2 * vim:ts=4:sw=4:expandtab
4 * i3 - an improved dynamic tiling window manager
5 * © 2009-2012 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 static uint32_t offset_next_write,
34 static i3_shmlog_header *header;
35 static char *logbuffer,
38 static int check_for_wrap(void) {
39 if (wrap_count == header->wrap_count)
42 /* The log wrapped. Print the remaining content and reset walk to the top
44 wrap_count = header->wrap_count;
45 const int len = (logbuffer + header->offset_last_wrap) - walk;
46 if (write(STDOUT_FILENO, walk, len) != len)
47 err(EXIT_FAILURE, "write()");
48 walk = logbuffer + sizeof(i3_shmlog_header);
52 static void print_till_end(void) {
54 const int len = (logbuffer + header->offset_next_write) - walk;
55 const int n = write(STDOUT_FILENO, walk, len);
57 err(EXIT_FAILURE, "write()");
63 int main(int argc, char *argv[]) {
64 int o, option_index = 0;
68 static struct option long_options[] = {
69 {"version", no_argument, 0, 'v'},
70 {"verbose", no_argument, 0, 'V'},
71 {"follow", no_argument, 0, 'f'},
72 {"help", no_argument, 0, 'h'},
75 char *options_string = "s:vfVh";
77 while ((o = getopt_long(argc, argv, options_string, long_options, &option_index)) != -1) {
79 printf("i3-dump-log " I3_VERSION "\n");
81 } else if (o == 'V') {
83 } else if (o == 'f') {
85 } else if (o == 'h') {
86 printf("i3-dump-log " I3_VERSION "\n");
87 printf("i3-dump-log [-f] [-s <socket>]\n");
92 char *shmname = root_atom_contents("I3_SHMLOG_PATH", NULL, 0);
93 if (shmname == NULL) {
94 /* Something failed. Let’s invest a little effort to find out what it
95 * is. This is hugely helpful for users who want to debug i3 but are
96 * not used to the procedure yet. */
97 xcb_connection_t *conn;
99 if ((conn = xcb_connect(NULL, &screen)) == NULL ||
100 xcb_connection_has_error(conn)) {
101 fprintf(stderr, "i3-dump-log: ERROR: Cannot connect to X11.\n\n");
102 if (getenv("DISPLAY") == NULL) {
103 fprintf(stderr, "Your DISPLAY environment variable is not set.\n");
104 fprintf(stderr, "Are you running i3-dump-log via SSH or on a virtual console?\n");
105 fprintf(stderr, "Try DISPLAY=:0 i3-dump-log\n");
108 fprintf(stderr, "FYI: The DISPLAY environment variable is set to \"%s\".\n", getenv("DISPLAY"));
111 if (root_atom_contents("I3_CONFIG_PATH", conn, screen) != NULL) {
112 fprintf(stderr, "i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled.\n\n");
113 if (!is_debug_build()) {
114 fprintf(stderr, "You seem to be using a release version of i3:\n %s\n\n", I3_VERSION);
115 fprintf(stderr, "Release versions do not use SHM logging by default,\ntherefore i3-dump-log does not work.\n\n");
116 fprintf(stderr, "Please follow this guide instead:\nhttp://i3wm.org/docs/debugging-release-version.html\n");
120 errx(EXIT_FAILURE, "Cannot get I3_SHMLOG_PATH atom contents. Is i3 running on this display?");
123 if (*shmname == '\0')
124 errx(EXIT_FAILURE, "Cannot dump log: SHM logging is disabled in i3.");
128 /* NB: While we must never write, we need O_RDWR for the pthread condvar. */
129 int logbuffer_shm = shm_open(shmname, O_RDWR, 0);
130 if (logbuffer_shm == -1)
131 err(EXIT_FAILURE, "Could not shm_open SHM segment for the i3 log (%s)", shmname);
133 if (fstat(logbuffer_shm, &statbuf) != 0)
134 err(EXIT_FAILURE, "stat(%s)", shmname);
136 /* NB: While we must never write, we need PROT_WRITE for the pthread condvar. */
137 logbuffer = mmap(NULL, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, logbuffer_shm, 0);
138 if (logbuffer == MAP_FAILED)
139 err(EXIT_FAILURE, "Could not mmap SHM segment for the i3 log");
141 header = (i3_shmlog_header *)logbuffer;
144 printf("next_write = %d, last_wrap = %d, logbuffer_size = %d, shmname = %s\n",
145 header->offset_next_write, header->offset_last_wrap, header->size, shmname);
146 walk = logbuffer + header->offset_next_write;
148 /* We first need to print old content in case there was at least one
149 * wrapping already. */
152 /* In case there was a write to the buffer already, skip the first
153 * old line, it very likely is mangled. Not a problem, though, the log
154 * is chatty enough to have plenty lines left. */
155 while (*walk != '\n')
160 /* In case there was no wrapping, this is a no-op, otherwise it prints the
165 /* Then start from the beginning and print the newer lines */
166 walk = logbuffer + sizeof(i3_shmlog_header);
170 /* Since pthread_cond_wait() expects a mutex, we need to provide one.
171 * To not lock i3 (that’s bad, mhkay?) we just define one outside of
172 * the shared memory. */
173 pthread_mutex_t dummy_mutex = PTHREAD_MUTEX_INITIALIZER;
174 pthread_mutex_lock(&dummy_mutex);
176 pthread_cond_wait(&(header->condvar), &dummy_mutex);
177 /* If this was not a spurious wakeup, print the new lines. */
178 if (header->offset_next_write != offset_next_write) {
179 offset_next_write = header->offset_next_write;