git/update-cache.c
Christopher Li 812666c8e6 [PATCH] introduce xmalloc and xrealloc
Introduce xmalloc and xrealloc to die gracefully with a descriptive
message when out of memory, rather than taking a SIGSEGV. 

Signed-off-by: Christopher Li<chrislgit@chrisli.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-26 12:00:58 -07:00

374 lines
8.1 KiB
C

/*
* GIT - The information manager from hell
*
* Copyright (C) Linus Torvalds, 2005
*/
#include <signal.h>
#include "cache.h"
/*
* Default to not allowing changes to the list of files. The
* tool doesn't actually care, but this makes it harder to add
* files to the revision control by mistake by doing something
* like "update-cache *" and suddenly having all the object
* files be revision controlled.
*/
static int allow_add = 0, allow_remove = 0, not_new = 0;
/* Three functions to allow overloaded pointer return; see linux/err.h */
static inline void *ERR_PTR(long error)
{
return (void *) error;
}
static inline long PTR_ERR(const void *ptr)
{
return (long) ptr;
}
static inline long IS_ERR(const void *ptr)
{
return (unsigned long)ptr > (unsigned long)-1000L;
}
static int index_fd(unsigned char *sha1, int fd, struct stat *st)
{
z_stream stream;
unsigned long size = st->st_size;
int max_out_bytes = size + 200;
void *out = xmalloc(max_out_bytes);
void *metadata = xmalloc(200);
int metadata_size;
void *in;
SHA_CTX c;
in = "";
if (size)
in = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (!out || (int)(long)in == -1)
return -1;
metadata_size = 1+sprintf(metadata, "blob %lu", size);
SHA1_Init(&c);
SHA1_Update(&c, metadata, metadata_size);
SHA1_Update(&c, in, size);
SHA1_Final(sha1, &c);
memset(&stream, 0, sizeof(stream));
deflateInit(&stream, Z_BEST_COMPRESSION);
/*
* ASCII size + nul byte
*/
stream.next_in = metadata;
stream.avail_in = metadata_size;
stream.next_out = out;
stream.avail_out = max_out_bytes;
while (deflate(&stream, 0) == Z_OK)
/* nothing */;
/*
* File content
*/
stream.next_in = in;
stream.avail_in = size;
while (deflate(&stream, Z_FINISH) == Z_OK)
/*nothing */;
deflateEnd(&stream);
return write_sha1_buffer(sha1, out, stream.total_out);
}
/*
* This only updates the "non-critical" parts of the directory
* cache, ie the parts that aren't tracked by GIT, and only used
* to validate the cache.
*/
static void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
{
ce->ce_ctime.sec = htonl(st->st_ctime);
ce->ce_mtime.sec = htonl(st->st_mtime);
#ifdef NSEC
ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
#endif
ce->ce_dev = htonl(st->st_dev);
ce->ce_ino = htonl(st->st_ino);
ce->ce_uid = htonl(st->st_uid);
ce->ce_gid = htonl(st->st_gid);
ce->ce_size = htonl(st->st_size);
}
static int add_file_to_cache(char *path)
{
int size, namelen;
struct cache_entry *ce;
struct stat st;
int fd;
fd = open(path, O_RDONLY);
if (fd < 0) {
if (errno == ENOENT) {
if (allow_remove)
return remove_file_from_cache(path);
}
return -1;
}
if (fstat(fd, &st) < 0) {
close(fd);
return -1;
}
namelen = strlen(path);
size = cache_entry_size(namelen);
ce = xmalloc(size);
memset(ce, 0, size);
memcpy(ce->name, path, namelen);
fill_stat_cache_info(ce, &st);
ce->ce_mode = create_ce_mode(st.st_mode);
ce->ce_flags = htons(namelen);
if (index_fd(ce->sha1, fd, &st) < 0)
return -1;
return add_cache_entry(ce, allow_add);
}
static int match_data(int fd, void *buffer, unsigned long size)
{
while (size) {
char compare[1024];
int ret = read(fd, compare, sizeof(compare));
if (ret <= 0 || ret > size || memcmp(buffer, compare, ret))
return -1;
size -= ret;
buffer += ret;
}
return 0;
}
static int compare_data(struct cache_entry *ce, unsigned long expected_size)
{
int match = -1;
int fd = open(ce->name, O_RDONLY);
if (fd >= 0) {
void *buffer;
unsigned long size;
char type[10];
buffer = read_sha1_file(ce->sha1, type, &size);
if (buffer) {
if (size == expected_size && !strcmp(type, "blob"))
match = match_data(fd, buffer, size);
free(buffer);
}
close(fd);
}
return match;
}
/*
* "refresh" does not calculate a new sha1 file or bring the
* cache up-to-date for mode/content changes. But what it
* _does_ do is to "re-match" the stat information of a file
* with the cache, so that you can refresh the cache for a
* file that hasn't been changed but where the stat entry is
* out of date.
*
* For example, you'd want to do this after doing a "read-tree",
* to link up the stat cache details with the proper files.
*/
static struct cache_entry *refresh_entry(struct cache_entry *ce)
{
struct stat st;
struct cache_entry *updated;
int changed, size;
if (stat(ce->name, &st) < 0)
return ERR_PTR(-errno);
changed = cache_match_stat(ce, &st);
if (!changed)
return ce;
/*
* If the mode has changed, there's no point in trying
* to refresh the entry - it's not going to match
*/
if (changed & MODE_CHANGED)
return ERR_PTR(-EINVAL);
if (compare_data(ce, st.st_size))
return ERR_PTR(-EINVAL);
size = ce_size(ce);
updated = xmalloc(size);
memcpy(updated, ce, size);
fill_stat_cache_info(updated, &st);
return updated;
}
static void refresh_cache(void)
{
int i;
for (i = 0; i < active_nr; i++) {
struct cache_entry *ce, *new;
ce = active_cache[i];
if (ce_stage(ce)) {
printf("%s: needs merge\n", ce->name);
while ((i < active_nr) &&
! strcmp(active_cache[i]->name, ce->name))
i++;
i--;
continue;
}
new = refresh_entry(ce);
if (IS_ERR(new)) {
if (!(not_new && PTR_ERR(new) == -ENOENT))
printf("%s: needs update\n", ce->name);
continue;
}
active_cache[i] = new;
}
}
/*
* We fundamentally don't like some paths: we don't want
* dot or dot-dot anywhere, and in fact, we don't even want
* any other dot-files (.git or anything else). They
* are hidden, for chist sake.
*
* Also, we don't want double slashes or slashes at the
* end that can make pathnames ambiguous.
*/
static int verify_path(char *path)
{
char c;
goto inside;
for (;;) {
if (!c)
return 1;
if (c == '/') {
inside:
c = *path++;
if (c != '/' && c != '.' && c != '\0')
continue;
return 0;
}
c = *path++;
}
}
static int add_cacheinfo(char *arg1, char *arg2, char *arg3)
{
int size, len;
unsigned int mode;
unsigned char sha1[20];
struct cache_entry *ce;
if (sscanf(arg1, "%o", &mode) != 1)
return -1;
if (get_sha1_hex(arg2, sha1))
return -1;
if (!verify_path(arg3))
return -1;
len = strlen(arg3);
size = cache_entry_size(len);
ce = xmalloc(size);
memset(ce, 0, size);
memcpy(ce->sha1, sha1, 20);
memcpy(ce->name, arg3, len);
ce->ce_flags = htons(len);
ce->ce_mode = create_ce_mode(mode);
return add_cache_entry(ce, allow_add);
}
static const char *lockfile_name = NULL;
static void remove_lock_file(void)
{
if (lockfile_name)
unlink(lockfile_name);
}
static void remove_lock_file_on_signal(int signo)
{
remove_lock_file();
}
int main(int argc, char **argv)
{
int i, newfd, entries;
int allow_options = 1;
static char lockfile[MAXPATHLEN+1];
const char *indexfile = get_index_file();
snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);
newfd = open(lockfile, O_RDWR | O_CREAT | O_EXCL, 0600);
if (newfd < 0)
die("unable to create new cachefile");
signal(SIGINT, remove_lock_file_on_signal);
atexit(remove_lock_file);
lockfile_name = lockfile;
entries = read_cache();
if (entries < 0)
die("cache corrupted");
for (i = 1 ; i < argc; i++) {
char *path = argv[i];
if (allow_options && *path == '-') {
if (!strcmp(path, "--")) {
allow_options = 0;
continue;
}
if (!strcmp(path, "--add")) {
allow_add = 1;
continue;
}
if (!strcmp(path, "--remove")) {
allow_remove = 1;
continue;
}
if (!strcmp(path, "--refresh")) {
refresh_cache();
continue;
}
if (!strcmp(path, "--cacheinfo")) {
if (i+3 >= argc || add_cacheinfo(argv[i+1], argv[i+2], argv[i+3]))
die("update-cache: --cacheinfo <mode> <sha1> <path>");
i += 3;
continue;
}
if (!strcmp(path, "--ignore-missing")) {
not_new = 1;
continue;
}
die("unknown option %s", path);
}
if (!verify_path(path)) {
fprintf(stderr, "Ignoring path %s\n", argv[i]);
continue;
}
if (add_file_to_cache(path))
die("Unable to add %s to database", path);
}
if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
die("Unable to write new cachefile");
lockfile_name = NULL;
return 0;
}