mirror of
https://github.com/git/git
synced 2024-08-28 20:20:07 +00:00
8723f21626
This patch introduces the MSB() macro to obtain the desired number of most significant bits from a given variable independently of the variable type. It is then used to better implement the overflow test on the OBJ_OFS_DELTA base offset variable with the property of always working correctly regardless of the type/size of that variable. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
406 lines
8.8 KiB
C
406 lines
8.8 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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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, enum object_type type,
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void *data, unsigned long size);
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static void write_object(unsigned nr, enum object_type type,
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void *buf, unsigned long size)
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{
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if (write_sha1_file(buf, size, typename(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, enum object_type 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, type, result, result_size);
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free(result);
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}
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static void added_object(unsigned nr, enum object_type type,
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void *data, 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 type, 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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if (!dry_run && buf)
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write_object(nr, type, buf, size);
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free(buf);
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}
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static void unpack_delta_entry(enum object_type type, 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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unsigned char base_sha1[20];
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if (type == 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 || MSB(base_offset, 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 (!prefixcmp(arg, "--pack_header=")) {
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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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