yan/archived-lcd4linux
1
0
Fork 0
mirror of https://github.com/netfun2000/lcd4linux.git synced 2026-02-27 09:44:34 +08:00
Code Issues Packages Projects Releases Wiki Activity

[lcd4linux @ 2005-09-02 05:27:08 by reinelt]

Browse Source 
double-fork daemonize patch from Petri Damsten

git-svn-id: https://ssl.bulix.org/svn/lcd4linux/trunk@586 3ae390bd-cb1e-0410-b409-cd5a39f66f1f
This commit is contained in:
reinelt
2005-09-02 05:27:08 +00:00
parent 6696076f07
commit 77693cbb08
1 changed files with 71 additions and 37 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lcd4linux.c
+71 -37
View File
@@ -1,4 +1,4 @@
/* $Id: lcd4linux.c,v 1.78 2005/05/08 04:32:44 reinelt Exp $
/* $Id: lcd4linux.c,v 1.79 2005/09/02 05:27:08 reinelt Exp $
*
* LCD4Linux
*
@@ -23,6 +23,9 @@
*
*
* $Log: lcd4linux.c,v $
* Revision 1.79 2005/09/02 05:27:08 reinelt
* double-fork daemonize patch from Petri Damsten
*
* Revision 1.78 2005/05/08 04:32:44 reinelt
* CodingStyle added and applied
*
@@ -450,6 +453,70 @@ void handler(int signal)
}
static void daemonize(void)
{
/* thanks to Petri Damsten, we now follow the guidelines from the UNIX Programming FAQ */
/* 1.7 How do I get my program to act like a daemon? */
/* http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16 */
/* especially the double-fork solved the 'lcd4linux dying when called from init' problem */
pid_t i;
int fd;
/* Step 1: fork() so that the parent can exit */
i = fork();
if (i < 0) {
error("fork(#1) failed: %s", strerror(errno));
exit(1);
}
if (i != 0)
exit(0);
/* Step 2: setsid() to become a process group and session group leader */
setsid();
/* Step 3: fork() again so the parent (the session group leader) can exit */
i = fork();
if (i < 0) {
error("fork(#2) failed: %s", strerror(errno));
exit(1);
}
if (i != 0)
exit(0);
/* Step 4: chdir("/") to ensure that our process doesn't keep any directory in use */
if (chdir("/") != 0) {
error("chdir(\"/\") failed: %s", strerror(errno));
exit(1);
}
/* Step 5: umask(0) so that we have complete control over the permissions of anything we write */
umask(0);
/* Step 6: Establish new open descriptors for stdin, stdout and stderr */
/* detach stdin */
if (freopen("/dev/null", "r", stdin) == NULL) {
error("freopen (/dev/null) failed: %s", strerror(errno));
exit(1);
}
/* detach stdout and stderr */
fd = open("/dev/null", O_WRONLY, 0666);
if (fd == -1) {
error("open (/dev/null) failed: %s", strerror(errno));
exit(1);
}
fflush(stdout);
dup2(fd, STDOUT_FILENO);
fflush(stderr);
dup2(fd, STDERR_FILENO);
close(fd);
}
int main(int argc, char *argv[])
{
char *cfg = "/etc/lcd4linux.conf";
@@ -546,48 +613,15 @@ int main(int argc, char *argv[])
}
if (!running_foreground) {
pid_t i;
int fd;
debug("going background...");
i = fork();
if (i < 0) {
error("fork() failed: %s", strerror(errno));
exit(1);
}
if (i != 0)
exit(0);
daemonize();
/* ignore nasty signals */
signal(SIGINT, SIG_IGN);
signal(SIGQUIT, SIG_IGN);
/* chdir("/") */
if (chdir("/") != 0) {
error("chdir(\"/\") failed: %s", strerror(errno));
exit(1);
}
/* we want full control over permissions */
umask(0);
/* detach stdin */
if (freopen("/dev/null", "r", stdin) == NULL) {
error("freopen (/dev/null) failed: %s", strerror(errno));
exit(1);
}
/* detach stdout and stderr */
fd = open("/dev/null", O_WRONLY, 0666);
if (fd == -1) {
error("open (/dev/null) failed: %s", strerror(errno));
exit(1);
}
fflush(stdout);
fflush(stderr);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
close(fd);
/* create PID file */
if ((pid = pid_init(PIDFILE)) != 0) {
error("lcd4linux already running as process %d", pid);