Hash :
7d0cdf82
Author :
Date :
2011-07-09T02:25:01
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/*
* This file is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2,
* as published by the Free Software Foundation.
*
* In addition to the permissions in the GNU General Public License,
* the authors give you unlimited permission to link the compiled
* version of this file into combinations with other programs,
* and to distribute those combinations without any restriction
* coming from the use of this file. (The General Public License
* restrictions do apply in other respects; for example, they cover
* modification of the file, and distribution when not linked into
* a combined executable.)
*
* This file is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#include "mwindow.h"
#include "odb.h"
#include "pack.h"
#include "delta-apply.h"
#include "git2/oid.h"
#include "git2/zlib.h"
unsigned char *pack_window_open(
struct pack_file *p,
git_mwindow **w_cursor,
off_t offset,
unsigned int *left)
{
if (p->mwf.fd == -1 && packfile_open(p) < GIT_SUCCESS)
return NULL;
/* Since packfiles end in a hash of their content and it's
* pointless to ask for an offset into the middle of that
* hash, and the pack_window_contains function above wouldn't match
* don't allow an offset too close to the end of the file.
*/
if (offset > (p->mwf.size - 20))
return NULL;
return git_mwindow_open(&p->mwf, w_cursor, offset, 20, left);
}
static unsigned long packfile_unpack_header1(
size_t *sizep,
git_otype *type,
const unsigned char *buf,
unsigned long len)
{
unsigned shift;
unsigned long size, c;
unsigned long used = 0;
c = buf[used++];
*type = (c >> 4) & 7;
size = c & 15;
shift = 4;
while (c & 0x80) {
if (len <= used || bitsizeof(long) <= shift)
return 0;
c = buf[used++];
size += (c & 0x7f) << shift;
shift += 7;
}
*sizep = (size_t)size;
return used;
}
int git_packfile_unpack_header(
size_t *size_p,
git_otype *type_p,
git_mwindow_file *mwf,
git_mwindow **w_curs,
off_t *curpos)
{
unsigned char *base;
unsigned int left;
unsigned long used;
/* pack_window_open() assures us we have [base, base + 20) available
* as a range that we can look at at. (Its actually the hash
* size that is assured.) With our object header encoding
* the maximum deflated object size is 2^137, which is just
* insane, so we know won't exceed what we have been given.
*/
// base = pack_window_open(p, w_curs, *curpos, &left);
base = git_mwindow_open(mwf, w_curs, *curpos, 20, &left);
if (base == NULL)
return GIT_ENOMEM;
used = packfile_unpack_header1(size_p, type_p, base, left);
if (used == 0)
return git__throw(GIT_EOBJCORRUPTED, "Header length is zero");
*curpos += used;
return GIT_SUCCESS;
}
int packfile_unpack_delta(
git_rawobj *obj,
struct pack_file *p,
git_mwindow **w_curs,
off_t curpos,
size_t delta_size,
git_otype delta_type,
off_t obj_offset)
{
off_t base_offset;
git_rawobj base, delta;
int error;
base_offset = get_delta_base(p, w_curs, &curpos, delta_type, obj_offset);
if (base_offset == 0)
return git__throw(GIT_EOBJCORRUPTED, "Delta offset is zero");
git_mwindow_close(w_curs);
error = packfile_unpack(&base, p, base_offset);
/*
* TODO: git.git tries to load the base from other packfiles
* or loose objects.
*
* We'll need to do this in order to support thin packs.
*/
if (error < GIT_SUCCESS)
return git__rethrow(error, "Corrupted delta");
error = packfile_unpack_compressed(&delta, p, w_curs, curpos, delta_size, delta_type);
if (error < GIT_SUCCESS) {
free(base.data);
return git__rethrow(error, "Corrupted delta");
}
obj->type = base.type;
error = git__delta_apply(obj,
base.data, base.len,
delta.data, delta.len);
free(base.data);
free(delta.data);
/* TODO: we might want to cache this shit. eventually */
//add_delta_base_cache(p, base_offset, base, base_size, *type);
return error; /* error set by git__delta_apply */
}
int packfile_unpack(
git_rawobj *obj,
struct pack_file *p,
off_t obj_offset)
{
git_mwindow *w_curs = NULL;
off_t curpos = obj_offset;
int error;
size_t size = 0;
git_otype type;
/*
* TODO: optionally check the CRC on the packfile
*/
obj->data = NULL;
obj->len = 0;
obj->type = GIT_OBJ_BAD;
error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos);
if (error < GIT_SUCCESS)
return git__rethrow(error, "Failed to unpack packfile");
switch (type) {
case GIT_OBJ_OFS_DELTA:
case GIT_OBJ_REF_DELTA:
error = packfile_unpack_delta(
obj, p, &w_curs, curpos,
size, type, obj_offset);
break;
case GIT_OBJ_COMMIT:
case GIT_OBJ_TREE:
case GIT_OBJ_BLOB:
case GIT_OBJ_TAG:
error = packfile_unpack_compressed(
obj, p, &w_curs, curpos,
size, type);
break;
default:
error = GIT_EOBJCORRUPTED;
break;
}
git_mwindow_close(&w_curs);
return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to unpack packfile");
}
int packfile_unpack_compressed(
git_rawobj *obj,
struct pack_file *p,
git_mwindow **w_curs,
off_t curpos,
size_t size,
git_otype type)
{
int st;
z_stream stream;
unsigned char *buffer, *in;
buffer = git__malloc(size + 1);
memset(buffer, 0x0, size + 1);
memset(&stream, 0, sizeof(stream));
stream.next_out = buffer;
stream.avail_out = size + 1;
st = inflateInit(&stream);
if (st != Z_OK) {
free(buffer);
return git__throw(GIT_EZLIB, "Error in zlib");
}
do {
in = pack_window_open(p, w_curs, curpos, &stream.avail_in);
stream.next_in = in;
st = inflate(&stream, Z_FINISH);
if (!stream.avail_out)
break; /* the payload is larger than it should be */
curpos += stream.next_in - in;
} while (st == Z_OK || st == Z_BUF_ERROR);
inflateEnd(&stream);
if ((st != Z_STREAM_END) || stream.total_out != size) {
free(buffer);
return git__throw(GIT_EZLIB, "Error in zlib");
}
obj->type = type;
obj->len = size;
obj->data = buffer;
return GIT_SUCCESS;
}
off_t get_delta_base(
struct pack_file *p,
git_mwindow **w_curs,
off_t *curpos,
git_otype type,
off_t delta_obj_offset)
{
unsigned char *base_info = pack_window_open(p, w_curs, *curpos, NULL);
off_t base_offset;
git_oid unused;
/* pack_window_open() assured us we have [base_info, base_info + 20)
* as a range that we can look at without walking off the
* end of the mapped window. Its actually the hash size
* that is assured. An OFS_DELTA longer than the hash size
* is stupid, as then a REF_DELTA would be smaller to store.
*/
if (type == GIT_OBJ_OFS_DELTA) {
unsigned used = 0;
unsigned char c = base_info[used++];
base_offset = c & 127;
while (c & 128) {
base_offset += 1;
if (!base_offset || MSB(base_offset, 7))
return 0; /* overflow */
c = base_info[used++];
base_offset = (base_offset << 7) + (c & 127);
}
base_offset = delta_obj_offset - base_offset;
if (base_offset <= 0 || base_offset >= delta_obj_offset)
return 0; /* out of bound */
*curpos += used;
} else if (type == GIT_OBJ_REF_DELTA) {
/* The base entry _must_ be in the same pack */
if (pack_entry_find_offset(&base_offset, &unused, p, (git_oid *)base_info, GIT_OID_HEXSZ) < GIT_SUCCESS)
return git__throw(GIT_EPACKCORRUPTED, "Base entry delta is not in the same pack");
*curpos += 20;
} else
return 0;
return base_offset;
}