[pisa-src] r2410 - in trunk/libpisa: sysdep_tun.c util.c

From: Christoph Viethen <christoph.viethen@xxxxxxxxxxxxxx>
To: pisa-src@xxxxxxxxxxxxx
Date: Fri, 14 Jan 2011 17:07:44 +0100
Author: viethen
Date: Fri Jan 14 17:07:44 2011
New Revision: 2410

Log:
Make handling of return value of open() conform to POSIX
(great thing is, this actually fixes a few bugs as well).

Make "point stdin, stdout, stderr to /dev/null" magic in
util.c a little more generic & (hopefully) more obvious.

Modified:
   trunk/libpisa/sysdep_tun.c
   trunk/libpisa/util.c

Modified: trunk/libpisa/sysdep_tun.c
==============================================================================
--- trunk/libpisa/sysdep_tun.c  Mon Jan 10 15:35:48 2011        (r2409)
+++ trunk/libpisa/sysdep_tun.c  Fri Jan 14 17:07:44 2011        (r2410)
@@ -40,7 +40,7 @@
 #ifdef IFF_TUN
     struct ifreq ifr;
 
-    if ((fd_tun = open("/dev/net/tun", O_RDWR)) < 0) {
+    if ((fd_tun = open("/dev/net/tun", O_RDWR)) == -1) {
         pisa_die("Couldn't open tunnel device. Are you root?", EXIT_FAILURE);
     }
 
@@ -59,7 +59,7 @@
 
     for (i = 0; i < 255; i++) {
         snprintf(name, sizeof(name), "/dev/tun%d", i);
-        if ((fd_tun = open(name, O_RDWR)) > 0) {
+        if ((fd_tun = open(name, O_RDWR)) >= 0) {
             snprintf(devicename, len, "tun%d", i);
             return fd_tun;
         }

Modified: trunk/libpisa/util.c
==============================================================================
--- trunk/libpisa/util.c        Mon Jan 10 15:35:48 2011        (r2409)
+++ trunk/libpisa/util.c        Fri Jan 14 17:07:44 2011        (r2410)
@@ -258,8 +258,8 @@
     char pid_str[8];
     int fd, pid, len;
 
-    if (!(fd = open(filename, O_RDWR | O_CREAT, 0644))) {
-        PISA_ERROR("Can't open lock file.");
+    if ((fd = open(filename, O_RDWR | O_CREAT, 0644)) == -1) {
+        PISA_ERROR("Can't open lock file.\n");
         exit(EXIT_FAILURE);
     }
 
@@ -297,29 +297,29 @@
     /* become a process group leader */
     setsid();
 
-    /* point stdin, stdout and stderr to /dev/null so we can't
-     * accidentially mess up a console */
+    /* stdin, stdout and stderr should be the only file descriptors at all
+     * used by our process at this point, so the following operations are
+     * expected to result in all of them pointing to /dev/null
+     * (this should keep us from accidentally messing up a console)
+     */
     close(STDIN_FILENO);
     close(STDOUT_FILENO);
     close(STDERR_FILENO);
 
-    /* no file descriptors should be used at this point, so we expect
-     * the first open call to return 0
-     */
-    if ((result = open("/dev/null", O_RDWR))) {
+    if ((result = open("/dev/null", O_RDWR)) != STDIN_FILENO) {
         PISA_ERROR("pisa_daemonize: open STDIN failed.\n");
     }
-    if (dup(result) != 1) {
+    if (dup(result) != STDOUT_FILENO) {
         PISA_ERROR("pisa_daemonize: dup STDOUT failed.\n");
     }
-    if (dup(result) != 2) {
+    if (dup(result) != STDERR_FILENO) {
         PISA_ERROR("pisa_daemonize: dup STDERR failed.\n");
     }
 
     /* change the current working directory to root in order
      * not to prevent any filesystems from being unmounted
      */
-    if (chdir("/") < 0) {
+    if (chdir("/") == -1) {
         PISA_ERROR("Failed to change current working directory to root.\n");
         exit(EXIT_FAILURE);
     }
-- 
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[pisa-src] r2410 - in trunk/libpisa: sysdep_tun.c util.c

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