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tag: v1.7.1-rc2
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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 "delta.h"
#include "pack.h"
#include "blob.h"
#include "commit.h"
#include "tag.h"
#include "tree.h"
#include "refs.h"
#include "pack-revindex.h"
#include "sha1-lookup.h"

#ifndef O_NOATIME
#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
#define O_NOATIME 01000000
#else
#define O_NOATIME 0
#endif
#endif

#ifdef NO_C99_FORMAT
#define SZ_FMT "lu"
static unsigned long sz_fmt(size_t s) { return (unsigned long)s; }
#else
#define SZ_FMT "zu"
static size_t sz_fmt(size_t s) { return s; }
#endif

const unsigned char null_sha1[20];

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)) {
*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 *name, *base;

if (!base) {
const char *sha1_file_directory = get_object_directory();
int len = strlen(sha1_file_directory);
base = xmalloc(len + 60);
memcpy(base, sha1_file_directory, len);
memset(base+len, 0, 60);
base[len] = '/';
base[len+3] = '/';
name = base + len + 1;
}
fill_sha1_path(name, sha1);
return base;
}

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 void read_info_alternates(const char * alternates, int depth);

/*
* 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, int len, const char * relative_base, int depth)
{
const char *objdir = get_object_directory();
struct alternate_object_database *ent;
struct alternate_object_database *alt;
/* 43 = 40-byte + 2 '/' + terminating NUL */
int pfxlen = len;
int entlen = pfxlen + 43;
int base_len = -1;

if (!is_absolute_path(entry) && relative_base) {
/* Relative alt-odb */
if (base_len < 0)
base_len = strlen(relative_base) + 1;
entlen += base_len;
pfxlen += base_len;
}
ent = xmalloc(sizeof(*ent) + entlen);

if (!is_absolute_path(entry) && relative_base) {
memcpy(ent->base, relative_base, base_len - 1);
ent->base[base_len - 1] = '/';
memcpy(ent->base + base_len, entry, len);
}
else
memcpy(ent->base, entry, pfxlen);

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 (!memcmp(ent->base, objdir, pfxlen)) {
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, const char *ep, int sep,
const char *relative_base, int depth)
{
const char *cp, *last;

if (depth > 5) {
error("%s: ignoring alternate object stores, nesting too deep.",
relative_base);
return;
}

last = alt;
while (last < ep) {
cp = last;
if (cp < ep && *cp == '#') {
while (cp < ep && *cp != sep)
cp++;
last = cp + 1;
continue;
}
while (cp < ep && *cp != sep)
cp++;
if (last != cp) {
if (!is_absolute_path(last) && depth) {
error("%s: ignoring relative alternate object store %s",
relative_base, last);
} else {
link_alt_odb_entry(last, cp - last,
relative_base, depth);
}
}
while (cp < ep && *cp == sep)
cp++;
last = cp;
}
}

static 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 = open(path, O_RDONLY);
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, 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/objects\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, 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, 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 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 = open(path, O_RDONLY);
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 != keep_fd) {
close(lru_p->pack_fd);
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 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;
}
}

/*
* 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);
if (p->index_data)
munmap((void *)p->index_data, p->index_size);
free(p->bad_object_sha1);
*pp = p->next;
free(p);
return;
}
pp = &p->next;
}
}

/*
* 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);

p->pack_fd = open(p->pack_name, O_RDONLY);
while (p->pack_fd < 0 && errno == EMFILE && unuse_one_window(p, -1))
p->pack_fd = open(p->pack_name, O_RDONLY);
if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
return -1;

/* 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);
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 int *left)
{
struct pack_window *win = *w_cursor;

if (p->pack_fd == -1 && open_packed_git(p))
die("packfile %s cannot be accessed", p->pack_name);

/* 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 (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;
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));
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;
}

struct packed_git *add_packed_git(const char *path, int path_len, int local)
{
struct stat st;
struct packed_git *p = alloc_packed_git(path_len + 2);

/*
* 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 = sha1_pack_index_name(sha1);
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)
{
pack->next = packed_git;
packed_git = pack;
}

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;

sprintf(path, "%s/pack", objdir);
len = strlen(path);
dir = opendir(path);
while (!dir && errno == EMFILE && unuse_one_window(packed_git, -1))
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 (!has_extension(de->d_name, ".idx"))
continue;

if (len + namelen + 1 > sizeof(path))
continue;

/* Don't reopen a pack we already have. */
strcpy(path + len, de->d_name);
for (p = packed_git; p; p = p->next) {
if (!memcmp(path, p->pack_name, len + namelen - 4))
break;
}
if (p)
continue;
/* 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);
if (!p)
continue;
install_packed_git(p);
}
closedir(dir);
}

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 int 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 1;
return 0;
}

int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
{
unsigned char real_sha1[20];
hash_sha1_file(map, size, type, real_sha1);
return hashcmp(sha1, real_sha1) ? -1 : 0;
}

static int git_open_noatime(const char *name)
{
static int sha1_file_open_flag = O_NOATIME;
int fd = open(name, O_RDONLY | sha1_file_open_flag);

/* Might the failure be due to O_NOATIME? */
if (fd < 0 && errno != ENOENT && sha1_file_open_flag) {
fd = open(name, O_RDONLY);
if (fd >= 0)
sha1_file_open_flag = 0;
}
return fd;
}

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;
}

static 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);
map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
}
close(fd);
}
return map;
}

static int legacy_loose_object(unsigned char *map)
{
unsigned int word;

/*
* Is it a zlib-compressed buffer? If so, the first byte
* must be 0x78 (15-bit window size, deflated), and the
* first 16-bit word is evenly divisible by 31
*/
word = (map[0] << 8) + map[1];
if (map[0] == 0x78 && !(word % 31))
return 1;
else
return 0;
}

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");
return 0;
}
c = buf[used++];
size += (c & 0x7f) << shift;
shift += 7;
}
*sizep = size;
return used;
}

static int unpack_sha1_header(z_stream *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 (legacy_loose_object(map)) {
git_inflate_init(stream);
return git_inflate(stream, 0);
}


/*
* 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 don't write it any longer. But 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;
}

static void *unpack_sha1_rest(z_stream *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 zer0,
* 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.
*/
static 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;
z_stream 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;
z_stream 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;
}

/* forward declaration for a mutually recursive function */
static int packed_object_info(struct packed_git *p, off_t offset,
unsigned long *sizep);

static int packed_delta_info(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos,
enum object_type type,
off_t obj_offset,
unsigned long *sizep)
{
off_t base_offset;

base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
if (!base_offset)
return OBJ_BAD;
type = packed_object_info(p, base_offset, NULL);
if (type <= OBJ_NONE) {
struct revindex_entry *revidx;
const unsigned char *base_sha1;
revidx = find_pack_revindex(p, base_offset);
if (!revidx)
return OBJ_BAD;
base_sha1 = nth_packed_object_sha1(p, revidx->nr);
mark_bad_packed_object(p, base_sha1);
type = sha1_object_info(base_sha1, NULL);
if (type <= OBJ_NONE)
return OBJ_BAD;
}

/* We choose to only get the type of the base object and
* ignore potentially corrupt pack file that expects the delta
* based on a base with a wrong size. This saves tons of
* inflate() calls.
*/
if (sizep) {
*sizep = get_size_from_delta(p, w_curs, curpos);
if (*sizep == 0)
type = OBJ_BAD;
}

return type;
}

static int unpack_object_header(struct packed_git *p,
struct pack_window **w_curs,
off_t *curpos,
unsigned long *sizep)
{
unsigned char *base;
unsigned int 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 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;
}

const char *packed_object_info_detail(struct packed_git *p,
off_t obj_offset,
unsigned long *size,
unsigned long *store_size,
unsigned int *delta_chain_length,
unsigned char *base_sha1)
{
struct pack_window *w_curs = NULL;
off_t curpos;
unsigned long dummy;
unsigned char *next_sha1;
enum object_type type;
struct revindex_entry *revidx;

*delta_chain_length = 0;
curpos = obj_offset;
type = unpack_object_header(p, &w_curs, &curpos, size);

revidx = find_pack_revindex(p, obj_offset);
*store_size = revidx[1].offset - obj_offset;

for (;;) {
switch (type) {
default:
die("pack %s contains unknown object type %d",
p->pack_name, type);
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
unuse_pack(&w_curs);
return typename(type);
case OBJ_OFS_DELTA:
obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
if (!obj_offset)
die("pack %s contains bad delta base reference of type %s",
p->pack_name, typename(type));
if (*delta_chain_length == 0) {
revidx = find_pack_revindex(p, obj_offset);
hashcpy(base_sha1, nth_packed_object_sha1(p, revidx->nr));
}
break;
case OBJ_REF_DELTA:
next_sha1 = use_pack(p, &w_curs, curpos, NULL);
if (*delta_chain_length == 0)
hashcpy(base_sha1, next_sha1);
obj_offset = find_pack_entry_one(next_sha1, p);
break;
}
(*delta_chain_length)++;
curpos = obj_offset;
type = unpack_object_header(p, &w_curs, &curpos, &dummy);
}
}

static int packed_object_info(struct packed_git *p, off_t obj_offset,
unsigned long *sizep)
{
struct pack_window *w_curs = NULL;
unsigned long size;
off_t curpos = obj_offset;
enum object_type type;

type = unpack_object_header(p, &w_curs, &curpos, &size);

switch (type) {
case OBJ_OFS_DELTA:
case OBJ_REF_DELTA:
type = packed_delta_info(p, &w_curs, curpos,
type, obj_offset, sizep);
break;
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
if (sizep)
*sizep = size;
break;
default:
error("unknown object type %i at offset %"PRIuMAX" in %s",
type, (uintmax_t)obj_offset, p->pack_name);
type = OBJ_BAD;
}
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;
z_stream 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 void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
unsigned long *base_size, enum object_type *type, int keep_cache)
{
void *ret;
unsigned long hash = pack_entry_hash(p, base_offset);
struct delta_base_cache_entry *ent = delta_base_cache + hash;

ret = ent->data;
if (!ret || ent->p != p || ent->base_offset != base_offset)
return unpack_entry(p, base_offset, type, base_size);

if (!keep_cache) {
ent->data = NULL;
ent->lru.next->prev = ent->lru.prev;
ent->lru.prev->next = ent->lru.next;
delta_base_cached -= ent->size;
} 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 *unpack_delta_entry(struct packed_git *p,
struct pack_window **w_curs,
off_t curpos,
unsigned long delta_size,
off_t obj_offset,
enum object_type *type,
unsigned long *sizep)
{
void *delta_data, *result, *base;
unsigned long base_size;
off_t base_offset;

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);
return NULL;
}
unuse_pack(w_curs);
base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
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, base_offset);
if (!revidx)
return NULL;
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)base_offset,
p->pack_name);
mark_bad_packed_object(p, base_sha1);
base = read_object(base_sha1, type, &base_size);
if (!base)
return NULL;
}

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);
free(base);
return NULL;
}
result = patch_delta(base, base_size,
delta_data, delta_size,
sizep);
if (!result)
die("failed to apply delta");
free(delta_data);
add_delta_base_cache(p, base_offset, base, base_size, *type);
return result;
}

int do_check_packed_object_crc;

void *unpack_entry(struct packed_git *p, off_t obj_offset,
enum object_type *type, unsigned long *sizep)
{
struct pack_window *w_curs = NULL;
off_t curpos = obj_offset;
void *data;

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;
}
}

*type = unpack_object_header(p, &w_curs, &curpos, sizep);
switch (*type) {
case OBJ_OFS_DELTA:
case OBJ_REF_DELTA:
data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
obj_offset, type, sizep);
break;
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
break;
default:
data = NULL;
error("unknown object type %i at offset %"PRIuMAX" in %s",
*type, (uintmax_t)obj_offset, p->pack_name);
}
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;
}

static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
{
static struct packed_git *last_found = (void *)1;
struct packed_git *p;
off_t offset;

prepare_packed_git();
if (!packed_git)
return 0;
p = (last_found == (void *)1) ? packed_git : last_found;

do {
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))
goto next;
}

offset = find_pack_entry_one(sha1, p);
if (offset) {
/*
* 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 (p->pack_fd == -1 && open_packed_git(p)) {
error("packfile %s cannot be accessed", p->pack_name);
goto next;
}
e->offset = offset;
e->p = p;
hashcpy(e->sha1, sha1);
last_found = p;
return 1;
}

next:
if (p == last_found)
p = packed_git;
else
p = p->next;
if (p == last_found)
p = p->next;
} while (p);
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, unsigned long *sizep)
{
int status;
unsigned long mapsize, size;
void *map;
z_stream stream;
char hdr[32];

map = map_sha1_file(sha1, &mapsize);
if (!map)
return error("unable to find %s", sha1_to_hex(sha1));
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 (sizep)
*sizep = size;
git_inflate_end(&stream);
munmap(map, mapsize);
return status;
}

int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
{
struct pack_entry e;
int status;

if (!find_pack_entry(sha1, &e)) {
/* Most likely it's a loose object. */
status = sha1_loose_object_info(sha1, sizep);
if (status >= 0)
return status;

/* Not a loose object; someone else may have just packed it. */
reprepare_packed_git();
if (!find_pack_entry(sha1, &e))
return status;
}

status = packed_object_info(e.p, e.offset, sizep);
if (status < 0) {
mark_bad_packed_object(e.p, sha1);
status = sha1_object_info(sha1, sizep);
}

return status;
}

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;
}

/*
* 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,
OBJ_TREE,
"",
0
};

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 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);
}

void *read_sha1_file_repl(const unsigned char *sha1,
enum object_type *type,
unsigned long *size,
const unsigned char **replacement)
{
const unsigned char *repl = lookup_replace_object(sha1);
void *data = read_object(repl, type, size);

/* die if we replaced an object with one that does not exist */
if (!data && repl != sha1)
die("replacement %s not found for %s",
sha1_to_hex(repl), sha1_to_hex(sha1));

/* legacy behavior is to die on corrupted objects */
if (!data && (has_loose_object(repl) || has_packed_and_bad(repl)))
die("object %s is corrupted", sha1_to_hex(repl));

if (replacement)
*replacement = repl;

return data;
}

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\n", 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];
z_stream stream;
git_SHA_CTX c;
unsigned char parano_sha1[20];
char *filename;
static char tmpfile[PATH_MAX];

filename = sha1_file_name(sha1);
fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
while (fd < 0 && errno == EMFILE && unuse_one_window(packed_git, -1))
fd = create_tmpfile(tmpfile, sizeof(tmpfile), filename);
if (fd < 0) {
if (errno == EACCES)
return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
else
return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
}

/* Set it up */
memset(&stream, 0, sizeof(stream));
deflateInit(&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 (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 = 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 = deflateEnd(&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(tmpfile, &utb) < 0)
warning("failed utime() on %s: %s",
tmpfile, strerror(errno));
}

return move_temp_to_file(tmpfile, 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;
return has_loose_object(sha1);
}

static int index_mem(unsigned char *sha1, void *buf, size_t size,
int write_object, enum object_type type, const char *path)
{
int ret, re_allocated = 0;

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 : 0)) {
buf = strbuf_detach(&nbuf, &size);
re_allocated = 1;
}
}

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;
}

#define SMALL_FILE_SIZE (32*1024)

int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
enum object_type type, const char *path)
{
int ret;
size_t size = xsize_t(st->st_size);

if (!S_ISREG(st->st_mode)) {
struct strbuf sbuf = STRBUF_INIT;
if (strbuf_read(&sbuf, fd, 4096) >= 0)
ret = index_mem(sha1, sbuf.buf, sbuf.len, write_object,
type, path);
else
ret = -1;
strbuf_release(&sbuf);
} else if (size <= SMALL_FILE_SIZE) {
char *buf = xmalloc(size);
if (size == read_in_full(fd, buf, size))
ret = index_mem(sha1, buf, size, write_object, type,
path);
else
ret = error("short read %s", strerror(errno));
free(buf);
} else if (size) {
void *buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
ret = index_mem(sha1, buf, size, write_object, type, path);
munmap(buf, size);
} else
ret = index_mem(sha1, NULL, size, write_object, type, path);
close(fd);
return ret;
}

int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
{
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, write_object, OBJ_BLOB, path) < 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 (!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;
}
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