refactor both i3-nagbar starts into src/util.c

With this change, libev >= 4 is a hard dependency. It should be present
in all major linux distributions (even the latest ubuntu LTS).

DEPENDS

@@ -10,7 +10,7 @@
 │ pkg-config  │ 0.25   │ 0.26   │ http://pkgconfig.freedesktop.org/      │
 │ libxcb      │ 1.1.93 │ 1.7    │ http://xcb.freedesktop.org/dist/       │
 │ xcb-util    │ 0.3.3  │ 0.3.8  │ http://xcb.freedesktop.org/dist/       │
-│ libev       │ 4.0    │ 4.04   │ http://libev.schmorp.de/               │
+│ libev       │ 4.0    │ 4.11   │ http://libev.schmorp.de/               │
 │ flex        │ 2.5.35 │ 2.5.35 │ http://flex.sourceforge.net/           │
 │ bison       │ 2.4.1  │ 2.4.1  │ http://www.gnu.org/software/bison/     │
 │ yajl        │ 1.0.8  │ 2.0.1  │ http://lloyd.github.com/yajl/          │

debian/control

@@ -14,7 +14,7 @@ Build-Depends: debhelper (>= 7.0.50~),
                xmlto,
                docbook-xml,
                pkg-config,
-               libev-dev,
+               libev-dev (>= 1:4.04),
                flex,
                bison,
                libyajl-dev,

i3-nagbar/main.c

@@ -10,6 +10,7 @@
  */
 #include <stdio.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 #include <stdlib.h>
 #include <stdbool.h>
@@ -20,6 +21,7 @@
 #include <stdint.h>
 #include <getopt.h>
 #include <limits.h>
+#include <fcntl.h>
 
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
@@ -135,7 +137,38 @@ static void handle_button_release(xcb_connection_t *conn, xcb_button_release_eve
     button_t *button = get_button_at(event->event_x, event->event_y);
     if (!button)
         return;
-    start_application(button->action);
+
+    /* We need to create a custom script containing our actual command
+     * since not every terminal emulator which is contained in
+     * i3-sensible-terminal supports -e with multiple arguments (and not
+     * all of them support -e with one quoted argument either).
+     *
+     * NB: The paths need to be unique, that is, don’t assume users close
+     * their nagbars at any point in time (and they still need to work).
+     * */
+    char *script_path = get_process_filename("nagbar-cmd");
+
+    int fd = open(script_path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IXUSR);
+    if (fd == -1) {
+        warn("Could not create temporary script to store the nagbar command");
+        return;
+    }
+    FILE *script = fdopen(fd, "w");
+    if (script == NULL) {
+        warn("Could not fdopen() temporary script to store the nagbar command");
+        return;
+    }
+    fprintf(script, "#!/bin/sh\nrm %s\n%s", script_path, button->action);
+    /* Also closes fd */
+    fclose(script);
+
+    char *terminal_cmd;
+    sasprintf(&terminal_cmd, "i3-sensible-terminal -e \"%s\"", script_path);
+
+    start_application(terminal_cmd);
+
+    free(terminal_cmd);
+    free(script_path);
 
     /* TODO: unset flag, re-render */
 }

include/config_parser.h

@@ -12,6 +12,8 @@
 
 #include <yajl/yajl_gen.h>
 
+extern pid_t config_error_nagbar_pid;
+
 /*
  * The result of a parse_config call. Currently unused, but the JSON output
  * will be useful in the future when we implement a config parsing IPC command.

include/key_press.h

@@ -10,6 +10,8 @@
 #ifndef I3_KEY_PRESS_H
 #define I3_KEY_PRESS_H
 
+extern pid_t command_error_nagbar_pid;
+
 /**
  * There was a key press. We compare this key code with our bindings table and pass
  * the bound action to parse_command().

include/libi3.h

@@ -355,4 +355,10 @@ xcb_visualtype_t *get_visualtype(xcb_screen_t *screen);
  */
 bool is_debug_build() __attribute__((const));
 
+/**
+ * Returns the name of a temporary file with the specified prefix.
+ *
+ */
+char *get_process_filename(const char *prefix);
+
 #endif

include/util.h

@@ -105,13 +105,6 @@ char *resolve_tilde(const char *path);
  */
 bool path_exists(const char *path);
 
-
-/**
- * Returns the name of a temporary file with the specified prefix.
- *
- */
-char *get_process_filename(const char *prefix);
-
 /**
  * Restart i3 in-place
  * appends -a to argument list to disable autostart
@@ -130,4 +123,23 @@ void *memmem(const void *l, size_t l_len, const void *s, size_t s_len);
 
 #endif
 
+/**
+ * Starts an i3-nagbar instance with the given parameters. Takes care of
+ * handling SIGCHLD and killing i3-nagbar when i3 exits.
+ *
+ * The resulting PID will be stored in *nagbar_pid and can be used with
+ * kill_nagbar() to kill the bar later on.
+ *
+ */
+void start_nagbar(pid_t *nagbar_pid, char *argv[]);
+
+/**
+ * Kills the i3-nagbar process, if *nagbar_pid != -1.
+ *
+ * If wait_for_it is set (restarting i3), this function will waitpid(),
+ * otherwise, ev is assumed to handle it (reloading).
+ *
+ */
+void kill_nagbar(pid_t *nagbar_pid, bool wait_for_it);
+
 #endif

libi3/get_process_filename.c

@@ -0,0 +1,58 @@
+/*
+ * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ * © 2009-2012 Michael Stapelberg and contributors (see also: LICENSE)
+ *
+ */
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <err.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <unistd.h>
+
+#include "libi3.h"
+
+/*
+ * Returns the name of a temporary file with the specified prefix.
+ *
+ */
+char *get_process_filename(const char *prefix) {
+    /* dir stores the directory path for this and all subsequent calls so that
+     * we only create a temporary directory once per i3 instance. */
+    static char *dir = NULL;
+    if (dir == NULL) {
+        /* Check if XDG_RUNTIME_DIR is set. If so, we use XDG_RUNTIME_DIR/i3 */
+        if ((dir = getenv("XDG_RUNTIME_DIR"))) {
+            char *tmp;
+            sasprintf(&tmp, "%s/i3", dir);
+            dir = tmp;
+			struct stat buf;
+			if (stat(dir, &buf) != 0) {
+                if (mkdir(dir, 0700) == -1) {
+                    perror("mkdir()");
+                    return NULL;
+                }
+            }
+        } else {
+            /* If not, we create a (secure) temp directory using the template
+             * /tmp/i3-<user>.XXXXXX */
+            struct passwd *pw = getpwuid(getuid());
+            const char *username = pw ? pw->pw_name : "unknown";
+            sasprintf(&dir, "/tmp/i3-%s.XXXXXX", username);
+            /* mkdtemp modifies dir */
+            if (mkdtemp(dir) == NULL) {
+                perror("mkdtemp()");
+                return NULL;
+            }
+        }
+    }
+    char *filename;
+    sasprintf(&filename, "%s/%s.%d", dir, prefix, getpid());
+    return filename;
+}

src/commands.c

@@ -1602,8 +1602,8 @@ void cmd_exit(I3_CMD) {
  */
 void cmd_reload(I3_CMD) {
     LOG("reloading\n");
-    kill_configerror_nagbar(false);
+    kill_nagbar(&config_error_nagbar_pid, false);
-    kill_commanderror_nagbar(false);
+    kill_nagbar(&command_error_nagbar_pid, false);
     load_configuration(conn, NULL, true);
     x_set_i3_atoms();
     /* Send an IPC event just in case the ws names have changed */

src/config_parser.c

@@ -43,10 +43,7 @@
 #define ystr(str) yajl_gen_string(command_output.json_gen, (unsigned char*)str, strlen(str))
 
 #ifndef TEST_PARSER
-static pid_t configerror_pid = -1;
+pid_t config_error_nagbar_pid = -1;
-/* The path to the temporary script files used by i3-nagbar. We need to keep
- * them around to delete the files in the i3-nagbar SIGCHLD handler. */
-static char *edit_script_path, *pager_script_path;
 static struct context *context;
 #endif
 
@@ -664,93 +661,6 @@ int main(int argc, char *argv[]) {
 
 #else
 
-/*
- * Writes the given command as a shell script to path.
- * Returns true unless something went wrong.
- *
- */
-static bool write_nagbar_script(const char *path, const char *command) {
-    int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IXUSR);
-    if (fd == -1) {
-        warn("Could not create temporary script to store the nagbar command");
-        return false;
-    }
-    write(fd, "#!/bin/sh\n", strlen("#!/bin/sh\n"));
-    write(fd, command, strlen(command));
-    close(fd);
-    return true;
-}
-
-/*
- * Handler which will be called when we get a SIGCHLD for the nagbar, meaning
- * it exited (or could not be started, depending on the exit code).
- *
- */
-static void nagbar_exited(EV_P_ ev_child *watcher, int revents) {
-    ev_child_stop(EV_A_ watcher);
-
-    if (unlink(edit_script_path) != 0)
-        warn("Could not delete temporary i3-nagbar script %s", edit_script_path);
-    if (unlink(pager_script_path) != 0)
-        warn("Could not delete temporary i3-nagbar script %s", pager_script_path);
-
-    if (!WIFEXITED(watcher->rstatus)) {
-        fprintf(stderr, "ERROR: i3-nagbar did not exit normally.\n");
-        return;
-    }
-
-    int exitcode = WEXITSTATUS(watcher->rstatus);
-    printf("i3-nagbar process exited with status %d\n", exitcode);
-    if (exitcode == 2) {
-        fprintf(stderr, "ERROR: i3-nagbar could not be found. Is it correctly installed on your system?\n");
-    }
-
-    configerror_pid = -1;
-}
-
-/* We need ev >= 4 for the following code. Since it is not *that* important (it
- * only makes sure that there are no i3-nagbar instances left behind) we still
- * support old systems with libev 3. */
-#if EV_VERSION_MAJOR >= 4
-/*
- * Cleanup handler. Will be called when i3 exits. Kills i3-nagbar with signal
- * SIGKILL (9) to make sure there are no left-over i3-nagbar processes.
- *
- */
-static void nagbar_cleanup(EV_P_ ev_cleanup *watcher, int revent) {
-    if (configerror_pid != -1) {
-        LOG("Sending SIGKILL (9) to i3-nagbar with PID %d\n", configerror_pid);
-        kill(configerror_pid, SIGKILL);
-    }
-}
-#endif
-
-/*
- * Kills the configerror i3-nagbar process, if any.
- *
- * Called when reloading/restarting.
- *
- * If wait_for_it is set (restarting), this function will waitpid(), otherwise,
- * ev is assumed to handle it (reloading).
- *
- */
-void kill_configerror_nagbar(bool wait_for_it) {
-    if (configerror_pid == -1)
-        return;
-
-    if (kill(configerror_pid, SIGTERM) == -1)
-        warn("kill(configerror_nagbar) failed");
-
-    if (!wait_for_it)
-        return;
-
-    /* When restarting, we don’t enter the ev main loop anymore and after the
-     * exec(), our old pid is no longer watched. So, ev won’t handle SIGCHLD
-     * for us and we would end up with a <defunct> process. Therefore we
-     * waitpid() here. */
-    waitpid(configerror_pid, NULL, 0);
-}
-
 /*
  * Goes through each line of buf (separated by \n) and checks for statements /
  * commands which only occur in i3 v4 configuration files. If it finds any, it
@@ -972,86 +882,6 @@ static void check_for_duplicate_bindings(struct context *context) {
     }
 }
 
-/*
- * Starts an i3-nagbar process which alerts the user that his configuration
- * file contains one or more errors. Also offers two buttons: One to launch an
- * $EDITOR on the config file and another one to launch a $PAGER on the error
- * logfile.
- *
- */
-static void start_configerror_nagbar(const char *config_path) {
-    if (only_check_config)
-        return;
-
-    fprintf(stderr, "Starting i3-nagbar due to configuration errors\n");
-
-    /* We need to create a custom script containing our actual command
-     * since not every terminal emulator which is contained in
-     * i3-sensible-terminal supports -e with multiple arguments (and not
-     * all of them support -e with one quoted argument either).
-     *
-     * NB: The paths need to be unique, that is, don’t assume users close
-     * their nagbars at any point in time (and they still need to work).
-     * */
-    edit_script_path = get_process_filename("nagbar-cfgerror-edit");
-    pager_script_path = get_process_filename("nagbar-cfgerror-pager");
-
-    configerror_pid = fork();
-    if (configerror_pid == -1) {
-        warn("Could not fork()");
-        return;
-    }
-
-    /* child */
-    if (configerror_pid == 0) {
-        char *edit_command, *pager_command;
-        sasprintf(&edit_command, "i3-sensible-editor \"%s\" && i3-msg reload\n", config_path);
-        sasprintf(&pager_command, "i3-sensible-pager \"%s\"\n", errorfilename);
-        if (!write_nagbar_script(edit_script_path, edit_command) ||
-            !write_nagbar_script(pager_script_path, pager_command))
-            return;
-
-        char *editaction,
-             *pageraction;
-        sasprintf(&editaction, "i3-sensible-terminal -e \"%s\"", edit_script_path);
-        sasprintf(&pageraction, "i3-sensible-terminal -e \"%s\"", pager_script_path);
-        char *argv[] = {
-            NULL, /* will be replaced by the executable path */
-            "-t",
-            (context->has_errors ? "error" : "warning"),
-            "-m",
-            (context->has_errors ?
-             "You have an error in your i3 config file!" :
-             "Your config is outdated. Please fix the warnings to make sure everything works."),
-            "-b",
-            "edit config",
-            editaction,
-            (errorfilename ? "-b" : NULL),
-            (context->has_errors ? "show errors" : "show warnings"),
-            pageraction,
-            NULL
-        };
-        exec_i3_utility("i3-nagbar", argv);
-    }
-
-    /* parent */
-    /* install a child watcher */
-    ev_child *child = smalloc(sizeof(ev_child));
-    ev_child_init(child, &nagbar_exited, configerror_pid, 0);
-    ev_child_start(main_loop, child);
-
-/* We need ev >= 4 for the following code. Since it is not *that* important (it
- * only makes sure that there are no i3-nagbar instances left behind) we still
- * support old systems with libev 3. */
-#if EV_VERSION_MAJOR >= 4
-    /* install a cleanup watcher (will be called when i3 exits and i3-nagbar is
-     * still running) */
-    ev_cleanup *cleanup = smalloc(sizeof(ev_cleanup));
-    ev_cleanup_init(cleanup, nagbar_cleanup);
-    ev_cleanup_start(main_loop, cleanup);
-#endif
-}
-
 /*
  * Parses the given file by first replacing the variables, then calling
  * parse_config and possibly launching i3-nagbar.
@@ -1222,7 +1052,31 @@ void parse_file(const char *f) {
         ELOG("FYI: You are using i3 version " I3_VERSION "\n");
         if (version == 3)
             ELOG("Please convert your configfile first, then fix any remaining errors (see above).\n");
-        start_configerror_nagbar(f);
+
+        char *editaction,
+             *pageraction;
+        sasprintf(&editaction, "i3-sensible-editor \"%s\" && i3-msg reload\n", f);
+        sasprintf(&pageraction, "i3-sensible-pager \"%s\"\n", errorfilename);
+        char *argv[] = {
+            NULL, /* will be replaced by the executable path */
+            "-t",
+            (context->has_errors ? "error" : "warning"),
+            "-m",
+            (context->has_errors ?
+             "You have an error in your i3 config file!" :
+             "Your config is outdated. Please fix the warnings to make sure everything works."),
+            "-b",
+            "edit config",
+            editaction,
+            (errorfilename ? "-b" : NULL),
+            (context->has_errors ? "show errors" : "show warnings"),
+            pageraction,
+            NULL
+        };
+
+        start_nagbar(&config_error_nagbar_pid, argv);
+        free(editaction);
+        free(pageraction);
     }
 
     FREE(context->line_copy);

src/key_press.c

@@ -19,169 +19,7 @@ static int current_nesting_level;
 static bool parse_error_key;
 static bool command_failed;
 
-/* XXX: I don’t want to touch too much of the nagbar code at once, but we
+pid_t command_error_nagbar_pid = -1;
- * should refactor this with src/cfgparse.y into a clean generic nagbar
- * interface. It might come in handy in other situations within i3, too. */
-static char *pager_script_path;
-static pid_t nagbar_pid = -1;
-
-/*
- * Handler which will be called when we get a SIGCHLD for the nagbar, meaning
- * it exited (or could not be started, depending on the exit code).
- *
- */
-static void nagbar_exited(EV_P_ ev_child *watcher, int revents) {
-    ev_child_stop(EV_A_ watcher);
-
-    if (unlink(pager_script_path) != 0)
-        warn("Could not delete temporary i3-nagbar script %s", pager_script_path);
-
-    if (!WIFEXITED(watcher->rstatus)) {
-        fprintf(stderr, "ERROR: i3-nagbar did not exit normally.\n");
-        return;
-    }
-
-    int exitcode = WEXITSTATUS(watcher->rstatus);
-    printf("i3-nagbar process exited with status %d\n", exitcode);
-    if (exitcode == 2) {
-        fprintf(stderr, "ERROR: i3-nagbar could not be found. Is it correctly installed on your system?\n");
-    }
-
-    nagbar_pid = -1;
-}
-
-/* We need ev >= 4 for the following code. Since it is not *that* important (it
- * only makes sure that there are no i3-nagbar instances left behind) we still
- * support old systems with libev 3. */
-#if EV_VERSION_MAJOR >= 4
-/*
- * Cleanup handler. Will be called when i3 exits. Kills i3-nagbar with signal
- * SIGKILL (9) to make sure there are no left-over i3-nagbar processes.
- *
- */
-static void nagbar_cleanup(EV_P_ ev_cleanup *watcher, int revent) {
-    if (nagbar_pid != -1) {
-        LOG("Sending SIGKILL (%d) to i3-nagbar with PID %d\n", SIGKILL, nagbar_pid);
-        kill(nagbar_pid, SIGKILL);
-    }
-}
-#endif
-
-/*
- * Writes the given command as a shell script to path.
- * Returns true unless something went wrong.
- *
- */
-static bool write_nagbar_script(const char *path, const char *command) {
-    int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR | S_IXUSR);
-    if (fd == -1) {
-        warn("Could not create temporary script to store the nagbar command");
-        return false;
-    }
-    write(fd, "#!/bin/sh\n", strlen("#!/bin/sh\n"));
-    write(fd, command, strlen(command));
-    close(fd);
-    return true;
-}
-
-/*
- * Starts an i3-nagbar process which alerts the user that his configuration
- * file contains one or more errors. Also offers two buttons: One to launch an
- * $EDITOR on the config file and another one to launch a $PAGER on the error
- * logfile.
- *
- */
-static void start_commanderror_nagbar(void) {
-    if (nagbar_pid != -1) {
-        DLOG("i3-nagbar for command error already running, not starting again.\n");
-        return;
-    }
-
-    DLOG("Starting i3-nagbar due to command error\n");
-
-    /* We need to create a custom script containing our actual command
-     * since not every terminal emulator which is contained in
-     * i3-sensible-terminal supports -e with multiple arguments (and not
-     * all of them support -e with one quoted argument either).
-     *
-     * NB: The paths need to be unique, that is, don’t assume users close
-     * their nagbars at any point in time (and they still need to work).
-     * */
-    pager_script_path = get_process_filename("nagbar-cfgerror-pager");
-
-    nagbar_pid = fork();
-    if (nagbar_pid == -1) {
-        warn("Could not fork()");
-        return;
-    }
-
-    /* child */
-    if (nagbar_pid == 0) {
-        char *pager_command;
-        sasprintf(&pager_command, "i3-sensible-pager \"%s\"\n", errorfilename);
-        if (!write_nagbar_script(pager_script_path, pager_command))
-            return;
-
-        char *pageraction;
-        sasprintf(&pageraction, "i3-sensible-terminal -e \"%s\"", pager_script_path);
-        char *argv[] = {
-            NULL, /* will be replaced by the executable path */
-            "-t",
-            "error",
-            "-m",
-            "The configured command for this shortcut could not be run successfully.",
-            "-b",
-            "show errors",
-            pageraction,
-            NULL
-        };
-        exec_i3_utility("i3-nagbar", argv);
-    }
-
-    /* parent */
-    /* install a child watcher */
-    ev_child *child = smalloc(sizeof(ev_child));
-    ev_child_init(child, &nagbar_exited, nagbar_pid, 0);
-    ev_child_start(main_loop, child);
-
-/* We need ev >= 4 for the following code. Since it is not *that* important (it
- * only makes sure that there are no i3-nagbar instances left behind) we still
- * support old systems with libev 3. */
-#if EV_VERSION_MAJOR >= 4
-    /* install a cleanup watcher (will be called when i3 exits and i3-nagbar is
-     * still running) */
-    ev_cleanup *cleanup = smalloc(sizeof(ev_cleanup));
-    ev_cleanup_init(cleanup, nagbar_cleanup);
-    ev_cleanup_start(main_loop, cleanup);
-#endif
-}
-
-/*
- * Kills the commanderror i3-nagbar process, if any.
- *
- * Called when reloading/restarting, since the user probably fixed his wrong
- * keybindings.
- *
- * If wait_for_it is set (restarting), this function will waitpid(), otherwise,
- * ev is assumed to handle it (reloading).
- *
- */
-void kill_commanderror_nagbar(bool wait_for_it) {
-    if (nagbar_pid == -1)
-        return;
-
-    if (kill(nagbar_pid, SIGTERM) == -1)
-        warn("kill(configerror_nagbar) failed");
-
-    if (!wait_for_it)
-        return;
-
-    /* When restarting, we don’t enter the ev main loop anymore and after the
-     * exec(), our old pid is no longer watched. So, ev won’t handle SIGCHLD
-     * for us and we would end up with a <defunct> process. Therefore we
-     * waitpid() here. */
-    waitpid(nagbar_pid, NULL, 0);
-}
 
 static int json_boolean(void *ctx, int boolval) {
     DLOG("Got bool: %d, parse_error_key %d, nesting_level %d\n", boolval, parse_error_key, current_nesting_level);
@@ -302,8 +140,23 @@ void handle_key_press(xcb_key_press_event_t *event) {
     if (state != yajl_status_ok) {
         ELOG("Could not parse my own reply. That's weird. reply is %.*s\n", (int)length, reply);
     } else {
-        if (command_failed)
+        if (command_failed) {
-            start_commanderror_nagbar();
+            char *pageraction;
+            sasprintf(&pageraction, "i3-sensible-pager \"%s\"\n", errorfilename);
+            char *argv[] = {
+                NULL, /* will be replaced by the executable path */
+                "-t",
+                "error",
+                "-m",
+                "The configured command for this shortcut could not be run successfully.",
+                "-b",
+                "show errors",
+                pageraction,
+                NULL
+            };
+            start_nagbar(&command_error_nagbar_pid, argv);
+            free(pageraction);
+        }
     }
 
     yajl_free(handle);

src/util.c

@@ -183,44 +183,6 @@ static char **append_argument(char **original, char *argument) {
     return result;
 }
 
-/*
- * Returns the name of a temporary file with the specified prefix.
- *
- */
-char *get_process_filename(const char *prefix) {
-    /* dir stores the directory path for this and all subsequent calls so that
-     * we only create a temporary directory once per i3 instance. */
-    static char *dir = NULL;
-    if (dir == NULL) {
-        /* Check if XDG_RUNTIME_DIR is set. If so, we use XDG_RUNTIME_DIR/i3 */
-        if ((dir = getenv("XDG_RUNTIME_DIR"))) {
-            char *tmp;
-            sasprintf(&tmp, "%s/i3", dir);
-            dir = tmp;
-            if (!path_exists(dir)) {
-                if (mkdir(dir, 0700) == -1) {
-                    perror("mkdir()");
-                    return NULL;
-                }
-            }
-        } else {
-            /* If not, we create a (secure) temp directory using the template
-             * /tmp/i3-<user>.XXXXXX */
-            struct passwd *pw = getpwuid(getuid());
-            const char *username = pw ? pw->pw_name : "unknown";
-            sasprintf(&dir, "/tmp/i3-%s.XXXXXX", username);
-            /* mkdtemp modifies dir */
-            if (mkdtemp(dir) == NULL) {
-                perror("mkdtemp()");
-                return NULL;
-            }
-        }
-    }
-    char *filename;
-    sasprintf(&filename, "%s/%s.%d", dir, prefix, getpid());
-    return filename;
-}
-
 #define y(x, ...) yajl_gen_ ## x (gen, ##__VA_ARGS__)
 #define ystr(str) yajl_gen_string(gen, (unsigned char*)str, strlen(str))
 
@@ -304,8 +266,8 @@ char *store_restart_layout(void) {
 void i3_restart(bool forget_layout) {
     char *restart_filename = forget_layout ? NULL : store_restart_layout();
 
-    kill_configerror_nagbar(true);
+    kill_nagbar(&config_error_nagbar_pid, true);
-    kill_commanderror_nagbar(true);
+    kill_nagbar(&command_error_nagbar_pid, true);
 
     restore_geometry();
 
@@ -382,3 +344,103 @@ void *memmem(const void *l, size_t l_len, const void *s, size_t s_len) {
 }
 
 #endif
+
+/*
+ * Handler which will be called when we get a SIGCHLD for the nagbar, meaning
+ * it exited (or could not be started, depending on the exit code).
+ *
+ */
+static void nagbar_exited(EV_P_ ev_child *watcher, int revents) {
+    ev_child_stop(EV_A_ watcher);
+
+    if (!WIFEXITED(watcher->rstatus)) {
+        ELOG("ERROR: i3-nagbar did not exit normally.\n");
+        return;
+    }
+
+    int exitcode = WEXITSTATUS(watcher->rstatus);
+    DLOG("i3-nagbar process exited with status %d\n", exitcode);
+    if (exitcode == 2) {
+        ELOG("ERROR: i3-nagbar could not be found. Is it correctly installed on your system?\n");
+    }
+
+    *((pid_t*)watcher->data) = -1;
+}
+
+/*
+ * Cleanup handler. Will be called when i3 exits. Kills i3-nagbar with signal
+ * SIGKILL (9) to make sure there are no left-over i3-nagbar processes.
+ *
+ */
+static void nagbar_cleanup(EV_P_ ev_cleanup *watcher, int revent) {
+    pid_t *nagbar_pid = (pid_t*)watcher->data;
+    if (*nagbar_pid != -1) {
+        LOG("Sending SIGKILL (%d) to i3-nagbar with PID %d\n", SIGKILL, *nagbar_pid);
+        kill(*nagbar_pid, SIGKILL);
+    }
+}
+
+/*
+ * Starts an i3-nagbar instance with the given parameters. Takes care of
+ * handling SIGCHLD and killing i3-nagbar when i3 exits.
+ *
+ * The resulting PID will be stored in *nagbar_pid and can be used with
+ * kill_nagbar() to kill the bar later on.
+ *
+ */
+void start_nagbar(pid_t *nagbar_pid, char *argv[]) {
+    if (*nagbar_pid != -1) {
+        DLOG("i3-nagbar already running (PID %d), not starting again.\n", *nagbar_pid);
+        return;
+    }
+
+    *nagbar_pid = fork();
+    if (*nagbar_pid == -1) {
+        warn("Could not fork()");
+        return;
+    }
+
+    /* child */
+    if (*nagbar_pid == 0)
+        exec_i3_utility("i3-nagbar", argv);
+
+    DLOG("Starting i3-nagbar with PID %d\n", *nagbar_pid);
+
+    /* parent */
+    /* install a child watcher */
+    ev_child *child = smalloc(sizeof(ev_child));
+    ev_child_init(child, &nagbar_exited, *nagbar_pid, 0);
+    child->data = nagbar_pid;
+    ev_child_start(main_loop, child);
+
+    /* install a cleanup watcher (will be called when i3 exits and i3-nagbar is
+     * still running) */
+    ev_cleanup *cleanup = smalloc(sizeof(ev_cleanup));
+    ev_cleanup_init(cleanup, nagbar_cleanup);
+    cleanup->data = nagbar_pid;
+    ev_cleanup_start(main_loop, cleanup);
+}
+
+/*
+ * Kills the i3-nagbar process, if *nagbar_pid != -1.
+ *
+ * If wait_for_it is set (restarting i3), this function will waitpid(),
+ * otherwise, ev is assumed to handle it (reloading).
+ *
+ */
+void kill_nagbar(pid_t *nagbar_pid, bool wait_for_it) {
+    if (*nagbar_pid == -1)
+        return;
+
+    if (kill(*nagbar_pid, SIGTERM) == -1)
+        warn("kill(configerror_nagbar) failed");
+
+    if (!wait_for_it)
+        return;
+
+    /* When restarting, we don’t enter the ev main loop anymore and after the
+     * exec(), our old pid is no longer watched. So, ev won’t handle SIGCHLD
+     * for us and we would end up with a <defunct> process. Therefore we
+     * waitpid() here. */
+    waitpid(*nagbar_pid, NULL, 0);
+}