slb

commit 159fd290d1bb6beb78bf775a4848122933713c95
parent d374e71cc2617393e7c01cc05bd15e8646df9347
Author: zerous Naveen Narayanan <zerous@nocebo.space>
Date:   Wed, 30 Oct 2019 20:41:36 +0100

Daemonize slb using daemoninit()

slb is intended to be used as a daemon and hence it doesn't need a
controlling terminal. This function is a template from Stevens APUE.

Diffstat:
M
slb.c
 | 
53
+++++++++++++++++++++++++++++++++++------------------

1 file changed, 35 insertions(+), 18 deletions(-)
diff --git a/slb.c b/slb.c
@@ -10,6 +10,23 @@
 #include "config.h"
 
 int
+daemoninit(void)
+{
+	pid_t p;
+
+	if ((p = fork()) == -1)
+		return -1;
+	else if (p != 0)
+		exit(0);
+
+	setsid();
+	chdir("/root");
+	umask(0);
+
+	return 0;
+}
+
+int
 pwread(const char *bat)
 {
 	char buf[4];
@@ -41,28 +58,28 @@ main(int argc, char **argv)
 	int t;
 	pid_t p;
 
-	
-	for (;;) {
-		tpow = 0;
-
-		for (int i = 0; i < sizeof(bat)/sizeof(*bat); i++) {
-			tpow += pwread(bat[i]);
-		}
+	if (!daemoninit())
+		for (;;) {
+			tpow = 0;
 
-		if (!pwread(ac) && (tpow < threshold)) {
-			if ((p = fork()) == -1)
-				err(1, "fork failed");
-			else if (p > 0) {
-				wait(NULL);
+			for (int i = 0; i < sizeof(bat)/sizeof(*bat); i++) {
+				tpow += pwread(bat[i]);
 			}
-			else if (p == 0) {
-				if ((t = execve(cmd,NULL,NULL)) == -1)
-					err(1, "execve failed");
+
+			if (!pwread(ac) && (tpow < threshold)) {
+				if ((p = fork()) == -1)
+					err(1, "fork failed");
+				else if (p > 0) {
+					wait(NULL);
+				}
+				else if (p == 0) {
+					if ((t = execve(cmd,NULL,NULL)) == -1)
+						err(1, "execve failed");
+				}
 			}
-		}
 
-		sleep(delay);
-	}
+			sleep(delay);
+		}
 
 	return 0;
 }