2 * vim:ts=4:sw=4:expandtab
4 * i3 - an improved dynamic tiling window manager
5 * © 2009 Michael Stapelberg and contributors (see also: LICENSE)
7 * i3-dump-log/main.c: Dumps the i3 SHM log to stdout.
14 #include <sys/types.h>
15 #include <sys/socket.h>
34 #if !defined(__OpenBSD__)
35 static uint32_t offset_next_write;
37 static uint32_t wrap_count;
39 static i3_shmlog_header *header;
40 static char *logbuffer,
42 static int ipcfd = -1;
44 static volatile bool interrupted = false;
46 static void sighandler(int signal) {
50 static void disable_shmlog(void) {
51 const char *disablecmd = "debuglog off; shmlog off";
52 if (ipc_send_message(ipcfd, strlen(disablecmd),
53 I3_IPC_MESSAGE_TYPE_COMMAND, (uint8_t *)disablecmd) != 0)
54 err(EXIT_FAILURE, "IPC send");
56 /* Ensure the command was sent by waiting for the reply: */
57 uint32_t reply_length = 0;
58 uint8_t *reply = NULL;
59 if (ipc_recv_message(ipcfd, I3_IPC_REPLY_TYPE_COMMAND,
60 &reply_length, &reply) != 0) {
61 err(EXIT_FAILURE, "IPC recv");
66 static int check_for_wrap(void) {
67 if (wrap_count == header->wrap_count)
70 /* The log wrapped. Print the remaining content and reset walk to the top
72 wrap_count = header->wrap_count;
73 const int len = (logbuffer + header->offset_last_wrap) - walk;
74 swrite(STDOUT_FILENO, walk, len);
75 walk = logbuffer + sizeof(i3_shmlog_header);
79 static void print_till_end(void) {
81 const int len = (logbuffer + header->offset_next_write) - walk;
82 swrite(STDOUT_FILENO, walk, len);
86 void errorlog(char *fmt, ...) {
90 vfprintf(stderr, fmt, args);
94 int main(int argc, char *argv[]) {
95 int o, option_index = 0;
97 #if !defined(__OpenBSD__)
101 static struct option long_options[] = {
102 {"version", no_argument, 0, 'v'},
103 {"verbose", no_argument, 0, 'V'},
104 #if !defined(__OpenBSD__)
105 {"follow", no_argument, 0, 'f'},
107 {"help", no_argument, 0, 'h'},
111 #if !defined(__OpenBSD__)
112 char *options_string = "s:vfVh";
114 char *options_string = "vVh";
117 while ((o = getopt_long(argc, argv, options_string, long_options, &option_index)) != -1) {
119 printf("i3-dump-log " I3_VERSION "\n");
121 } else if (o == 'V') {
123 #if !defined(__OpenBSD__)
124 } else if (o == 'f') {
127 } else if (o == 'h') {
128 printf("i3-dump-log " I3_VERSION "\n");
129 #if !defined(__OpenBSD__)
130 printf("i3-dump-log [-fhVv]\n");
132 printf("i3-dump-log [-hVv]\n");
138 char *shmname = root_atom_contents("I3_SHMLOG_PATH", NULL, 0);
139 if (shmname == NULL) {
140 /* Something failed. Let’s invest a little effort to find out what it
141 * is. This is hugely helpful for users who want to debug i3 but are
142 * not used to the procedure yet. */
143 xcb_connection_t *conn;
145 if ((conn = xcb_connect(NULL, &screen)) == NULL ||
146 xcb_connection_has_error(conn)) {
147 fprintf(stderr, "i3-dump-log: ERROR: Cannot connect to X11.\n\n");
148 if (getenv("DISPLAY") == NULL) {
149 fprintf(stderr, "Your DISPLAY environment variable is not set.\n");
150 fprintf(stderr, "Are you running i3-dump-log via SSH or on a virtual console?\n");
151 fprintf(stderr, "Try DISPLAY=:0 i3-dump-log\n");
154 fprintf(stderr, "FYI: The DISPLAY environment variable is set to \"%s\".\n", getenv("DISPLAY"));
157 if (root_atom_contents("I3_CONFIG_PATH", conn, screen) != NULL) {
158 fprintf(stderr, "i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled. Enabling SHM log until cancelled\n\n");
159 ipcfd = ipc_connect(NULL);
160 const char *enablecmd = "debuglog on; shmlog 5242880";
161 if (ipc_send_message(ipcfd, strlen(enablecmd),
162 I3_IPC_MESSAGE_TYPE_COMMAND, (uint8_t *)enablecmd) != 0)
163 err(EXIT_FAILURE, "IPC send");
164 /* By the time we receive a reply, I3_SHMLOG_PATH is set: */
165 uint32_t reply_length = 0;
166 uint8_t *reply = NULL;
167 if (ipc_recv_message(ipcfd, I3_IPC_REPLY_TYPE_COMMAND,
168 &reply_length, &reply) != 0) {
169 err(EXIT_FAILURE, "IPC recv");
173 atexit(disable_shmlog);
176 shmname = root_atom_contents("I3_SHMLOG_PATH", NULL, 0);
177 if (shmname == NULL && !is_debug_build()) {
178 fprintf(stderr, "You seem to be using a release version of i3:\n %s\n\n", I3_VERSION);
179 fprintf(stderr, "Release versions do not use SHM logging by default,\ntherefore i3-dump-log does not work.\n\n");
180 fprintf(stderr, "Please follow this guide instead:\nhttps://i3wm.org/docs/debugging-release-version.html\n");
184 if (shmname == NULL) {
185 errx(EXIT_FAILURE, "Cannot get I3_SHMLOG_PATH atom contents. Is i3 running on this display?");
189 if (*shmname == '\0')
190 errx(EXIT_FAILURE, "Cannot dump log: SHM logging is disabled in i3.");
194 /* NB: While we must never write, we need O_RDWR for the pthread condvar. */
195 int logbuffer_shm = shm_open(shmname, O_RDWR, 0);
196 if (logbuffer_shm == -1)
197 err(EXIT_FAILURE, "Could not shm_open SHM segment for the i3 log (%s)", shmname);
199 if (fstat(logbuffer_shm, &statbuf) != 0)
200 err(EXIT_FAILURE, "stat(%s)", shmname);
202 /* NB: While we must never write, we need PROT_WRITE for the pthread condvar. */
203 logbuffer = mmap(NULL, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, logbuffer_shm, 0);
204 if (logbuffer == MAP_FAILED)
205 err(EXIT_FAILURE, "Could not mmap SHM segment for the i3 log");
207 header = (i3_shmlog_header *)logbuffer;
210 printf("next_write = %d, last_wrap = %d, logbuffer_size = %d, shmname = %s\n",
211 header->offset_next_write, header->offset_last_wrap, header->size, shmname);
213 walk = logbuffer + header->offset_next_write;
215 /* We first need to print old content in case there was at least one
216 * wrapping already. */
219 /* In case there was a write to the buffer already, skip the first
220 * old line, it very likely is mangled. Not a problem, though, the log
221 * is chatty enough to have plenty lines left. */
222 while (*walk != '\n')
227 /* In case there was no wrapping, this is a no-op, otherwise it prints the
232 /* Then start from the beginning and print the newer lines */
233 walk = logbuffer + sizeof(i3_shmlog_header);
236 #if !defined(__OpenBSD__)
241 /* Handle SIGINT gracefully to invoke atexit handlers, if any. */
242 struct sigaction action;
243 action.sa_handler = sighandler;
244 sigemptyset(&action.sa_mask);
246 sigaction(SIGINT, &action, NULL);
248 /* Since pthread_cond_wait() expects a mutex, we need to provide one.
249 * To not lock i3 (that’s bad, mhkay?) we just define one outside of
250 * the shared memory. */
251 pthread_mutex_t dummy_mutex = PTHREAD_MUTEX_INITIALIZER;
252 pthread_mutex_lock(&dummy_mutex);
253 while (!interrupted) {
254 pthread_cond_wait(&(header->condvar), &dummy_mutex);
255 /* If this was not a spurious wakeup, print the new lines. */
256 if (header->offset_next_write != offset_next_write) {
257 offset_next_write = header->offset_next_write;