Commit a1fafc4a96e07d20678a243d2f158c4a3f06a17a - pseudo

Try to handle blocking open. This is a heck of a special case: If you call open on a FIFO/pipe, and you didn't have O_NONBLOCK, and you used O_RDONLY or O_WRONLY, but not O_RDWR, the open can block forever. Unfortunately, pseudo assumes syscalls complete. We attempt to drop the lock and restore our state, then recover it later. Why? Because the .NET runtime does this for a debug hook. Seebs 5 years ago

2 changed file(s) with 41 addition(s) and 0 deletion(s). Raw diff Collapse all Expand all

-0

ChangeLog.txt less more

	0	2019-04-10:
	1	* (seebs) Experimental workaround for special non-blocking open
	2	case.
	3
0	4	2019-04-09:
1	5	* (seebs) Partial fix for db corruption issue.
2	6	* (seebs) Make a glibc renameat2 wrapper that just fails because

+37

-0

ports/linux/guts/openat.c less more

6	6	* int rc = -1;
7	7	*/
8	8	struct stat64 buf;
	9	int overly_magic_nonblocking = 0;
9	10	int existed = 1;
10	11	int save_errno;
	12	sigset_t local_saved_sigmask;
11	13
12	14	/* mask out mode bits appropriately */
13	15	mode = mode & ~pseudo_umask;

60	62	errno = save_errno;
61	63	}
62	64
	65	/* if a pipe is opened without O_NONBLOCK, for only reading or
	66	* only writing, it can block forever. We need to do extra magic
	67	* in that case...
	68	*/
	69	if (!(flags & O_NONBLOCK) && ((flags & (O_WRONLY \| O_RDONLY \| O_RDWR)) != O_RDWR)) {
	70	save_errno = errno;
	71	#ifdef PSEUDO_NO_REAL_AT_FUNCTIONS
	72	rc = real___xstat64(_STAT_VER, path, &buf);
	73	#else
	74	rc = real___fxstatat64(_STAT_VER, dirfd, path, &buf, 0);
	75	#endif
	76	if (rc != -1 && S_ISFIFO(buf.st_mode)) {
	77	overly_magic_nonblocking = 1;
	78	}
	79	}
	80
	81	/* this is a horrible special case and i do not know whether it will work */
	82	if (overly_magic_nonblocking) {
	83	pseudo_droplock();
	84	sigprocmask(SIG_SETMASK, &pseudo_saved_sigmask, &local_saved_sigmask);
	85	}
63	86	/* because we are not actually root, secretly mask in 0600 to the
64	87	* underlying mode. The ", 0" is because the only time mode matters
65	88	* is if a file is going to be created, in which case it's

70	93	#else
71	94	rc = real_openat(dirfd, path, flags, PSEUDO_FS_MODE(mode, 0));
72	95	#endif
	96	if (overly_magic_nonblocking) {
	97	save_errno = errno;
	98	sigprocmask(SIG_SETMASK, &local_saved_sigmask, NULL);
	99	/* well this is a problem. we can't NOT proceed; we may have
	100	* already opened the file! we can't even return up the call
	101	* stack to stuff that's going to try to drop the lock.
	102	*/
	103	if (pseudo_getlock()) {
	104	pseudo_diag("PANIC: after opening a readonly/writeonly FIFO (path '%s', fd %d, errno %d, saved errno %d), could not regain lock. unrecoverable. sorry. bye.\n",
	105	path, rc, errno, save_errno);
	106	abort();
	107	}
	108	errno = save_errno;
	109	}
73	110
74	111	if (rc != -1) {
75	112	save_errno = errno;