta_size,
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unsigned nr)
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{
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void *delta_data, *base;
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unsigned long base_size;
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char type[20];
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unsigned char base_sha1[20];
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if (kind == OBJ_REF_DELTA) {
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hashcpy(base_sha1, fill(20));
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use(20);
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delta_data = get_data(delta_size);
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if (dry_run || !delta_data) {
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free(delta_data);
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return;
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}
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if (!has_sha1_file(base_sha1)) {
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hashcpy(obj_list[nr].sha1, null_sha1);
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add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
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return;
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}
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} else {
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unsigned base_found = 0;
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unsigned char *pack, c;
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unsigned long base_offset;
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unsigned lo, mid, hi;
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pack = fill(1);
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c = *pack;
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use(1);
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base_offset = c & 127;
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while (c & 128) {
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base_offset += 1;
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if (!base_offset || base_offset & ~(~0UL >> 7))
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die("offset value overflow for delta base object");
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pack = fill(1);
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c = *pack;
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use(1);
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base_offset = (base_offset << 7) + (c & 127);
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}
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base_offset = obj_list[nr].offset - base_offset;
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delta_data = get_data(delta_size);
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if (dry_run || !delta_data) {
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free(delta_data);
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return;
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}
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lo = 0;
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hi = nr;
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while (lo < hi) {
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mid = (lo + hi)/2;
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if (base_offset < obj_list[mid].offset) {
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hi = mid;
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} else if (base_offset > obj_list[mid].offset) {
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lo = mid + 1;
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} else {
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hashcpy(base_sha1, obj_list[mid].sha1);
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base_found = !is_null_sha1(base_sha1);
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break;
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}
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}
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if (!base_found) {
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/* The delta base object is itself a delta that
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has not been resolved yet. */
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hashcpy(obj_list[nr].sha1, null_sha1);
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add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
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return;
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}
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}
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base = read_sha1_file(base_sha1, type, &base_size);
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if (!base) {
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error("failed to read delta-pack base object %s",
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sha1_to_hex(base_sha1));
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if (!recover)
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exit(1);
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has_errors = 1;
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return;
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}
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resolve_delta(nr, type, base, base_size, delta_data, delta_size);
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free(base);
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}
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static void unpack_one(unsigned nr, unsigned total)
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{
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unsigned shift;
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unsigned char *pack, c;
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unsigned long size;
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enum object_type type;
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obj_list[nr].offset = consumed_bytes;
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pack = fill(1);
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c = *pack;
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use(1);
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type = (c >> 4) & 7;
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size = (c & 15);
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shift = 4;
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while (c & 0x80) {
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pack = fill(1);
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c = *pack;
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use(1);
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size += (c & 0x7f) << shift;
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shift += 7;
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}
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if (!quiet) {
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static unsigned long last_sec;
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static unsigned last_percent;
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struct timeval now;
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unsigned percentage = ((nr+1) * 100) / total;
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gettimeofday(&now, NULL);
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if (percentage != last_percent || now.tv_sec != last_sec) {
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last_sec = now.tv_sec;
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last_percent = percentage;
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fprintf(stderr, "%4u%% (%u/%u) done\r",
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percentage, (nr+1), total);
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}
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}
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switch (type) {
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case OBJ_COMMIT:
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case OBJ_TREE:
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case OBJ_BLOB:
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case OBJ_TAG:
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unpack_non_delta_entry(type, size, nr);
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return;
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case OBJ_REF_DELTA:
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case OBJ_OFS_DELTA:
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unpack_delta_entry(type, size, nr);
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return;
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default:
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error("bad object type %d", type);
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has_errors = 1;
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if (recover)
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return;
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exit(1);
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}
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}
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static void unpack_all(void)
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{
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int i;
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struct pack_header *hdr = fill(sizeof(struct pack_header));
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unsigned nr_objects = ntohl(hdr->hdr_entries);
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if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
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die("bad pack file");
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if (!pack_version_ok(hdr->hdr_version))
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die("unknown pack file version %d", ntohl(hdr->hdr_version));
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fprintf(stderr, "Unpacking %d objects\n", nr_objects);
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obj_list = xmalloc(nr_objects * sizeof(*obj_list));
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use(sizeof(struct pack_header));
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for (i = 0; i < nr_objects; i++)
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unpack_one(i, nr_objects);
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if (delta_list)
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die("unresolved deltas left after unpacking");
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}
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int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
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{
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int i;
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unsigned char sha1[20];
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git_config(git_default_config);
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quiet = !isatty(2);
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for (i = 1 ; i < argc; i++) {
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const char *arg = argv[i];
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if (*arg == '-') {
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if (!strcmp(arg, "-n")) {
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dry_run = 1;
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continue;
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}
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if (!strcmp(arg, "-q")) {
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quiet = 1;
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continue;
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}
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if (!strcmp(arg, "-r")) {
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recover = 1;
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continue;
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}
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if (!strncmp(arg, "--pack_header=", 14)) {
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struct pack_header *hdr;
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char *c;
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hdr = (struct pack_header *)buffer;
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hdr->hdr_signature = htonl(PACK_SIGNATURE);
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hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
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if (*c != ',')
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die("bad %s", arg);
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hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
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if (*c)
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die("bad %s", arg);
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len = sizeof(*hdr);
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continue;
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}
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usage(unpack_usage);
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}
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/* We don't take any non-flag arguments now.. Maybe some day */
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usage(unpack_usage);
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}
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SHA1_Init(&ctx);
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unpack_all();
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SHA1_Update(&ctx, buffer, offset);
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SHA1_Final(sha1, &ctx);
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if (hashcmp(fill(20), sha1))
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die("final sha1 did not match");
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use(20);
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/* Write the last part of the buffer to stdout */
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while (len) {
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int ret = xwrite(1, buffer + offset, len);
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if (ret <= 0)
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break;
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len -= ret;
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offset += ret;
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}
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/* All done */
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if (!quiet)
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fprintf(stderr, "\n");
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return has_errors;
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}
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