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(disassoc): Rewrite for POSIX, return status. Caller changed.

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Problems with the old code:
* Insufficient error checking.
* It used TIOCNOTTY (obsolete BSDism) to get rid of the controlling
  tty, except for hpux || Rel4, where it attempted to use the POSIX
  way, but screwed up.
* It left file descriptors 0, 1, 2 in a somewhat weird state.
This commit is contained in:
Markus Armbruster 2005-10-25 18:42:03 +00:00
parent 551263cb07
commit a6a87af6ed
4 changed files with 44 additions and 34 deletions
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66
src/lib/gen/disassoc.c
View file

@ -25,48 +25,54 @@
*
* ---
*
* disassoc.c: Fork and close
* disassoc.c: Boilerplate daemonization code
*
* Known contributors to this file:
* Doug Hay, 1998
* Markus Armbruster, 2005
*/
/*
* boilerplate daemon code; disassociate from
* the current tty by forking, closing all file
* descriptors, opening slash, and ioctl-ing
* TIOCNOTTY
* See W. Richard Stevens: UNIX Network Programming, Vol. 1
*/
#include <sys/types.h>
#if !defined(_WIN32)
#include <sys/ioctl.h>
#include <unistd.h> /* fork close dup2 */
#endif
#include <fcntl.h>
#include "gen.h"
#include <sys/types.h>
#include <unistd.h>
#include "prototypes.h"
void
int
disassoc(void)
{
#if !defined(_WIN32)
pid_t pid;
int i;
if (fork() != 0)
exit(0);
for (i = 0; i < 2; i++)
(void)close(i);
(void)open("/", O_RDONLY, 0);
(void)dup2(0, 1);
(void)dup2(0, 2);
#if defined hpux || defined Rel4
setsid();
#else
i = open("/dev/tty", O_RDWR, 0);
if (i > 0) {
(void)ioctl(i, TIOCNOTTY, 0);
(void)close(i);
}
#endif
#endif
if ((pid = fork()) < 0)
return -1;
else if (pid)
_exit(0); /* parent */
/* Become session leader of new session, lose controlling tty */
if (setsid() < 0)
return -1;
/* Lose session leader status, so we can't acquire a controlling tty */
if ((pid = fork()) < 0)
return -1;
else if (pid)
_exit(0); /* parent */
/* Note: no controlling tty, therefore no SIGHUP sent */
/* datadir is working directory, that's fine */
/* We opened a bunch of files already, so just close 0..2 */
for (i = 0; i < 3; i++)
close(i);
/* Library code may use 0..2; make sure that's safe */
open("/dev/null", O_RDWR);
dup(0);
dup(0);
return 0;
}