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git/refs.c
Junio C Hamano 40aaae88ad Better error message when we are unable to lock the index file
Most of the callers except the one in refs.c use the function to
update the index file.  Among the index writers, everybody
except write-tree dies if they cannot open it for writing.

This gives the function an extra argument, to tell it to die
when it cannot create a new file as the lockfile.

The only caller that does not have to die is write-tree, because
updating the index for the cache-tree part is optional and not
being able to do so does not affect the correctness.  I think we
do not have to be so careful and make the failure into die() the
same way as other callers, but that would be a different patch.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-08-12 17:08:25 -07:00

518 lines
12 KiB
C

#include "refs.h"
#include "cache.h"
#include <errno.h>
/* We allow "recursive" symbolic refs. Only within reason, though */
#define MAXDEPTH 5
const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
{
int depth = MAXDEPTH, len;
char buffer[256];
for (;;) {
struct stat st;
char *buf;
int fd;
if (--depth < 0)
return NULL;
/* Special case: non-existing file.
* Not having the refs/heads/new-branch is OK
* if we are writing into it, so is .git/HEAD
* that points at refs/heads/master still to be
* born. It is NOT OK if we are resolving for
* reading.
*/
if (lstat(path, &st) < 0) {
if (reading || errno != ENOENT)
return NULL;
memset(sha1, 0, 20);
return path;
}
/* Follow "normalized" - ie "refs/.." symlinks by hand */
if (S_ISLNK(st.st_mode)) {
len = readlink(path, buffer, sizeof(buffer)-1);
if (len >= 5 && !memcmp("refs/", buffer, 5)) {
path = git_path("%.*s", len, buffer);
continue;
}
}
/*
* Anything else, just open it and try to use it as
* a ref
*/
fd = open(path, O_RDONLY);
if (fd < 0)
return NULL;
len = read(fd, buffer, sizeof(buffer)-1);
close(fd);
/*
* Is it a symbolic ref?
*/
if (len < 4 || memcmp("ref:", buffer, 4))
break;
buf = buffer + 4;
len -= 4;
while (len && isspace(*buf))
buf++, len--;
while (len && isspace(buf[len-1]))
buf[--len] = 0;
path = git_path("%.*s", len, buf);
}
if (len < 40 || get_sha1_hex(buffer, sha1))
return NULL;
return path;
}
int create_symref(const char *git_HEAD, const char *refs_heads_master)
{
const char *lockpath;
char ref[1000];
int fd, len, written;
#ifndef NO_SYMLINK_HEAD
if (prefer_symlink_refs) {
unlink(git_HEAD);
if (!symlink(refs_heads_master, git_HEAD))
return 0;
fprintf(stderr, "no symlink - falling back to symbolic ref\n");
}
#endif
len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
if (sizeof(ref) <= len) {
error("refname too long: %s", refs_heads_master);
return -1;
}
lockpath = mkpath("%s.lock", git_HEAD);
fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
written = write(fd, ref, len);
close(fd);
if (written != len) {
unlink(lockpath);
error("Unable to write to %s", lockpath);
return -2;
}
if (rename(lockpath, git_HEAD) < 0) {
unlink(lockpath);
error("Unable to create %s", git_HEAD);
return -3;
}
if (adjust_shared_perm(git_HEAD)) {
unlink(lockpath);
error("Unable to fix permissions on %s", lockpath);
return -4;
}
return 0;
}
int read_ref(const char *filename, unsigned char *sha1)
{
if (resolve_ref(filename, sha1, 1))
return 0;
return -1;
}
static int do_for_each_ref(const char *base, int (*fn)(const char *path, const unsigned char *sha1), int trim)
{
int retval = 0;
DIR *dir = opendir(git_path("%s", base));
if (dir) {
struct dirent *de;
int baselen = strlen(base);
char *path = xmalloc(baselen + 257);
if (!strncmp(base, "./", 2)) {
base += 2;
baselen -= 2;
}
memcpy(path, base, baselen);
if (baselen && base[baselen-1] != '/')
path[baselen++] = '/';
while ((de = readdir(dir)) != NULL) {
unsigned char sha1[20];
struct stat st;
int namelen;
if (de->d_name[0] == '.')
continue;
namelen = strlen(de->d_name);
if (namelen > 255)
continue;
if (has_extension(de->d_name, ".lock"))
continue;
memcpy(path + baselen, de->d_name, namelen+1);
if (stat(git_path("%s", path), &st) < 0)
continue;
if (S_ISDIR(st.st_mode)) {
retval = do_for_each_ref(path, fn, trim);
if (retval)
break;
continue;
}
if (read_ref(git_path("%s", path), sha1) < 0) {
error("%s points nowhere!", path);
continue;
}
if (!has_sha1_file(sha1)) {
error("%s does not point to a valid "
"commit object!", path);
continue;
}
retval = fn(path + trim, sha1);
if (retval)
break;
}
free(path);
closedir(dir);
}
return retval;
}
int head_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
unsigned char sha1[20];
if (!read_ref(git_path("HEAD"), sha1))
return fn("HEAD", sha1);
return 0;
}
int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
return do_for_each_ref("refs", fn, 0);
}
int for_each_tag_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
return do_for_each_ref("refs/tags", fn, 10);
}
int for_each_branch_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
return do_for_each_ref("refs/heads", fn, 11);
}
int for_each_remote_ref(int (*fn)(const char *path, const unsigned char *sha1))
{
return do_for_each_ref("refs/remotes", fn, 13);
}
int get_ref_sha1(const char *ref, unsigned char *sha1)
{
if (check_ref_format(ref))
return -1;
return read_ref(git_path("refs/%s", ref), sha1);
}
/*
* Make sure "ref" is something reasonable to have under ".git/refs/";
* We do not like it if:
*
* - any path component of it begins with ".", or
* - it has double dots "..", or
* - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
* - it ends with a "/".
*/
static inline int bad_ref_char(int ch)
{
return (((unsigned) ch) <= ' ' ||
ch == '~' || ch == '^' || ch == ':' ||
/* 2.13 Pattern Matching Notation */
ch == '?' || ch == '*' || ch == '[');
}
int check_ref_format(const char *ref)
{
int ch, level;
const char *cp = ref;
level = 0;
while (1) {
while ((ch = *cp++) == '/')
; /* tolerate duplicated slashes */
if (!ch)
return -1; /* should not end with slashes */
/* we are at the beginning of the path component */
if (ch == '.' || bad_ref_char(ch))
return -1;
/* scan the rest of the path component */
while ((ch = *cp++) != 0) {
if (bad_ref_char(ch))
return -1;
if (ch == '/')
break;
if (ch == '.' && *cp == '.')
return -1;
}
level++;
if (!ch) {
if (level < 2)
return -1; /* at least of form "heads/blah" */
return 0;
}
}
}
static struct ref_lock *verify_lock(struct ref_lock *lock,
const unsigned char *old_sha1, int mustexist)
{
char buf[40];
int nr, fd = open(lock->ref_file, O_RDONLY);
if (fd < 0 && (mustexist || errno != ENOENT)) {
error("Can't verify ref %s", lock->ref_file);
unlock_ref(lock);
return NULL;
}
nr = read(fd, buf, 40);
close(fd);
if (nr != 40 || get_sha1_hex(buf, lock->old_sha1) < 0) {
error("Can't verify ref %s", lock->ref_file);
unlock_ref(lock);
return NULL;
}
if (memcmp(lock->old_sha1, old_sha1, 20)) {
error("Ref %s is at %s but expected %s", lock->ref_file,
sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
unlock_ref(lock);
return NULL;
}
return lock;
}
static struct ref_lock *lock_ref_sha1_basic(const char *path,
int plen,
const unsigned char *old_sha1, int mustexist)
{
const char *orig_path = path;
struct ref_lock *lock;
struct stat st;
lock = xcalloc(1, sizeof(struct ref_lock));
lock->lock_fd = -1;
plen = strlen(path) - plen;
path = resolve_ref(path, lock->old_sha1, mustexist);
if (!path) {
int last_errno = errno;
error("unable to resolve reference %s: %s",
orig_path, strerror(errno));
unlock_ref(lock);
errno = last_errno;
return NULL;
}
lock->lk = xcalloc(1, sizeof(struct lock_file));
lock->ref_file = strdup(path);
lock->log_file = strdup(git_path("logs/%s", lock->ref_file + plen));
lock->force_write = lstat(lock->ref_file, &st) && errno == ENOENT;
if (safe_create_leading_directories(lock->ref_file))
die("unable to create directory for %s", lock->ref_file);
lock->lock_fd = hold_lock_file_for_update(lock->lk, lock->ref_file, 1);
return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
}
struct ref_lock *lock_ref_sha1(const char *ref,
const unsigned char *old_sha1, int mustexist)
{
if (check_ref_format(ref))
return NULL;
return lock_ref_sha1_basic(git_path("refs/%s", ref),
5 + strlen(ref), old_sha1, mustexist);
}
struct ref_lock *lock_any_ref_for_update(const char *ref,
const unsigned char *old_sha1, int mustexist)
{
return lock_ref_sha1_basic(git_path("%s", ref),
strlen(ref), old_sha1, mustexist);
}
void unlock_ref(struct ref_lock *lock)
{
if (lock->lock_fd >= 0) {
close(lock->lock_fd);
/* Do not free lock->lk -- atexit() still looks at them */
if (lock->lk)
rollback_lock_file(lock->lk);
}
if (lock->ref_file)
free(lock->ref_file);
if (lock->log_file)
free(lock->log_file);
free(lock);
}
static int log_ref_write(struct ref_lock *lock,
const unsigned char *sha1, const char *msg)
{
int logfd, written, oflags = O_APPEND | O_WRONLY;
unsigned maxlen, len;
char *logrec;
const char *committer;
if (log_all_ref_updates) {
if (safe_create_leading_directories(lock->log_file) < 0)
return error("unable to create directory for %s",
lock->log_file);
oflags |= O_CREAT;
}
logfd = open(lock->log_file, oflags, 0666);
if (logfd < 0) {
if (!log_all_ref_updates && errno == ENOENT)
return 0;
return error("Unable to append to %s: %s",
lock->log_file, strerror(errno));
}
committer = git_committer_info(1);
if (msg) {
maxlen = strlen(committer) + strlen(msg) + 2*40 + 5;
logrec = xmalloc(maxlen);
len = snprintf(logrec, maxlen, "%s %s %s\t%s\n",
sha1_to_hex(lock->old_sha1),
sha1_to_hex(sha1),
committer,
msg);
}
else {
maxlen = strlen(committer) + 2*40 + 4;
logrec = xmalloc(maxlen);
len = snprintf(logrec, maxlen, "%s %s %s\n",
sha1_to_hex(lock->old_sha1),
sha1_to_hex(sha1),
committer);
}
written = len <= maxlen ? write(logfd, logrec, len) : -1;
free(logrec);
close(logfd);
if (written != len)
return error("Unable to append to %s", lock->log_file);
return 0;
}
int write_ref_sha1(struct ref_lock *lock,
const unsigned char *sha1, const char *logmsg)
{
static char term = '\n';
if (!lock)
return -1;
if (!lock->force_write && !memcmp(lock->old_sha1, sha1, 20)) {
unlock_ref(lock);
return 0;
}
if (write(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
write(lock->lock_fd, &term, 1) != 1
|| close(lock->lock_fd) < 0) {
error("Couldn't write %s", lock->lk->filename);
unlock_ref(lock);
return -1;
}
if (log_ref_write(lock, sha1, logmsg) < 0) {
unlock_ref(lock);
return -1;
}
if (commit_lock_file(lock->lk)) {
error("Couldn't set %s", lock->ref_file);
unlock_ref(lock);
return -1;
}
lock->lock_fd = -1;
unlock_ref(lock);
return 0;
}
int read_ref_at(const char *ref, unsigned long at_time, unsigned char *sha1)
{
const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
char *tz_c;
int logfd, tz;
struct stat st;
unsigned long date;
unsigned char logged_sha1[20];
logfile = git_path("logs/%s", ref);
logfd = open(logfile, O_RDONLY, 0);
if (logfd < 0)
die("Unable to read log %s: %s", logfile, strerror(errno));
fstat(logfd, &st);
if (!st.st_size)
die("Log %s is empty.", logfile);
logdata = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
close(logfd);
lastrec = NULL;
rec = logend = logdata + st.st_size;
while (logdata < rec) {
if (logdata < rec && *(rec-1) == '\n')
rec--;
lastgt = NULL;
while (logdata < rec && *(rec-1) != '\n') {
rec--;
if (*rec == '>')
lastgt = rec;
}
if (!lastgt)
die("Log %s is corrupt.", logfile);
date = strtoul(lastgt + 1, &tz_c, 10);
if (date <= at_time) {
if (lastrec) {
if (get_sha1_hex(lastrec, logged_sha1))
die("Log %s is corrupt.", logfile);
if (get_sha1_hex(rec + 41, sha1))
die("Log %s is corrupt.", logfile);
if (memcmp(logged_sha1, sha1, 20)) {
tz = strtoul(tz_c, NULL, 10);
fprintf(stderr,
"warning: Log %s has gap after %s.\n",
logfile, show_rfc2822_date(date, tz));
}
}
else if (date == at_time) {
if (get_sha1_hex(rec + 41, sha1))
die("Log %s is corrupt.", logfile);
}
else {
if (get_sha1_hex(rec + 41, logged_sha1))
die("Log %s is corrupt.", logfile);
if (memcmp(logged_sha1, sha1, 20)) {
tz = strtoul(tz_c, NULL, 10);
fprintf(stderr,
"warning: Log %s unexpectedly ended on %s.\n",
logfile, show_rfc2822_date(date, tz));
}
}
munmap((void*)logdata, st.st_size);
return 0;
}
lastrec = rec;
}
rec = logdata;
while (rec < logend && *rec != '>' && *rec != '\n')
rec++;
if (rec == logend || *rec == '\n')
die("Log %s is corrupt.", logfile);
date = strtoul(rec + 1, &tz_c, 10);
tz = strtoul(tz_c, NULL, 10);
if (get_sha1_hex(logdata, sha1))
die("Log %s is corrupt.", logfile);
munmap((void*)logdata, st.st_size);
fprintf(stderr, "warning: Log %s only goes back to %s.\n",
logfile, show_rfc2822_date(date, tz));
return 0;
}