From 38869004fe025454010c2da08287e2256b103d02 Mon Sep 17 00:00:00 2001 From: Bas Pape Date: Mon, 10 Sep 2012 16:47:05 +0200 Subject: [PATCH] Replace exit with backtrace in crash dialog When the user hits 'b', attach gdb and dump a backtrace to the tmpdir --- src/sighandler.c | 139 ++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 119 insertions(+), 20 deletions(-) diff --git a/src/sighandler.c b/src/sighandler.c index 3a9307e1..fe8c9f64 100644 --- a/src/sighandler.c +++ b/src/sighandler.c @@ -16,11 +16,14 @@ #include #include #include +#include #include #include +static void open_popups(void); + static xcb_gcontext_t pixmap_gc; static xcb_pixmap_t pixmap; static int raised_signal; @@ -29,11 +32,84 @@ static char *crash_text[] = { "i3 just crashed.", "To debug this problem, either attach gdb now", "or press", - "- 'e' to exit and get a core-dump,", + "- 'b' to save a backtrace (needs GDB),", "- 'r' to restart i3 in-place or", "- 'f' to forget the current layout and restart" }; static int crash_text_longest = 5; +static int backtrace_string_index = 3; +static int backtrace_done = 0; + +/* + * Attach gdb to pid_parent and dump a backtrace to i3-backtrace.$pid in the + * tmpdir + */ +static int backtrace(void) { + char *tmpdir = getenv("TMPDIR"); + if (tmpdir == NULL) + tmpdir = "/tmp"; + + pid_t pid_parent = getpid(); + + char *filename = NULL; + if (sasprintf(&filename, "%s/i3-backtrace.%d.txt", tmpdir, pid_parent) == -1 + || filename == NULL) + filename = "i3-backtrace.txt"; + + pid_t pid_gdb = fork(); + if (pid_gdb < 0) { + DLOG("Failed to fork for GDB\n"); + return -1; + } else if (pid_gdb == 0) { + /* child */ + + /* close standard streams in case i3 is started from a terminal; gdb + * needs to run without controlling terminal for it to work properly in + * this situation */ + close(STDIN_FILENO); + close(STDOUT_FILENO); + close(STDERR_FILENO); + + char *pid_s = NULL; + sasprintf(&pid_s, "%d", pid_parent); + + char *gdb_log_cmd = NULL; + if (sasprintf(&gdb_log_cmd, "set logging file %s", filename) == -1 + || gdb_log_cmd == NULL) + gdb_log_cmd = "set logging file i3-backtrace.txt"; + + char *args[] = { + "gdb", + start_argv[0], + "-p", + pid_s, + "-batch", + "-nx", + "-ex", gdb_log_cmd, + "-ex", "set logging on", + "-ex", "bt full", + "-ex", "quit", + NULL + }; + execvp(args[0], args); + DLOG("Failed to exec GDB\n"); + exit(1); + } + int status = 0; + struct stat bt; + + waitpid(pid_gdb, &status, 0); + + /* see if the backtrace was succesful or not */ + if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { + DLOG("GDB did not run properly\n"); + return -1; + } else if (stat(filename, &bt) == -1) { + DLOG("GDB executed succesfully, but no backtrace was generated\n"); + return -1; + } + return 1; +} /* * Draw the window containing the info text @@ -51,9 +127,23 @@ static int sig_draw_window(xcb_window_t win, int width, int height, int font_hei /* restore font color */ set_font_colors(pixmap_gc, get_colorpixel("#FFFFFF"), get_colorpixel("#000000")); + char *bt_colour = "#FFFFFF"; + if (backtrace_done < 0) + bt_colour = "#AA0000"; + else if (backtrace_done > 0) + bt_colour = "#00AA00"; + for (int i = 0; crash_text_i3strings[i] != NULL; ++i) { + /* fix the colour for the backtrace line when it finished */ + if (i == backtrace_string_index) + set_font_colors(pixmap_gc, get_colorpixel(bt_colour), get_colorpixel("#000000")); + draw_text(crash_text_i3strings[i], pixmap, pixmap_gc, 8, 5 + i * font_height, width - 16); + + /* and reset the colour again for other lines */ + if (i == backtrace_string_index) + set_font_colors(pixmap_gc, get_colorpixel("#FFFFFF"), get_colorpixel("#000000")); } /* Copy the contents of the pixmap to the real window */ @@ -64,7 +154,7 @@ static int sig_draw_window(xcb_window_t win, int width, int height, int font_hei } /* - * Handles keypresses of 'e' or 'r' to exit or restart i3 + * Handles keypresses of 'b', 'r' and 'f' to get a backtrace or restart i3 * */ static int sig_handle_key_press(void *ignored, xcb_connection_t *conn, xcb_key_press_event_t *event) { @@ -77,10 +167,15 @@ static int sig_handle_key_press(void *ignored, xcb_connection_t *conn, xcb_key_p xcb_keysym_t sym = xcb_key_press_lookup_keysym(keysyms, event, state); - if (sym == 'e') { - DLOG("User issued exit-command, raising error again.\n"); - raise(raised_signal); - exit(1); + if (sym == 'b') { + DLOG("User issued core-dump command.\n"); + + /* fork and exec/attach GDB to the parent to get a backtrace in the + * tmpdir */ + backtrace_done = backtrace(); + + /* re-open the windows to indicate that it's finished */ + open_popups(); } if (sym == 'r') @@ -129,20 +224,7 @@ static xcb_window_t open_input_window(xcb_connection_t *conn, Rect screen_rect, return win; } -/* - * Handle signals - * It creates a window asking the user to restart in-place - * or exit to generate a core dump - * - */ -void handle_signal(int sig, siginfo_t *info, void *data) { - DLOG("i3 crashed. SIG: %d\n", sig); - - struct sigaction action; - action.sa_handler = SIG_DFL; - sigaction(sig, &action, NULL); - raised_signal = sig; - +static void open_popups() { /* width and height of the popup window, so that the text fits in */ int crash_text_num = sizeof(crash_text) / sizeof(char*); int height = 13 + (crash_text_num * config.font.height); @@ -182,6 +264,23 @@ void handle_signal(int sig, siginfo_t *info, void *data) { sig_draw_window(win, width, height, config.font.height, crash_text_i3strings); xcb_flush(conn); } +} + +/* + * Handle signals + * It creates a window asking the user to restart in-place + * or exit to generate a core dump + * + */ +void handle_signal(int sig, siginfo_t *info, void *data) { + DLOG("i3 crashed. SIG: %d\n", sig); + + struct sigaction action; + action.sa_handler = SIG_DFL; + sigaction(sig, &action, NULL); + raised_signal = sig; + + open_popups(); xcb_generic_event_t *event; /* Yay, more own eventhandlers… */ -- 2.39.5