rework how spawning processes works. this prevents programs that flush to

stderr splode

diff --git a/scrotwm.c b/scrotwm.c
index 9dadbee..97f4c08 100644 (file)
--- a/scrotwm.c
+++ b/scrotwm.c
@@ -66,6 +66,7 @@ static const char     *cvstag = "$scrotwm$";
 #include <string.h>
 #include <util.h>
 #include <pwd.h>
+#include <paths.h>
 #include <ctype.h>
 
 #include <sys/types.h>
@@ -1251,39 +1252,56 @@ find_window(Window id)
 void
 spawn(struct swm_region *r, union arg *args)
 {
-       char                    *ret;
-       int                     si;
+       int                     fd;
+       char                    *ret = NULL;
 
        DNPRINTF(SWM_D_MISC, "spawn: %s\n", args->argv[0]);
-       /*
-        * The double-fork construct avoids zombie processes and keeps the code
-        * clean from stupid signal handlers.
-        */
+
        if (fork() == 0) {
-               if (fork() == 0) {
-                       if (display)
-                               close(ConnectionNumber(display));
-                       setenv("LD_PRELOAD", SWM_LIB, 1);
-                       if (asprintf(&ret, "%d", r->ws->idx)) {
-                               setenv("_SWM_WS", ret, 1);
-                               free(ret);
-                       }
-                       if (asprintf(&ret, "%d", getpid())) {
-                               setenv("_SWM_PID", ret, 1);
-                               free(ret);
-                       }
-                       setsid();
-                       /* kill stdin, mplayer, ssh-add etc. need that */
-                       si = open("/dev/null", O_RDONLY, 0);
-                       if (si == -1)
-                               err(1, "open /dev/null");
-                       if (dup2(si, 0) == -1)
-                               err(1, "dup2 /dev/null");
-                       execvp(args->argv[0], args->argv);
-                       fprintf(stderr, "execvp failed\n");
-                       perror(" failed");
+               if (display)
+                       close(ConnectionNumber(display));
+
+               setenv("LD_PRELOAD", SWM_LIB, 1);
+
+               if (asprintf(&ret, "%d", r->ws->idx) == -1) {
+                       perror("_SWM_WS");
+                       _exit(1);
                }
-               exit(0);
+               setenv("_SWM_WS", ret, 1);
+               free(ret);
+               ret = NULL;
+
+               if (asprintf(&ret, "%d", getpid()) == -1) {
+                       perror("_SWM_PID");
+                       _exit(1);
+               }
+               setenv("_SWM_PID", ret, 1);
+               free(ret);
+               ret = NULL;
+
+               if (setsid() == -1) {
+                       perror("setsid");
+                       _exit(1);
+               }
+
+               /*
+                * close stdin and stdout to prevent interaction between apps
+                * and the baraction script
+                * leave stderr open to record errors
+               */
+               if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) == -1) {
+                       perror("open");
+                       _exit(1);
+               }
+               dup2(fd, STDIN_FILENO);
+               dup2(fd, STDOUT_FILENO);
+               if (fd > 2)
+                       close(fd);
+
+               execvp(args->argv[0], args->argv);
+
+               perror("execvp");
+               _exit(1);
        }
 }