cosmopolitan/libc/stdio/pclose.c
Justine Tunney 3f0bcdc3ef
Improve cancellations, randomness, and time
- Exhaustively document cancellation points
- Rename SIGCANCEL to SIGTHR just like BSDs
- Further improve POSIX thread cancellations
- Ensure asynchronous cancellations work correctly
- Elevate the quality of getrandom() and getentropy()
- Make futexes cancel correctly on OpenBSD 6.x and 7.x
- Add reboot.com and shutdown.com to examples directory
- Remove underscore prefix from awesome timespec_*() APIs
- Create assertions that help verify our cancellation points
- Remove bad timespec APIs (cmp generalizes eq/ne/gt/gte/lt/lte)
2022-11-05 23:45:32 -07:00

69 lines
3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2021 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/rusage.h"
#include "libc/errno.h"
#include "libc/stdio/stdio.h"
#include "libc/sysv/errfuns.h"
/**
* Closes stream created by popen().
*
* This function may be interrupted or cancelled, however it won't
* actually return until the child process has terminated. Thus we
* always release the resource, and errors are purely advisory.
*
* @return termination status of subprocess, or -1 w/ ECHILD
* @raise ECANCELED if thread was cancelled in masked mode
* @raise ECHILD if child pid didn't exist
* @raise EINTR if signal was delivered
* @cancellationpoint
*/
int pclose(FILE *f) {
int e, rc, ws, pid;
bool iscancelled, wasinterrupted;
pid = f->pid;
fclose(f);
if (!pid) return 0;
iscancelled = false;
wasinterrupted = false;
for (e = errno;;) {
if (wait4(pid, &ws, 0, 0) != -1) {
rc = ws;
break;
} else if (errno == ECANCELED) {
iscancelled = true;
errno = e;
} else if (errno == EINTR) {
wasinterrupted = true;
errno = e;
} else {
rc = echild();
break;
}
}
if (iscancelled) {
return ecanceled();
} else if (wasinterrupted) {
return eintr();
} else {
return rc;
}
}