weston: add wait-for-debugger option

When you need to start Weston via weston-launch, systemd unit, or any
other runner, it is annoying to try to get in with a debugger,
especially if the thing you are interested in happens at start-up. To
make it easy, a new option is introduced.

The new option, implemented both as a command line option and a
weston.ini option, raises SIGSTOP early in the start-up, before the
weston_compositor has been created. This allows one to attach a debugger
at a known point in execution, and resume execution with SIGCONT.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Acked-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Ian Ray <ian.ray@ge.com>

diff --git a/compositor/main.c b/compositor/main.c
index 9f00ee3..32fb33e 100644 (file)
--- a/compositor/main.c
+++ b/compositor/main.c
@@ -557,6 +557,7 @@ usage(int error_code)
                "  --log=FILE\t\tLog to the given file\n"
                "  -c, --config=FILE\tConfig file to load, defaults to weston.ini\n"
                "  --no-config\t\tDo not read weston.ini\n"
+               "  --wait-for-debugger\tRaise SIGSTOP on start-up\n"
                "  -h, --help\t\tThis help message\n\n");
 
 #if defined(BUILD_DRM_COMPOSITOR)
@@ -1787,6 +1788,7 @@ int main(int argc, char *argv[])
        struct weston_seat *seat;
        struct wet_compositor user_data;
        int require_input;
+       int32_t wait_for_debugger = 0;
 
        const struct weston_option core_options[] = {
                { WESTON_OPTION_STRING, "backend", 'B', &backend },
@@ -1800,6 +1802,7 @@ int main(int argc, char *argv[])
                { WESTON_OPTION_BOOLEAN, "version", 0, &version },
                { WESTON_OPTION_BOOLEAN, "no-config", 0, &noconfig },
                { WESTON_OPTION_STRING, "config", 'c', &config_file },
+               { WESTON_OPTION_BOOLEAN, "wait-for-debugger", 0, &wait_for_debugger },
        };
 
        if (os_fd_set_cloexec(fileno(stdin))) {
@@ -1863,6 +1866,16 @@ int main(int argc, char *argv[])
 
        section = weston_config_get_section(config, "core", NULL, NULL);
 
+       if (!wait_for_debugger)
+               weston_config_section_get_bool(section, "wait-for-debugger",
+                                              &wait_for_debugger, 0);
+       if (wait_for_debugger) {
+               weston_log("Weston PID is %ld - "
+                          "waiting for debugger, send SIGCONT to continue...\n",
+                          (long)getpid());
+               raise(SIGSTOP);
+       }
+
        if (!backend) {
                weston_config_section_get_string(section, "backend", &backend,
                                                 NULL);

diff --git a/man/weston.ini.man b/man/weston.ini.man
index 4cfefc9..f237fd6 100644 (file)
--- a/man/weston.ini.man
+++ b/man/weston.ini.man
@@ -181,6 +181,14 @@ require an input device for launch
 sets Weston's pageflip timeout in milliseconds.  This sets a timer to exit
 gracefully with a log message and an exit code of 1 in case the DRM driver is
 non-responsive.  Setting it to 0 disables this feature.
+.TP 7
+.BI "wait-for-debugger=" true
+Raises SIGSTOP before initializing the compositor. This allows the user to
+attach with a debugger and continue execution by sending SIGCONT. This is
+useful for debugging a crash on start-up when it would be inconvenient to
+launch weston directly from a debugger. Boolean, defaults to
+.BR false .
+There is also a command line option to do the same.
 
 .SH "LIBINPUT SECTION"
 The

diff --git a/man/weston.man b/man/weston.man
index face229..33f0a0b 100644 (file)
--- a/man/weston.man
+++ b/man/weston.man
@@ -165,6 +165,14 @@ Weston will export
 .B WAYLAND_DISPLAY
 with this value in the environment for all child processes to allow them to
 connect to the right server automatically.
+.TP
+\fB\-\-wait-for-debugger\fR
+Raises SIGSTOP before initializing the compositor. This allows the user to
+attach with a debugger and continue execution by sending SIGCONT. This is
+useful for debugging a crash on start-up when it would be inconvenient to
+launch weston directly from a debugger. There is also a
+.IR weston.ini " option to do the same."
+.
 .SS DRM backend options:
 See
 .BR weston-drm (7).