mirror of
https://github.com/git/git.git
synced 2024-05-24 03:46:12 +02:00
git-unpack-objects: re-write to read from stdin
It gets a bit more complicated to unpack in a streaming environment, but here it is. The rewrite is actually a lot cleaner in other ways, it's just a bit more subtle.
This commit is contained in:
Linus Torvalds
parent
75c660ac93
commit
67e5a5ece4
420
unpack-objects.c
420
unpack-objects.c
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@ -4,278 +4,213 @@
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#include "pack.h"
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static int dry_run;
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static int nr_entries;
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static const char *base_name;
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static const char unpack_usage[] = "git-unpack-objects basename";
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static const char unpack_usage[] = "git-unpack-objects < pack-file";
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struct pack_entry {
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unsigned int offset; /* network byte order */
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unsigned char sha1[20];
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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, eof;
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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 (eof)
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die("unable to fill input");
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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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memcpy(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 = read(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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if (errno == EAGAIN || errno == EINTR)
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continue;
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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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}
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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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if (!size)
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return buf;
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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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die("inflate returned %d\n", ret);
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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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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 size;
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void *delta;
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struct delta_info *next;
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};
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static void *pack_base;
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static unsigned long pack_size;
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static void *index_base;
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static unsigned long index_size;
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static struct delta_info *delta_list;
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static struct pack_entry **pack_list;
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static void *map_file(const char *suffix, unsigned long *sizep)
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static void add_delta_to_list(unsigned char *base_sha1, void *delta, unsigned long size)
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{
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static char pathname[PATH_MAX];
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unsigned long len;
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int fd;
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struct stat st;
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void *map;
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struct delta_info *info = xmalloc(sizeof(*info));
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len = snprintf(pathname, PATH_MAX, "%s.%s", base_name, suffix);
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if (len >= PATH_MAX)
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die("bad pack base-name");
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fd = open(pathname, O_RDONLY);
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if (fd < 0 || fstat(fd, &st))
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die("unable to open '%s'", pathname);
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len = st.st_size;
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if (!len)
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die("bad pack file '%s'", pathname);
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map = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
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if (-1 == (int)(long)map)
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die("unable to mmap '%s'", pathname);
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close(fd);
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*sizep = len;
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return map;
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memcpy(info->base_sha1, base_sha1, 20);
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info->size = size;
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info->delta = delta;
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info->next = delta_list;
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delta_list = info;
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}
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static int sort_by_offset(const void *_a, const void *_b)
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static void added_object(unsigned char *sha1, char *type, void *data, unsigned long size);
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static int resolve_delta(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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struct pack_entry *a = *(struct pack_entry **)_a;
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struct pack_entry *b = *(struct pack_entry **)_b;
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unsigned int o1, o2;
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void *result;
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unsigned long result_size;
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unsigned char sha1[20];
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o1 = ntohl(a->offset);
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o2 = ntohl(b->offset);
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return o1 < o2 ? -1 : 1;
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}
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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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static int check_index(void)
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{
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unsigned int *array = index_base;
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unsigned int nr;
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int i;
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if (index_size < 4*256 + 20)
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return error("index file too small");
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nr = 0;
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for (i = 0; i < 256; i++) {
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unsigned int n = ntohl(array[i]);
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if (n < nr)
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return error("non-monotonic index");
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nr = n;
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}
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/*
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* Total size:
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* - 256 index entries 4 bytes each
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* - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
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* - 20-byte SHA1 of the packfile
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* - 20-byte SHA1 file checksum
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*/
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if (index_size != 4*256 + nr * 24 + 20 + 20)
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return error("wrong index file size");
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nr_entries = nr;
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pack_list = xmalloc(nr * sizeof(struct pack_entry *));
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for (i = 0; i < nr; i++)
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pack_list[i] = index_base + 4*256 + i*24;
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qsort(pack_list, nr, sizeof(*pack_list), sort_by_offset);
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printf("%d entries\n", nr);
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if (write_sha1_file(result, result_size, type, sha1) < 0)
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die("failed to write object");
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added_object(sha1, type, result, result_size);
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free(result);
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return 0;
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}
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static int unpack_non_delta_entry(struct pack_entry *entry,
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enum object_type kind,
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unsigned char *data,
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unsigned long size,
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unsigned long left)
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static void added_object(unsigned char *sha1, char *type, void *data, unsigned long size)
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{
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int st;
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z_stream stream;
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char *buffer;
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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 (!memcmp(info->base_sha1, sha1, 20)) {
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*p = info->next;
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p = &delta_list;
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resolve_delta(type, data, size, 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 int unpack_non_delta_entry(enum object_type kind, unsigned long size)
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{
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void *buf = get_data(size);
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unsigned char sha1[20];
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char *type;
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printf("%s %c %lu\n", sha1_to_hex(entry->sha1), ".CTBGD"[kind], size);
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if (dry_run)
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return 0;
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buffer = xmalloc(size + 1);
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buffer[size] = 0;
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memset(&stream, 0, sizeof(stream));
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stream.next_in = data;
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stream.avail_in = left;
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stream.next_out = buffer;
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stream.avail_out = size;
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inflateInit(&stream);
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st = inflate(&stream, Z_FINISH);
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inflateEnd(&stream);
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if ((st != Z_STREAM_END) || stream.total_out != size)
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goto err_finish;
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switch (kind) {
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case OBJ_COMMIT: type = "commit"; break;
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case OBJ_TREE: type = "tree"; break;
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case OBJ_BLOB: type = "blob"; break;
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case OBJ_TAG: type = "tag"; break;
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default: goto err_finish;
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default: die("bad type %d", kind);
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}
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if (write_sha1_file(buffer, size, type, sha1) < 0)
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die("failed to write %s (%s)",
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sha1_to_hex(entry->sha1), type);
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printf("%s %s\n", sha1_to_hex(sha1), type);
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if (memcmp(sha1, entry->sha1, 20))
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die("resulting %s have wrong SHA1", type);
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finish:
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st = 0;
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free(buffer);
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return st;
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err_finish:
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st = -1;
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goto finish;
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}
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static int find_pack_entry(unsigned char *sha1, struct pack_entry **ent)
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{
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int *level1_ofs = index_base;
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int hi = ntohl(level1_ofs[*sha1]);
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int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
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void *index = index_base + 4*256;
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do {
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int mi = (lo + hi) / 2;
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int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
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if (!cmp) {
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*ent = index + 24 * mi;
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return 1;
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}
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if (cmp > 0)
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hi = mi;
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else
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lo = mi+1;
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} while (lo < hi);
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if (write_sha1_file(buf, size, type, sha1) < 0)
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die("failed to write object");
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added_object(sha1, type, buf, size);
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free(buf);
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return 0;
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}
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/* forward declaration for a mutually recursive function */
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static void unpack_entry(struct pack_entry *);
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static int unpack_delta_entry(struct pack_entry *entry,
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unsigned char *base_sha1,
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unsigned long delta_size,
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unsigned long left)
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static int unpack_delta_entry(unsigned long delta_size)
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{
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void *data, *delta_data, *result, *base;
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unsigned long data_size, result_size, base_size;
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z_stream stream;
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int st;
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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 sha1[20];
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unsigned char base_sha1[20];
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if (left < 20)
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die("truncated pack file");
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data = base_sha1 + 20;
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data_size = left - 20;
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printf("%s D %lu", sha1_to_hex(entry->sha1), delta_size);
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printf(" %s\n", sha1_to_hex(base_sha1));
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memcpy(base_sha1, fill(20), 20);
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use(20);
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if (dry_run)
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return 0;
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delta_data = get_data(delta_size);
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/* pack+5 is the base sha1, unless we have it, we need to
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* unpack it first.
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*/
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if (!has_sha1_file(base_sha1)) {
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struct pack_entry *base;
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if (!find_pack_entry(base_sha1, &base))
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die("cannot find delta-pack base object");
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unpack_entry(base);
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add_delta_to_list(base_sha1, delta_data, delta_size);
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return 0;
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}
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delta_data = xmalloc(delta_size);
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memset(&stream, 0, sizeof(stream));
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stream.next_in = data;
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stream.avail_in = data_size;
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stream.next_out = delta_data;
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stream.avail_out = delta_size;
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inflateInit(&stream);
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st = inflate(&stream, Z_FINISH);
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inflateEnd(&stream);
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if ((st != Z_STREAM_END) || stream.total_out != delta_size)
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die("delta data unpack failed");
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base = read_sha1_file(base_sha1, type, &base_size);
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if (!base)
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die("failed to read delta-pack base object %s", sha1_to_hex(base_sha1));
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result = patch_delta(base, base_size,
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delta_data, 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_data);
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if (write_sha1_file(result, result_size, type, sha1) < 0)
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die("failed to write %s (%s)",
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sha1_to_hex(entry->sha1), type);
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free(result);
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printf("%s %s\n", sha1_to_hex(sha1), type);
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if (memcmp(sha1, entry->sha1, 20))
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die("resulting %s have wrong SHA1", type);
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return 0;
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return resolve_delta(type, base, base_size, delta_data, delta_size);
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}
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static void unpack_entry(struct pack_entry *entry)
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static void unpack_one(void)
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{
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unsigned long offset, size, left;
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unsigned char *pack, c;
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int type;
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unsigned long size;
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enum object_type type;
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/* Have we done this one already due to deltas based on it? */
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if (lookup_object(entry->sha1))
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return;
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offset = ntohl(entry->offset);
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if (offset >= pack_size)
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goto bad;
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pack = pack_base + offset;
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c = *pack++;
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offset++;
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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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while (c & 0x80) {
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if (offset >= pack_size)
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goto bad;
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offset++;
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pack = fill(1);
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c = *pack++;
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use(1);
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size = (size << 7) + (c & 0x7f);
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}
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left = pack_size - offset;
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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(entry, type, pack, size, left);
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unpack_non_delta_entry(type, size);
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return;
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case OBJ_DELTA:
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unpack_delta_entry(entry, pack, size, left);
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unpack_delta_entry(size);
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return;
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default:
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die("bad object type %d", type);
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}
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bad:
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die("corrupted pack file");
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}
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/*
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|
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@ -285,17 +220,28 @@ static void unpack_entry(struct pack_entry *entry)
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*/
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static void unpack_all(void)
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{
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int i = nr_entries;
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int i;
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struct pack_header *hdr = fill(sizeof(struct pack_header));
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unsigned version = ntohl(hdr->hdr_version);
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unsigned nr_objects = ntohl(hdr->hdr_entries);
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while (--i >= 0) {
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struct pack_entry *entry = pack_list[i];
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unpack_entry(entry);
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}
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if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
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die("bad pack file");
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if (version != 1)
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die("unable to handle pack file version %d", version);
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fprintf(stderr, "Unpacking %d objects\n", nr_objects);
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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();
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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 main(int argc, char **argv)
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{
|
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int i;
|
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unsigned char sha1[20];
|
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|
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for (i = 1 ; i < argc; i++) {
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const char *arg = argv[i];
|
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|
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@ -307,16 +253,32 @@ int main(int argc, char **argv)
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}
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usage(unpack_usage);
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}
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if (base_name)
|
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usage(unpack_usage);
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base_name = arg;
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}
|
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if (!base_name)
|
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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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index_base = map_file("idx", &index_size);
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pack_base = map_file("pack", &pack_size);
|
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if (check_index() < 0)
|
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die("bad index file");
|
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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 (memcmp(fill(20), sha1, 20))
|
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die("final sha1 did not match");
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use(20);
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|
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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 = write(1, buffer + offset, len);
|
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if (!ret)
|
||||
break;
|
||||
if (ret < 0) {
|
||||
if (errno == EAGAIN || errno == EINTR)
|
||||
continue;
|
||||
break;
|
||||
}
|
||||
len -= ret;
|
||||
offset += ret;
|
||||
}
|
||||
|
||||
/* All done */
|
||||
return 0;
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue