Merge branch 'fix-dump-log-errmsg'

i3-dump-log/main.c

@@ -55,8 +55,35 @@ int main(int argc, char *argv[]) {
     }
 
     char *shmname = root_atom_contents("I3_SHMLOG_PATH");
-    if (shmname == NULL)
+    if (shmname == NULL) {
+        /* Something failed. Let’s invest a little effort to find out what it
+         * is. This is hugely helpful for users who want to debug i3 but are
+         * not used to the procedure yet. */
+        xcb_connection_t *conn;
+        int screen;
+        if ((conn = xcb_connect(NULL, &screen)) == NULL ||
+            xcb_connection_has_error(conn)) {
+            fprintf(stderr, "i3-dump-log: ERROR: Cannot connect to X11.\n\n");
+            if (getenv("DISPLAY") == NULL) {
+                fprintf(stderr, "Your DISPLAY environment variable is not set.\n");
+                fprintf(stderr, "Are you running i3-dump-log via SSH or on a virtual console?\n");
+                fprintf(stderr, "Try DISPLAY=:0 i3-dump-log\n");
+                exit(1);
+            }
+            fprintf(stderr, "FYI: The DISPLAY environment variable is set to \"%s\".\n", getenv("DISPLAY"));
+            exit(1);
+        }
+        if (root_atom_contents("I3_CONFIG_PATH") != NULL) {
+            fprintf(stderr, "i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled.\n\n");
+            if (!is_debug_build()) {
+                fprintf(stderr, "You seem to be using a release version of i3:\n  %s\n\n", I3_VERSION);
+                fprintf(stderr, "Release versions do not use SHM logging by default,\ntherefore i3-dump-log does not work.\n\n");
+                fprintf(stderr, "Please follow this guide instead:\nhttp://i3wm.org/docs/debugging-release-version.html\n");
+                exit(1);
+            }
+        }
         errx(EXIT_FAILURE, "Cannot get I3_SHMLOG_PATH atom contents. Is i3 running on this display?");
+    }
 
     if (*shmname == '\0')
         errx(EXIT_FAILURE, "Cannot dump log: SHM logging is disabled in i3.");

include/libi3.h

@@ -242,4 +242,11 @@ void draw_text(char *text, size_t text_len, bool is_ucs2, xcb_drawable_t drawabl
  */
 int predict_text_width(char *text, size_t text_len, bool is_ucs2);
 
+/**
+ * Returns true if this version of i3 is a debug build (anything which is not a
+ * release version), based on the git version number.
+ *
+ */
+bool is_debug_build() __attribute__((const));
+
 #endif

libi3/is_debug_build.c

@@ -0,0 +1,17 @@
+#include <string.h>
+#include <stdbool.h>
+
+/*
+ * Returns true if this version of i3 is a debug build (anything which is not a
+ * release version), based on the git version number.
+ *
+ */
+bool is_debug_build() {
+    /* i3_version contains either something like this:
+     *     "4.0.2 (2011-11-11, branch "release")".
+     * or: "4.0.2-123-gCOFFEEBABE (2011-11-11, branch "next")".
+     *
+     * So we check for the offset of the first opening round bracket to
+     * determine whether this is a git version or a release version. */
+    return ((strchr(I3_VERSION, '(') - I3_VERSION) > 10);
+}

src/main.c

@@ -25,9 +25,6 @@
  * RLIM_INFINITY for i3 debugging versions. */
 struct rlimit original_rlimit_core;
 
-/* Whether this version of i3 is a debug build or a release build. */
-bool debug_build = false;
-
 /** The number of file descriptors passed via socket activation. */
 int listen_fds;
 
@@ -246,7 +243,7 @@ static void handle_signal(int sig, siginfo_t *info, void *data) {
 int main(int argc, char *argv[]) {
     /* Keep a symbol pointing to the I3_VERSION string constant so that we have
      * it in gdb backtraces. */
-    const char *i3_version = I3_VERSION;
+    const char *i3_version __attribute__ ((unused)) = I3_VERSION;
     char *override_configpath = NULL;
     bool autostart = true;
     char *layout_path = NULL;
@@ -291,16 +288,8 @@ int main(int argc, char *argv[]) {
      * (file) logging. */
     init_logging();
 
-    /* i3_version contains either something like this:
-     *     "4.0.2 (2011-11-11, branch "release")".
-     * or: "4.0.2-123-gCOFFEEBABE (2011-11-11, branch "next")".
-     *
-     * So we check for the offset of the first opening round bracket to
-     * determine whether this is a git version or a release version. */
-    debug_build = ((strchr(i3_version, '(') - i3_version) > 10);
-
     /* On non-release builds, disable SHM logging by default. */
-    shmlog_size = (debug_build ? 25 * 1024 * 1024 : 0);
+    shmlog_size = (is_debug_build() ? 25 * 1024 * 1024 : 0);
 
     start_argv = argv;
 
@@ -475,7 +464,7 @@ int main(int argc, char *argv[]) {
     init_logging();
 
     /* Try to enable core dumps by default when running a debug build */
-    if (debug_build) {
+    if (is_debug_build()) {
         struct rlimit limit = { RLIM_INFINITY, RLIM_INFINITY };
         setrlimit(RLIMIT_CORE, &limit);