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.
12 #include <sys/types.h>
13 #include <sys/socket.h>
31 #if !defined(__OpenBSD__)
32 static uint32_t offset_next_write;
34 static uint32_t wrap_count;
36 static i3_shmlog_header *header;
37 static char *logbuffer,
40 static int check_for_wrap(void) {
41 if (wrap_count == header->wrap_count)
44 /* The log wrapped. Print the remaining content and reset walk to the top
46 wrap_count = header->wrap_count;
47 const int len = (logbuffer + header->offset_last_wrap) - walk;
48 swrite(STDOUT_FILENO, walk, len);
49 walk = logbuffer + sizeof(i3_shmlog_header);
53 static void print_till_end(void) {
55 const int len = (logbuffer + header->offset_next_write) - walk;
56 swrite(STDOUT_FILENO, walk, len);
60 int main(int argc, char *argv[]) {
61 int o, option_index = 0;
63 #if !defined(__OpenBSD__)
67 static struct option long_options[] = {
68 {"version", no_argument, 0, 'v'},
69 {"verbose", no_argument, 0, 'V'},
70 #if !defined(__OpenBSD__)
71 {"follow", no_argument, 0, 'f'},
73 {"help", no_argument, 0, 'h'},
77 #if !defined(__OpenBSD__)
78 char *options_string = "s:vfVh";
80 char *options_string = "vVh";
83 while ((o = getopt_long(argc, argv, options_string, long_options, &option_index)) != -1) {
85 printf("i3-dump-log " I3_VERSION "\n");
87 } else if (o == 'V') {
89 #if !defined(__OpenBSD__)
90 } else if (o == 'f') {
93 } else if (o == 'h') {
94 printf("i3-dump-log " I3_VERSION "\n");
95 #if !defined(__OpenBSD__)
96 printf("i3-dump-log [-fhVv]\n");
98 printf("i3-dump-log [-hVv]\n");
104 char *shmname = root_atom_contents("I3_SHMLOG_PATH", NULL, 0);
105 if (shmname == NULL) {
106 /* Something failed. Let’s invest a little effort to find out what it
107 * is. This is hugely helpful for users who want to debug i3 but are
108 * not used to the procedure yet. */
109 xcb_connection_t *conn;
111 if ((conn = xcb_connect(NULL, &screen)) == NULL ||
112 xcb_connection_has_error(conn)) {
113 fprintf(stderr, "i3-dump-log: ERROR: Cannot connect to X11.\n\n");
114 if (getenv("DISPLAY") == NULL) {
115 fprintf(stderr, "Your DISPLAY environment variable is not set.\n");
116 fprintf(stderr, "Are you running i3-dump-log via SSH or on a virtual console?\n");
117 fprintf(stderr, "Try DISPLAY=:0 i3-dump-log\n");
120 fprintf(stderr, "FYI: The DISPLAY environment variable is set to \"%s\".\n", getenv("DISPLAY"));
123 if (root_atom_contents("I3_CONFIG_PATH", conn, screen) != NULL) {
124 fprintf(stderr, "i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled.\n\n");
125 if (!is_debug_build()) {
126 fprintf(stderr, "You seem to be using a release version of i3:\n %s\n\n", I3_VERSION);
127 fprintf(stderr, "Release versions do not use SHM logging by default,\ntherefore i3-dump-log does not work.\n\n");
128 fprintf(stderr, "Please follow this guide instead:\nhttp://i3wm.org/docs/debugging-release-version.html\n");
132 errx(EXIT_FAILURE, "Cannot get I3_SHMLOG_PATH atom contents. Is i3 running on this display?");
135 if (*shmname == '\0')
136 errx(EXIT_FAILURE, "Cannot dump log: SHM logging is disabled in i3.");
140 /* NB: While we must never write, we need O_RDWR for the pthread condvar. */
141 int logbuffer_shm = shm_open(shmname, O_RDWR, 0);
142 if (logbuffer_shm == -1)
143 err(EXIT_FAILURE, "Could not shm_open SHM segment for the i3 log (%s)", shmname);
145 if (fstat(logbuffer_shm, &statbuf) != 0)
146 err(EXIT_FAILURE, "stat(%s)", shmname);
148 /* NB: While we must never write, we need PROT_WRITE for the pthread condvar. */
149 logbuffer = mmap(NULL, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, logbuffer_shm, 0);
150 if (logbuffer == MAP_FAILED)
151 err(EXIT_FAILURE, "Could not mmap SHM segment for the i3 log");
153 header = (i3_shmlog_header *)logbuffer;
156 printf("next_write = %d, last_wrap = %d, logbuffer_size = %d, shmname = %s\n",
157 header->offset_next_write, header->offset_last_wrap, header->size, shmname);
159 walk = logbuffer + header->offset_next_write;
161 /* We first need to print old content in case there was at least one
162 * wrapping already. */
165 /* In case there was a write to the buffer already, skip the first
166 * old line, it very likely is mangled. Not a problem, though, the log
167 * is chatty enough to have plenty lines left. */
168 while (*walk != '\n')
173 /* In case there was no wrapping, this is a no-op, otherwise it prints the
178 /* Then start from the beginning and print the newer lines */
179 walk = logbuffer + sizeof(i3_shmlog_header);
182 #if !defined(__OpenBSD__)
184 /* Since pthread_cond_wait() expects a mutex, we need to provide one.
185 * To not lock i3 (that’s bad, mhkay?) we just define one outside of
186 * the shared memory. */
187 pthread_mutex_t dummy_mutex = PTHREAD_MUTEX_INITIALIZER;
188 pthread_mutex_lock(&dummy_mutex);
190 pthread_cond_wait(&(header->condvar), &dummy_mutex);
191 /* If this was not a spurious wakeup, print the new lines. */
192 if (header->offset_next_write != offset_next_write) {
193 offset_next_write = header->offset_next_write;