i3 - improved tiling WM

i3bar: Don't start child unless status_command

Patch status: merged

Patch by Tony Crisci

Long description:

If a command is passed to `start_child` which is NULL, such as in the
case when there is no `status_command` specified in the bar config, do
not start a child process to listen on stdin.

fixes #1140

To apply this patch, use:
curl http://cr.i3wm.org/patch/355/raw.patch | git am

b/i3bar/src/child.c

20 
@@ -452,10 +452,16 @@ void child_write_output(void) {
21 
 /*
22 
  * Start a child-process with the specified command and reroute stdin.
23 
  * We actually start a $SHELL to execute the command so we don't have to care
24 
- * about arguments and such
25 
+ * about arguments and such.
26 
+ *
27 
+ * If `command' is NULL, such as in the case when no `status_command' is given
28 
+ * in the bar config, no child will be started.
29 
  *
30 
  */
31 
 void start_child(char *command) {
32 
+    if (command == NULL)
33 
+        return;
34 
+
35 
     /* Allocate a yajl parser which will be used to parse stdin. */
36 
     memset(&callbacks, '\0', sizeof(yajl_callbacks));
37 
     callbacks.yajl_map_key = stdin_map_key;
38 
@@ -478,43 +484,41 @@ void start_child(char *command) {
39 
     gen = yajl_gen_alloc(NULL);
40 
 #endif
41
42 
-    if (command != NULL) {
43 
-        int pipe_in[2]; /* pipe we read from */
44 
-        int pipe_out[2]; /* pipe we write to */
45 
+    int pipe_in[2]; /* pipe we read from */
46 
+    int pipe_out[2]; /* pipe we write to */
47
48 
-        if (pipe(pipe_in) == -1)
49 
-            err(EXIT_FAILURE, "pipe(pipe_in)");
50 
-        if (pipe(pipe_out) == -1)
51 
-            err(EXIT_FAILURE, "pipe(pipe_out)");
52 
+    if (pipe(pipe_in) == -1)
53 
+        err(EXIT_FAILURE, "pipe(pipe_in)");
54 
+    if (pipe(pipe_out) == -1)
55 
+        err(EXIT_FAILURE, "pipe(pipe_out)");
56
57 
-        child.pid = fork();
58 
-        switch (child.pid) {
59 
-            case -1:
60 
-                ELOG("Couldn't fork(): %s\n", strerror(errno));
61 
-                exit(EXIT_FAILURE);
62 
-            case 0:
63 
-                /* Child-process. Reroute streams and start shell */
64 
+    child.pid = fork();
65 
+    switch (child.pid) {
66 
+        case -1:
67 
+            ELOG("Couldn't fork(): %s\n", strerror(errno));
68 
+            exit(EXIT_FAILURE);
69 
+        case 0:
70 
+            /* Child-process. Reroute streams and start shell */
71
72 
-                close(pipe_in[0]);
73 
-                close(pipe_out[1]);
74 
+            close(pipe_in[0]);
75 
+            close(pipe_out[1]);
76
77 
-                dup2(pipe_in[1], STDOUT_FILENO);
78 
-                dup2(pipe_out[0], STDIN_FILENO);
79 
+            dup2(pipe_in[1], STDOUT_FILENO);
80 
+            dup2(pipe_out[0], STDIN_FILENO);
81
82 
-                setpgid(child.pid, 0);
83 
-                execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, (char*) NULL);
84 
-                return;
85 
-            default:
86 
-                /* Parent-process. Reroute streams */
87 
+            setpgid(child.pid, 0);
88 
+            execl(_PATH_BSHELL, _PATH_BSHELL, "-c", command, (char*) NULL);
89 
+            return;
90 
+        default:
91 
+            /* Parent-process. Reroute streams */
92
93 
-                close(pipe_in[1]);
94 
-                close(pipe_out[0]);
95 
+            close(pipe_in[1]);
96 
+            close(pipe_out[0]);
97
98 
-                dup2(pipe_in[0], STDIN_FILENO);
99 
-                child_stdin = pipe_out[1];
100 
+            dup2(pipe_in[0], STDIN_FILENO);
101 
+            child_stdin = pipe_out[1];
102
103 
-                break;
104 
-        }
105 
+            break;
106 
     }
107
108 
     /* We set O_NONBLOCK because blocking is evil in event-driven software */

b/i3bar/src/config.c

113 
@@ -127,10 +127,6 @@ static int config_string_cb(void *params_, const unsigned char *val, unsigned in
114 
     }
115
116 
     if (!strcmp(cur_key, "status_command")) {
117 
-        /* We cannot directly start the child here, because start_child() also
118 
-         * needs to be run when no command was specified (to setup stdin).
119 
-         * Therefore we save the command in 'config' and access it later in
120 
-         * got_bar_config() */
121 
         DLOG("command = %.*s\n", len, val);
122 
         sasprintf(&config.command, "%.*s", len, val);
123 
         return 1;

b/i3bar/src/ipc.c

128 
@@ -100,9 +100,6 @@ void got_bar_config(char *reply) {
129 
     /* Resolve color strings to colorpixels and save them, then free the strings. */
130 
     init_colors(&(config.colors));
131
132 
-    /* The name of this function is actually misleading. Even if no command is
133 
-     * specified, this function initiates the watchers to listen on stdin and
134 
-     * react accordingly */
135 
     start_child(config.command);
136 
     FREE(config.command);
137 
 }