Use kill(pid, 0) to check if the process is alive

include/i3status.h

@@ -51,7 +51,7 @@ typedef enum { CS_DISCHARGING, CS_CHARGING, CS_FULL } charging_status_t;
 /* src/general.c */
 char *skip_character(char *input, char character, int amount);
 void die(const char *fmt, ...);
-bool slurp(char *filename, char *destination, int size);
+bool slurp(const char *filename, char *destination, int size);
 
 /* src/output.c */
 void print_seperator();

src/general.c

@@ -13,7 +13,7 @@
  * Reads size bytes into the destination buffer from filename.
  *
  */
-bool slurp(char *filename, char *destination, int size) {
+bool slurp(const char *filename, char *destination, int size) {
         int fd;
 
         if ((fd = open(filename, O_RDONLY)) == -1)

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);
+        if (!slurp((globbuf.gl_pathc > 0 ? globbuf.gl_pathv[0] : path), pidbuf, sizeof(pidbuf))) {
+                globfree(&globbuf);
+                return false;
+        }
         globfree(&globbuf);
-        if (fd < 0)
-                return false;
-        (void)read(fd, pidbuf, sizeof(pidbuf));
-        (void)close(fd);
 
-#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);
 }