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add daemonizing function; modify test of copy running

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This commit is contained in:
Edward Emelianov
2026-03-31 11:51:41 +03:00
parent 3b6d262583
commit a2b7977866
4 changed files with 143 additions and 32 deletions
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67
daemon.c
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@@ -21,6 +21,7 @@
#include <stdio.h> // printf, fopen, ...
#include <unistd.h> // getpid
#include <signal.h>
#include <stdio.h> // perror
#include <sys/types.h> // opendir
#include <dirent.h> // opendir
@@ -73,42 +74,19 @@ void WEAK sl_iffound_deflt(pid_t pid){
/**
* check wether there is a same running process
* exit if there is a running process or error
* Checking have 3 steps:
* 1) lock executable file
* 2) check pidfile (if you run a copy?)
* 3) check /proc for executables with the same name (no/wrong pidfile)
* @param selfname - argv[0] or NULL for non-locking
* Checking have 2 steps:
* 1) check pidfile and its owner (if you run a copy?)
* 2) check /proc for executables with the same name (no/wrong pidfile)
* @param selfname - deprecated, maybe remove in next versions
* @param pidfilename - name of pidfile or NULL if none
*/
void sl_check4running(char *selfname, char *pidfilename){
void sl_check4running(char _U_ *selfname, char *pidfilename){
DIR *dir;
FILE *pidfile, *fself;
FILE *pidfile;
struct dirent *de;
struct stat s_buf;
pid_t pid = 0, self;
struct flock fl;
char *name, *myname;
if(selfname){ // block self
fself = fopen(selfname, "r"); // open self binary to lock
if(!fself){
WARN("fopen()");
goto selfpid;
}
memset(&fl, 0, sizeof(struct flock));
fl.l_type = F_WRLCK;
if(fcntl(fileno(fself), F_GETLK, &fl) == -1){ // check locking
WARN("fcntl()");
goto selfpid;
}
if(fl.l_type != F_UNLCK){ // file is locking - exit
sl_iffound_deflt(fl.l_pid);
}
fl.l_type = F_RDLCK;
if(fcntl(fileno(fself), F_SETLKW, &fl) == -1){
WARN("fcntl()");
}
}
selfpid:
self = getpid(); // get self PID
if(!(dir = opendir(PROC_BASE))){ // open /proc directory
ERR(PROC_BASE);
@@ -120,9 +98,11 @@ void sl_check4running(char *selfname, char *pidfilename){
if(pidfilename && stat(pidfilename, &s_buf) == 0){ // pidfile exists
pidfile = fopen(pidfilename, "r");
if(pidfile){
if(fscanf(pidfile, "%d", &pid) > 0){ // read PID of (possibly) running process
if((name = sl_getPSname(pid)) && strncmp(name, myname, 255) == 0)
if(fscanf(pidfile, "%d", &pid) == 1){ // read PID of (possibly) running process
if((name = sl_getPSname(pid)) && strncmp(name, myname, 255) == 0){
sl_iffound_deflt(pid);
exit(1); // run `exit` if user forgot to do it himself
}
}
fclose(pidfile);
}
@@ -131,8 +111,10 @@ void sl_check4running(char *selfname, char *pidfilename){
while((de = readdir(dir))){ // scan /proc
if(!(pid = (pid_t)atoi(de->d_name)) || pid == self) // pass non-PID files and self
continue;
if((name = sl_getPSname(pid)) && strncmp(name, myname, 255) == 0)
if((name = sl_getPSname(pid)) && strncmp(name, myname, 255) == 0){
sl_iffound_deflt(pid);
exit(1);
}
}
closedir(dir);
free(myname);
@@ -143,3 +125,24 @@ void sl_check4running(char *selfname, char *pidfilename){
fclose(pidfile);
}
}
/**
* @brief sl_daemonize - prepare for daemonize:
* - close stdin/out/err and reopen to /dev/null
* - croot /
* - umask(0)
* - ignore SIGHUP
* @return non-zero if failed
*/
int sl_daemonize(){
if(chdir("/")) return -1;
umask(0);
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
if(open("/dev/null", O_RDWR) < 0) return -1;
if(dup(0) < 0) return -1;
if(dup(0) < 0) return -1;
if(SIG_ERR == signal(SIGHUP, SIG_IGN)) return -1;
return 0;
}