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Merge branch 'mh/safe-create-leading-directories'

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Code clean-up and protection against concurrent write access to the
ref namespace.

* mh/safe-create-leading-directories:
  rename_tmp_log(): on SCLD_VANISHED, retry
  rename_tmp_log(): limit the number of remote_empty_directories() attempts
  rename_tmp_log(): handle a possible mkdir/rmdir race
  rename_ref(): extract function rename_tmp_log()
  remove_dir_recurse(): handle disappearing files and directories
  remove_dir_recurse(): tighten condition for removing unreadable dir
  lock_ref_sha1_basic(): if locking fails with ENOENT, retry
  lock_ref_sha1_basic(): on SCLD_VANISHED, retry
  safe_create_leading_directories(): add new error value SCLD_VANISHED
  cmd_init_db(): when creating directories, handle errors conservatively
  safe_create_leading_directories(): introduce enum for return values
  safe_create_leading_directories(): always restore slash at end of loop
  safe_create_leading_directories(): split on first of multiple slashes
  safe_create_leading_directories(): rename local variable
  safe_create_leading_directories(): add explicit "slash" pointer
  safe_create_leading_directories(): reduce scope of local variable
  safe_create_leading_directories(): fix format of "if" chaining
This commit is contained in:
Junio C Hamano
2014-01-27 10:45:33 -08:00
parent c380cf85a7 08f555cb82
commit d0956cfa8e
6 changed files with 155 additions and 67 deletions
Download Patch File Download Diff File Expand all files Collapse all files

92
refs.c
View File

@ -2039,6 +2039,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
int type, lflags;
int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
int missing = 0;
int attempts_remaining = 3;
lock = xcalloc(1, sizeof(struct ref_lock));
lock->lock_fd = -1;
@ -2080,7 +2081,7 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
lock->lk = xcalloc(1, sizeof(struct lock_file));
lflags = LOCK_DIE_ON_ERROR;
lflags = 0;
if (flags & REF_NODEREF) {
refname = orig_refname;
lflags |= LOCK_NODEREF;
@ -2093,13 +2094,32 @@ static struct ref_lock *lock_ref_sha1_basic(const char *refname,
if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
lock->force_write = 1;
if (safe_create_leading_directories(ref_file)) {
retry:
switch (safe_create_leading_directories(ref_file)) {
case SCLD_OK:
break; /* success */
case SCLD_VANISHED:
if (--attempts_remaining > 0)
goto retry;
/* fall through */
default:
last_errno = errno;
error("unable to create directory for %s", ref_file);
goto error_return;
}
lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
if (lock->lock_fd < 0) {
if (errno == ENOENT && --attempts_remaining > 0)
/*
* Maybe somebody just deleted one of the
* directories leading to ref_file. Try
* again:
*/
goto retry;
else
unable_to_lock_index_die(ref_file, errno);
}
return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
error_return:
@ -2508,6 +2528,51 @@ int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
*/
#define TMP_RENAMED_LOG "logs/refs/.tmp-renamed-log"
static int rename_tmp_log(const char *newrefname)
{
int attempts_remaining = 4;
retry:
switch (safe_create_leading_directories(git_path("logs/%s", newrefname))) {
case SCLD_OK:
break; /* success */
case SCLD_VANISHED:
if (--attempts_remaining > 0)
goto retry;
/* fall through */
default:
error("unable to create directory for %s", newrefname);
return -1;
}
if (rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
/*
* rename(a, b) when b is an existing
* directory ought to result in ISDIR, but
* Solaris 5.8 gives ENOTDIR. Sheesh.
*/
if (remove_empty_directories(git_path("logs/%s", newrefname))) {
error("Directory not empty: logs/%s", newrefname);
return -1;
}
goto retry;
} else if (errno == ENOENT && --attempts_remaining > 0) {
/*
* Maybe another process just deleted one of
* the directories in the path to newrefname.
* Try again from the beginning.
*/
goto retry;
} else {
error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
newrefname, strerror(errno));
return -1;
}
}
return 0;
}
int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
{
unsigned char sha1[20], orig_sha1[20];
@ -2555,30 +2620,9 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
}
}
if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
error("unable to create directory for %s", newrefname);
if (log && rename_tmp_log(newrefname))
goto rollback;
}
retry:
if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
if (errno==EISDIR || errno==ENOTDIR) {
/*
* rename(a, b) when b is an existing
* directory ought to result in ISDIR, but
* Solaris 5.8 gives ENOTDIR. Sheesh.
*/
if (remove_empty_directories(git_path("logs/%s", newrefname))) {
error("Directory not empty: logs/%s", newrefname);
goto rollback;
}
goto retry;
} else {
error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
newrefname, strerror(errno));
goto rollback;
}
}
logmoved = log;
lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);