63ae26f87a
This provides (minimal) documentation for the --non-empty command-line option to the pack-objects command. Signed-off-by: Nikolai Weibull <nikolai@bitwi.se> Signed-off-by: Junio C Hamano <junkio@cox.net>
563 lines
13 KiB
C
563 lines
13 KiB
C
#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 "csum-file.h"
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static const char pack_usage[] = "git-pack-objects [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
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struct object_entry {
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unsigned char sha1[20];
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unsigned long size;
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unsigned long offset;
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unsigned int depth;
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unsigned int hash;
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enum object_type type;
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unsigned long delta_size;
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struct object_entry *delta;
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};
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static unsigned char object_list_sha1[20];
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static int non_empty = 0;
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static int local = 0;
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static int incremental = 0;
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static struct object_entry **sorted_by_sha, **sorted_by_type;
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static struct object_entry *objects = NULL;
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static int nr_objects = 0, nr_alloc = 0;
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static const char *base_name;
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static unsigned char pack_file_sha1[20];
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static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
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{
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unsigned long othersize, delta_size;
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char type[10];
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void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
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void *delta_buf;
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if (!otherbuf)
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die("unable to read %s", sha1_to_hex(entry->delta->sha1));
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delta_buf = diff_delta(otherbuf, othersize,
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buf, size, &delta_size, 0);
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if (!delta_buf || delta_size != entry->delta_size)
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die("delta size changed");
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free(buf);
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free(otherbuf);
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return delta_buf;
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}
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/*
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* The per-object header is a pretty dense thing, which is
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* - first byte: low four bits are "size", then three bits of "type",
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* and the high bit is "size continues".
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* - each byte afterwards: low seven bits are size continuation,
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* with the high bit being "size continues"
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*/
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static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
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{
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int n = 1;
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unsigned char c;
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if (type < OBJ_COMMIT || type > OBJ_DELTA)
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die("bad type %d", type);
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c = (type << 4) | (size & 15);
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size >>= 4;
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while (size) {
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*hdr++ = c | 0x80;
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c = size & 0x7f;
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size >>= 7;
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n++;
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}
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*hdr = c;
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return n;
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}
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static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
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{
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unsigned long size;
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char type[10];
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void *buf = read_sha1_file(entry->sha1, type, &size);
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unsigned char header[10];
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unsigned hdrlen, datalen;
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enum object_type obj_type;
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if (!buf)
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die("unable to read %s", sha1_to_hex(entry->sha1));
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if (size != entry->size)
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die("object %s size inconsistency (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
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/*
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* The object header is a byte of 'type' followed by zero or
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* more bytes of length. For deltas, the 20 bytes of delta sha1
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* follows that.
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*/
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obj_type = entry->type;
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if (entry->delta) {
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buf = delta_against(buf, size, entry);
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size = entry->delta_size;
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obj_type = OBJ_DELTA;
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}
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hdrlen = encode_header(obj_type, size, header);
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sha1write(f, header, hdrlen);
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if (entry->delta) {
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sha1write(f, entry->delta, 20);
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hdrlen += 20;
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}
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datalen = sha1write_compressed(f, buf, size);
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free(buf);
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return hdrlen + datalen;
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}
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static unsigned long write_one(struct sha1file *f,
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struct object_entry *e,
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unsigned long offset)
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{
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if (e->offset)
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/* offset starts from header size and cannot be zero
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* if it is written already.
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*/
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return offset;
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e->offset = offset;
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offset += write_object(f, e);
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/* if we are delitified, write out its base object. */
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if (e->delta)
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offset = write_one(f, e->delta, offset);
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return offset;
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}
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static void write_pack_file(void)
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{
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int i;
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struct sha1file *f;
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unsigned long offset;
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unsigned long mb;
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struct pack_header hdr;
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if (!base_name)
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f = sha1fd(1, "<stdout>");
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else
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f = sha1create("%s-%s.%s", base_name, sha1_to_hex(object_list_sha1), "pack");
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hdr.hdr_signature = htonl(PACK_SIGNATURE);
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hdr.hdr_version = htonl(PACK_VERSION);
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hdr.hdr_entries = htonl(nr_objects);
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sha1write(f, &hdr, sizeof(hdr));
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offset = sizeof(hdr);
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for (i = 0; i < nr_objects; i++)
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offset = write_one(f, objects + i, offset);
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sha1close(f, pack_file_sha1, 1);
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mb = offset >> 20;
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offset &= 0xfffff;
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}
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static void write_index_file(void)
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{
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int i;
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struct sha1file *f = sha1create("%s-%s.%s", base_name, sha1_to_hex(object_list_sha1), "idx");
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struct object_entry **list = sorted_by_sha;
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struct object_entry **last = list + nr_objects;
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unsigned int array[256];
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/*
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* Write the first-level table (the list is sorted,
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* but we use a 256-entry lookup to be able to avoid
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* having to do eight extra binary search iterations).
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*/
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for (i = 0; i < 256; i++) {
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struct object_entry **next = list;
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while (next < last) {
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struct object_entry *entry = *next;
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if (entry->sha1[0] != i)
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break;
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next++;
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}
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array[i] = htonl(next - sorted_by_sha);
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list = next;
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}
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sha1write(f, array, 256 * sizeof(int));
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/*
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* Write the actual SHA1 entries..
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*/
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list = sorted_by_sha;
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for (i = 0; i < nr_objects; i++) {
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struct object_entry *entry = *list++;
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unsigned int offset = htonl(entry->offset);
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sha1write(f, &offset, 4);
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sha1write(f, entry->sha1, 20);
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}
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sha1write(f, pack_file_sha1, 20);
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sha1close(f, NULL, 1);
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}
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static int add_object_entry(unsigned char *sha1, unsigned int hash)
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{
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unsigned int idx = nr_objects;
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struct object_entry *entry;
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if (incremental || local) {
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struct packed_git *p;
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for (p = packed_git; p; p = p->next) {
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struct pack_entry e;
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if (find_pack_entry_one(sha1, &e, p)) {
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if (incremental)
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return 0;
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if (local && !p->pack_local)
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return 0;
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}
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}
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}
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if (idx >= nr_alloc) {
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unsigned int needed = (idx + 1024) * 3 / 2;
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objects = xrealloc(objects, needed * sizeof(*entry));
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nr_alloc = needed;
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}
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entry = objects + idx;
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memset(entry, 0, sizeof(*entry));
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memcpy(entry->sha1, sha1, 20);
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entry->hash = hash;
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nr_objects = idx+1;
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return 1;
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}
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static void check_object(struct object_entry *entry)
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{
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char type[20];
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if (!sha1_object_info(entry->sha1, type, &entry->size)) {
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if (!strcmp(type, "commit")) {
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entry->type = OBJ_COMMIT;
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} else if (!strcmp(type, "tree")) {
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entry->type = OBJ_TREE;
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} else if (!strcmp(type, "blob")) {
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entry->type = OBJ_BLOB;
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} else if (!strcmp(type, "tag")) {
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entry->type = OBJ_TAG;
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} else
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die("unable to pack object %s of type %s",
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sha1_to_hex(entry->sha1), type);
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}
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else
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die("unable to get type of object %s",
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sha1_to_hex(entry->sha1));
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}
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static void get_object_details(void)
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{
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int i;
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struct object_entry *entry = objects;
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for (i = 0; i < nr_objects; i++)
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check_object(entry++);
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}
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typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
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static entry_sort_t current_sort;
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static int sort_comparator(const void *_a, const void *_b)
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{
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struct object_entry *a = *(struct object_entry **)_a;
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struct object_entry *b = *(struct object_entry **)_b;
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return current_sort(a,b);
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}
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static struct object_entry **create_sorted_list(entry_sort_t sort)
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{
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struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
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int i;
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for (i = 0; i < nr_objects; i++)
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list[i] = objects + i;
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current_sort = sort;
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qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
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return list;
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}
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static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
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{
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return memcmp(a->sha1, b->sha1, 20);
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}
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static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
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{
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if (a->type < b->type)
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return -1;
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if (a->type > b->type)
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return 1;
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if (a->hash < b->hash)
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return -1;
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if (a->hash > b->hash)
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return 1;
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if (a->size < b->size)
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return -1;
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if (a->size > b->size)
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return 1;
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return a < b ? -1 : (a > b);
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}
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struct unpacked {
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struct object_entry *entry;
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void *data;
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};
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/*
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* We search for deltas _backwards_ in a list sorted by type and
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* by size, so that we see progressively smaller and smaller files.
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* That's because we prefer deltas to be from the bigger file
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* to the smaller - deletes are potentially cheaper, but perhaps
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* more importantly, the bigger file is likely the more recent
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* one.
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*/
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static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
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{
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struct object_entry *cur_entry = cur->entry;
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struct object_entry *old_entry = old->entry;
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unsigned long size, oldsize, delta_size, sizediff;
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long max_size;
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void *delta_buf;
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/* Don't bother doing diffs between different types */
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if (cur_entry->type != old_entry->type)
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return -1;
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size = cur_entry->size;
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if (size < 50)
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return -1;
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oldsize = old_entry->size;
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sizediff = oldsize > size ? oldsize - size : size - oldsize;
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if (sizediff > size / 8)
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return -1;
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if (old_entry->depth >= max_depth)
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return 0;
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/*
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* NOTE!
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*
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* We always delta from the bigger to the smaller, since that's
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* more space-efficient (deletes don't have to say _what_ they
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* delete).
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*/
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max_size = size / 2 - 20;
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if (cur_entry->delta)
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max_size = cur_entry->delta_size-1;
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if (sizediff >= max_size)
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return -1;
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delta_buf = diff_delta(old->data, oldsize,
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cur->data, size, &delta_size, max_size);
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if (!delta_buf)
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return 0;
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cur_entry->delta = old_entry;
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cur_entry->delta_size = delta_size;
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cur_entry->depth = old_entry->depth + 1;
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free(delta_buf);
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return 0;
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}
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static void find_deltas(struct object_entry **list, int window, int depth)
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{
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int i, idx;
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unsigned int array_size = window * sizeof(struct unpacked);
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struct unpacked *array = xmalloc(array_size);
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memset(array, 0, array_size);
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i = nr_objects;
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idx = 0;
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while (--i >= 0) {
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struct object_entry *entry = list[i];
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struct unpacked *n = array + idx;
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unsigned long size;
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char type[10];
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int j;
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free(n->data);
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n->entry = entry;
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n->data = read_sha1_file(entry->sha1, type, &size);
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if (size != entry->size)
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die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
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j = window;
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while (--j > 0) {
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unsigned int other_idx = idx + j;
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struct unpacked *m;
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if (other_idx >= window)
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other_idx -= window;
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m = array + other_idx;
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if (!m->entry)
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break;
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if (try_delta(n, m, depth) < 0)
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break;
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}
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idx++;
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if (idx >= window)
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idx = 0;
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}
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for (i = 0; i < window; ++i)
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free(array[i].data);
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free(array);
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}
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static void prepare_pack(int window, int depth)
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{
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get_object_details();
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fprintf(stderr, "Packing %d objects\n", nr_objects);
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sorted_by_type = create_sorted_list(type_size_sort);
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if (window && depth)
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find_deltas(sorted_by_type, window+1, depth);
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write_pack_file();
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}
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static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
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{
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static const char cache[] = "pack-cache/pack-%s.%s";
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char *cached_pack, *cached_idx;
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int ifd, ofd, ifd_ix = -1;
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cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
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ifd = open(cached_pack, O_RDONLY);
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if (ifd < 0)
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return 0;
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if (!pack_to_stdout) {
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cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
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ifd_ix = open(cached_idx, O_RDONLY);
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if (ifd_ix < 0) {
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close(ifd);
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return 0;
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}
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}
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fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
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sha1_to_hex(sha1));
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if (pack_to_stdout) {
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if (copy_fd(ifd, 1))
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exit(1);
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close(ifd);
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}
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else {
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char name[PATH_MAX];
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snprintf(name, sizeof(name),
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"%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
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ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
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if (ofd < 0)
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die("unable to open %s (%s)", name, strerror(errno));
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if (copy_fd(ifd, ofd))
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exit(1);
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close(ifd);
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snprintf(name, sizeof(name),
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"%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
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ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
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if (ofd < 0)
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die("unable to open %s (%s)", name, strerror(errno));
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if (copy_fd(ifd_ix, ofd))
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exit(1);
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close(ifd_ix);
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puts(sha1_to_hex(sha1));
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}
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return 1;
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}
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int main(int argc, char **argv)
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{
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SHA_CTX ctx;
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char line[PATH_MAX + 20];
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int window = 10, depth = 10, pack_to_stdout = 0;
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struct object_entry **list;
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int i;
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setup_git_directory();
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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("--non-empty", arg)) {
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non_empty = 1;
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continue;
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}
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if (!strcmp("--local", arg)) {
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local = 1;
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continue;
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}
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if (!strcmp("--incremental", arg)) {
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incremental = 1;
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continue;
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}
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if (!strncmp("--window=", arg, 9)) {
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char *end;
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window = strtoul(arg+9, &end, 0);
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if (!arg[9] || *end)
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usage(pack_usage);
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continue;
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}
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if (!strncmp("--depth=", arg, 8)) {
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char *end;
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depth = strtoul(arg+8, &end, 0);
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if (!arg[8] || *end)
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usage(pack_usage);
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continue;
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}
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if (!strcmp("--stdout", arg)) {
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pack_to_stdout = 1;
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continue;
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}
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usage(pack_usage);
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}
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if (base_name)
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usage(pack_usage);
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base_name = arg;
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}
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if (pack_to_stdout != !base_name)
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usage(pack_usage);
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prepare_packed_git();
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while (fgets(line, sizeof(line), stdin) != NULL) {
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unsigned int hash;
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char *p;
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unsigned char sha1[20];
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if (get_sha1_hex(line, sha1))
|
|
die("expected sha1, got garbage:\n %s", line);
|
|
hash = 0;
|
|
p = line+40;
|
|
while (*p) {
|
|
unsigned char c = *p++;
|
|
if (isspace(c))
|
|
continue;
|
|
hash = hash * 11 + c;
|
|
}
|
|
add_object_entry(sha1, hash);
|
|
}
|
|
if (non_empty && !nr_objects)
|
|
return 0;
|
|
|
|
sorted_by_sha = create_sorted_list(sha1_sort);
|
|
SHA1_Init(&ctx);
|
|
list = sorted_by_sha;
|
|
for (i = 0; i < nr_objects; i++) {
|
|
struct object_entry *entry = *list++;
|
|
SHA1_Update(&ctx, entry->sha1, 20);
|
|
}
|
|
SHA1_Final(object_list_sha1, &ctx);
|
|
|
|
if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
|
|
;
|
|
else {
|
|
prepare_pack(window, depth);
|
|
if (!pack_to_stdout) {
|
|
write_index_file();
|
|
puts(sha1_to_hex(object_list_sha1));
|
|
}
|
|
}
|
|
return 0;
|
|
}
|