From cf091024335052e4774d44179e80e1948da8610f Mon Sep 17 00:00:00 2001
From: Michael Stapelberg <michael@stapelberg.de>
Date: Sun, 28 Nov 2010 16:45:34 +0100
Subject: Use kill(pid, 0) to check if the process is alive

---
 src/process_runs.c | 45 +++++++++++----------------------------------
 1 file changed, 11 insertions(+), 34 deletions(-)

(limited to 'src/process_runs.c')

diff --git a/src/process_runs.c b/src/process_runs.c
index d8513a5..88979f0 100644
--- a/src/process_runs.c
+++ b/src/process_runs.c
@@ -3,54 +3,31 @@
 #include <glob.h>
 #include <string.h>
 #include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
-
-#ifndef LINUX
-/* TODO: correctly check for *BSD */
-#include <sys/param.h>
-#include <sys/sysctl.h>
-#include <sys/resource.h>
-#endif
+#include <errno.h>
+#include <signal.h>
 
 #include "i3status.h"
 
 /*
- * Checks if the PID in path is still valid by checking:
- *  (Linux) if /proc/<pid> exists
- *  (NetBSD) if sysctl returns process infos for this pid
+ * Checks if the PID in path is still valid by sending signal 0 (does not do
+ * anything). kill() will return ESRCH if the process does not exist and 0 or
+ * EPERM (depending on the uid) if it exists.
  *
  */
 bool process_runs(const char *path) {
-        char pidbuf[16];
+        static char pidbuf[16];
         static glob_t globbuf;
-        int fd;
         memset(pidbuf, 0, sizeof(pidbuf));
 
         if (glob(path, GLOB_NOCHECK | GLOB_TILDE, NULL, &globbuf) < 0)
                 die("glob() failed\n");
-        fd = open((globbuf.gl_pathc > 0 ? globbuf.gl_pathv[0] : path), O_RDONLY);
-        globfree(&globbuf);
-        if (fd < 0)
+        if (!slurp((globbuf.gl_pathc > 0 ? globbuf.gl_pathv[0] : path), pidbuf, sizeof(pidbuf))) {
+                globfree(&globbuf);
                 return false;
-        (void)read(fd, pidbuf, sizeof(pidbuf));
-        (void)close(fd);
+        }
+        globfree(&globbuf);
 
-#if defined(LINUX) || defined(__GNU__) || defined(__GLIBC__)
-        struct stat statbuf;
-        char procbuf[512];
-        (void)snprintf(procbuf, sizeof(procbuf), "/proc/%ld", strtol(pidbuf, NULL, 10));
-        return (stat(procbuf, &statbuf) >= 0);
-#else
-        /* TODO: correctly check for NetBSD. Evaluate if this runs on OpenBSD/FreeBSD */
-        struct kinfo_proc info;
-        size_t length = sizeof(struct kinfo_proc);
-        int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID, strtol(pidbuf, NULL, 10) };
-        if (sysctl(mib, 4, &info, &length, NULL, 0) < 0)
-                return false;
-        return (length != 0);
-#endif
+        return (kill(strtol(pidbuf, NULL, 10), 0) == 0 || errno == EPERM);
 }
-- 
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