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885 lines (735 loc) · 20.4 KB
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/*
* Copyright (C) 2009-2012 the libgit2 contributors
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#include "common.h"
#include "odb.h"
#include "pack.h"
#include "delta-apply.h"
#include "sha1_lookup.h"
#include "mwindow.h"
#include "fileops.h"
#include "git2/oid.h"
#include <zlib.h>
static int packfile_open(struct git_pack_file *p);
static git_off_t nth_packed_object_offset(const struct git_pack_file *p, uint32_t n);
int packfile_unpack_compressed(
git_rawobj *obj,
struct git_pack_file *p,
git_mwindow **w_curs,
git_off_t *curpos,
size_t size,
git_otype type);
/* Can find the offset of an object given
* a prefix of an identifier.
* Throws GIT_EAMBIGUOUSOIDPREFIX if short oid
* is ambiguous within the pack.
* This method assumes that len is between
* GIT_OID_MINPREFIXLEN and GIT_OID_HEXSZ.
*/
static int pack_entry_find_offset(
git_off_t *offset_out,
git_oid *found_oid,
struct git_pack_file *p,
const git_oid *short_oid,
size_t len);
static int packfile_error(const char *message)
{
giterr_set(GITERR_ODB, "Invalid pack file - %s", message);
return -1;
}
/***********************************************************
*
* PACK INDEX METHODS
*
***********************************************************/
static void pack_index_free(struct git_pack_file *p)
{
if (p->oids) {
git__free(p->oids);
p->oids = NULL;
}
if (p->index_map.data) {
git_futils_mmap_free(&p->index_map);
p->index_map.data = NULL;
}
}
static int pack_index_check(const char *path, struct git_pack_file *p)
{
struct git_pack_idx_header *hdr;
uint32_t version, nr, i, *index;
void *idx_map;
size_t idx_size;
struct stat st;
int error;
/* TODO: properly open the file without access time using O_NOATIME */
git_file fd = git_futils_open_ro(path);
if (fd < 0)
return fd;
if (p_fstat(fd, &st) < 0 ||
!S_ISREG(st.st_mode) ||
!git__is_sizet(st.st_size) ||
(idx_size = (size_t)st.st_size) < 4 * 256 + 20 + 20)
{
p_close(fd);
giterr_set(GITERR_OS, "Failed to check pack index.");
return -1;
}
error = git_futils_mmap_ro(&p->index_map, fd, 0, idx_size);
p_close(fd);
if (error < 0)
return error;
hdr = idx_map = p->index_map.data;
if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
version = ntohl(hdr->idx_version);
if (version < 2 || version > 2) {
git_futils_mmap_free(&p->index_map);
return packfile_error("unsupported index version");
}
} else
version = 1;
nr = 0;
index = idx_map;
if (version > 1)
index += 2; /* skip index header */
for (i = 0; i < 256; i++) {
uint32_t n = ntohl(index[i]);
if (n < nr) {
git_futils_mmap_free(&p->index_map);
return packfile_error("index is non-monotonic");
}
nr = n;
}
if (version == 1) {
/*
* Total size:
* - 256 index entries 4 bytes each
* - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
* - 20-byte SHA1 of the packfile
* - 20-byte SHA1 file checksum
*/
if (idx_size != 4*256 + nr * 24 + 20 + 20) {
git_futils_mmap_free(&p->index_map);
return packfile_error("index is corrupted");
}
} else if (version == 2) {
/*
* Minimum size:
* - 8 bytes of header
* - 256 index entries 4 bytes each
* - 20-byte sha1 entry * nr
* - 4-byte crc entry * nr
* - 4-byte offset entry * nr
* - 20-byte SHA1 of the packfile
* - 20-byte SHA1 file checksum
* And after the 4-byte offset table might be a
* variable sized table containing 8-byte entries
* for offsets larger than 2^31.
*/
unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20;
unsigned long max_size = min_size;
if (nr)
max_size += (nr - 1)*8;
if (idx_size < min_size || idx_size > max_size) {
git_futils_mmap_free(&p->index_map);
return packfile_error("wrong index size");
}
}
p->index_version = version;
p->num_objects = nr;
return 0;
}
static int pack_index_open(struct git_pack_file *p)
{
char *idx_name;
int error;
size_t name_len, offset;
if (p->index_map.data)
return 0;
idx_name = git__strdup(p->pack_name);
GITERR_CHECK_ALLOC(idx_name);
name_len = strlen(idx_name);
offset = name_len - strlen(".pack");
assert(offset < name_len); /* make sure no underflow */
strncpy(idx_name + offset, ".idx", name_len - offset);
error = pack_index_check(idx_name, p);
git__free(idx_name);
return error;
}
static unsigned char *pack_window_open(
struct git_pack_file *p,
git_mwindow **w_cursor,
git_off_t offset,
unsigned int *left)
{
if (p->mwf.fd == -1 && packfile_open(p) < 0)
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 int packfile_unpack_header1(
unsigned long *usedp,
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)
return GIT_EBUFS;
if (bitsizeof(long) <= shift) {
*usedp = 0;
return -1;
}
c = buf[used++];
size += (c & 0x7f) << shift;
shift += 7;
}
*sizep = (size_t)size;
*usedp = used;
return 0;
}
int git_packfile_unpack_header(
size_t *size_p,
git_otype *type_p,
git_mwindow_file *mwf,
git_mwindow **w_curs,
git_off_t *curpos)
{
unsigned char *base;
unsigned int left;
unsigned long used;
int ret;
/* 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_EBUFS;
ret = packfile_unpack_header1(&used, size_p, type_p, base, left);
git_mwindow_close(w_curs);
if (ret == GIT_EBUFS)
return ret;
else if (ret < 0)
return packfile_error("header length is zero");
*curpos += used;
return 0;
}
static int packfile_unpack_delta(
git_rawobj *obj,
struct git_pack_file *p,
git_mwindow **w_curs,
git_off_t *curpos,
size_t delta_size,
git_otype delta_type,
git_off_t obj_offset)
{
git_off_t base_offset;
git_rawobj base, delta;
int error;
base_offset = get_delta_base(p, w_curs, curpos, delta_type, obj_offset);
git_mwindow_close(w_curs);
if (base_offset == 0)
return packfile_error("delta offset is zero");
if (base_offset < 0) /* must actually be an error code */
return (int)base_offset;
error = git_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 < 0)
return error;
error = packfile_unpack_compressed(&delta, p, w_curs, curpos, delta_size, delta_type);
git_mwindow_close(w_curs);
if (error < 0) {
git__free(base.data);
return error;
}
obj->type = base.type;
error = git__delta_apply(obj, base.data, base.len, delta.data, delta.len);
git__free(base.data);
git__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 git_packfile_unpack(
git_rawobj *obj,
struct git_pack_file *p,
git_off_t *obj_offset)
{
git_mwindow *w_curs = NULL;
git_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);
git_mwindow_close(&w_curs);
if (error < 0)
return error;
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 = packfile_error("invalid packfile type in header");;
break;
}
*obj_offset = curpos;
return error;
}
static void *use_git_alloc(void *opaq, unsigned int count, unsigned int size)
{
GIT_UNUSED(opaq);
return git__calloc(count, size);
}
static void use_git_free(void *opaq, void *ptr)
{
GIT_UNUSED(opaq);
git__free(ptr);
}
int packfile_unpack_compressed(
git_rawobj *obj,
struct git_pack_file *p,
git_mwindow **w_curs,
git_off_t *curpos,
size_t size,
git_otype type)
{
int st;
z_stream stream;
unsigned char *buffer, *in;
buffer = git__calloc(1, size + 1);
GITERR_CHECK_ALLOC(buffer);
memset(&stream, 0, sizeof(stream));
stream.next_out = buffer;
stream.avail_out = (uInt)size + 1;
stream.zalloc = use_git_alloc;
stream.zfree = use_git_free;
st = inflateInit(&stream);
if (st != Z_OK) {
git__free(buffer);
giterr_set(GITERR_ZLIB, "Failed to inflate packfile");
return -1;
}
do {
in = pack_window_open(p, w_curs, *curpos, &stream.avail_in);
stream.next_in = in;
st = inflate(&stream, Z_FINISH);
git_mwindow_close(w_curs);
if (!stream.avail_out)
break; /* the payload is larger than it should be */
if (st == Z_BUF_ERROR && in == NULL) {
inflateEnd(&stream);
git__free(buffer);
return GIT_EBUFS;
}
*curpos += stream.next_in - in;
} while (st == Z_OK || st == Z_BUF_ERROR);
inflateEnd(&stream);
if ((st != Z_STREAM_END) || stream.total_out != size) {
git__free(buffer);
giterr_set(GITERR_ZLIB, "Failed to inflate packfile");
return -1;
}
obj->type = type;
obj->len = size;
obj->data = buffer;
return 0;
}
/*
* curpos is where the data starts, delta_obj_offset is the where the
* header starts
*/
git_off_t get_delta_base(
struct git_pack_file *p,
git_mwindow **w_curs,
git_off_t *curpos,
git_otype type,
git_off_t delta_obj_offset)
{
unsigned int left = 0;
unsigned char *base_info;
git_off_t base_offset;
git_oid unused;
base_info = pack_window_open(p, w_curs, *curpos, &left);
/* Assumption: the only reason this would fail is because the file is too small */
if (base_info == NULL)
return GIT_EBUFS;
/* 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) {
if (left <= used)
return GIT_EBUFS;
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) {
/* If we have the cooperative cache, search in it first */
if (p->has_cache) {
int pos;
struct git_pack_entry key;
git_oid_fromraw(&key.sha1, base_info);
pos = git_vector_bsearch(&p->cache, &key);
if (pos >= 0) {
*curpos += 20;
return ((struct git_pack_entry *)git_vector_get(&p->cache, pos))->offset;
}
}
/* 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) < 0)
return packfile_error("base entry delta is not in the same pack");
*curpos += 20;
} else
return 0;
return base_offset;
}
/***********************************************************
*
* PACKFILE METHODS
*
***********************************************************/
static struct git_pack_file *packfile_alloc(size_t extra)
{
struct git_pack_file *p = git__calloc(1, sizeof(*p) + extra);
if (p != NULL)
p->mwf.fd = -1;
return p;
}
void packfile_free(struct git_pack_file *p)
{
assert(p);
/* clear_delta_base_cache(); */
git_mwindow_free_all(&p->mwf);
git_mwindow_file_deregister(&p->mwf);
if (p->mwf.fd != -1)
p_close(p->mwf.fd);
pack_index_free(p);
git__free(p->bad_object_sha1);
git__free(p);
}
static int packfile_open(struct git_pack_file *p)
{
struct stat st;
struct git_pack_header hdr;
git_oid sha1;
unsigned char *idx_sha1;
assert(p->index_map.data);
if (!p->index_map.data && pack_index_open(p) < 0)
return git_odb__error_notfound("failed to open packfile", NULL);
/* TODO: open with noatime */
p->mwf.fd = git_futils_open_ro(p->pack_name);
if (p->mwf.fd < 0)
return p->mwf.fd;
if (p_fstat(p->mwf.fd, &st) < 0 ||
git_mwindow_file_register(&p->mwf) < 0)
goto cleanup;
/* If we created the struct before we had the pack we lack size. */
if (!p->mwf.size) {
if (!S_ISREG(st.st_mode))
goto cleanup;
p->mwf.size = (git_off_t)st.st_size;
} else if (p->mwf.size != st.st_size)
goto cleanup;
#if 0
/* We leave these file descriptors open with sliding mmap;
* there is no point keeping them open across exec(), though.
*/
fd_flag = fcntl(p->mwf.fd, F_GETFD, 0);
if (fd_flag < 0)
goto cleanup;
fd_flag |= FD_CLOEXEC;
if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
goto cleanup;
#endif
/* Verify we recognize this pack file format. */
if (p_read(p->mwf.fd, &hdr, sizeof(hdr)) < 0 ||
hdr.hdr_signature != htonl(PACK_SIGNATURE) ||
!pack_version_ok(hdr.hdr_version))
goto cleanup;
/* Verify the pack matches its index. */
if (p->num_objects != ntohl(hdr.hdr_entries) ||
p_lseek(p->mwf.fd, p->mwf.size - GIT_OID_RAWSZ, SEEK_SET) == -1 ||
p_read(p->mwf.fd, sha1.id, GIT_OID_RAWSZ) < 0)
goto cleanup;
idx_sha1 = ((unsigned char *)p->index_map.data) + p->index_map.len - 40;
if (git_oid_cmp(&sha1, (git_oid *)idx_sha1) == 0)
return 0;
cleanup:
giterr_set(GITERR_OS, "Invalid packfile '%s'", p->pack_name);
p_close(p->mwf.fd);
p->mwf.fd = -1;
return -1;
}
int git_packfile_check(struct git_pack_file **pack_out, const char *path)
{
struct stat st;
struct git_pack_file *p;
size_t path_len;
*pack_out = NULL;
path_len = strlen(path);
p = packfile_alloc(path_len + 2);
GITERR_CHECK_ALLOC(p);
/*
* Make sure a corresponding .pack file exists and that
* the index looks sane.
*/
path_len -= strlen(".idx");
if (path_len < 1) {
git__free(p);
return git_odb__error_notfound("invalid packfile path", NULL);
}
memcpy(p->pack_name, path, path_len);
strcpy(p->pack_name + path_len, ".keep");
if (git_path_exists(p->pack_name) == true)
p->pack_keep = 1;
strcpy(p->pack_name + path_len, ".pack");
if (p_stat(p->pack_name, &st) < 0 || !S_ISREG(st.st_mode)) {
git__free(p);
return git_odb__error_notfound("packfile not found", NULL);
}
/* ok, it looks sane as far as we can check without
* actually mapping the pack file.
*/
p->mwf.size = st.st_size;
p->pack_local = 1;
p->mtime = (git_time_t)st.st_mtime;
/* see if we can parse the sha1 oid in the packfile name */
if (path_len < 40 ||
git_oid_fromstr(&p->sha1, path + path_len - GIT_OID_HEXSZ) < 0)
memset(&p->sha1, 0x0, GIT_OID_RAWSZ);
*pack_out = p;
return 0;
}
/***********************************************************
*
* PACKFILE ENTRY SEARCH INTERNALS
*
***********************************************************/
static git_off_t nth_packed_object_offset(const struct git_pack_file *p, uint32_t n)
{
const unsigned char *index = p->index_map.data;
index += 4 * 256;
if (p->index_version == 1) {
return ntohl(*((uint32_t *)(index + 24 * n)));
} else {
uint32_t off;
index += 8 + p->num_objects * (20 + 4);
off = ntohl(*((uint32_t *)(index + 4 * n)));
if (!(off & 0x80000000))
return off;
index += p->num_objects * 4 + (off & 0x7fffffff) * 8;
return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) |
ntohl(*((uint32_t *)(index + 4)));
}
}
static int git__memcmp4(const void *a, const void *b) {
return memcmp(a, b, 4);
}
int git_pack_foreach_entry(
struct git_pack_file *p,
int (*cb)(git_oid *oid, void *data),
void *data)
{
const unsigned char *index = p->index_map.data, *current;
uint32_t i;
if (index == NULL) {
int error;
if ((error = pack_index_open(p)) < 0)
return error;
assert(p->index_map.data);
index = p->index_map.data;
}
if (p->index_version > 1) {
index += 8;
}
index += 4 * 256;
if (p->oids == NULL) {
git_vector offsets, oids;
int error;
if ((error = git_vector_init(&oids, p->num_objects, NULL)))
return error;
if ((error = git_vector_init(&offsets, p->num_objects, git__memcmp4)))
return error;
if (p->index_version > 1) {
const unsigned char *off = index + 24 * p->num_objects;
for (i = 0; i < p->num_objects; i++)
git_vector_insert(&offsets, (void*)&off[4 * i]);
git_vector_sort(&offsets);
git_vector_foreach(&offsets, i, current)
git_vector_insert(&oids, (void*)&index[5 * (current - off)]);
} else {
for (i = 0; i < p->num_objects; i++)
git_vector_insert(&offsets, (void*)&index[24 * i]);
git_vector_sort(&offsets);
git_vector_foreach(&offsets, i, current)
git_vector_insert(&oids, (void*)¤t[4]);
}
git_vector_free(&offsets);
p->oids = (git_oid **)oids.contents;
}
for (i = 0; i < p->num_objects; i++)
if (cb(p->oids[i], data))
return GIT_EUSER;
return 0;
}
static int pack_entry_find_offset(
git_off_t *offset_out,
git_oid *found_oid,
struct git_pack_file *p,
const git_oid *short_oid,
size_t len)
{
const uint32_t *level1_ofs = p->index_map.data;
const unsigned char *index = p->index_map.data;
unsigned hi, lo, stride;
int pos, found = 0;
const unsigned char *current = 0;
*offset_out = 0;
if (index == NULL) {
int error;
if ((error = pack_index_open(p)) < 0)
return error;
assert(p->index_map.data);
index = p->index_map.data;
level1_ofs = p->index_map.data;
}
if (p->index_version > 1) {
level1_ofs += 2;
index += 8;
}
index += 4 * 256;
hi = ntohl(level1_ofs[(int)short_oid->id[0]]);
lo = ((short_oid->id[0] == 0x0) ? 0 : ntohl(level1_ofs[(int)short_oid->id[0] - 1]));
if (p->index_version > 1) {
stride = 20;
} else {
stride = 24;
index += 4;
}
#ifdef INDEX_DEBUG_LOOKUP
printf("%02x%02x%02x... lo %u hi %u nr %d\n",
short_oid->id[0], short_oid->id[1], short_oid->id[2], lo, hi, p->num_objects);
#endif
/* Use git.git lookup code */
pos = sha1_entry_pos(index, stride, 0, lo, hi, p->num_objects, short_oid->id);
if (pos >= 0) {
/* An object matching exactly the oid was found */
found = 1;
current = index + pos * stride;
} else {
/* No object was found */
/* pos refers to the object with the "closest" oid to short_oid */
pos = - 1 - pos;
if (pos < (int)p->num_objects) {
current = index + pos * stride;
if (!git_oid_ncmp(short_oid, (const git_oid *)current, len))
found = 1;
}
}
if (found && len != GIT_OID_HEXSZ && pos + 1 < (int)p->num_objects) {
/* Check for ambiguousity */
const unsigned char *next = current + stride;
if (!git_oid_ncmp(short_oid, (const git_oid *)next, len)) {
found = 2;
}
}
if (!found)
return git_odb__error_notfound("failed to find offset for pack entry", short_oid);
if (found > 1)
return git_odb__error_ambiguous("found multiple offsets for pack entry");
*offset_out = nth_packed_object_offset(p, pos);
git_oid_fromraw(found_oid, current);
#ifdef INDEX_DEBUG_LOOKUP
{
unsigned char hex_sha1[GIT_OID_HEXSZ + 1];
git_oid_fmt(hex_sha1, found_oid);
hex_sha1[GIT_OID_HEXSZ] = '\0';
printf("found lo=%d %s\n", lo, hex_sha1);
}
#endif
return 0;
}
int git_pack_entry_find(
struct git_pack_entry *e,
struct git_pack_file *p,
const git_oid *short_oid,
size_t len)
{
git_off_t offset;
git_oid found_oid;
int error;
assert(p);
if (len == GIT_OID_HEXSZ && p->num_bad_objects) {
unsigned i;
for (i = 0; i < p->num_bad_objects; i++)
if (git_oid_cmp(short_oid, &p->bad_object_sha1[i]) == 0)
return packfile_error("bad object found in packfile");
}
error = pack_entry_find_offset(&offset, &found_oid, p, short_oid, len);
if (error < 0)
return error;
/* we found a unique entry in the index;
* make sure the packfile backing the index
* still exists on disk */
if (p->mwf.fd == -1 && (error = packfile_open(p)) < 0)
return error;
e->offset = offset;
e->p = p;
git_oid_cpy(&e->sha1, &found_oid);
return 0;
}
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