sbase/setsid.c
FRIGN 6f207dac5f Don't return but _exit after failed exec*() and fork()
Quoting POSIX[0]:
"Care should be taken, also, to call _exit() rather than exit() if exec cannot be used, since
exit() flushes and closes standard I/O channels, thereby damaging the parent process' standard
I/O data structures. (Even with fork(), it is wrong to call exit(), since buffered data would
then be flushed twice.)"

[0]: http://pubs.opengroup.org/onlinepubs/009695399/functions/vfork.html
2015-03-09 01:12:59 +01:00

45 lines
622 B
C

/* See LICENSE file for copyright and license details. */
#include <errno.h>
#include <unistd.h>
#include "util.h"
static void
usage(void)
{
eprintf("usage: %s cmd [arg ...]\n", argv0);
}
int
main(int argc, char *argv[])
{
int savederrno;
ARGBEGIN {
default:
usage();
} ARGEND;
if (!argc)
usage();
if (getpgrp() == getpid()) {
switch (fork()) {
case -1:
weprintf("fork:");
_exit(1);
case 0:
break;
default:
return 0;
}
}
if (setsid() < 0)
eprintf("setsid:");
execvp(argv[0], argv);
savederrno = errno;
weprintf("execvp %s:", argv[0]);
_exit(126 + (savederrno == ENOENT));
}