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git-commit-vandalism/sha1_file.c
Jeff King 45e8a74873 has_sha1_file: re-check pack directory before giving up 
When we read a sha1 file, we first look for a packed
version, then a loose version, and then re-check the pack
directory again before concluding that we cannot find it.
This lets us handle a process that is writing to the
repository simultaneously (e.g., receive-pack writing a new
pack followed by a ref update, or git-repack packing
existing loose objects into a new pack).

However, we do not do the same trick with has_sha1_file; we
only check the packed objects once, followed by loose
objects. This means that we might incorrectly report that we
do not have an object, even though we could find it if we
simply re-checked the pack directory.

By itself, this is usually not a big deal. The other process
is running simultaneously, so we may run has_sha1_file
before it writes, anyway. It is a race whether we see the
object or not.  However, we may also see other things
the writing process has done (like updating refs); and in
that case, we must be able to also see the new objects.

For example, imagine we are doing a for_each_ref iteration,
and somebody simultaneously pushes. Receive-pack may write
the pack and update a ref after we have examined the
objects/pack directory, but before the iteration gets to the
updated ref. When we do finally see the updated ref,
for_each_ref will call has_sha1_file to check whether the
ref is broken. If has_sha1_file returns the wrong answer, we
erroneously will think that the ref is broken.

For a normal iteration without DO_FOR_EACH_INCLUDE_BROKEN,
this means that the caller does not see the ref at all
(neither the old nor the new value).  So not only will we
fail to see the new value of the ref (which is acceptable,
since we are running simultaneously with the writer, and we
might well read the ref before the writer commits its
write), but we will not see the old value either. For
programs that act on reachability like pack-objects or
prune, this can cause data loss, as we may see the objects
referenced by the original ref value as dangling (and either
omit them from the pack, or delete them via prune).

There's no test included here, because the success case is
two processes running simultaneously forever. But you can
replicate the issue with:

  # base.sh
  # run this in one terminal; it creates and pushes
  # repeatedly to a repository
  git init parent &&
  (cd parent &&

    # create a base commit that will trigger us looking at
    # the objects/pack directory before we hit the updated ref
    echo content >file &&
    git add file &&
    git commit -m base &&

    # set the unpack limit abnormally low, which
    # lets us simulate full-size pushes using tiny ones
    git config receive.unpackLimit 1
  ) &&
  git clone parent child &&
  cd child &&
  n=0 &&
  while true; do
    echo $n >file && git add file && git commit -m $n &&
    git push origin HEAD:refs/remotes/child/master &&
    n=$(($n + 1))
  done

  # fsck.sh
  # now run this simultaneously in another terminal; it
  # repeatedly fscks, looking for us to consider the
  # newly-pushed ref broken. We cannot use for-each-ref
  # here, as it uses DO_FOR_EACH_INCLUDE_BROKEN, which
  # skips the has_sha1_file check (and if it wants
  # more information on the object, it will actually read
  # the object, which does the proper two-step lookup)
  cd parent &&
  while true; do
    broken=`git fsck 2>&1 | grep remotes/child`
    if test -n "$broken"; then
      echo $broken
      exit 1
    fi
  done

Without this patch, the fsck loop fails within a few seconds
(and almost instantly if the test repository actually has a
large number of refs). With it, the two can run
indefinitely.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-30 14:53:45 -07:00

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/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*
* This handles basic git sha1 object files - packing, unpacking,
* creation etc.
*/
#include "cache.h"
#include "string-list.h"
#include "delta.h"
#include "pack.h"
#include "blob.h"
#include "commit.h"
#include "run-command.h"
#include "tag.h"
#include "tree.h"
#include "tree-walk.h"
#include "refs.h"
#include "pack-revindex.h"
#include "sha1-lookup.h"
#include "bulk-checkin.h"
#include "streaming.h"
#include "dir.h"
#ifndef O_NOATIME
#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
#define O_NOATIME 01000000
#else
#define O_NOATIME 0
#endif
#endif
#define SZ_FMT PRIuMAX
static inline uintmax_t sz_fmt(size_t s) { return s; }
const unsigned char null_sha1[20];
static const char *no_log_pack_access = "no_log_pack_access";
static const char *log_pack_access;
/*
* This is meant to hold a *small* number of objects that you would
* want read_sha1_file() to be able to return, but yet you do not want
* to write them into the object store (e.g. a browse-only
* application).
*/
static struct cached_object {
unsigned char sha1[20];
enum object_type type;
void *buf;
unsigned long size;
} *cached_objects;
static int cached_object_nr, cached_object_alloc;
static struct cached_object empty_tree = {
EMPTY_TREE_SHA1_BIN_LITERAL,
OBJ_TREE,
"",
0
};
static struct packed_git *last_found_pack;
static struct cached_object *find_cached_object(const unsigned char *sha1)
{
int i;
struct cached_object *co = cached_objects;
for (i = 0; i < cached_object_nr; i++, co++) {
if (!hashcmp(co->sha1, sha1))
return co;
}
if (!hashcmp(sha1, empty_tree.sha1))
return &empty_tree;
return NULL;
}
int mkdir_in_gitdir(const char *path)
{
if (mkdir(path, 0777)) {
int saved_errno = errno;
struct stat st;
struct strbuf sb = STRBUF_INIT;
if (errno != EEXIST)
return -1;
/*
* Are we looking at a path in a symlinked worktree
* whose original repository does not yet have it?
* e.g. .git/rr-cache pointing at its original
* repository in which the user hasn't performed any
* conflict resolution yet?
*/
if (lstat(path, &st) || !S_ISLNK(st.st_mode) ||
strbuf_readlink(&sb, path, st.st_size) ||
!is_absolute_path(sb.buf) ||
mkdir(sb.buf, 0777)) {
strbuf_release(&sb);
errno = saved_errno;
return -1;
}
strbuf_release(&sb);
}
return adjust_shared_perm(path);
}
int safe_create_leading_directories(char *path)
{
char *pos = path + offset_1st_component(path);
struct stat st;
while (pos) {
pos = strchr(pos, '/');
if (!pos)
break;
while (*++pos == '/')
;
if (!*pos)
break;
*--pos = '\0';
if (!stat(path, &st)) {
/* path exists */
if (!S_ISDIR(st.st_mode)) {
*pos = '/';
return -3;
}
}
else if (mkdir(path, 0777)) {
if (errno == EEXIST &&
!stat(path, &st) && S_ISDIR(st.st_mode)) {
; /* somebody created it since we checked */
} else {
*pos = '/';
return -1;
}
}
else if (adjust_shared_perm(path)) {
*pos = '/';
return -2;
}
*pos++ = '/';
}
return 0;
}
int safe_create_leading_directories_const(const char *path)
{
/* path points to cache entries, so xstrdup before messing with it */
char *buf = xstrdup(path);
int result = safe_create_leading_directories(buf);
free(buf);
return result;
}
static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
{
int i;
for (i = 0; i < 20; i++) {
static char hex[] = "0123456789abcdef";
unsigned int val = sha1[i];
char *pos = pathbuf + i*2 + (i > 0);
*pos++ = hex[val >> 4];
*pos = hex[val & 0xf];
}
}
/*
* NOTE! This returns a statically allocated buffer, so you have to be
* careful about using it. Do an "xstrdup()" if you need to save the
* filename.
*
* Also note that this returns the location for creating. Reading
* SHA1 file can happen from any alternate directory listed in the
* DB_ENVIRONMENT environment variable if it is not found in
* the primary object database.
*/
char *sha1_file_name(const unsigned char *sha1)
{
static char buf[PATH_MAX];
const char *objdir;
int len;
objdir = get_object_directory();
len = strlen(objdir);
/* '/' + sha1(2) + '/' + sha1(38) + '\0' */
if (len + 43 > PATH_MAX)
die("insanely long object directory %s", objdir);
memcpy(buf, objdir, len);
buf[len] = '/';
buf[len+3] = '/';
buf[len+42] = '\0';
fill_sha1_path(buf + len + 1, sha1);
return buf;
}
static char *sha1_get_pack_name(const unsigned char *sha1,
char **name, char **base, const char *which)
{
static const char hex[] = "0123456789abcdef";
char *buf;
int i;
if (!*base) {
const char *sha1_file_directory = get_object_directory();
int len = strlen(sha1_file_directory);
*base = xmalloc(len + 60);
sprintf(*base, "%s/pack/pack-1234567890123456789012345678901234567890.%s",
sha1_file_directory, which);
*name = *base + len + 11;
}
buf = *name;
for (i = 0; i < 20; i++) {
unsigned int val = *sha1++;
*buf++ = hex[val >> 4];
*buf++ = hex[val & 0xf];
}
return *base;
}
char *sha1_pack_name(const unsigned char *sha1)
{
static char *name, *base;
return sha1_get_pack_name(sha1, &name, &base, "pack");
}
char *sha1_pack_index_name(const unsigned char *sha1)
{
static char *name, *base;
return sha1_get_pack_name(sha1, &name, &base, "idx");
}
struct alternate_object_database *alt_odb_list;
static struct alternate_object_database **alt_odb_tail;
static int git_open_noatime(const char *name);
/*
* Prepare alternate object database registry.
*
* The variable alt_odb_list points at the list of struct
* alternate_object_database. The elements on this list come from
* non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
* environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
* whose contents is similar to that environment variable but can be
* LF separated. Its base points at a statically allocated buffer that
* contains "/the/directory/corresponding/to/.git/objects/...", while
* its name points just after the slash at the end of ".git/objects/"
* in the example above, and has enough space to hold 40-byte hex
* SHA1, an extra slash for the first level indirection, and the
* terminating NUL.
*/
static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth)
{
const char *objdir = get_object_directory();
struct alternate_object_database *ent;
struct alternate_object_database *alt;
int pfxlen, entlen;
struct strbuf pathbuf = STRBUF_INIT;
if (!is_absolute_path(entry) && relative_base) {
strbuf_addstr(&pathbuf, real_path(relative_base));
strbuf_addch(&pathbuf, '/');
}
strbuf_addstr(&pathbuf, entry);
normalize_path_copy(pathbuf.buf, pathbuf.buf);
pfxlen = strlen(pathbuf.buf);
/*
* The trailing slash after the directory name is given by
* this function at the end. Remove duplicates.
*/
while (pfxlen && pathbuf.buf[pfxlen-1] == '/')
pfxlen -= 1;
entlen = pfxlen + 43; /* '/' + 2 hex + '/' + 38 hex + NUL */
ent = xmalloc(sizeof(*ent) + entlen);
memcpy(ent->base, pathbuf.buf, pfxlen);
strbuf_release(&pathbuf);
ent->name = ent->base + pfxlen + 1;
ent->base[pfxlen + 3] = '/';
ent->base[pfxlen] = ent->base[entlen-1] = 0;
/* Detect cases where alternate disappeared */
if (!is_directory(ent->base)) {
error("object directory %s does not exist; "
"check .git/objects/info/alternates.",
ent->base);
free(ent);
return -1;
}
/* Prevent the common mistake of listing the same
* thing twice, or object directory itself.
*/
for (alt = alt_odb_list; alt; alt = alt->next) {
if (!memcmp(ent->base, alt->base, pfxlen)) {
free(ent);
return -1;
}
}
if (!strcmp(ent->base, objdir)) {
free(ent);
return -1;
}
/* add the alternate entry */
*alt_odb_tail = ent;
alt_odb_tail = &(ent->next);
ent->next = NULL;
/* recursively add alternates */
read_info_alternates(ent->base, depth + 1);
ent->base[pfxlen] = '/';
return 0;
}
static void link_alt_odb_entries(const char *alt, int len, int sep,
const char *relative_base, int depth)
{
struct string_list entries = STRING_LIST_INIT_NODUP;
char *alt_copy;
int i;
if (depth > 5) {
error("%s: ignoring alternate object stores, nesting too deep.",
relative_base);
return;
}
alt_copy = xmemdupz(alt, len);
string_list_split_in_place(&entries, alt_copy, sep, -1);
for (i = 0; i < entries.nr; i++) {
const char *entry = entries.items[i].string;
if (entry[0] == '\0' || entry[0] == '#')
continue;
if (!is_absolute_path(entry) && depth) {
error("%s: ignoring relative alternate object store %s",
relative_base, entry);
} else {
link_alt_odb_entry(entry, relative_base, depth);
}
}
string_list_clear(&entries, 0);
free(alt_copy);
}
void read_info_alternates(const char * relative_base, int depth)
{
char *map;
size_t mapsz;
struct stat st;
const char alt_file_name[] = "info/alternates";
/* Given that relative_base is no longer than PATH_MAX,
ensure that "path" has enough space to append "/", the
file name, "info/alternates", and a trailing NUL. */
char path[PATH_MAX + 1 + sizeof alt_file_name];
int fd;
sprintf(path, "%s/%s", relative_base, alt_file_name);
fd = git_open_noatime(path);
if (fd < 0)
return;
if (fstat(fd, &st) || (st.st_size == 0)) {
close(fd);
return;
}
mapsz = xsize_t(st.st_size);
map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
link_alt_odb_entries(map, mapsz, '\n', relative_base, depth);
munmap(map, mapsz);
}
void add_to_alternates_file(const char *reference)
{
struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
int fd = hold_lock_file_for_append(lock, git_path("objects/info/alternates"), LOCK_DIE_ON_ERROR);
char *alt = mkpath("%s\n", reference);
write_or_die(fd, alt, strlen(alt));
if (commit_lock_file(lock))
die("could not close alternates file");
if (alt_odb_tail)
link_alt_odb_entries(alt, strlen(alt), '\n', NULL, 0);
}
void foreach_alt_odb(alt_odb_fn fn, void *cb)
{
struct alternate_object_database *ent;
prepare_alt_odb();
for (ent = alt_odb_list; ent; ent = ent->next)
if (fn(ent, cb))
return;
}
void prepare_alt_odb(void)
{
const char *alt;
if (alt_odb_tail)
return;
alt = getenv(ALTERNATE_DB_ENVIRONMENT);
if (!alt) alt = "";
alt_odb_tail = &alt_odb_list;
link_alt_odb_entries(alt, strlen(alt), PATH_SEP, NULL, 0);
read_info_alternates(get_object_directory(), 0);
}
static int has_loose_object_local(const unsigned char *sha1)
{
char *name = sha1_file_name(sha1);
return !access(name, F_OK);
}
int has_loose_object_nonlocal(const unsigned char *sha1)
{
struct alternate_object_database *alt;
prepare_alt_odb();
for (alt = alt_odb_list; alt; alt = alt->next) {
fill_sha1_path(alt->name, sha1);
if (!access(alt->base, F_OK))
return 1;
}
return 0;
}
static int has_loose_object(const unsigned char *sha1)
{
return has_loose_object_local(sha1) ||
has_loose_object_nonlocal(sha1);
}
static unsigned int pack_used_ctr;
static unsigned int pack_mmap_calls;
static unsigned int peak_pack_open_windows;
static unsigned int pack_open_windows;
static unsigned int pack_open_fds;
static unsigned int pack_max_fds;
static size_t peak_pack_mapped;
static size_t pack_mapped;
struct packed_git *packed_git;
void pack_report(void)
{
fprintf(stderr,
"pack_report: getpagesize() = %10" SZ_FMT "\n"
"pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
"pack_report: core.packedGitLimit = %10" SZ_FMT "\n",
sz_fmt(getpagesize()),
sz_fmt(packed_git_window_size),
sz_fmt(packed_git_limit));
fprintf(stderr,
"pack_report: pack_used_ctr = %10u\n"
"pack_report: pack_mmap_calls = %10u\n"
"pack_report: pack_open_windows = %10u / %10u\n"
"pack_report: pack_mapped = "
"%10" SZ_FMT " / %10" SZ_FMT "\n",
pack_used_ctr,
pack_mmap_calls,
pack_open_windows, peak_pack_open_windows,
sz_fmt(pack_mapped), sz_fmt(peak_pack_mapped));
}
static int check_packed_git_idx(const char *path, struct packed_git *p)
{
void *idx_map;
struct pack_idx_header *hdr;
size_t idx_size;
uint32_t version, nr, i, *index;
int fd = git_open_noatime(path);
struct stat st;
if (fd < 0)
return -1;
if (fstat(fd, &st)) {
close(fd);
return -1;
}
idx_size = xsize_t(st.st_size);
if (idx_size < 4 * 256 + 20 + 20) {
close(fd);
return error("index file %s is too small", path);
}
idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
hdr = idx_map;
if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) {
version = ntohl(hdr->idx_version);
if (version < 2 || version > 2) {
munmap(idx_map, idx_size);
return error("index file %s is version %"PRIu32
" and is not supported by this binary"
" (try upgrading GIT to a newer version)",
path, 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) {
munmap(idx_map, idx_size);
return error("non-monotonic index %s", path);
}
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) {
munmap(idx_map, idx_size);
return error("wrong index v1 file size in %s", path);
}
} 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) {
munmap(idx_map, idx_size);
return error("wrong index v2 file size in %s", path);
}
if (idx_size != min_size &&
/*
* make sure we can deal with large pack offsets.
* 31-bit signed offset won't be enough, neither
* 32-bit unsigned one will be.
*/
(sizeof(off_t) <= 4)) {
munmap(idx_map, idx_size);
return error("pack too large for current definition of off_t in %s", path);
}
}
p->index_version = version;
p->index_data = idx_map;
p->index_size = idx_size;
p->num_objects = nr;
return 0;
}
int open_pack_index(struct packed_git *p)
{
char *idx_name;
int ret;
if (p->index_data)
return 0;
idx_name = xstrdup(p->pack_name);
strcpy(idx_name + strlen(idx_name) - strlen(".pack"), ".idx");
ret = check_packed_git_idx(idx_name, p);
free(idx_name);
return ret;
}
static void scan_windows(struct packed_git *p,
struct packed_git **lru_p,
struct pack_window **lru_w,
struct pack_window **lru_l)
{
struct pack_window *w, *w_l;
for (w_l = NULL, w = p->windows; w; w = w->next) {
if (!w->inuse_cnt) {
if (!*lru_w || w->last_used < (*lru_w)->last_used) {
*lru_p = p;
*lru_w = w;
*lru_l = w_l;
}
}
w_l = w;
}
}
static int unuse_one_window(struct packed_git *current, int keep_fd)
{
struct packed_git *p, *lru_p = NULL;
struct pack_window *lru_w = NULL, *lru_l = NULL;
if (current)
scan_windows(current, &lru_p, &lru_w, &lru_l);
for (p = packed_git; p; p = p->next)
scan_windows(p, &lru_p, &lru_w, &lru_l);
if (lru_p) {
munmap(lru_w->base, lru_w->len);
pack_mapped -= lru_w->len;
if (lru_l)
lru_l->next = lru_w->next;
else {
lru_p->windows = lru_w->next;
if (!lru_p->windows && lru_p->pack_fd != -1
&& lru_p->pack_fd != keep_fd) {
close(lru_p->pack_fd);
pack_open_fds--;
lru_p->pack_fd = -1;
}
}
free(lru_w);
pack_open_windows--;
return 1;
}
return 0;
}
void release_pack_memory(size_t need, int fd)
{
size_t cur = pack_mapped;
while (need >= (cur - pack_mapped) && unuse_one_window(NULL, fd))
; /* nothing */
}
void *xmmap(void *start, size_t length,
int prot, int flags, int fd, off_t offset)
{
void *ret = mmap(start, length, prot, flags, fd, offset);
if (ret == MAP_FAILED) {
if (!length)
return NULL;
release_pack_memory(length, fd);
ret = mmap(start, length, prot, flags, fd, offset);
if (ret == MAP_FAILED)
die_errno("Out of memory? mmap failed");
}
return ret;
}
void close_pack_windows(struct packed_git *p)
{
while (p->windows) {
struct pack_window *w = p->windows;
if (w->inuse_cnt)
die("pack '%s' still has open windows to it",
p->pack_name);
munmap(w->base, w->len);
pack_mapped -= w->len;
pack_open_windows--;
p->windows = w->next;
free(w);
}
}
void unuse_pack(struct pack_window **w_cursor)
{
struct pack_window *w = *w_cursor;
if (w) {
w->inuse_cnt--;
*w_cursor = NULL;
}
}
void close_pack_index(struct packed_git *p)
{
if (p->index_data) {
munmap((void *)p->index_data, p->index_size);
p->index_data = NULL;
}
}
/*
* This is used by git-repack in case a newly created pack happens to
* contain the same set of objects as an existing one. In that case
* the resulting file might be different even if its name would be the
* same. It is best to close any reference to the old pack before it is
* replaced on disk. Of course no index pointers nor windows for given pack
* must subsist at this point. If ever objects from this pack are requested
* again, the new version of the pack will be reinitialized through
* reprepare_packed_git().
*/
void free_pack_by_name(const char *pack_name)
{
struct packed_git *p, **pp = &packed_git;
while (*pp) {
p = *pp;
if (strcmp(pack_name, p->pack_name) == 0) {
clear_delta_base_cache();
close_pack_windows(p);
if (p->pack_fd != -1) {
close(p->pack_fd);
pack_open_fds--;
}
close_pack_index(p);
free(p->bad_object_sha1);
*pp = p->next;
if (last_found_pack == p)
last_found_pack = NULL;
free(p);
return;
}
pp = &p->next;
}
}
static unsigned int get_max_fd_limit(void)
{
#ifdef RLIMIT_NOFILE
struct rlimit lim;
if (getrlimit(RLIMIT_NOFILE, &lim))
die_errno("cannot get RLIMIT_NOFILE");
return lim.rlim_cur;
#elif defined(_SC_OPEN_MAX)
return sysconf(_SC_OPEN_MAX);
#elif defined(OPEN_MAX)
return OPEN_MAX;
#else
return 1; /* see the caller ;-) */
#endif
}
/*
* Do not call this directly as this leaks p->pack_fd on error return;
* call open_packed_git() instead.
*/
static int open_packed_git_1(struct packed_git *p)
{
struct stat st;
struct pack_header hdr;
unsigned char sha1[20];
unsigned char *idx_sha1;
long fd_flag;
if (!p->index_data && open_pack_index(p))
return error("packfile %s index unavailable", p->pack_name);
if (!pack_max_fds) {
unsigned int max_fds = get_max_fd_limit();
/* Save 3 for stdin/stdout/stderr, 22 for work */
if (25 < max_fds)
pack_max_fds = max_fds - 25;
else
pack_max_fds = 1;
}
while (pack_max_fds <= pack_open_fds && unuse_one_window(NULL, -1))
; /* nothing */
p->pack_fd = git_open_noatime(p->pack_name);
if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
return -1;
pack_open_fds++;
/* If we created the struct before we had the pack we lack size. */
if (!p->pack_size) {
if (!S_ISREG(st.st_mode))
return error("packfile %s not a regular file", p->pack_name);
p->pack_size = st.st_size;
} else if (p->pack_size != st.st_size)
return error("packfile %s size changed", p->pack_name);
/* We leave these file descriptors open with sliding mmap;
* there is no point keeping them open across exec(), though.
*/
fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
if (fd_flag < 0)
return error("cannot determine file descriptor flags");
fd_flag |= FD_CLOEXEC;
if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
return error("cannot set FD_CLOEXEC");
/* Verify we recognize this pack file format. */
if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
return error("file %s is far too short to be a packfile", p->pack_name);
if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
return error("file %s is not a GIT packfile", p->pack_name);
if (!pack_version_ok(hdr.hdr_version))
return error("packfile %s is version %"PRIu32" and not"
" supported (try upgrading GIT to a newer version)",
p->pack_name, ntohl(hdr.hdr_version));
/* Verify the pack matches its index. */
if (p->num_objects != ntohl(hdr.hdr_entries))
return error("packfile %s claims to have %"PRIu32" objects"
" while index indicates %"PRIu32" objects",
p->pack_name, ntohl(hdr.hdr_entries),
p->num_objects);
if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
return error("end of packfile %s is unavailable", p->pack_name);
if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
return error("packfile %s signature is unavailable", p->pack_name);
idx_sha1 = ((unsigned char *)p->index_data) + p->index_size - 40;
if (hashcmp(sha1, idx_sha1))
return error("packfile %s does not match index", p->pack_name);
return 0;
}
static int open_packed_git(struct packed_git *p)
{
if (!open_packed_git_1(p))
return 0;
if (p->pack_fd != -1) {
close(p->pack_fd);
pack_open_fds--;
p->pack_fd = -1;
}
return -1;
}
static int in_window(struct pack_window *win, off_t offset)
{
/* We must promise at least 20 bytes (one hash) after the
* offset is available from this window, otherwise the offset
* is not actually in this window and a different window (which
* has that one hash excess) must be used. This is to support
* the object header and delta base parsing routines below.
*/
off_t win_off = win->offset;
return win_off <= offset
&& (offset + 20) <= (win_off + win->len);
}
unsigned char *use_pack(struct packed_git *p,
struct pack_window **w_cursor,
off_t offset,
unsigned long *left)
{
struct pack_window *win = *w_cursor;
/* 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 in_window function above wouldn't match
* don't allow an offset too close to the end of the file.
*/
if (!p->pack_size && p->pack_fd == -1 && open_packed_git(p))
die("packfile %s cannot be accessed", p->pack_name);
if (offset > (p->pack_size - 20))
die("offset beyond end of packfile (truncated pack?)");
if (!win || !in_window(win, offset)) {
if (win)
win->inuse_cnt--;
for (win = p->windows; win; win = win->next) {
if (in_window(win, offset))
break;
}
if (!win) {
size_t window_align = packed_git_window_size / 2;
off_t len;
if (p->pack_fd == -1 && open_packed_git(p))
die("packfile %s cannot be accessed", p->pack_name);
win = xcalloc(1, sizeof(*win));
win->offset = (offset / window_align) * window_align;
len = p->pack_size - win->offset;
if (len > packed_git_window_size)
len = packed_git_window_size;
win->len = (size_t)len;
pack_mapped += win->len;
while (packed_git_limit < pack_mapped
&& unuse_one_window(p, p->pack_fd))
; /* nothing */
win->base = xmmap(NULL, win->len,
PROT_READ, MAP_PRIVATE,
p->pack_fd, win->offset);
if (win->base == MAP_FAILED)
die("packfile %s cannot be mapped: %s",
p->pack_name,
strerror(errno));
if (!win->offset && win->len == p->pack_size
&& !p->do_not_close) {
close(p->pack_fd);
pack_open_fds--;
p->pack_fd = -1;
}
pack_mmap_calls++;
pack_open_windows++;
if (pack_mapped > peak_pack_mapped)
peak_pack_mapped = pack_mapped;
if (pack_open_windows > peak_pack_open_windows)
peak_pack_open_windows = pack_open_windows;
win->next = p->windows;
p->windows = win;
}
}
if (win != *w_cursor) {
win->last_used = pack_used_ctr++;
win->inuse_cnt++;
*w_cursor = win;
}
offset -= win->offset;
if (left)
*left = win->len - xsize_t(offset);
return win->base + offset;
}
static struct packed_git *alloc_packed_git(int extra)
{
struct packed_git *p = xmalloc(sizeof(*p) + extra);
memset(p, 0, sizeof(*p));
p->pack_fd = -1;
return p;
}
static void try_to_free_pack_memory(size_t size)
{
release_pack_memory(size, -1);
}
struct packed_git *add_packed_git(const char *path, int path_len, int local)
{
static int have_set_try_to_free_routine;
struct stat st;
struct packed_git *p = alloc_packed_git(path_len + 2);
if (!have_set_try_to_free_routine) {
have_set_try_to_free_routine = 1;
set_try_to_free_routine(try_to_free_pack_memory);
}
/*
* Make sure a corresponding .pack file exists and that
* the index looks sane.
*/
path_len -= strlen(".idx");
if (path_len < 1) {
free(p);
return NULL;
}
memcpy(p->pack_name, path, path_len);
strcpy(p->pack_name + path_len, ".keep");
if (!access(p->pack_name, F_OK))
p->pack_keep = 1;
strcpy(p->pack_name + path_len, ".pack");
if (stat(p->pack_name, &st) || !S_ISREG(st.st_mode)) {
free(p);
return NULL;
}
/* ok, it looks sane as far as we can check without
* actually mapping the pack file.
*/
p->pack_size = st.st_size;
p->pack_local = local;
p->mtime = st.st_mtime;
if (path_len < 40 || get_sha1_hex(path + path_len - 40, p->sha1))
hashclr(p->sha1);
return p;
}
struct packed_git *parse_pack_index(unsigned char *sha1, const char *idx_path)
{
const char *path = sha1_pack_name(sha1);
struct packed_git *p = alloc_packed_git(strlen(path) + 1);
strcpy(p->pack_name, path);
hashcpy(p->sha1, sha1);
if (check_packed_git_idx(idx_path, p)) {
free(p);
return NULL;
}
return p;
}
void install_packed_git(struct packed_git *pack)
{
if (pack->pack_fd != -1)
pack_open_fds++;
pack->next = packed_git;
packed_git = pack;
}
void (*report_garbage)(const char *desc, const char *path);
static void report_helper(const struct string_list *list,
int seen_bits, int first, int last)
{
const char *msg;
switch (seen_bits) {
case 0:
msg = "no corresponding .idx nor .pack";
break;
case 1:
msg = "no corresponding .idx";
break;
case 2:
msg = "no corresponding .pack";
break;
default:
return;
}
for (; first < last; first++)
report_garbage(msg, list->items[first].string);
}
static void report_pack_garbage(struct string_list *list)
{
int i, baselen = -1, first = 0, seen_bits = 0;
if (!report_garbage)
return;
sort_string_list(list);
for (i = 0; i < list->nr; i++) {
const char *path = list->items[i].string;
if (baselen != -1 &&
strncmp(path, list->items[first].string, baselen)) {
report_helper(list, seen_bits, first, i);
baselen = -1;
seen_bits = 0;
}
if (baselen == -1) {
const char *dot = strrchr(path, '.');
if (!dot) {
report_garbage("garbage found", path);
continue;
}
baselen = dot - path + 1;
first = i;
}
if (!strcmp(path + baselen, "pack"))
seen_bits |= 1;
else if (!strcmp(path + baselen, "idx"))
seen_bits |= 2;
}
report_helper(list, seen_bits, first, list->nr);
}
static void prepare_packed_git_one(char *objdir, int local)
{
/* Ensure that this buffer is large enough so that we can
append "/pack/" without clobbering the stack even if
strlen(objdir) were PATH_MAX. */
char path[PATH_MAX + 1 + 4 + 1 + 1];
int len;
DIR *dir;
struct dirent *de;
struct string_list garbage = STRING_LIST_INIT_DUP;
sprintf(path, "%s/pack", objdir);
len = strlen(path);
dir = opendir(path);
if (!dir) {
if (errno != ENOENT)
error("unable to open object pack directory: %s: %s",
path, strerror(errno));
return;
}
path[len++] = '/';
while ((de = readdir(dir)) != NULL) {
int namelen = strlen(de->d_name);
struct packed_git *p;
if (len + namelen + 1 > sizeof(path)) {
if (report_garbage) {
struct strbuf sb = STRBUF_INIT;
strbuf_addf(&sb, "%.*s/%s", len - 1, path, de->d_name);
report_garbage("path too long", sb.buf);
strbuf_release(&sb);
}
continue;
}
if (is_dot_or_dotdot(de->d_name))
continue;
strcpy(path + len, de->d_name);
if (has_extension(de->d_name, ".idx")) {
/* Don't reopen a pack we already have. */
for (p = packed_git; p; p = p->next) {
if (!memcmp(path, p->pack_name, len + namelen - 4))
break;
}
if (p == NULL &&
/*
* See if it really is a valid .idx file with
* corresponding .pack file that we can map.
*/
(p = add_packed_git(path, len + namelen, local)) != NULL)
install_packed_git(p);
}
if (!report_garbage)
continue;
if (has_extension(de->d_name, ".idx") ||
has_extension(de->d_name, ".pack") ||
has_extension(de->d_name, ".keep"))
string_list_append(&garbage, path);
else
report_garbage("garbage found", path);
}
closedir(dir);
report_pack_garbage(&garbage);
string_list_clear(&garbage, 0);
}
static int sort_pack(const void *a_, const void *b_)
{
struct packed_git *a = *((struct packed_git **)a_);
struct packed_git *b = *((struct packed_git **)b_);
int st;
/*
* Local packs tend to contain objects specific to our
* variant of the project than remote ones. In addition,
* remote ones could be on a network mounted filesystem.
* Favor local ones for these reasons.
*/
st = a->pack_local - b->pack_local;
if (st)
return -st;
/*
* Younger packs tend to contain more recent objects,
* and more recent objects tend to get accessed more
* often.
*/
if (a->mtime < b->mtime)
return 1;
else if (a->mtime == b->mtime)
return 0;
return -1;
}
static void rearrange_packed_git(void)
{
struct packed_git **ary, *p;
int i, n;
for (n = 0, p = packed_git; p; p = p->next)
n++;
if (n < 2)
return;
/* prepare an array of packed_git for easier sorting */
ary = xcalloc(n, sizeof(struct packed_git *));
for (n = 0, p = packed_git; p; p = p->next)
ary[n++] = p;
qsort(ary, n, sizeof(struct packed_git *), sort_pack);
/* link them back again */
for (i = 0; i < n - 1; i++)
ary[i]->next = ary[i + 1];
ary[n - 1]->next = NULL;
packed_git = ary[0];
free(ary);
}
static int prepare_packed_git_run_once = 0;
void prepare_packed_git(void)
{
struct alternate_object_database *alt;
if (prepare_packed_git_run_once)
return;
prepare_packed_git_one(get_object_directory(), 1);
prepare_alt_odb();
for (alt = alt_odb_list; alt; alt = alt->next) {
alt->name[-1] = 0;
prepare_packed_git_one(alt->base, 0);
alt->name[-1] = '/';
}
rearrange_packed_git();
prepare_packed_git_run_once = 1;
}
void reprepare_packed_git(void)
{
discard_revindex();
prepare_packed_git_run_once = 0;
prepare_packed_git();
}
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 + 20 * i))
return;
p->bad_object_sha1 = xrealloc(p->bad_object_sha1, 20 * (p->num_bad_objects + 1));
hashcpy(p->bad_object_sha1 + 20 * 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.
* With "map" == NULL, try reading the object named with "sha1" using
* the streaming interface and rehash it to do the same.
*/
int check_sha1_signature(const unsigned char *sha1, void *map,
unsigned long size, const char *type)
{
unsigned char real_sha1[20];
enum object_type obj_type;
struct git_istream *st;
git_SHA_CTX c;
char hdr[32];
int hdrlen;
if (map) {
hash_sha1_file(map, size, type, real_sha1);
return hashcmp(sha1, real_sha1) ? -1 : 0;
}
st = open_istream(sha1, &obj_type, &size, NULL);
if (!st)
return -1;
/* Generate the header */
hdrlen = sprintf(hdr, "%s %lu", typename(obj_type), size) + 1;
/* Sha1.. */
git_SHA1_Init(&c);
git_SHA1_Update(&c, hdr, hdrlen);
for (;;) {
char buf[1024 * 16];
ssize_t readlen = read_istream(st, buf, sizeof(buf));
if (readlen < 0) {
close_istream(st);
return -1;
}
if (!readlen)
break;
git_SHA1_Update(&c, buf, readlen);
}
git_SHA1_Final(real_sha1, &c);
close_istream(st);
return hashcmp(sha1, real_sha1) ? -1 : 0;
}
static int git_open_noatime(const char *name)
{
static int sha1_file_open_flag = O_NOATIME;
for (;;) {
int fd = open(name, O_RDONLY | sha1_file_open_flag);
if (fd >= 0)
return fd;
/* Might the failure be due to O_NOATIME? */
if (errno != ENOENT && sha1_file_open_flag) {
sha1_file_open_flag = 0;
continue;
}
return -1;
}
}
static int stat_sha1_file(const unsigned char *sha1, struct stat *st)
{
char *name = sha1_file_name(sha1);
struct alternate_object_database *alt;
if (!lstat(name, st))
return 0;
prepare_alt_odb();
errno = ENOENT;
for (alt = alt_odb_list; alt; alt = alt->next) {
name = alt->name;
fill_sha1_path(name, sha1);
if (!lstat(alt->base, st))
return 0;
}
return -1;
}
static int open_sha1_file(const unsigned char *sha1)
{
int fd;
char *name = sha1_file_name(sha1);
struct alternate_object_database *alt;
fd = git_open_noatime(name);
if (fd >= 0)
return fd;
prepare_alt_odb();
errno = ENOENT;
for (alt = alt_odb_list; alt; alt = alt->next) {
name = alt->name;
fill_sha1_path(name, sha1);
fd = git_open_noatime(alt->base);
if (fd >= 0)
return fd;
}
return -1;
}
void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
{
void *map;
int fd;
fd = open_sha1_file(sha1);
map = NULL;
if (fd >= 0) {
struct stat st;
if (!fstat(fd, &st)) {
*size = xsize_t(st.st_size);
if (!*size) {
/* mmap() is forbidden on empty files */
error("object file %s is empty", sha1_file_name(sha1));
return NULL;
}
map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
}
close(fd);
}
return map;
}
/*
* There used to be a second loose object header format which
* was meant to mimic the in-pack format, allowing for direct
* copy of the object data. This format turned up not to be
* really worth it and we no longer write loose objects in that
* format.
*/
static int experimental_loose_object(unsigned char *map)
{
unsigned int word;
/*
* We must determine if the buffer contains the standard
* zlib-deflated stream or the experimental format based
* on the in-pack object format. Compare the header byte
* for each format:
*
* RFC1950 zlib w/ deflate : 0www1000 : 0 <= www <= 7
* Experimental pack-based : Stttssss : ttt = 1,2,3,4
*
* If bit 7 is clear and bits 0-3 equal 8, the buffer MUST be
* in standard loose-object format, UNLESS it is a Git-pack
* format object *exactly* 8 bytes in size when inflated.
*
* However, RFC1950 also specifies that the 1st 16-bit word
* must be divisible by 31 - this checksum tells us our buffer
* is in the standard format, giving a false positive only if
* the 1st word of the Git-pack format object happens to be
* divisible by 31, ie:
* ((byte0 * 256) + byte1) % 31 = 0
* => 0ttt10000www1000 % 31 = 0
*
* As it happens, this case can only arise for www=3 & ttt=1
* - ie, a Commit object, which would have to be 8 bytes in
* size. As no Commit can be that small, we find that the
* combination of these two criteria (bitmask & checksum)
* can always correctly determine the buffer format.
*/
word = (map[0] << 8) + map[1];
if ((map[0] & 0x8F) == 0x08 && !(word % 31))
return 0;
else
return 1;
}
unsigned long unpack_object_header_buffer(const unsigned char *buf,
unsigned long len, enum object_type *type, unsigned long *sizep)
{
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) {
error("bad object header");
size = used = 0;
break;
}
c = buf[used++];
size += (c & 0x7f) << shift;
shift += 7;
}
*sizep = size;
return used;
}
int unpack_sha1_header(git_zstream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
{
unsigned long size, used;
static const char valid_loose_object_type[8] = {
0, /* OBJ_EXT */
1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
0, /* "delta" and others are invalid in a loose object */
};
enum object_type type;
/* Get the data stream */
memset(stream, 0, sizeof(*stream));
stream->next_in = map;
stream->avail_in = mapsize;
stream->next_out = buffer;
stream->avail_out = bufsiz;
if (experimental_loose_object(map)) {
/*
* The old experimental format we no longer produce;
* we can still read it.
*/
used = unpack_object_header_buffer(map, mapsize, &type, &size);
if (!used || !valid_loose_object_type[type])
return -1;
map += used;
mapsize -= used;
/* Set up the stream for the rest.. */
stream->next_in = map;
stream->avail_in = mapsize;
git_inflate_init(stream);
/* And generate the fake traditional header */
stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
typename(type), size);
return 0;
}
git_inflate_init(stream);
return git_inflate(stream, 0);
}
static void *unpack_sha1_rest(git_zstream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
{
int bytes = strlen(buffer) + 1;
unsigned char *buf = xmallocz(size);
unsigned long n;
int status = Z_OK;
n = stream->total_out - bytes;
if (n > size)
n = size;
memcpy(buf, (char *) buffer + bytes, n);
bytes = n;
if (bytes <= size) {
/*
* The above condition must be (bytes <= size), not
* (bytes < size). In other words, even though we
* expect no more output and set avail_out to zero,
* the input zlib stream may have bytes that express
* "this concludes the stream", and we *do* want to
* eat that input.
*
* Otherwise we would not be able to test that we
* consumed all the input to reach the expected size;
* we also want to check that zlib tells us that all
* went well with status == Z_STREAM_END at the end.
*/
stream->next_out = buf + bytes;
stream->avail_out = size - bytes;
while (status == Z_OK)
status = git_inflate(stream, Z_FINISH);
}
if (status == Z_STREAM_END && !stream->avail_in) {
git_inflate_end(stream);
return buf;
}
if (status < 0)
error("corrupt loose object '%s'", sha1_to_hex(sha1));
else if (stream->avail_in)
error("garbage at end of loose object '%s'",
sha1_to_hex(sha1));
free(buf);
return NULL;
}
/*
* We used to just use "sscanf()", but that's actually way
* too permissive for what we want to check. So do an anal
* object header parse by hand.
*/
int parse_sha1_header(const char *hdr, unsigned long *sizep)
{
char type[10];
int i;
unsigned long size;
/*
* The type can be at most ten bytes (including the
* terminating '\0' that we add), and is followed by
* a space.
*/
i = 0;
for (;;) {
char c = *hdr++;
if (c == ' ')
break;
type[i++] = c;
if (i >= sizeof(type))
return -1;
}
type[i] = 0;
/*
* The length must follow immediately, and be in canonical
* decimal format (ie "010" is not valid).
*/
size = *hdr++ - '0';
if (size > 9)
return -1;
if (size) {
for (;;) {
unsigned long c = *hdr - '0';
if (c > 9)
break;
hdr++;
size = size * 10 + c;
}
}
*sizep = size;
/*
* The length must be followed by a zero byte
*/
return *hdr ? -1 : type_from_string(type);
}
static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
{
int ret;
git_zstream stream;
char hdr[8192];
ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
return NULL;
return unpack_sha1_rest(&stream, hdr, *size, sha1);
}
unsigned long get_size_from_delta(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos)
{
const unsigned char *data;
unsigned char delta_head[20], *in;
git_zstream stream;
int st;
memset(&stream, 0, sizeof(stream));
stream.next_out = delta_head;
stream.avail_out = sizeof(delta_head);
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);
curpos += stream.next_in - in;
} while ((st == Z_OK || st == Z_BUF_ERROR) &&
stream.total_out < sizeof(delta_head));
git_inflate_end(&stream);
if ((st != Z_STREAM_END) && stream.total_out != sizeof(delta_head)) {
error("delta data unpack-initial failed");
return 0;
}
/* Examine the initial part of the delta to figure out
* the result size.
*/
data = delta_head;
/* ignore base size */
get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
/* Read the result size */
return get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
}
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;
}
int unpack_object_header(struct packed_git *p,
struct pack_window **w_curs,
off_t *curpos,
unsigned long *sizep)
{
unsigned char *base;
unsigned long left;
unsigned long used;
enum object_type type;
/* use_pack() assures us we have [base, base + 20) available
* as a range that we can look 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 = use_pack(p, w_curs, *curpos, &left);
used = unpack_object_header_buffer(base, left, &type, sizep);
if (!used) {
type = OBJ_BAD;
} else
*curpos += used;
return type;
}
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);
poi_stack = xmalloc(sizeof(off_t)*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 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.
*/
type = unpack_object_header(p, &w_curs, &curpos, &size);
if (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->typep = packed_to_object_type(p, obj_offset, type, &w_curs, curpos);
if (*oi->typep < 0) {
type = OBJ_BAD;
goto out;
}
}
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(size);
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;
}
#define MAX_DELTA_CACHE (256)
static size_t delta_base_cached;
static struct delta_base_cache_lru_list {
struct delta_base_cache_lru_list *prev;
struct delta_base_cache_lru_list *next;
} delta_base_cache_lru = { &delta_base_cache_lru, &delta_base_cache_lru };
static struct delta_base_cache_entry {
struct delta_base_cache_lru_list lru;
void *data;
struct packed_git *p;
off_t base_offset;
unsigned long size;
enum object_type type;
} delta_base_cache[MAX_DELTA_CACHE];
static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
{
unsigned long hash;
hash = (unsigned long)p + (unsigned long)base_offset;
hash += (hash >> 8) + (hash >> 16);
return hash % MAX_DELTA_CACHE;
}
static struct delta_base_cache_entry *
get_delta_base_cache_entry(struct packed_git *p, off_t base_offset)
{
unsigned long hash = pack_entry_hash(p, base_offset);
return delta_base_cache + hash;
}
static int eq_delta_base_cache_entry(struct delta_base_cache_entry *ent,
struct packed_git *p, off_t base_offset)
{
return (ent->data && ent->p == p && ent->base_offset == base_offset);
}
static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
{
struct delta_base_cache_entry *ent;
ent = get_delta_base_cache_entry(p, base_offset);
return eq_delta_base_cache_entry(ent, p, base_offset);
}
static void clear_delta_base_cache_entry(struct delta_base_cache_entry *ent)
{
ent->data = NULL;
ent->lru.next->prev = ent->lru.prev;
ent->lru.prev->next = ent->lru.next;
delta_base_cached -= ent->size;
}
static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
unsigned long *base_size, enum object_type *type, int keep_cache)
{
struct delta_base_cache_entry *ent;
void *ret;
ent = get_delta_base_cache_entry(p, base_offset);
if (!eq_delta_base_cache_entry(ent, p, base_offset))
return unpack_entry(p, base_offset, type, base_size);
ret = ent->data;
if (!keep_cache)
clear_delta_base_cache_entry(ent);
else
ret = xmemdupz(ent->data, ent->size);
*type = ent->type;
*base_size = ent->size;
return ret;
}
static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
{
if (ent->data) {
free(ent->data);
ent->data = NULL;
ent->lru.next->prev = ent->lru.prev;
ent->lru.prev->next = ent->lru.next;
delta_base_cached -= ent->size;
}
}
void clear_delta_base_cache(void)
{
unsigned long p;
for (p = 0; p < MAX_DELTA_CACHE; p++)
release_delta_base_cache(&delta_base_cache[p]);
}
static void add_delta_base_cache(struct packed_git *p, off_t base_offset,
void *base, unsigned long base_size, enum object_type type)
{
unsigned long hash = pack_entry_hash(p, base_offset);
struct delta_base_cache_entry *ent = delta_base_cache + hash;
struct delta_base_cache_lru_list *lru;
release_delta_base_cache(ent);
delta_base_cached += base_size;
for (lru = delta_base_cache_lru.next;
delta_base_cached > delta_base_cache_limit
&& lru != &delta_base_cache_lru;
lru = lru->next) {
struct delta_base_cache_entry *f = (void *)lru;
if (f->type == OBJ_BLOB)
release_delta_base_cache(f);
}
for (lru = delta_base_cache_lru.next;
delta_base_cached > delta_base_cache_limit
&& lru != &delta_base_cache_lru;
lru = lru->next) {
struct delta_base_cache_entry *f = (void *)lru;
release_delta_base_cache(f);
}
ent->p = p;
ent->base_offset = base_offset;
ent->type = type;
ent->data = base;
ent->size = base_size;
ent->lru.next = &delta_base_cache_lru;
ent->lru.prev = delta_base_cache_lru.prev;
delta_base_cache_lru.prev->next = &ent->lru;
delta_base_cache_lru.prev = &ent->lru;
}
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 FILE *log_file;
if (!log_pack_access)
log_pack_access = getenv("GIT_TRACE_PACK_ACCESS");
if (!log_pack_access)
log_pack_access = no_log_pack_access;
if (log_pack_access == no_log_pack_access)
return;
if (!log_file) {
log_file = fopen(log_pack_access, "w");
if (!log_file) {
error("cannot open pack access log '%s' for writing: %s",
log_pack_access, strerror(errno));
log_pack_access = no_log_pack_access;
return;
}
}
fprintf(log_file, "%s %"PRIuMAX"\n",
p->pack_name, (uintmax_t)obj_offset);
fflush(log_file);
}
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;
if (log_pack_access != no_log_pack_access)
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;
if (do_check_packed_object_crc && p->index_version > 1) {
struct revindex_entry *revidx = find_pack_revindex(p, obj_offset);
unsigned long 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);
unuse_pack(&w_curs);
return NULL;
}
}
ent = get_delta_base_cache_entry(p, curpos);
if (eq_delta_base_cache_entry(ent, p, curpos)) {
type = ent->type;
data = ent->data;
size = ent->size;
clear_delta_base_cache_entry(ent);
base_from_cache = 1;
break;
}
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);
delta_stack = xmalloc(sizeof(*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 in 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;
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);
}
}
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;
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);
}
*final_type = type;
*final_size = size;
unuse_pack(&w_curs);
return data;
}
const unsigned char *nth_packed_object_sha1(struct packed_git *p,
uint32_t n)
{
const unsigned char *index = p->index_data;
if (!index) {
if (open_pack_index(p))
return NULL;
index = p->index_data;
}
if (n >= p->num_objects)
return NULL;
index += 4 * 256;
if (p->index_version == 1) {
return index + 24 * n + 4;
} else {
index += 8;
return index + 20 * n;
}
}
off_t nth_packed_object_offset(const struct packed_git *p, uint32_t n)
{
const unsigned char *index = p->index_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)));
}
}
off_t find_pack_entry_one(const unsigned char *sha1,
struct packed_git *p)
{
const uint32_t *level1_ofs = p->index_data;
const unsigned char *index = p->index_data;
unsigned hi, lo, stride;
static int use_lookup = -1;
static int debug_lookup = -1;
if (debug_lookup < 0)
debug_lookup = !!getenv("GIT_DEBUG_LOOKUP");
if (!index) {
if (open_pack_index(p))
return 0;
level1_ofs = p->index_data;
index = p->index_data;
}
if (p->index_version > 1) {
level1_ofs += 2;
index += 8;
}
index += 4 * 256;
hi = ntohl(level1_ofs[*sha1]);
lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
if (p->index_version > 1) {
stride = 20;
} else {
stride = 24;
index += 4;
}
if (debug_lookup)
printf("%02x%02x%02x... lo %u hi %u nr %"PRIu32"\n",
sha1[0], sha1[1], sha1[2], lo, hi, p->num_objects);
if (use_lookup < 0)
use_lookup = !!getenv("GIT_USE_LOOKUP");
if (use_lookup) {
int pos = sha1_entry_pos(index, stride, 0,
lo, hi, p->num_objects, sha1);
if (pos < 0)
return 0;
return nth_packed_object_offset(p, pos);
}
do {
unsigned mi = (lo + hi) / 2;
int cmp = hashcmp(index + mi * stride, sha1);
if (debug_lookup)
printf("lo %u hi %u rg %u mi %u\n",
lo, hi, hi - lo, mi);
if (!cmp)
return nth_packed_object_offset(p, mi);
if (cmp > 0)
hi = mi;
else
lo = mi+1;
} while (lo < hi);
return 0;
}
int is_pack_valid(struct packed_git *p)
{
/* An already open pack is known to be valid. */
if (p->pack_fd != -1)
return 1;
/* If the pack has one window completely covering the
* file size, the pack is known to be valid even if
* the descriptor is not currently open.
*/
if (p->windows) {
struct pack_window *w = p->windows;
if (!w->offset && w->len == p->pack_size)
return 1;
}
/* Force the pack to open to prove its valid. */
return !open_packed_git(p);
}
static int fill_pack_entry(const unsigned char *sha1,
struct pack_entry *e,
struct packed_git *p)
{
off_t offset;
if (p->num_bad_objects) {
unsigned i;
for (i = 0; i < p->num_bad_objects; i++)
if (!hashcmp(sha1, p->bad_object_sha1 + 20 * i))
return 0;
}
offset = find_pack_entry_one(sha1, p);
if (!offset)
return 0;
/*
* We are about to tell the caller where they can locate the
* requested object. We better make sure the packfile is
* still here and can be accessed before supplying that
* answer, as it may have been deleted since the index was
* loaded!
*/
if (!is_pack_valid(p)) {
warning("packfile %s cannot be accessed", p->pack_name);
return 0;
}
e->offset = offset;
e->p = p;
hashcpy(e->sha1, sha1);
return 1;
}
static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
{
struct packed_git *p;
prepare_packed_git();
if (!packed_git)
return 0;
if (last_found_pack && fill_pack_entry(sha1, e, last_found_pack))
return 1;
for (p = packed_git; p; p = p->next) {
if (p == last_found_pack || !fill_pack_entry(sha1, e, p))
continue;
last_found_pack = p;
return 1;
}
return 0;
}
struct packed_git *find_sha1_pack(const unsigned char *sha1,
struct packed_git *packs)
{
struct packed_git *p;
for (p = packs; p; p = p->next) {
if (find_pack_entry_one(sha1, p))
return p;
}
return NULL;
}
static int sha1_loose_object_info(const unsigned char *sha1,
struct object_info *oi)
{
int status;
unsigned long mapsize, size;
void *map;
git_zstream stream;
char hdr[32];
/*
* If we don't care about type or size, then we don't
* need to look inside the object at all.
*/
if (!oi->typep && !oi->sizep) {
if (oi->disk_sizep) {
struct stat st;
if (stat_sha1_file(sha1, &st) < 0)
return -1;
*oi->disk_sizep = st.st_size;
}
return 0;
}
map = map_sha1_file(sha1, &mapsize);
if (!map)
return -1;
if (oi->disk_sizep)
*oi->disk_sizep = mapsize;
if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
status = error("unable to unpack %s header",
sha1_to_hex(sha1));
else if ((status = parse_sha1_header(hdr, &size)) < 0)
status = error("unable to parse %s header", sha1_to_hex(sha1));
else if (oi->sizep)
*oi->sizep = size;
git_inflate_end(&stream);
munmap(map, mapsize);
if (oi->typep)
*oi->typep = status;
return 0;
}
/* returns enum object_type or negative */
int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
{
struct cached_object *co;
struct pack_entry e;
int rtype;
co = find_cached_object(sha1);
if (co) {
if (oi->typep)
*(oi->typep) = co->type;
if (oi->sizep)
*(oi->sizep) = co->size;
if (oi->disk_sizep)
*(oi->disk_sizep) = 0;
oi->whence = OI_CACHED;
return 0;
}
if (!find_pack_entry(sha1, &e)) {
/* Most likely it's a loose object. */
if (!sha1_loose_object_info(sha1, oi)) {
oi->whence = OI_LOOSE;
return 0;
}
/* Not a loose object; someone else may have just packed it. */
reprepare_packed_git();
if (!find_pack_entry(sha1, &e))
return -1;
}
rtype = packed_object_info(e.p, e.offset, oi);
if (rtype < 0) {
mark_bad_packed_object(e.p, sha1);
return sha1_object_info_extended(sha1, oi);
} else if (in_delta_base_cache(e.p, e.offset)) {
oi->whence = OI_DBCACHED;
} else {
oi->whence = OI_PACKED;
oi->u.packed.offset = e.offset;
oi->u.packed.pack = e.p;
oi->u.packed.is_delta = (rtype == OBJ_REF_DELTA ||
rtype == OBJ_OFS_DELTA);
}
return 0;
}
int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
{
enum object_type type;
struct object_info oi = {NULL};
oi.typep = &type;
oi.sizep = sizep;
if (sha1_object_info_extended(sha1, &oi) < 0)
return -1;
return type;
}
static void *read_packed_sha1(const unsigned char *sha1,
enum object_type *type, unsigned long *size)
{
struct pack_entry e;
void *data;
if (!find_pack_entry(sha1, &e))
return NULL;
data = cache_or_unpack_entry(e.p, e.offset, size, type, 1);
if (!data) {
/*
* We're probably in deep shit, but let's try to fetch
* the required object anyway from another pack or loose.
* This should happen only in the presence of a corrupted
* pack, and is better than failing outright.
*/
error("failed to read object %s at offset %"PRIuMAX" from %s",
sha1_to_hex(sha1), (uintmax_t)e.offset, e.p->pack_name);
mark_bad_packed_object(e.p, sha1);
data = read_object(sha1, type, size);
}
return data;
}
int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
unsigned char *sha1)
{
struct cached_object *co;
hash_sha1_file(buf, len, typename(type), sha1);
if (has_sha1_file(sha1) || find_cached_object(sha1))
return 0;
if (cached_object_alloc <= cached_object_nr) {
cached_object_alloc = alloc_nr(cached_object_alloc);
cached_objects = xrealloc(cached_objects,
sizeof(*cached_objects) *
cached_object_alloc);
}
co = &cached_objects[cached_object_nr++];
co->size = len;
co->type = type;
co->buf = xmalloc(len);
memcpy(co->buf, buf, len);
hashcpy(co->sha1, sha1);
return 0;
}
static void *read_object(const unsigned char *sha1, enum object_type *type,
unsigned long *size)
{
unsigned long mapsize;
void *map, *buf;
struct cached_object *co;
co = find_cached_object(sha1);
if (co) {
*type = co->type;
*size = co->size;
return xmemdupz(co->buf, co->size);
}
buf = read_packed_sha1(sha1, type, size);
if (buf)
return buf;
map = map_sha1_file(sha1, &mapsize);
if (map) {
buf = unpack_sha1_file(map, mapsize, type, size, sha1);
munmap(map, mapsize);
return buf;
}
reprepare_packed_git();
return read_packed_sha1(sha1, type, size);
}
/*
* This function dies on corrupt objects; the callers who want to
* deal with them should arrange to call read_object() and give error
* messages themselves.
*/
void *read_sha1_file_extended(const unsigned char *sha1,
enum object_type *type,
unsigned long *size,
unsigned flag)
{
void *data;
char *path;
const struct packed_git *p;
const unsigned char *repl = (flag & READ_SHA1_FILE_REPLACE)
? lookup_replace_object(sha1) : sha1;
errno = 0;
data = read_object(repl, type, size);
if (data)
return data;
if (errno && errno != ENOENT)
die_errno("failed to read object %s", sha1_to_hex(sha1));
/* die if we replaced an object with one that does not exist */
if (repl != sha1)
die("replacement %s not found for %s",
sha1_to_hex(repl), sha1_to_hex(sha1));
if (has_loose_object(repl)) {
path = sha1_file_name(sha1);
die("loose object %s (stored in %s) is corrupt",
sha1_to_hex(repl), path);
}
if ((p = has_packed_and_bad(repl)) != NULL)
die("packed object %s (stored in %s) is corrupt",
sha1_to_hex(repl), p->pack_name);
return NULL;
}
void *read_object_with_reference(const unsigned char *sha1,
const char *required_type_name,
unsigned long *size,
unsigned char *actual_sha1_return)
{
enum object_type type, required_type;
void *buffer;
unsigned long isize;
unsigned char actual_sha1[20];
required_type = type_from_string(required_type_name);
hashcpy(actual_sha1, sha1);
while (1) {
int ref_length = -1;
const char *ref_type = NULL;
buffer = read_sha1_file(actual_sha1, &type, &isize);
if (!buffer)
return NULL;
if (type == required_type) {
*size = isize;
if (actual_sha1_return)
hashcpy(actual_sha1_return, actual_sha1);
return buffer;
}
/* Handle references */
else if (type == OBJ_COMMIT)
ref_type = "tree ";
else if (type == OBJ_TAG)
ref_type = "object ";
else {
free(buffer);
return NULL;
}
ref_length = strlen(ref_type);
if (ref_length + 40 > isize ||
memcmp(buffer, ref_type, ref_length) ||
get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
free(buffer);
return NULL;
}
free(buffer);
/* Now we have the ID of the referred-to object in
* actual_sha1. Check again. */
}
}
static void write_sha1_file_prepare(const void *buf, unsigned long len,
const char *type, unsigned char *sha1,
char *hdr, int *hdrlen)
{
git_SHA_CTX c;
/* Generate the header */
*hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
/* Sha1.. */
git_SHA1_Init(&c);
git_SHA1_Update(&c, hdr, *hdrlen);
git_SHA1_Update(&c, buf, len);
git_SHA1_Final(sha1, &c);
}
/*
* Move the just written object into its final resting place.
* NEEDSWORK: this should be renamed to finalize_temp_file() as
* "moving" is only a part of what it does, when no patch between
* master to pu changes the call sites of this function.
*/
int move_temp_to_file(const char *tmpfile, const char *filename)
{
int ret = 0;
if (object_creation_mode == OBJECT_CREATION_USES_RENAMES)
goto try_rename;
else if (link(tmpfile, filename))
ret = errno;
/*
* Coda hack - coda doesn't like cross-directory links,
* so we fall back to a rename, which will mean that it
* won't be able to check collisions, but that's not a
* big deal.
*
* The same holds for FAT formatted media.
*
* When this succeeds, we just return. We have nothing
* left to unlink.
*/
if (ret && ret != EEXIST) {
try_rename:
if (!rename(tmpfile, filename))
goto out;
ret = errno;
}
unlink_or_warn(tmpfile);
if (ret) {
if (ret != EEXIST) {
return error("unable to write sha1 filename %s: %s", filename, strerror(ret));
}
/* FIXME!!! Collision check here ? */
}
out:
if (adjust_shared_perm(filename))
return error("unable to set permission to '%s'", filename);
return 0;
}
static int write_buffer(int fd, const void *buf, size_t len)
{
if (write_in_full(fd, buf, len) < 0)
return error("file write error (%s)", strerror(errno));
return 0;
}
int hash_sha1_file(const void *buf, unsigned long len, const char *type,
unsigned char *sha1)
{
char hdr[32];
int hdrlen;
write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
return 0;
}
/* Finalize a file on disk, and close it. */
static void close_sha1_file(int fd)
{
if (fsync_object_files)
fsync_or_die(fd, "sha1 file");
if (close(fd) != 0)
die_errno("error when closing sha1 file");
}
/* Size of directory component, including the ending '/' */
static inline int directory_size(const char *filename)
{
const char *s = strrchr(filename, '/');
if (!s)
return 0;
return s - filename + 1;
}
/*
* This creates a temporary file in the same directory as the final
* 'filename'
*
* We want to avoid cross-directory filename renames, because those
* can have problems on various filesystems (FAT, NFS, Coda).
*/
static int create_tmpfile(char *buffer, size_t bufsiz, const char *filename)
{
int fd, dirlen = directory_size(filename);
if (dirlen + 20 > bufsiz) {
errno = ENAMETOOLONG;
return -1;
}
memcpy(buffer, filename, dirlen);
strcpy(buffer + dirlen, "tmp_obj_XXXXXX");
fd = git_mkstemp_mode(buffer, 0444);
if (fd < 0 && dirlen && errno == ENOENT) {
/* Make sure the directory exists */
memcpy(buffer, filename, dirlen);
buffer[dirlen-1] = 0;
if (mkdir(buffer, 0777) || adjust_shared_perm(buffer))
return -1;
/* Try again */
strcpy(buffer + dirlen - 1, "/tmp_obj_XXXXXX");
fd = git_mkstemp_mode(buffer, 0444);
}
return fd;
}
static int write_loose_object(const unsigned char *sha1, char *hdr, int hdrlen,
const void *buf, unsigned long len, time_t mtime)
{
int fd, ret;
unsigned char compressed[4096];
git_zstream stream;
git_SHA_CTX c;
unsigned char parano_sha1[20];
char *filename;
static char tmp_file[PATH_MAX];
filename = sha1_file_name(sha1);
fd = create_tmpfile(tmp_file, sizeof(tmp_file), filename);
if (fd < 0) {
if (errno == EACCES)
return error("insufficient permission for adding an object to repository database %s", get_object_directory());
else
return error("unable to create temporary file: %s", strerror(errno));
}
/* Set it up */
memset(&stream, 0, sizeof(stream));
git_deflate_init(&stream, zlib_compression_level);
stream.next_out = compressed;
stream.avail_out = sizeof(compressed);
git_SHA1_Init(&c);
/* First header.. */
stream.next_in = (unsigned char *)hdr;
stream.avail_in = hdrlen;
while (git_deflate(&stream, 0) == Z_OK)
; /* nothing */
git_SHA1_Update(&c, hdr, hdrlen);
/* Then the data itself.. */
stream.next_in = (void *)buf;
stream.avail_in = len;
do {
unsigned char *in0 = stream.next_in;
ret = git_deflate(&stream, Z_FINISH);
git_SHA1_Update(&c, in0, stream.next_in - in0);
if (write_buffer(fd, compressed, stream.next_out - compressed) < 0)
die("unable to write sha1 file");
stream.next_out = compressed;
stream.avail_out = sizeof(compressed);
} while (ret == Z_OK);
if (ret != Z_STREAM_END)
die("unable to deflate new object %s (%d)", sha1_to_hex(sha1), ret);
ret = git_deflate_end_gently(&stream);
if (ret != Z_OK)
die("deflateEnd on object %s failed (%d)", sha1_to_hex(sha1), ret);
git_SHA1_Final(parano_sha1, &c);
if (hashcmp(sha1, parano_sha1) != 0)
die("confused by unstable object source data for %s", sha1_to_hex(sha1));
close_sha1_file(fd);
if (mtime) {
struct utimbuf utb;
utb.actime = mtime;
utb.modtime = mtime;
if (utime(tmp_file, &utb) < 0)
warning("failed utime() on %s: %s",
tmp_file, strerror(errno));
}
return move_temp_to_file(tmp_file, filename);
}
int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
{
unsigned char sha1[20];
char hdr[32];
int hdrlen;
/* Normally if we have it in the pack then we do not bother writing
* it out into .git/objects/??/?{38} file.
*/
write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
if (returnsha1)
hashcpy(returnsha1, sha1);
if (has_sha1_file(sha1))
return 0;
return write_loose_object(sha1, hdr, hdrlen, buf, len, 0);
}
int force_object_loose(const unsigned char *sha1, time_t mtime)
{
void *buf;
unsigned long len;
enum object_type type;
char hdr[32];
int hdrlen;
int ret;
if (has_loose_object(sha1))
return 0;
buf = read_packed_sha1(sha1, &type, &len);
if (!buf)
return error("cannot read sha1_file for %s", sha1_to_hex(sha1));
hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
ret = write_loose_object(sha1, hdr, hdrlen, buf, len, mtime);
free(buf);
return ret;
}
int has_pack_index(const unsigned char *sha1)
{
struct stat st;
if (stat(sha1_pack_index_name(sha1), &st))
return 0;
return 1;
}
int has_sha1_pack(const unsigned char *sha1)
{
struct pack_entry e;
return find_pack_entry(sha1, &e);
}
int has_sha1_file(const unsigned char *sha1)
{
struct pack_entry e;
if (find_pack_entry(sha1, &e))
return 1;
if (has_loose_object(sha1))
return 1;
reprepare_packed_git();
return find_pack_entry(sha1, &e);
}
static void check_tree(const void *buf, size_t size)
{
struct tree_desc desc;
struct name_entry entry;
init_tree_desc(&desc, buf, size);
while (tree_entry(&desc, &entry))
/* do nothing
* tree_entry() will die() on malformed entries */
;
}
static void check_commit(const void *buf, size_t size)
{
struct commit c;
memset(&c, 0, sizeof(c));
if (parse_commit_buffer(&c, buf, size))
die("corrupt commit");
}
static void check_tag(const void *buf, size_t size)
{
struct tag t;
memset(&t, 0, sizeof(t));
if (parse_tag_buffer(&t, buf, size))
die("corrupt tag");
}
static int index_mem(unsigned char *sha1, void *buf, size_t size,
enum object_type type,
const char *path, unsigned flags)
{
int ret, re_allocated = 0;
int write_object = flags & HASH_WRITE_OBJECT;
if (!type)
type = OBJ_BLOB;
/*
* Convert blobs to git internal format
*/
if ((type == OBJ_BLOB) && path) {
struct strbuf nbuf = STRBUF_INIT;
if (convert_to_git(path, buf, size, &nbuf,
write_object ? safe_crlf : SAFE_CRLF_FALSE)) {
buf = strbuf_detach(&nbuf, &size);
re_allocated = 1;
}
}
if (flags & HASH_FORMAT_CHECK) {
if (type == OBJ_TREE)
check_tree(buf, size);
if (type == OBJ_COMMIT)
check_commit(buf, size);
if (type == OBJ_TAG)
check_tag(buf, size);
}
if (write_object)
ret = write_sha1_file(buf, size, typename(type), sha1);
else
ret = hash_sha1_file(buf, size, typename(type), sha1);
if (re_allocated)
free(buf);
return ret;
}
static int index_pipe(unsigned char *sha1, int fd, enum object_type type,
const char *path, unsigned flags)
{
struct strbuf sbuf = STRBUF_INIT;
int ret;
if (strbuf_read(&sbuf, fd, 4096) >= 0)
ret = index_mem(sha1, sbuf.buf, sbuf.len, type, path, flags);
else
ret = -1;
strbuf_release(&sbuf);
return ret;
}
#define SMALL_FILE_SIZE (32*1024)
static int index_core(unsigned char *sha1, int fd, size_t size,
enum object_type type, const char *path,
unsigned flags)
{
int ret;
if (!size) {
ret = index_mem(sha1, NULL, size, type, path, flags);
} else if (size <= SMALL_FILE_SIZE) {
char *buf = xmalloc(size);
if (size == read_in_full(fd, buf, size))
ret = index_mem(sha1, buf, size, type, path, flags);
else
ret = error("short read %s", strerror(errno));
free(buf);
} else {
void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
ret = index_mem(sha1, buf, size, type, path, flags);
munmap(buf, size);
}
return ret;
}
/*
* This creates one packfile per large blob unless bulk-checkin
* machinery is "plugged".
*
* This also bypasses the usual "convert-to-git" dance, and that is on
* purpose. We could write a streaming version of the converting
* functions and insert that before feeding the data to fast-import
* (or equivalent in-core API described above). However, that is
* somewhat complicated, as we do not know the size of the filter
* result, which we need to know beforehand when writing a git object.
* Since the primary motivation for trying to stream from the working
* tree file and to avoid mmaping it in core is to deal with large
* binary blobs, they generally do not want to get any conversion, and
* callers should avoid this code path when filters are requested.
*/
static int index_stream(unsigned char *sha1, int fd, size_t size,
enum object_type type, const char *path,
unsigned flags)
{
return index_bulk_checkin(sha1, fd, size, type, path, flags);
}
int index_fd(unsigned char *sha1, int fd, struct stat *st,
enum object_type type, const char *path, unsigned flags)
{
int ret;
size_t size = xsize_t(st->st_size);
if (!S_ISREG(st->st_mode))
ret = index_pipe(sha1, fd, type, path, flags);
else if (size <= big_file_threshold || type != OBJ_BLOB ||
(path && would_convert_to_git(path, NULL, 0, 0)))
ret = index_core(sha1, fd, size, type, path, flags);
else
ret = index_stream(sha1, fd, size, type, path, flags);
close(fd);
return ret;
}
int index_path(unsigned char *sha1, const char *path, struct stat *st, unsigned flags)
{
int fd;
struct strbuf sb = STRBUF_INIT;
switch (st->st_mode & S_IFMT) {
case S_IFREG:
fd = open(path, O_RDONLY);
if (fd < 0)
return error("open(\"%s\"): %s", path,
strerror(errno));
if (index_fd(sha1, fd, st, OBJ_BLOB, path, flags) < 0)
return error("%s: failed to insert into database",
path);
break;
case S_IFLNK:
if (strbuf_readlink(&sb, path, st->st_size)) {
char *errstr = strerror(errno);
return error("readlink(\"%s\"): %s", path,
errstr);
}
if (!(flags & HASH_WRITE_OBJECT))
hash_sha1_file(sb.buf, sb.len, blob_type, sha1);
else if (write_sha1_file(sb.buf, sb.len, blob_type, sha1))
return error("%s: failed to insert into database",
path);
strbuf_release(&sb);
break;
case S_IFDIR:
return resolve_gitlink_ref(path, "HEAD", sha1);
default:
return error("%s: unsupported file type", path);
}
return 0;
}
int read_pack_header(int fd, struct pack_header *header)
{
if (read_in_full(fd, header, sizeof(*header)) < sizeof(*header))
/* "eof before pack header was fully read" */
return PH_ERROR_EOF;
if (header->hdr_signature != htonl(PACK_SIGNATURE))
/* "protocol error (pack signature mismatch detected)" */
return PH_ERROR_PACK_SIGNATURE;
if (!pack_version_ok(header->hdr_version))
/* "protocol error (pack version unsupported)" */
return PH_ERROR_PROTOCOL;
return 0;
}
void assert_sha1_type(const unsigned char *sha1, enum object_type expect)
{
enum object_type type = sha1_object_info(sha1, NULL);
if (type < 0)
die("%s is not a valid object", sha1_to_hex(sha1));
if (type != expect)
die("%s is not a valid '%s' object", sha1_to_hex(sha1),
typename(expect));
}
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