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https://github.com/git/git
synced 2024-08-28 20:20:07 +00:00
teach git-unpack-objects about deltas with offset to base
For delta resolution to be possible, a list of sha1/offset tuple must be constructed in memory in order to load the appropriate base object. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
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eb32d236df
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209c554ab4
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@ -15,7 +15,7 @@ static const char unpack_usage[] = "git-unpack-objects [-n] [-q] [-r] < pack-fil
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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;
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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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@ -51,6 +51,7 @@ static void use(int bytes)
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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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@ -89,35 +90,49 @@ static void *get_data(unsigned long size)
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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 char *base_sha1, void *delta, unsigned long size)
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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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static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size);
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static void write_object(void *buf, unsigned long size, const char *type)
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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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if (write_sha1_file(buf, size, type, sha1) < 0)
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};
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static struct obj_info *obj_list;
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static void added_object(unsigned nr, const char *type, void *data,
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unsigned long size);
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static void write_object(unsigned nr, void *buf, unsigned long size,
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const char *type)
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{
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if (write_sha1_file(buf, size, type, obj_list[nr].sha1) < 0)
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die("failed to write object");
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added_object(sha1, type, buf, size);
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added_object(nr, type, buf, size);
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}
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static void resolve_delta(const char *type,
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static void resolve_delta(unsigned nr, const char *type,
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void *base, unsigned long base_size,
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void *delta, unsigned long delta_size)
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{
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@ -130,20 +145,23 @@ static void resolve_delta(const char *type,
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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(result, result_size, type);
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write_object(nr, result, result_size, type);
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free(result);
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}
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static void added_object(unsigned char *sha1, const char *type, void *data, unsigned long size)
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static void added_object(unsigned nr, const char *type, void *data,
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unsigned long size)
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{
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struct delta_info **p = &delta_list;
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struct delta_info *info;
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while ((info = *p) != NULL) {
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if (!hashcmp(info->base_sha1, sha1)) {
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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(type, data, size, info->delta, info->size);
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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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@ -151,7 +169,8 @@ static void added_object(unsigned char *sha1, const char *type, void *data, unsi
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}
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}
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static void unpack_non_delta_entry(enum object_type kind, unsigned long size)
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static void unpack_non_delta_entry(enum object_type kind, unsigned long size,
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unsigned nr)
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{
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void *buf = get_data(size);
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const char *type;
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@ -164,30 +183,80 @@ static void unpack_non_delta_entry(enum object_type kind, unsigned long size)
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default: die("bad type %d", kind);
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}
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if (!dry_run && buf)
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write_object(buf, size, type);
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write_object(nr, buf, size, type);
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free(buf);
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}
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static void unpack_delta_entry(unsigned long delta_size)
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static void unpack_delta_entry(enum object_type kind, unsigned long delta_size,
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unsigned nr)
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{
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void *delta_data, *base;
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unsigned long base_size;
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char type[20];
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unsigned char base_sha1[20];
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hashcpy(base_sha1, fill(20));
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use(20);
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if (kind == OBJ_REF_DELTA) {
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hashcpy(base_sha1, fill(20));
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use(20);
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delta_data = get_data(delta_size);
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if (dry_run || !delta_data) {
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free(delta_data);
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return;
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}
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if (!has_sha1_file(base_sha1)) {
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hashcpy(obj_list[nr].sha1, null_sha1);
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add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
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return;
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}
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} else {
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unsigned base_found = 0;
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unsigned char *pack, c;
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unsigned long base_offset;
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unsigned lo, mid, hi;
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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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pack = fill(1);
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c = *pack;
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use(1);
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base_offset = c & 127;
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while (c & 128) {
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base_offset += 1;
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if (!base_offset || base_offset & ~(~0UL >> 7))
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die("offset value overflow for delta base object");
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pack = fill(1);
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c = *pack;
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use(1);
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base_offset = (base_offset << 7) + (c & 127);
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}
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base_offset = obj_list[nr].offset - base_offset;
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delta_data = get_data(delta_size);
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if (dry_run || !delta_data) {
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free(delta_data);
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return;
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}
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lo = 0;
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hi = nr;
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while (lo < hi) {
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mid = (lo + hi)/2;
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if (base_offset < obj_list[mid].offset) {
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hi = mid;
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} else if (base_offset > obj_list[mid].offset) {
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lo = mid + 1;
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} else {
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hashcpy(base_sha1, obj_list[mid].sha1);
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base_found = !is_null_sha1(base_sha1);
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break;
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}
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}
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if (!base_found) {
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/* The delta base object is itself a delta that
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has not been resolved yet. */
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hashcpy(obj_list[nr].sha1, null_sha1);
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add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
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return;
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}
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}
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if (!has_sha1_file(base_sha1)) {
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add_delta_to_list(base_sha1, delta_data, delta_size);
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return;
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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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has_errors = 1;
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return;
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}
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resolve_delta(type, base, base_size, delta_data, delta_size);
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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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@ -208,6 +277,8 @@ static void unpack_one(unsigned nr, unsigned total)
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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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@ -216,7 +287,7 @@ static void unpack_one(unsigned nr, unsigned total)
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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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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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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 * 100) / total;
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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", percentage, nr, total);
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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_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);
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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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unpack_delta_entry(size);
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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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@ -265,9 +338,10 @@ static void unpack_all(void)
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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+1, nr_objects);
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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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