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pack: move clear_delta_base_cache(), packed_object_info(), unpack_entry() 

Both sha1_file.c and packfile.c now need read_object(), so a copy of
read_object() was created in packfile.c.

This patch makes both mark_bad_packed_object() and has_packed_and_bad()
global. Unlike most of the other patches in this series, these 2
functions need to remain global.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jonathan Tan 2017-08-18 15:20:30 -07:00 committed by Junio C Hamano
parent 3588dd6e99
commit f1d8130be0
4 changed files with 685 additions and 670 deletions
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7
cache.h
View File

@ -1187,9 +1187,6 @@ extern void *map_sha1_file(const unsigned char *sha1, unsigned long *size);
extern int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz);
extern int parse_sha1_header(const char *hdr, unsigned long *sizep);
/* global flag to enable extra checks when accessing packed objects */
extern int do_check_packed_object_crc;
extern int check_sha1_signature(const unsigned char *sha1, void *buf, unsigned long size, const char *type);
extern int finalize_object_file(const char *tmpfile, const char *filename);
@ -1623,8 +1620,6 @@ extern int odb_mkstemp(struct strbuf *template, const char *pattern);
*/
extern int odb_pack_keep(const char *name);
extern void clear_delta_base_cache(void);
/*
* Make sure that a pointer access into an mmap'd index file is within bounds,
* and can provide at least 8 bytes of data.
@ -1662,7 +1657,6 @@ extern off_t nth_packed_object_offset(const struct packed_git *, uint32_t n);
extern off_t find_pack_entry_one(const unsigned char *sha1, struct packed_git *);
extern int is_pack_valid(struct packed_git *);
extern void *unpack_entry(struct packed_git *, off_t, enum object_type *, unsigned long *);
/*
* Iterate over the files in the loose-object parts of the object
@ -1773,7 +1767,6 @@ struct object_info {
/* Do not retry packed storage after checking packed and loose storage */
#define OBJECT_INFO_QUICK 8
extern int sha1_object_info_extended(const unsigned char *, struct object_info *, unsigned flags);
extern int packed_object_info(struct packed_git *pack, off_t offset, struct object_info *);
/* Dumb servers support */
extern int update_server_info(int);

661
packfile.c
View File

@ -5,6 +5,8 @@
#include "mergesort.h"
#include "packfile.h"
#include "delta.h"
#include "list.h"
#include "streaming.h"
char *odb_pack_name(struct strbuf *buf,
const unsigned char *sha1,
@ -975,3 +977,662 @@ int unpack_object_header(struct packed_git *p,
return type;
}
void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1)
{
unsigned i;
for (i = 0; i < p->num_bad_objects; i++)
if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
return;
p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
st_mult(GIT_MAX_RAWSZ,
st_add(p->num_bad_objects, 1)));
hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
p->num_bad_objects++;
}
const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
{
struct packed_git *p;
unsigned i;
for (p = packed_git; p; p = p->next)
for (i = 0; i < p->num_bad_objects; i++)
if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
return p;
return NULL;
}
static off_t get_delta_base(struct packed_git *p,
struct pack_window **w_curs,
off_t *curpos,
enum object_type type,
off_t delta_obj_offset)
{
unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
off_t base_offset;
/* use_pack() 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 == 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 == OBJ_REF_DELTA) {
/* The base entry _must_ be in the same pack */
base_offset = find_pack_entry_one(base_info, p);
*curpos += 20;
} else
die("I am totally screwed");
return base_offset;
}
/*
* Like get_delta_base above, but we return the sha1 instead of the pack
* offset. This means it is cheaper for REF deltas (we do not have to do
* the final object lookup), but more expensive for OFS deltas (we
* have to load the revidx to convert the offset back into a sha1).
*/
static const unsigned char *get_delta_base_sha1(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos,
enum object_type type,
off_t delta_obj_offset)
{
if (type == OBJ_REF_DELTA) {
unsigned char *base = use_pack(p, w_curs, curpos, NULL);
return base;
} else if (type == OBJ_OFS_DELTA) {
struct revindex_entry *revidx;
off_t base_offset = get_delta_base(p, w_curs, &curpos,
type, delta_obj_offset);
if (!base_offset)
return NULL;
revidx = find_pack_revindex(p, base_offset);
if (!revidx)
return NULL;
return nth_packed_object_sha1(p, revidx->nr);
} else
return NULL;
}
static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
{
int type;
struct revindex_entry *revidx;
const unsigned char *sha1;
revidx = find_pack_revindex(p, obj_offset);
if (!revidx)
return OBJ_BAD;
sha1 = nth_packed_object_sha1(p, revidx->nr);
mark_bad_packed_object(p, sha1);
type = sha1_object_info(sha1, NULL);
if (type <= OBJ_NONE)
return OBJ_BAD;
return type;
}
#define POI_STACK_PREALLOC 64
static enum object_type packed_to_object_type(struct packed_git *p,
off_t obj_offset,
enum object_type type,
struct pack_window **w_curs,
off_t curpos)
{
off_t small_poi_stack[POI_STACK_PREALLOC];
off_t *poi_stack = small_poi_stack;
int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
off_t base_offset;
unsigned long size;
/* Push the object we're going to leave behind */
if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
poi_stack_alloc = alloc_nr(poi_stack_nr);
ALLOC_ARRAY(poi_stack, poi_stack_alloc);
memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
} else {
ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
}
poi_stack[poi_stack_nr++] = obj_offset;
/* If parsing the base offset fails, just unwind */
base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
if (!base_offset)
goto unwind;
curpos = obj_offset = base_offset;
type = unpack_object_header(p, w_curs, &curpos, &size);
if (type <= OBJ_NONE) {
/* If getting the base itself fails, we first
* retry the base, otherwise unwind */
type = retry_bad_packed_offset(p, base_offset);
if (type > OBJ_NONE)
goto out;
goto unwind;
}
}
switch (type) {
case OBJ_BAD:
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
break;
default:
error("unknown object type %i at offset %"PRIuMAX" in %s",
type, (uintmax_t)obj_offset, p->pack_name);
type = OBJ_BAD;
}
out:
if (poi_stack != small_poi_stack)
free(poi_stack);
return type;
unwind:
while (poi_stack_nr) {
obj_offset = poi_stack[--poi_stack_nr];
type = retry_bad_packed_offset(p, obj_offset);
if (type > OBJ_NONE)
goto out;
}
type = OBJ_BAD;
goto out;
}
static struct hashmap delta_base_cache;
static size_t delta_base_cached;
static LIST_HEAD(delta_base_cache_lru);
struct delta_base_cache_key {
struct packed_git *p;
off_t base_offset;
};
struct delta_base_cache_entry {
struct hashmap hash;
struct delta_base_cache_key key;
struct list_head lru;
void *data;
unsigned long size;
enum object_type type;
};
static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
{
unsigned int hash;
hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
hash += (hash >> 8) + (hash >> 16);
return hash;
}
static struct delta_base_cache_entry *
get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
{
struct hashmap_entry entry;
struct delta_base_cache_key key;
if (!delta_base_cache.cmpfn)
return NULL;
hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
key.p = p;
key.base_offset = base_offset;
return hashmap_get(&delta_base_cache, &entry, &key);
}
static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
const struct delta_base_cache_key *b)
{
return a->p == b->p && a->base_offset == b->base_offset;
}
static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
const void *va, const void *vb,
const void *vkey)
{
const struct delta_base_cache_entry *a = va, *b = vb;
const struct delta_base_cache_key *key = vkey;
if (key)
return !delta_base_cache_key_eq(&a->key, key);
else
return !delta_base_cache_key_eq(&a->key, &b->key);
}
static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
{
return !!get_delta_base_cache_entry(p, base_offset);
}
/*
* Remove the entry from the cache, but do _not_ free the associated
* entry data. The caller takes ownership of the "data" buffer, and
* should copy out any fields it wants before detaching.
*/
static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
{
hashmap_remove(&delta_base_cache, ent, &ent->key);
list_del(&ent->lru);
delta_base_cached -= ent->size;
free(ent);
}
static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
unsigned long *base_size, enum object_type *type)
{
struct delta_base_cache_entry *ent;
ent = get_delta_base_cache_entry(p, base_offset);
if (!ent)
return unpack_entry(p, base_offset, type, base_size);
if (type)
*type = ent->type;
if (base_size)
*base_size = ent->size;
return xmemdupz(ent->data, ent->size);
}
static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
{
free(ent->data);
detach_delta_base_cache_entry(ent);
}
void clear_delta_base_cache(void)
{
struct list_head *lru, *tmp;
list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
struct delta_base_cache_entry *entry =
list_entry(lru, struct delta_base_cache_entry, lru);
release_delta_base_cache(entry);
}
}
static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
void *base, unsigned long base_size, enum object_type type)
{
struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
struct list_head *lru, *tmp;
delta_base_cached += base_size;
list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
struct delta_base_cache_entry *f =
list_entry(lru, struct delta_base_cache_entry, lru);
if (delta_base_cached <= delta_base_cache_limit)
break;
release_delta_base_cache(f);
}
ent->key.p = p;
ent->key.base_offset = base_offset;
ent->type = type;
ent->data = base;
ent->size = base_size;
list_add_tail(&ent->lru, &delta_base_cache_lru);
if (!delta_base_cache.cmpfn)
hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
hashmap_add(&delta_base_cache, ent);
}
int packed_object_info(struct packed_git *p, off_t obj_offset,
struct object_info *oi)
{
struct pack_window *w_curs = NULL;
unsigned long size;
off_t curpos = obj_offset;
enum object_type type;
/*
* We always get the representation type, but only convert it to
* a "real" type later if the caller is interested.
*/
if (oi->contentp) {
*oi->contentp = cache_or_unpack_entry(p, obj_offset, oi->sizep,
&type);
if (!*oi->contentp)
type = OBJ_BAD;
} else {
type = unpack_object_header(p, &w_curs, &curpos, &size);
}
if (!oi->contentp && oi->sizep) {
if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
off_t tmp_pos = curpos;
off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
type, obj_offset);
if (!base_offset) {
type = OBJ_BAD;
goto out;
}
*oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
if (*oi->sizep == 0) {
type = OBJ_BAD;
goto out;
}
} else {
*oi->sizep = size;
}
}
if (oi->disk_sizep) {
struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
*oi->disk_sizep = revidx[1].offset - obj_offset;
}
if (oi->typep || oi->typename) {
enum object_type ptot;
ptot = packed_to_object_type(p, obj_offset, type, &w_curs,
curpos);
if (oi->typep)
*oi->typep = ptot;
if (oi->typename) {
const char *tn = typename(ptot);
if (tn)
strbuf_addstr(oi->typename, tn);
}
if (ptot < 0) {
type = OBJ_BAD;
goto out;
}
}
if (oi->delta_base_sha1) {
if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
const unsigned char *base;
base = get_delta_base_sha1(p, &w_curs, curpos,
type, obj_offset);
if (!base) {
type = OBJ_BAD;
goto out;
}
hashcpy(oi->delta_base_sha1, base);
} else
hashclr(oi->delta_base_sha1);
}
oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
OI_PACKED;
out:
unuse_pack(&w_curs);
return type;
}
static void *unpack_compressed_entry(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos,
unsigned long size)
{
int st;
git_zstream stream;
unsigned char *buffer, *in;
buffer = xmallocz_gently(size);
if (!buffer)
return NULL;
memset(&stream, 0, sizeof(stream));
stream.next_out = buffer;
stream.avail_out = size + 1;
git_inflate_init(&stream);
do {
in = use_pack(p, w_curs, curpos, &stream.avail_in);
stream.next_in = in;
st = git_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);
git_inflate_end(&stream);
if ((st != Z_STREAM_END) || stream.total_out != size) {
free(buffer);
return NULL;
}
return buffer;
}
static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
{
static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
p->pack_name, (uintmax_t)obj_offset);
}
int do_check_packed_object_crc;
#define UNPACK_ENTRY_STACK_PREALLOC 64
struct unpack_entry_stack_ent {
off_t obj_offset;
off_t curpos;
unsigned long size;
};
static void *read_object(const unsigned char *sha1, enum object_type *type,
unsigned long *size)
{
struct object_info oi = OBJECT_INFO_INIT;
void *content;
oi.typep = type;
oi.sizep = size;
oi.contentp = &content;
if (sha1_object_info_extended(sha1, &oi, 0) < 0)
return NULL;
return content;
}
void *unpack_entry(struct packed_git *p, off_t obj_offset,
enum object_type *final_type, unsigned long *final_size)
{
struct pack_window *w_curs = NULL;
off_t curpos = obj_offset;
void *data = NULL;
unsigned long size;
enum object_type type;
struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
int base_from_cache = 0;
write_pack_access_log(p, obj_offset);
/* PHASE 1: drill down to the innermost base object */
for (;;) {
off_t base_offset;
int i;
struct delta_base_cache_entry *ent;
ent = get_delta_base_cache_entry(p, curpos);
if (ent) {
type = ent->type;
data = ent->data;
size = ent->size;
detach_delta_base_cache_entry(ent);
base_from_cache = 1;
break;
}
if (do_check_packed_object_crc && p->index_version > 1) {
struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
off_t len = revidx[1].offset - obj_offset;
if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
const unsigned char *sha1 =
nth_packed_object_sha1(p, revidx->nr);
error("bad packed object CRC for %s",
sha1_to_hex(sha1));
mark_bad_packed_object(p, sha1);
data = NULL;
goto out;
}
}
type = unpack_object_header(p, &w_curs, &curpos, &size);
if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
break;
base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
if (!base_offset) {
error("failed to validate delta base reference "
"at offset %"PRIuMAX" from %s",
(uintmax_t)curpos, p->pack_name);
/* bail to phase 2, in hopes of recovery */
data = NULL;
break;
}
/* push object, proceed to base */
if (delta_stack_nr >= delta_stack_alloc
&& delta_stack == small_delta_stack) {
delta_stack_alloc = alloc_nr(delta_stack_nr);
ALLOC_ARRAY(delta_stack, delta_stack_alloc);
memcpy(delta_stack, small_delta_stack,
sizeof(*delta_stack)*delta_stack_nr);
} else {
ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
}
i = delta_stack_nr++;
delta_stack[i].obj_offset = obj_offset;
delta_stack[i].curpos = curpos;
delta_stack[i].size = size;
curpos = obj_offset = base_offset;
}
/* PHASE 2: handle the base */
switch (type) {
case OBJ_OFS_DELTA:
case OBJ_REF_DELTA:
if (data)
die("BUG: unpack_entry: left loop at a valid delta");
break;
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
if (!base_from_cache)
data = unpack_compressed_entry(p, &w_curs, curpos, size);
break;
default:
data = NULL;
error("unknown object type %i at offset %"PRIuMAX" in %s",
type, (uintmax_t)obj_offset, p->pack_name);
}
/* PHASE 3: apply deltas in order */
/* invariants:
* 'data' holds the base data, or NULL if there was corruption
*/
while (delta_stack_nr) {
void *delta_data;
void *base = data;
void *external_base = NULL;
unsigned long delta_size, base_size = size;
int i;
data = NULL;
if (base)
add_delta_base_cache(p, obj_offset, base, base_size, type);
if (!base) {
/*
* We're probably in deep shit, but let's try to fetch
* the required base anyway from another pack or loose.
* This is costly but should happen only in the presence
* of a corrupted pack, and is better than failing outright.
*/
struct revindex_entry *revidx;
const unsigned char *base_sha1;
revidx = find_pack_revindex(p, obj_offset);
if (revidx) {
base_sha1 = nth_packed_object_sha1(p, revidx->nr);
error("failed to read delta base object %s"
" at offset %"PRIuMAX" from %s",
sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
p->pack_name);
mark_bad_packed_object(p, base_sha1);
base = read_object(base_sha1, &type, &base_size);
external_base = base;
}
}
i = --delta_stack_nr;
obj_offset = delta_stack[i].obj_offset;
curpos = delta_stack[i].curpos;
delta_size = delta_stack[i].size;
if (!base)
continue;
delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
if (!delta_data) {
error("failed to unpack compressed delta "
"at offset %"PRIuMAX" from %s",
(uintmax_t)curpos, p->pack_name);
data = NULL;
free(external_base);
continue;
}
data = patch_delta(base, base_size,
delta_data, delta_size,
&size);
/*
* We could not apply the delta; warn the user, but keep going.
* Our failure will be noticed either in the next iteration of
* the loop, or if this is the final delta, in the caller when
* we return NULL. Those code paths will take care of making
* a more explicit warning and retrying with another copy of
* the object.
*/
if (!data)
error("failed to apply delta");
free(delta_data);
free(external_base);
}
if (final_type)
*final_type = type;
if (final_size)
*final_size = size;
out:
unuse_pack(&w_curs);
if (delta_stack != small_delta_stack)
free(delta_stack);
return data;
}

10
packfile.h
View File

@ -60,8 +60,10 @@ extern unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t
extern void close_pack_windows(struct packed_git *);
extern void close_all_packs(void);
extern void unuse_pack(struct pack_window **);
extern void clear_delta_base_cache(void);
extern struct packed_git *add_packed_git(const char *path, size_t path_len, int local);
extern void *unpack_entry(struct packed_git *, off_t, enum object_type *, unsigned long *);
extern unsigned long unpack_object_header_buffer(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep);
extern unsigned long get_size_from_delta(struct packed_git *, struct pack_window **, off_t);
extern int unpack_object_header(struct packed_git *, struct pack_window **, off_t *, unsigned long *);
@ -70,4 +72,12 @@ extern void release_pack_memory(size_t);
extern int open_packed_git(struct packed_git *p);
/* global flag to enable extra checks when accessing packed objects */
extern int do_check_packed_object_crc;
extern int packed_object_info(struct packed_git *pack, off_t offset, struct object_info *);
extern void mark_bad_packed_object(struct packed_git *p, const unsigned char *sha1);
extern const struct packed_git *has_packed_and_bad(const unsigned char *sha1);
#endif

677
sha1_file.c
View File

@ -719,32 +719,6 @@ void *xmmap(void *start, size_t length,
return ret;
}
static void mark_bad_packed_object(struct packed_git *p,
const unsigned char *sha1)
{
unsigned i;
for (i = 0; i < p->num_bad_objects; i++)
if (!hashcmp(sha1, p->bad_object_sha1 + GIT_SHA1_RAWSZ * i))
return;
p->bad_object_sha1 = xrealloc(p->bad_object_sha1,
st_mult(GIT_MAX_RAWSZ,
st_add(p->num_bad_objects, 1)));
hashcpy(p->bad_object_sha1 + GIT_SHA1_RAWSZ * p->num_bad_objects, sha1);
p->num_bad_objects++;
}
static const struct packed_git *has_packed_and_bad(const unsigned char *sha1)
{
struct packed_git *p;
unsigned i;
for (p = packed_git; p; p = p->next)
for (i = 0; i < p->num_bad_objects; i++)
if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
return p;
return NULL;
}
/*
* With an in-core object data in "map", rehash it to make sure the
* object name actually matches "sha1" to detect object corruption.
@ -1101,629 +1075,6 @@ int parse_sha1_header(const char *hdr, unsigned long *sizep)
return parse_sha1_header_extended(hdr, &oi, 0);
}
static off_t get_delta_base(struct packed_git *p,
struct pack_window **w_curs,
off_t *curpos,
enum object_type type,
off_t delta_obj_offset)
{
unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
off_t base_offset;
/* use_pack() 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 == 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 == OBJ_REF_DELTA) {
/* The base entry _must_ be in the same pack */
base_offset = find_pack_entry_one(base_info, p);
*curpos += 20;
} else
die("I am totally screwed");
return base_offset;
}
/*
* Like get_delta_base above, but we return the sha1 instead of the pack
* offset. This means it is cheaper for REF deltas (we do not have to do
* the final object lookup), but more expensive for OFS deltas (we
* have to load the revidx to convert the offset back into a sha1).
*/
static const unsigned char *get_delta_base_sha1(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos,
enum object_type type,
off_t delta_obj_offset)
{
if (type == OBJ_REF_DELTA) {
unsigned char *base = use_pack(p, w_curs, curpos, NULL);
return base;
} else if (type == OBJ_OFS_DELTA) {
struct revindex_entry *revidx;
off_t base_offset = get_delta_base(p, w_curs, &curpos,
type, delta_obj_offset);
if (!base_offset)
return NULL;
revidx = find_pack_revindex(p, base_offset);
if (!revidx)
return NULL;
return nth_packed_object_sha1(p, revidx->nr);
} else
return NULL;
}
static int retry_bad_packed_offset(struct packed_git *p, off_t obj_offset)
{
int type;
struct revindex_entry *revidx;
const unsigned char *sha1;
revidx = find_pack_revindex(p, obj_offset);
if (!revidx)
return OBJ_BAD;
sha1 = nth_packed_object_sha1(p, revidx->nr);
mark_bad_packed_object(p, sha1);
type = sha1_object_info(sha1, NULL);
if (type <= OBJ_NONE)
return OBJ_BAD;
return type;
}
#define POI_STACK_PREALLOC 64
static enum object_type packed_to_object_type(struct packed_git *p,
off_t obj_offset,
enum object_type type,
struct pack_window **w_curs,
off_t curpos)
{
off_t small_poi_stack[POI_STACK_PREALLOC];
off_t *poi_stack = small_poi_stack;
int poi_stack_nr = 0, poi_stack_alloc = POI_STACK_PREALLOC;
while (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
off_t base_offset;
unsigned long size;
/* Push the object we're going to leave behind */
if (poi_stack_nr >= poi_stack_alloc && poi_stack == small_poi_stack) {
poi_stack_alloc = alloc_nr(poi_stack_nr);
ALLOC_ARRAY(poi_stack, poi_stack_alloc);
memcpy(poi_stack, small_poi_stack, sizeof(off_t)*poi_stack_nr);
} else {
ALLOC_GROW(poi_stack, poi_stack_nr+1, poi_stack_alloc);
}
poi_stack[poi_stack_nr++] = obj_offset;
/* If parsing the base offset fails, just unwind */
base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
if (!base_offset)
goto unwind;
curpos = obj_offset = base_offset;
type = unpack_object_header(p, w_curs, &curpos, &size);
if (type <= OBJ_NONE) {
/* If getting the base itself fails, we first
* retry the base, otherwise unwind */
type = retry_bad_packed_offset(p, base_offset);
if (type > OBJ_NONE)
goto out;
goto unwind;
}
}
switch (type) {
case OBJ_BAD:
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
break;
default:
error("unknown object type %i at offset %"PRIuMAX" in %s",
type, (uintmax_t)obj_offset, p->pack_name);
type = OBJ_BAD;
}
out:
if (poi_stack != small_poi_stack)
free(poi_stack);
return type;
unwind:
while (poi_stack_nr) {
obj_offset = poi_stack[--poi_stack_nr];
type = retry_bad_packed_offset(p, obj_offset);
if (type > OBJ_NONE)
goto out;
}
type = OBJ_BAD;
goto out;
}
static struct hashmap delta_base_cache;
static size_t delta_base_cached;
static LIST_HEAD(delta_base_cache_lru);
struct delta_base_cache_key {
struct packed_git *p;
off_t base_offset;
};
struct delta_base_cache_entry {
struct hashmap hash;
struct delta_base_cache_key key;
struct list_head lru;
void *data;
unsigned long size;
enum object_type type;
};
static unsigned int pack_entry_hash(struct packed_git *p, off_t base_offset)
{
unsigned int hash;
hash = (unsigned int)(intptr_t)p + (unsigned int)base_offset;
hash += (hash >> 8) + (hash >> 16);
return hash;
}
static struct delta_base_cache_entry *
get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
{
struct hashmap_entry entry;
struct delta_base_cache_key key;
if (!delta_base_cache.cmpfn)
return NULL;
hashmap_entry_init(&entry, pack_entry_hash(p, base_offset));
key.p = p;
key.base_offset = base_offset;
return hashmap_get(&delta_base_cache, &entry, &key);
}
static int delta_base_cache_key_eq(const struct delta_base_cache_key *a,
const struct delta_base_cache_key *b)
{
return a->p == b->p && a->base_offset == b->base_offset;
}
static int delta_base_cache_hash_cmp(const void *unused_cmp_data,
const void *va, const void *vb,
const void *vkey)
{
const struct delta_base_cache_entry *a = va, *b = vb;
const struct delta_base_cache_key *key = vkey;
if (key)
return !delta_base_cache_key_eq(&a->key, key);
else
return !delta_base_cache_key_eq(&a->key, &b->key);
}
static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
{
return !!get_delta_base_cache_entry(p, base_offset);
}
/*
* Remove the entry from the cache, but do _not_ free the associated
* entry data. The caller takes ownership of the "data" buffer, and
* should copy out any fields it wants before detaching.
*/
static void detach_delta_base_cache_entry(struct delta_base_cache_entry *ent)
{
hashmap_remove(&delta_base_cache, ent, &ent->key);
list_del(&ent->lru);
delta_base_cached -= ent->size;
free(ent);
}
static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
unsigned long *base_size, enum object_type *type)
{
struct delta_base_cache_entry *ent;
ent = get_delta_base_cache_entry(p, base_offset);
if (!ent)
return unpack_entry(p, base_offset, type, base_size);
if (type)
*type = ent->type;
if (base_size)
*base_size = ent->size;
return xmemdupz(ent->data, ent->size);
}
static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
{
free(ent->data);
detach_delta_base_cache_entry(ent);
}
void clear_delta_base_cache(void)
{
struct list_head *lru, *tmp;
list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
struct delta_base_cache_entry *entry =
list_entry(lru, struct delta_base_cache_entry, lru);
release_delta_base_cache(entry);
}
}
static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
void *base, unsigned long base_size, enum object_type type)
{
struct delta_base_cache_entry *ent = xmalloc(sizeof(*ent));
struct list_head *lru, *tmp;
delta_base_cached += base_size;
list_for_each_safe(lru, tmp, &delta_base_cache_lru) {
struct delta_base_cache_entry *f =
list_entry(lru, struct delta_base_cache_entry, lru);
if (delta_base_cached <= delta_base_cache_limit)
break;
release_delta_base_cache(f);
}
ent->key.p = p;
ent->key.base_offset = base_offset;
ent->type = type;
ent->data = base;
ent->size = base_size;
list_add_tail(&ent->lru, &delta_base_cache_lru);
if (!delta_base_cache.cmpfn)
hashmap_init(&delta_base_cache, delta_base_cache_hash_cmp, NULL, 0);
hashmap_entry_init(ent, pack_entry_hash(p, base_offset));
hashmap_add(&delta_base_cache, ent);
}
int packed_object_info(struct packed_git *p, off_t obj_offset,
struct object_info *oi)
{
struct pack_window *w_curs = NULL;
unsigned long size;
off_t curpos = obj_offset;
enum object_type type;
/*
* We always get the representation type, but only convert it to
* a "real" type later if the caller is interested.
*/
if (oi->contentp) {
*oi->contentp = cache_or_unpack_entry(p, obj_offset, oi->sizep,
&type);
if (!*oi->contentp)
type = OBJ_BAD;
} else {
type = unpack_object_header(p, &w_curs, &curpos, &size);
}
if (!oi->contentp && oi->sizep) {
if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
off_t tmp_pos = curpos;
off_t base_offset = get_delta_base(p, &w_curs, &tmp_pos,
type, obj_offset);
if (!base_offset) {
type = OBJ_BAD;
goto out;
}
*oi->sizep = get_size_from_delta(p, &w_curs, tmp_pos);
if (*oi->sizep == 0) {
type = OBJ_BAD;
goto out;
}
} else {
*oi->sizep = size;
}
}
if (oi->disk_sizep) {
struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
*oi->disk_sizep = revidx[1].offset - obj_offset;
}
if (oi->typep || oi->typename) {
enum object_type ptot;
ptot = packed_to_object_type(p, obj_offset, type, &w_curs,
curpos);
if (oi->typep)
*oi->typep = ptot;
if (oi->typename) {
const char *tn = typename(ptot);
if (tn)
strbuf_addstr(oi->typename, tn);
}
if (ptot < 0) {
type = OBJ_BAD;
goto out;
}
}
if (oi->delta_base_sha1) {
if (type == OBJ_OFS_DELTA || type == OBJ_REF_DELTA) {
const unsigned char *base;
base = get_delta_base_sha1(p, &w_curs, curpos,
type, obj_offset);
if (!base) {
type = OBJ_BAD;
goto out;
}
hashcpy(oi->delta_base_sha1, base);
} else
hashclr(oi->delta_base_sha1);
}
oi->whence = in_delta_base_cache(p, obj_offset) ? OI_DBCACHED :
OI_PACKED;
out:
unuse_pack(&w_curs);
return type;
}
static void *unpack_compressed_entry(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos,
unsigned long size)
{
int st;
git_zstream stream;
unsigned char *buffer, *in;
buffer = xmallocz_gently(size);
if (!buffer)
return NULL;
memset(&stream, 0, sizeof(stream));
stream.next_out = buffer;
stream.avail_out = size + 1;
git_inflate_init(&stream);
do {
in = use_pack(p, w_curs, curpos, &stream.avail_in);
stream.next_in = in;
st = git_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);
git_inflate_end(&stream);
if ((st != Z_STREAM_END) || stream.total_out != size) {
free(buffer);
return NULL;
}
return buffer;
}
static void *read_object(const unsigned char *sha1, enum object_type *type,
unsigned long *size);
static void write_pack_access_log(struct packed_git *p, off_t obj_offset)
{
static struct trace_key pack_access = TRACE_KEY_INIT(PACK_ACCESS);
trace_printf_key(&pack_access, "%s %"PRIuMAX"\n",
p->pack_name, (uintmax_t)obj_offset);
}
int do_check_packed_object_crc;
#define UNPACK_ENTRY_STACK_PREALLOC 64
struct unpack_entry_stack_ent {
off_t obj_offset;
off_t curpos;
unsigned long size;
};
void *unpack_entry(struct packed_git *p, off_t obj_offset,
enum object_type *final_type, unsigned long *final_size)
{
struct pack_window *w_curs = NULL;
off_t curpos = obj_offset;
void *data = NULL;
unsigned long size;
enum object_type type;
struct unpack_entry_stack_ent small_delta_stack[UNPACK_ENTRY_STACK_PREALLOC];
struct unpack_entry_stack_ent *delta_stack = small_delta_stack;
int delta_stack_nr = 0, delta_stack_alloc = UNPACK_ENTRY_STACK_PREALLOC;
int base_from_cache = 0;
write_pack_access_log(p, obj_offset);
/* PHASE 1: drill down to the innermost base object */
for (;;) {
off_t base_offset;
int i;
struct delta_base_cache_entry *ent;
ent = get_delta_base_cache_entry(p, curpos);
if (ent) {
type = ent->type;
data = ent->data;
size = ent->size;
detach_delta_base_cache_entry(ent);
base_from_cache = 1;
break;
}
if (do_check_packed_object_crc && p->index_version > 1) {
struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
off_t len = revidx[1].offset - obj_offset;
if (check_pack_crc(p, &w_curs, obj_offset, len, revidx->nr)) {
const unsigned char *sha1 =
nth_packed_object_sha1(p, revidx->nr);
error("bad packed object CRC for %s",
sha1_to_hex(sha1));
mark_bad_packed_object(p, sha1);
data = NULL;
goto out;
}
}
type = unpack_object_header(p, &w_curs, &curpos, &size);
if (type != OBJ_OFS_DELTA && type != OBJ_REF_DELTA)
break;
base_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
if (!base_offset) {
error("failed to validate delta base reference "
"at offset %"PRIuMAX" from %s",
(uintmax_t)curpos, p->pack_name);
/* bail to phase 2, in hopes of recovery */
data = NULL;
break;
}
/* push object, proceed to base */
if (delta_stack_nr >= delta_stack_alloc
&& delta_stack == small_delta_stack) {
delta_stack_alloc = alloc_nr(delta_stack_nr);
ALLOC_ARRAY(delta_stack, delta_stack_alloc);
memcpy(delta_stack, small_delta_stack,
sizeof(*delta_stack)*delta_stack_nr);
} else {
ALLOC_GROW(delta_stack, delta_stack_nr+1, delta_stack_alloc);
}
i = delta_stack_nr++;
delta_stack[i].obj_offset = obj_offset;
delta_stack[i].curpos = curpos;
delta_stack[i].size = size;
curpos = obj_offset = base_offset;
}
/* PHASE 2: handle the base */
switch (type) {
case OBJ_OFS_DELTA:
case OBJ_REF_DELTA:
if (data)
die("BUG: unpack_entry: left loop at a valid delta");
break;
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
if (!base_from_cache)
data = unpack_compressed_entry(p, &w_curs, curpos, size);
break;
default:
data = NULL;
error("unknown object type %i at offset %"PRIuMAX" in %s",
type, (uintmax_t)obj_offset, p->pack_name);
}
/* PHASE 3: apply deltas in order */
/* invariants:
* 'data' holds the base data, or NULL if there was corruption
*/
while (delta_stack_nr) {
void *delta_data;
void *base = data;
void *external_base = NULL;
unsigned long delta_size, base_size = size;
int i;
data = NULL;
if (base)
add_delta_base_cache(p, obj_offset, base, base_size, type);
if (!base) {
/*
* We're probably in deep shit, but let's try to fetch
* the required base anyway from another pack or loose.
* This is costly but should happen only in the presence
* of a corrupted pack, and is better than failing outright.
*/
struct revindex_entry *revidx;
const unsigned char *base_sha1;
revidx = find_pack_revindex(p, obj_offset);
if (revidx) {
base_sha1 = nth_packed_object_sha1(p, revidx->nr);
error("failed to read delta base object %s"
" at offset %"PRIuMAX" from %s",
sha1_to_hex(base_sha1), (uintmax_t)obj_offset,
p->pack_name);
mark_bad_packed_object(p, base_sha1);
base = read_object(base_sha1, &type, &base_size);
external_base = base;
}
}
i = --delta_stack_nr;
obj_offset = delta_stack[i].obj_offset;
curpos = delta_stack[i].curpos;
delta_size = delta_stack[i].size;
if (!base)
continue;
delta_data = unpack_compressed_entry(p, &w_curs, curpos, delta_size);
if (!delta_data) {
error("failed to unpack compressed delta "
"at offset %"PRIuMAX" from %s",
(uintmax_t)curpos, p->pack_name);
data = NULL;
free(external_base);
continue;
}
data = patch_delta(base, base_size,
delta_data, delta_size,
&size);
/*
* We could not apply the delta; warn the user, but keep going.
* Our failure will be noticed either in the next iteration of
* the loop, or if this is the final delta, in the caller when
* we return NULL. Those code paths will take care of making
* a more explicit warning and retrying with another copy of
* the object.
*/
if (!data)
error("failed to apply delta");
free(delta_data);
free(external_base);
}
if (final_type)
*final_type = type;
if (final_size)
*final_size = size;
out:
unuse_pack(&w_curs);
if (delta_stack != small_delta_stack)
free(delta_stack);
return data;
}
const unsigned char *nth_packed_object_sha1(struct packed_git *p,
uint32_t n)
{
@ -2083,6 +1434,20 @@ int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
return type;
}
static void *read_object(const unsigned char *sha1, enum object_type *type,
unsigned long *size)
{
struct object_info oi = OBJECT_INFO_INIT;
void *content;
oi.typep = type;
oi.sizep = size;
oi.contentp = &content;
if (sha1_object_info_extended(sha1, &oi, 0) < 0)
return NULL;
return content;
}
int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
unsigned char *sha1)
{
@ -2101,20 +1466,6 @@ int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
return 0;
}
static void *read_object(const unsigned char *sha1, enum object_type *type,
unsigned long *size)
{
struct object_info oi = OBJECT_INFO_INIT;
void *content;
oi.typep = type;
oi.sizep = size;
oi.contentp = &content;
if (sha1_object_info_extended(sha1, &oi, 0) < 0)
return NULL;
return content;
}
/*
* This function dies on corrupt objects; the callers who want to
* deal with them should arrange to call read_object() and give error