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tag: v1.6.1-rc3
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#include "builtin.h"
#include "cache.h"
#include "object.h"
#include "delta.h"
#include "pack.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"
#include "tree-walk.h"
#include "progress.h"
#include "decorate.h"
#include "fsck.h"

static int dry_run, quiet, recover, has_errors, strict;
static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict] < pack-file";

/* We always read in 4kB chunks. */
static unsigned char buffer[4096];
static unsigned int offset, len;
static off_t consumed_bytes;
static git_SHA_CTX ctx;

/*
* When running under --strict mode, objects whose reachability are
* suspect are kept in core without getting written in the object
* store.
*/
struct obj_buffer {
char *buffer;
unsigned long size;
};

static struct decoration obj_decorate;

static struct obj_buffer *lookup_object_buffer(struct object *base)
{
return lookup_decoration(&obj_decorate, base);
}

static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
{
struct obj_buffer *obj;
obj = xcalloc(1, sizeof(struct obj_buffer));
obj->buffer = buffer;
obj->size = size;
if (add_decoration(&obj_decorate, object, obj))
die("object %s tried to add buffer twice!", sha1_to_hex(object->sha1));
}

/*
* Make sure at least "min" bytes are available in the buffer, and
* return the pointer to the buffer.
*/
static void *fill(int min)
{
if (min <= len)
return buffer + offset;
if (min > sizeof(buffer))
die("cannot fill %d bytes", min);
if (offset) {
git_SHA1_Update(&ctx, buffer, offset);
memmove(buffer, buffer + offset, len);
offset = 0;
}
do {
ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
if (ret <= 0) {
if (!ret)
die("early EOF");
die("read error on input: %s", strerror(errno));
}
len += ret;
} while (len < min);
return buffer;
}

static void use(int bytes)
{
if (bytes > len)
die("used more bytes than were available");
len -= bytes;
offset += bytes;

/* make sure off_t is sufficiently large not to wrap */
if (consumed_bytes > consumed_bytes + bytes)
die("pack too large for current definition of off_t");
consumed_bytes += bytes;
}

static void *get_data(unsigned long size)
{
z_stream stream;
void *buf = xmalloc(size);

memset(&stream, 0, sizeof(stream));

stream.next_out = buf;
stream.avail_out = size;
stream.next_in = fill(1);
stream.avail_in = len;
inflateInit(&stream);

for (;;) {
int ret = inflate(&stream, 0);
use(len - stream.avail_in);
if (stream.total_out == size && ret == Z_STREAM_END)
break;
if (ret != Z_OK) {
error("inflate returned %d\n", ret);
free(buf);
buf = NULL;
if (!recover)
exit(1);
has_errors = 1;
break;
}
stream.next_in = fill(1);
stream.avail_in = len;
}
inflateEnd(&stream);
return buf;
}

struct delta_info {
unsigned char base_sha1[20];
unsigned nr;
off_t base_offset;
unsigned long size;
void *delta;
struct delta_info *next;
};

static struct delta_info *delta_list;

static void add_delta_to_list(unsigned nr, unsigned const char *base_sha1,
off_t base_offset,
void *delta, unsigned long size)
{
struct delta_info *info = xmalloc(sizeof(*info));

hashcpy(info->base_sha1, base_sha1);
info->base_offset = base_offset;
info->size = size;
info->delta = delta;
info->nr = nr;
info->next = delta_list;
delta_list = info;
}

struct obj_info {
off_t offset;
unsigned char sha1[20];
struct object *obj;
};

#define FLAG_OPEN (1u<<20)
#define FLAG_WRITTEN (1u<<21)

static struct obj_info *obj_list;
unsigned nr_objects;

/*
* Called only from check_object() after it verified this object
* is Ok.
*/
static void write_cached_object(struct object *obj)
{
unsigned char sha1[20];
struct obj_buffer *obj_buf = lookup_object_buffer(obj);
if (write_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), sha1) < 0)
die("failed to write object %s", sha1_to_hex(obj->sha1));
obj->flags |= FLAG_WRITTEN;
}

/*
* At the very end of the processing, write_rest() scans the objects
* that have reachability requirements and calls this function.
* Verify its reachability and validity recursively and write it out.
*/
static int check_object(struct object *obj, int type, void *data)
{
if (!obj)
return 0;

if (obj->flags & FLAG_WRITTEN)
return 1;

if (type != OBJ_ANY && obj->type != type)
die("object type mismatch");

if (!(obj->flags & FLAG_OPEN)) {
unsigned long size;
int type = sha1_object_info(obj->sha1, &size);
if (type != obj->type || type <= 0)
die("object of unexpected type");
obj->flags |= FLAG_WRITTEN;
return 1;
}

if (fsck_object(obj, 1, fsck_error_function))
die("Error in object");
if (!fsck_walk(obj, check_object, 0))
die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
write_cached_object(obj);
return 1;
}

static void write_rest(void)
{
unsigned i;
for (i = 0; i < nr_objects; i++)
check_object(obj_list[i].obj, OBJ_ANY, 0);
}

static void added_object(unsigned nr, enum object_type type,
void *data, unsigned long size);

/*
* Write out nr-th object from the list, now we know the contents
* of it. Under --strict, this buffers structured objects in-core,
* to be checked at the end.
*/
static void write_object(unsigned nr, enum object_type type,
void *buf, unsigned long size)
{
if (!strict) {
if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
die("failed to write object");
added_object(nr, type, buf, size);
free(buf);
obj_list[nr].obj = NULL;
} else if (type == OBJ_BLOB) {
struct blob *blob;
if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
die("failed to write object");
added_object(nr, type, buf, size);
free(buf);

blob = lookup_blob(obj_list[nr].sha1);
if (blob)
blob->object.flags |= FLAG_WRITTEN;
else
die("invalid blob object");
obj_list[nr].obj = NULL;
} else {
struct object *obj;
int eaten;
hash_sha1_file(buf, size, typename(type), obj_list[nr].sha1);
added_object(nr, type, buf, size);
obj = parse_object_buffer(obj_list[nr].sha1, type, size, buf, &eaten);
if (!obj)
die("invalid %s", typename(type));
add_object_buffer(obj, buf, size);
obj->flags |= FLAG_OPEN;
obj_list[nr].obj = obj;
}
}

static void resolve_delta(unsigned nr, enum object_type type,
void *base, unsigned long base_size,
void *delta, unsigned long delta_size)
{
void *result;
unsigned long result_size;

result = patch_delta(base, base_size,
delta, delta_size,
&result_size);
if (!result)
die("failed to apply delta");
free(delta);
write_object(nr, type, result, result_size);
}

/*
* We now know the contents of an object (which is nr-th in the pack);
* resolve all the deltified objects that are based on it.
*/
static void added_object(unsigned nr, enum object_type type,
void *data, unsigned long size)
{
struct delta_info **p = &delta_list;
struct delta_info *info;

while ((info = *p) != NULL) {
if (!hashcmp(info->base_sha1, obj_list[nr].sha1) ||
info->base_offset == obj_list[nr].offset) {
*p = info->next;
p = &delta_list;
resolve_delta(info->nr, type, data, size,
info->delta, info->size);
free(info);
continue;
}
p = &info->next;
}
}

static void unpack_non_delta_entry(enum object_type type, unsigned long size,
unsigned nr)
{
void *buf = get_data(size);

if (!dry_run && buf)
write_object(nr, type, buf, size);
else
free(buf);
}

static int resolve_against_held(unsigned nr, const unsigned char *base,
void *delta_data, unsigned long delta_size)
{
struct object *obj;
struct obj_buffer *obj_buffer;
obj = lookup_object(base);
if (!obj)
return 0;
obj_buffer = lookup_object_buffer(obj);
if (!obj_buffer)
return 0;
resolve_delta(nr, obj->type, obj_buffer->buffer,
obj_buffer->size, delta_data, delta_size);
return 1;
}

static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
unsigned nr)
{
void *delta_data, *base;
unsigned long base_size;
unsigned char base_sha1[20];

if (type == OBJ_REF_DELTA) {
hashcpy(base_sha1, fill(20));
use(20);
delta_data = get_data(delta_size);
if (dry_run || !delta_data) {
free(delta_data);
return;
}
if (has_sha1_file(base_sha1))
; /* Ok we have this one */
else if (resolve_against_held(nr, base_sha1,
delta_data, delta_size))
return; /* we are done */
else {
/* cannot resolve yet --- queue it */
hashcpy(obj_list[nr].sha1, null_sha1);
add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
return;
}
} else {
unsigned base_found = 0;
unsigned char *pack, c;
off_t base_offset;
unsigned lo, mid, hi;

pack = fill(1);
c = *pack;
use(1);
base_offset = c & 127;
while (c & 128) {
base_offset += 1;
if (!base_offset || MSB(base_offset, 7))
die("offset value overflow for delta base object");
pack = fill(1);
c = *pack;
use(1);
base_offset = (base_offset << 7) + (c & 127);
}
base_offset = obj_list[nr].offset - base_offset;
if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
die("offset value out of bound for delta base object");

delta_data = get_data(delta_size);
if (dry_run || !delta_data) {
free(delta_data);
return;
}
lo = 0;
hi = nr;
while (lo < hi) {
mid = (lo + hi)/2;
if (base_offset < obj_list[mid].offset) {
hi = mid;
} else if (base_offset > obj_list[mid].offset) {
lo = mid + 1;
} else {
hashcpy(base_sha1, obj_list[mid].sha1);
base_found = !is_null_sha1(base_sha1);
break;
}
}
if (!base_found) {
/*
* The delta base object is itself a delta that
* has not been resolved yet.
*/
hashcpy(obj_list[nr].sha1, null_sha1);
add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
return;
}
}

if (resolve_against_held(nr, base_sha1, delta_data, delta_size))
return;

base = read_sha1_file(base_sha1, &type, &base_size);
if (!base) {
error("failed to read delta-pack base object %s",
sha1_to_hex(base_sha1));
if (!recover)
exit(1);
has_errors = 1;
return;
}
resolve_delta(nr, type, base, base_size, delta_data, delta_size);
free(base);
}

static void unpack_one(unsigned nr)
{
unsigned shift;
unsigned char *pack, c;
unsigned long size;
enum object_type type;

obj_list[nr].offset = consumed_bytes;

pack = fill(1);
c = *pack;
use(1);
type = (c >> 4) & 7;
size = (c & 15);
shift = 4;
while (c & 0x80) {
pack = fill(1);
c = *pack;
use(1);
size += (c & 0x7f) << shift;
shift += 7;
}

switch (type) {
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
unpack_non_delta_entry(type, size, nr);
return;
case OBJ_REF_DELTA:
case OBJ_OFS_DELTA:
unpack_delta_entry(type, size, nr);
return;
default:
error("bad object type %d", type);
has_errors = 1;
if (recover)
return;
exit(1);
}
}

static void unpack_all(void)
{
int i;
struct progress *progress = NULL;
struct pack_header *hdr = fill(sizeof(struct pack_header));

nr_objects = ntohl(hdr->hdr_entries);

if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
die("bad pack file");
if (!pack_version_ok(hdr->hdr_version))
die("unknown pack file version %"PRIu32,
ntohl(hdr->hdr_version));
use(sizeof(struct pack_header));

if (!quiet)
progress = start_progress("Unpacking objects", nr_objects);
obj_list = xcalloc(nr_objects, sizeof(*obj_list));
for (i = 0; i < nr_objects; i++) {
unpack_one(i);
display_progress(progress, i + 1);
}
stop_progress(&progress);

if (delta_list)
die("unresolved deltas left after unpacking");
}

int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
{
int i;
unsigned char sha1[20];

git_config(git_default_config, NULL);

quiet = !isatty(2);

for (i = 1 ; i < argc; i++) {
const char *arg = argv[i];

if (*arg == '-') {
if (!strcmp(arg, "-n")) {
dry_run = 1;
continue;
}
if (!strcmp(arg, "-q")) {
quiet = 1;
continue;
}
if (!strcmp(arg, "-r")) {
recover = 1;
continue;
}
if (!strcmp(arg, "--strict")) {
strict = 1;
continue;
}
if (!prefixcmp(arg, "--pack_header=")) {
struct pack_header *hdr;
char *c;

hdr = (struct pack_header *)buffer;
hdr->hdr_signature = htonl(PACK_SIGNATURE);
hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
if (*c != ',')
die("bad %s", arg);
hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
if (*c)
die("bad %s", arg);
len = sizeof(*hdr);
continue;
}
usage(unpack_usage);
}

/* We don't take any non-flag arguments now.. Maybe some day */
usage(unpack_usage);
}
git_SHA1_Init(&ctx);
unpack_all();
git_SHA1_Update(&ctx, buffer, offset);
git_SHA1_Final(sha1, &ctx);
if (strict)
write_rest();
if (hashcmp(fill(20), sha1))
die("final sha1 did not match");
use(20);

/* Write the last part of the buffer to stdout */
while (len) {
int ret = xwrite(1, buffer + offset, len);
if (ret <= 0)
break;
len -= ret;
offset += ret;
}

/* All done */
return has_errors;
}
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