i3 - improved tiling WM

Wait for the child process to surface the exit status.

Patch status: needinfo

Patch by Wael M. Nasreddine

To apply this patch, use:
curl http://cr.i3wm.org/patch/625/raw.patch | git am

b/i3lock.c

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@@ -6,6 +6,7 @@
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  * See LICENSE for licensing information
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  *
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  */
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+#include <sys/wait.h>
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 #include <stdio.h>
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 #include <stdlib.h>
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 #include <string.h>
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@@ -514,7 +515,7 @@ static int conv_callback(int num_msg, const struct pam_message **msg,
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  * See also man libev(3): "ev_prepare" and "ev_check" - customise your event loop
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  *
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  */
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-static void xcb_got_event(EV_P_ struct ev_io *w, int revents) {
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+static void xcb_got_event(EV_P_ struct ev_io *xcb, int revents) {
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     /* empty, because xcb_prepare_cb and xcb_check_cb are used */
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 }
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@@ -522,7 +523,7 @@ static void xcb_got_event(EV_P_ struct ev_io *w, int revents) {
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  * Flush before blocking (and waiting for new events)
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  *
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  */
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-static void xcb_prepare_cb(EV_P_ ev_prepare *w, int revents) {
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+static void xcb_prepare_cb(EV_P_ ev_prepare *xcb, int revents) {
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     xcb_flush(conn);
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 }
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@@ -531,7 +532,10 @@ static void xcb_prepare_cb(EV_P_ ev_prepare *w, int revents) {
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  * xcb_poll_for_event() which knows better than we can ever know.
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  *
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  */
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-static void xcb_check_cb(EV_P_ ev_check *w, int revents) {
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+static void xcb_check_cb(EV_P_ ev_check *xcb, int revents) {
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+    pid_t cpid, w;
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+    int status;
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+
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     xcb_generic_event_t *event;
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     while ((event = xcb_poll_for_event(conn)) != NULL) {
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@@ -571,11 +575,22 @@ static void xcb_check_cb(EV_P_ ev_check *w, int revents) {
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                      * expect to get another MapNotify, but better be sure… */
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                     dont_fork = true;
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-                    /* In the parent process, we exit */
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-                    if (fork() != 0)
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-                        exit(0);
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+                     cpid = fork();
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+                     if (cpid == -1)
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+                         errx(EXIT_FAILURE, "Couldn't fork.");
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+
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+                     if (cpid == 0) { // Code execured by the child
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+                         ev_loop_fork(EV_DEFAULT);
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+                     } else {         // Code execured by the parent
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+                         do {
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+                             w = waitpid(cpid, &status, WUNTRACED | WCONTINUED);
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+
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+                             if (w == -1)
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+                                 errx(EXIT_FAILURE, "Couldn't wait for the child.");
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+                         } while (!WIFEXITED(status) && !WIFSIGNALED(status));
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-                    ev_loop_fork(EV_DEFAULT);
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+                         exit(EXIT_SUCCESS);
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+                     }
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                 }
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                 break;
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