/*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* 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 "pack.h"
#include "odb.h"
#include "delta.h"
#include "sha1_lookup.h"
#include "mwindow.h"
#include "fileops.h"
#include "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);
static 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;
}
/********************
* Delta base cache
********************/
static git_pack_cache_entry *new_cache_object(git_rawobj *source)
{
git_pack_cache_entry *e = git__calloc(1, sizeof(git_pack_cache_entry));
if (!e)
return NULL;
git_atomic_inc(&e->refcount);
memcpy(&e->raw, source, sizeof(git_rawobj));
return e;
}
static void free_cache_object(void *o)
{
git_pack_cache_entry *e = (git_pack_cache_entry *)o;
if (e != NULL) {
assert(e->refcount.val == 0);
git__free(e->raw.data);
git__free(e);
}
}
static void cache_free(git_pack_cache *cache)
{
git_pack_cache_entry *entry;
if (cache->entries) {
git_offmap_foreach_value(cache->entries, entry, {
free_cache_object(entry);
});
git_offmap_free(cache->entries);
cache->entries = NULL;
}
}
static int cache_init(git_pack_cache *cache)
{
cache->entries = git_offmap_alloc();
GITERR_CHECK_ALLOC(cache->entries);
cache->memory_limit = GIT_PACK_CACHE_MEMORY_LIMIT;
if (git_mutex_init(&cache->lock)) {
giterr_set(GITERR_OS, "failed to initialize pack cache mutex");
git__free(cache->entries);
cache->entries = NULL;
return -1;
}
return 0;
}
static git_pack_cache_entry *cache_get(git_pack_cache *cache, git_off_t offset)
{
khiter_t k;
git_pack_cache_entry *entry = NULL;
if (git_mutex_lock(&cache->lock) < 0)
return NULL;
k = git_offmap_lookup_index(cache->entries, offset);
if (git_offmap_valid_index(cache->entries, k)) { /* found it */
entry = git_offmap_value_at(cache->entries, k);
git_atomic_inc(&entry->refcount);
entry->last_usage = cache->use_ctr++;
}
git_mutex_unlock(&cache->lock);
return entry;
}
/* Run with the cache lock held */
static void free_lowest_entry(git_pack_cache *cache)
{
git_off_t offset;
git_pack_cache_entry *entry;
git_offmap_foreach(cache->entries, offset, entry, {
if (entry && entry->refcount.val == 0) {
cache->memory_used -= entry->raw.len;
git_offmap_delete(cache->entries, offset);
free_cache_object(entry);
}
});
}
static int cache_add(
git_pack_cache_entry **cached_out,
git_pack_cache *cache,
git_rawobj *base,
git_off_t offset)
{
git_pack_cache_entry *entry;
int error, exists = 0;
khiter_t k;
if (base->len > GIT_PACK_CACHE_SIZE_LIMIT)
return -1;
entry = new_cache_object(base);
if (entry) {
if (git_mutex_lock(&cache->lock) < 0) {
giterr_set(GITERR_OS, "failed to lock cache");
git__free(entry);
return -1;
}
/* Add it to the cache if nobody else has */
exists = git_offmap_exists(cache->entries, offset);
if (!exists) {
while (cache->memory_used + base->len > cache->memory_limit)
free_lowest_entry(cache);
k = git_offmap_put(cache->entries, offset, &error);
assert(error != 0);
git_offmap_set_value_at(cache->entries, k, entry);
cache->memory_used += entry->raw.len;
*cached_out = entry;
}
git_mutex_unlock(&cache->lock);
/* Somebody beat us to adding it into the cache */
if (exists) {
git__free(entry);
return -1;
}
}
return 0;
}
/***********************************************************
*
* 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) {
p_close(fd);
giterr_set(GITERR_OS, "unable to stat pack index '%s'", path);
return -1;
}
if (!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_ODB, "invalid pack index '%s'", path);
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->num_objects = nr;
p->index_version = version;
return 0;
}
static int pack_index_open(struct git_pack_file *p)
{
int error = 0;
size_t name_len;
git_buf idx_name;
if (p->index_version > -1)
return 0;
name_len = strlen(p->pack_name);
assert(name_len > strlen(".pack")); /* checked by git_pack_file alloc */
if (git_buf_init(&idx_name, name_len) < 0)
return -1;
git_buf_put(&idx_name, p->pack_name, name_len - strlen(".pack"));
git_buf_puts(&idx_name, ".idx");
if (git_buf_oom(&idx_name)) {
git_buf_free(&idx_name);
return -1;
}
if ((error = git_mutex_lock(&p->lock)) < 0) {
git_buf_free(&idx_name);
return error;
}
if (p->index_version == -1)
error = pack_index_check(idx_name.ptr, p);
git_buf_free(&idx_name);
git_mutex_unlock(&p->lock);
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.
*
* Don't allow a negative offset, as that means we've wrapped
* around.
*/
if (offset > (p->mwf.size - 20))
return NULL;
if (offset < 0)
return NULL;
return git_mwindow_open(&p->mwf, w_cursor, offset, 20, left);
}
/*
* The per-object header is a pretty dense thing, which is
* - first byte: low four bits are "size",
* then three bits of "type",
* with the high bit being "size continues".
* - each byte afterwards: low seven bits are size continuation,
* with the high bit being "size continues"
*/
size_t git_packfile__object_header(unsigned char *hdr, size_t size, git_otype type)
{
unsigned char *hdr_base;
unsigned char c;
assert(type >= GIT_OBJ_COMMIT && type <= GIT_OBJ_REF_DELTA);
/* TODO: add support for chunked objects; see git.git 6c0d19b1 */
c = (unsigned char)((type << 4) | (size & 15));
size >>= 4;
hdr_base = hdr;
while (size) {
*hdr++ = c | 0x80;
c = size & 0x7f;
size >>= 7;
}
*hdr++ = c;
return (hdr - hdr_base);
}
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) {
giterr_set(GITERR_ODB, "buffer too small");
return GIT_EBUFS;
}
if (bitsizeof(long) <= shift) {
*usedp = 0;
giterr_set(GITERR_ODB, "packfile corrupted");
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;
}
int git_packfile_resolve_header(
size_t *size_p,
git_otype *type_p,
struct git_pack_file *p,
git_off_t offset)
{
git_mwindow *w_curs = NULL;
git_off_t curpos = offset;
size_t size;
git_otype type;
git_off_t base_offset;
int error;
error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos);
if (error < 0)
return error;
if (type == GIT_OBJ_OFS_DELTA || type == GIT_OBJ_REF_DELTA) {
size_t base_size;
git_packfile_stream stream;
base_offset = get_delta_base(p, &w_curs, &curpos, type, offset);
git_mwindow_close(&w_curs);
if ((error = git_packfile_stream_open(&stream, p, curpos)) < 0)
return error;
error = git_delta_read_header_fromstream(&base_size, size_p, &stream);
git_packfile_stream_free(&stream);
if (error < 0)
return error;
} else {
*size_p = size;
base_offset = 0;
}
while (type == GIT_OBJ_OFS_DELTA || type == GIT_OBJ_REF_DELTA) {
curpos = base_offset;
error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos);
if (error < 0)
return error;
if (type != GIT_OBJ_OFS_DELTA && type != GIT_OBJ_REF_DELTA)
break;
base_offset = get_delta_base(p, &w_curs, &curpos, type, base_offset);
git_mwindow_close(&w_curs);
}
*type_p = type;
return error;
}
#define SMALL_STACK_SIZE 64
/**
* Generate the chain of dependencies which we need to get to the
* object at `off`. `chain` is used a stack, popping gives the right
* order to apply deltas on. If an object is found in the pack's base
* cache, we stop calculating there.
*/
static int pack_dependency_chain(git_dependency_chain *chain_out,
git_pack_cache_entry **cached_out, git_off_t *cached_off,
struct pack_chain_elem *small_stack, size_t *stack_sz,
struct git_pack_file *p, git_off_t obj_offset)
{
git_dependency_chain chain = GIT_ARRAY_INIT;
git_mwindow *w_curs = NULL;
git_off_t curpos = obj_offset, base_offset;
int error = 0, use_heap = 0;
size_t size, elem_pos;
git_otype type;
elem_pos = 0;
while (true) {
struct pack_chain_elem *elem;
git_pack_cache_entry *cached = NULL;
/* if we have a base cached, we can stop here instead */
if ((cached = cache_get(&p->bases, obj_offset)) != NULL) {
*cached_out = cached;
*cached_off = obj_offset;
break;
}
/* if we run out of space on the small stack, use the array */
if (elem_pos == SMALL_STACK_SIZE) {
git_array_init_to_size(chain, elem_pos);
GITERR_CHECK_ARRAY(chain);
memcpy(chain.ptr, small_stack, elem_pos * sizeof(struct pack_chain_elem));
chain.size = elem_pos;
use_heap = 1;
}
curpos = obj_offset;
if (!use_heap) {
elem = &small_stack[elem_pos];
} else {
elem = git_array_alloc(chain);
if (!elem) {
error = -1;
goto on_error;
}
}
elem->base_key = obj_offset;
error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos);
if (error < 0)
goto on_error;
elem->offset = curpos;
elem->size = size;
elem->type = type;
elem->base_key = obj_offset;
if (type != GIT_OBJ_OFS_DELTA && type != GIT_OBJ_REF_DELTA)
break;
base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
git_mwindow_close(&w_curs);
if (base_offset == 0) {
error = packfile_error("delta offset is zero");
goto on_error;
}
if (base_offset < 0) { /* must actually be an error code */
error = (int)base_offset;
goto on_error;
}
/* we need to pass the pos *after* the delta-base bit */
elem->offset = curpos;
/* go through the loop again, but with the new object */
obj_offset = base_offset;
elem_pos++;
}
*stack_sz = elem_pos + 1;
*chain_out = chain;
return error;
on_error:
git_array_clear(chain);
return error;
}
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, free_base = 0;
git_dependency_chain chain = GIT_ARRAY_INIT;
struct pack_chain_elem *elem = NULL, *stack;
git_pack_cache_entry *cached = NULL;
struct pack_chain_elem small_stack[SMALL_STACK_SIZE];
size_t stack_size = 0, elem_pos, alloclen;
git_otype base_type;
/*
* TODO: optionally check the CRC on the packfile
*/
error = pack_dependency_chain(&chain, &cached, obj_offset, small_stack, &stack_size, p, *obj_offset);
if (error < 0)
return error;
obj->data = NULL;
obj->len = 0;
obj->type = GIT_OBJ_BAD;
/* let's point to the right stack */
stack = chain.ptr ? chain.ptr : small_stack;
elem_pos = stack_size;
if (cached) {
memcpy(obj, &cached->raw, sizeof(git_rawobj));
base_type = obj->type;
elem_pos--; /* stack_size includes the base, which isn't actually there */
} else {
elem = &stack[--elem_pos];
base_type = elem->type;
}
switch (base_type) {
case GIT_OBJ_COMMIT:
case GIT_OBJ_TREE:
case GIT_OBJ_BLOB:
case GIT_OBJ_TAG:
if (!cached) {
curpos = elem->offset;
error = packfile_unpack_compressed(obj, p, &w_curs, &curpos, elem->size, elem->type);
git_mwindow_close(&w_curs);
base_type = elem->type;
}
if (error < 0)
goto cleanup;
break;
case GIT_OBJ_OFS_DELTA:
case GIT_OBJ_REF_DELTA:
error = packfile_error("dependency chain ends in a delta");
goto cleanup;
default:
error = packfile_error("invalid packfile type in header");
goto cleanup;
}
/*
* Finding the object we want a cached base element is
* problematic, as we need to make sure we don't accidentally
* give the caller the cached object, which it would then feel
* free to free, so we need to copy the data.
*/
if (cached && stack_size == 1) {
void *data = obj->data;
GITERR_CHECK_ALLOC_ADD(&alloclen, obj->len, 1);
obj->data = git__malloc(alloclen);
GITERR_CHECK_ALLOC(obj->data);
memcpy(obj->data, data, obj->len + 1);
git_atomic_dec(&cached->refcount);
goto cleanup;
}
/* we now apply each consecutive delta until we run out */
while (elem_pos > 0 && !error) {
git_rawobj base, delta;
/*
* We can now try to add the base to the cache, as
* long as it's not already the cached one.
*/
if (!cached)
free_base = !!cache_add(&cached, &p->bases, obj, elem->base_key);
elem = &stack[elem_pos - 1];
curpos = elem->offset;
error = packfile_unpack_compressed(&delta, p, &w_curs, &curpos, elem->size, elem->type);
git_mwindow_close(&w_curs);
if (error < 0)
break;
/* the current object becomes the new base, on which we apply the delta */
base = *obj;
obj->data = NULL;
obj->len = 0;
obj->type = GIT_OBJ_BAD;
error = git_delta_apply(&obj->data, &obj->len, base.data, base.len, delta.data, delta.len);
obj->type = base_type;
/*
* We usually don't want to free the base at this
* point, as we put it into the cache in the previous
* iteration. free_base lets us know that we got the
* base object directly from the packfile, so we can free it.
*/
git__free(delta.data);
if (free_base) {
free_base = 0;
git__free(base.data);
}
if (cached) {
git_atomic_dec(&cached->refcount);
cached = NULL;
}
if (error < 0)
break;
elem_pos--;
}
cleanup:
if (error < 0) {
git__free(obj->data);
if (cached)
git_atomic_dec(&cached->refcount);
}
if (elem)
*obj_offset = curpos;
git_array_clear(chain);
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 git_packfile_stream_open(git_packfile_stream *obj, struct git_pack_file *p, git_off_t curpos)
{
int st;
memset(obj, 0, sizeof(git_packfile_stream));
obj->curpos = curpos;
obj->p = p;
obj->zstream.zalloc = use_git_alloc;
obj->zstream.zfree = use_git_free;
obj->zstream.next_in = Z_NULL;
obj->zstream.next_out = Z_NULL;
st = inflateInit(&obj->zstream);
if (st != Z_OK) {
giterr_set(GITERR_ZLIB, "failed to init packfile stream");
return -1;
}
return 0;
}
ssize_t git_packfile_stream_read(git_packfile_stream *obj, void *buffer, size_t len)
{
unsigned char *in;
size_t written;
int st;
if (obj->done)
return 0;
in = pack_window_open(obj->p, &obj->mw, obj->curpos, &obj->zstream.avail_in);
if (in == NULL)
return GIT_EBUFS;
obj->zstream.next_out = buffer;
obj->zstream.avail_out = (unsigned int)len;
obj->zstream.next_in = in;
st = inflate(&obj->zstream, Z_SYNC_FLUSH);
git_mwindow_close(&obj->mw);
obj->curpos += obj->zstream.next_in - in;
written = len - obj->zstream.avail_out;
if (st != Z_OK && st != Z_STREAM_END) {
giterr_set(GITERR_ZLIB, "error reading from the zlib stream");
return -1;
}
if (st == Z_STREAM_END)
obj->done = 1;
/* If we didn't write anything out but we're not done, we need more data */
if (!written && st != Z_STREAM_END)
return GIT_EBUFS;
return written;
}
void git_packfile_stream_free(git_packfile_stream *obj)
{
inflateEnd(&obj->zstream);
}
static 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)
{
size_t buf_size;
int st;
z_stream stream;
unsigned char *buffer, *in;
GITERR_CHECK_ALLOC_ADD(&buf_size, size, 1);
buffer = git__calloc(1, buf_size);
GITERR_CHECK_ALLOC(buffer);
memset(&stream, 0, sizeof(stream));
stream.next_out = buffer;
stream.avail_out = (uInt)buf_size;
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 init zlib stream on unpack");
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, "error inflating zlib stream");
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++];
size_t unsigned_base_offset = c & 127;
while (c & 128) {
if (left <= used)
return GIT_EBUFS;
unsigned_base_offset += 1;
if (!unsigned_base_offset || MSB(unsigned_base_offset, 7))
return 0; /* overflow */
c = base_info[used++];
unsigned_base_offset = (unsigned_base_offset << 7) + (c & 127);
}
if (unsigned_base_offset == 0 || (size_t)delta_obj_offset <= unsigned_base_offset)
return 0; /* out of bound */
base_offset = delta_obj_offset - unsigned_base_offset;
*curpos += used;
} else if (type == GIT_OBJ_REF_DELTA) {
/* If we have the cooperative cache, search in it first */
if (p->has_cache) {
khiter_t k;
git_oid oid;
git_oid_fromraw(&oid, base_info);
k = git_oidmap_lookup_index(p->idx_cache, &oid);
if (git_oidmap_valid_index(p->idx_cache, k)) {
*curpos += 20;
return ((struct git_pack_entry *)git_oidmap_value_at(p->idx_cache, k))->offset;
} else {
/* If we're building an index, don't try to find the pack
* entry; we just haven't seen it yet. We'll make
* progress again in the next loop.
*/
return GIT_PASSTHROUGH;
}
}
/* 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
*
***********************************************************/
void git_packfile_close(struct git_pack_file *p, bool unlink_packfile)
{
if (p->mwf.fd >= 0) {
git_mwindow_free_all_locked(&p->mwf);
p_close(p->mwf.fd);
p->mwf.fd = -1;
}
if (unlink_packfile)
p_unlink(p->pack_name);
}
void git_packfile_free(struct git_pack_file *p)
{
if (!p)
return;
cache_free(&p->bases);
git_packfile_close(p, false);
pack_index_free(p);
git__free(p->bad_object_sha1);
git_mutex_free(&p->lock);
git_mutex_free(&p->bases.lock);
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;
if (p->index_version == -1 && pack_index_open(p) < 0)
return git_odb__error_notfound("failed to open packfile", NULL, 0);
/* if mwf opened by another thread, return now */
if (git_mutex_lock(&p->lock) < 0)
return packfile_error("failed to get lock for open");
if (p->mwf.fd >= 0) {
git_mutex_unlock(&p->lock);
return 0;
}
/* TODO: open with noatime */
p->mwf.fd = git_futils_open_ro(p->pack_name);
if (p->mwf.fd < 0)
goto cleanup;
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)
goto cleanup;
git_mutex_unlock(&p->lock);
return 0;
cleanup:
giterr_set(GITERR_OS, "invalid packfile '%s'", p->pack_name);
if (p->mwf.fd >= 0)
p_close(p->mwf.fd);
p->mwf.fd = -1;
git_mutex_unlock(&p->lock);
return -1;
}
int git_packfile__name(char **out, const char *path)
{
size_t path_len;
git_buf buf = GIT_BUF_INIT;
path_len = strlen(path);
if (path_len < strlen(".idx"))
return git_odb__error_notfound("invalid packfile path", NULL, 0);
if (git_buf_printf(&buf, "%.*s.pack", (int)(path_len - strlen(".idx")), path) < 0)
return -1;
*out = git_buf_detach(&buf);
return 0;
}
int git_packfile_alloc(struct git_pack_file **pack_out, const char *path)
{
struct stat st;
struct git_pack_file *p;
size_t path_len = path ? strlen(path) : 0, alloc_len;
*pack_out = NULL;
if (path_len < strlen(".idx"))
return git_odb__error_notfound("invalid packfile path", NULL, 0);
GITERR_CHECK_ALLOC_ADD(&alloc_len, sizeof(*p), path_len);
GITERR_CHECK_ALLOC_ADD(&alloc_len, alloc_len, 2);
p = git__calloc(1, alloc_len);
GITERR_CHECK_ALLOC(p);
memcpy(p->pack_name, path, path_len + 1);
/*
* Make sure a corresponding .pack file exists and that
* the index looks sane.
*/
if (git__suffixcmp(path, ".idx") == 0) {
size_t root_len = path_len - strlen(".idx");
memcpy(p->pack_name + root_len, ".keep", sizeof(".keep"));
if (git_path_exists(p->pack_name) == true)
p->pack_keep = 1;
memcpy(p->pack_name + root_len, ".pack", sizeof(".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, 0);
}
/* ok, it looks sane as far as we can check without
* actually mapping the pack file.
*/
p->mwf.fd = -1;
p->mwf.size = st.st_size;
p->pack_local = 1;
p->mtime = (git_time_t)st.st_mtime;
p->index_version = -1;
if (git_mutex_init(&p->lock)) {
giterr_set(GITERR_OS, "failed to initialize packfile mutex");
git__free(p);
return -1;
}
if (cache_init(&p->bases) < 0) {
git__free(p);
return -1;
}
*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;
const unsigned char *end = index + p->index_map.len;
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;
/* Make sure we're not being sent out of bounds */
if (index >= end - 8)
return -1;
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,
git_odb_foreach_cb cb,
void *data)
{
const unsigned char *index = p->index_map.data, *current;
uint32_t i;
int error = 0;
if (index == NULL) {
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;
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 **)git_vector_detach(NULL, NULL, &oids);
}
for (i = 0; i < p->num_objects; i++)
if ((error = cb(p->oids[i], data)) != 0)
return giterr_set_after_callback(error);
return error;
}
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;
const unsigned char *index;
unsigned hi, lo, stride;
int pos, found = 0;
git_off_t offset;
const unsigned char *current = 0;
*offset_out = 0;
if (p->index_version == -1) {
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
pos = sha1_position(index, stride, lo, hi, 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, len);
if (found > 1)
return git_odb__error_ambiguous("found multiple offsets for pack entry");
if ((offset = nth_packed_object_offset(p, pos)) < 0) {
giterr_set(GITERR_ODB, "packfile index is corrupt");
return -1;
}
*offset_out = offset;
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;
}
