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Do not loop flock()

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There's no need to loop until flock was successfully as flock() would simply
block till a previous lock has been released.
There's more to do to fix it properly, see my comments in the patch.

Reported-by: James Le Cuirot <chewi@aura-online.co.uk>
X-Gentoo-Bug: 360013
X-Gentoo-Bug-URL: https://bugs.gentoo.org/360013
This commit is contained in:
Christian Ruppert 2012-01-28 16:40:49 +01:00
parent 58e04035ed
commit 6be8a0679b
1 changed files with 21 additions and 7 deletions
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28
src/rc/runscript.c
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@ -288,6 +288,13 @@ cleanup(void)
#endif
}
/* Buffer and lock all output messages so that we get readable content */
/* FIXME: Use a dynamic lock file that contains the tty/pts as well.
* For example openrc-pts8.lock or openrc-tty1.lock.
* Using a static lock file makes no sense, esp. in multi-user environments.
* Why don't we use (f)printf, as it is thread-safe through POSIX already?
* Bug: 360013
*/
static int
write_prefix(const char *buffer, size_t bytes, bool *prefixed)
{
@ -297,14 +304,20 @@ write_prefix(const char *buffer, size_t bytes, bool *prefixed)
ssize_t ret = 0;
int fd = fileno(stdout), lock_fd = -1;
/* Spin until we lock the prefix */
for (;;) {
lock_fd = open(PREFIX_LOCK, O_WRONLY | O_CREAT, 0664);
if (lock_fd != -1)
if (flock(lock_fd, LOCK_EX) == 0)
break;
close(lock_fd);
/*
* Lock the prefix.
* open() may fail here when running as user, as RC_SVCDIR may not be writable.
*/
lock_fd = open(PREFIX_LOCK, O_WRONLY | O_CREAT, 0664);
if (lock_fd != -1) {
if (flock(lock_fd, LOCK_EX) != 0)
eerror("flock() failed: %s", strerror(errno));
}
#ifdef RC_DEBUG
else
ewarn("Couldn't open the prefix lock, please make sure you have enough permissions");
#endif
for (i = 0; i < bytes; i++) {
/* We don't prefix eend calls (cursor up) */
@ -332,6 +345,7 @@ write_prefix(const char *buffer, size_t bytes, bool *prefixed)
/* Release the lock */
close(lock_fd);
return ret;
}