gri3-wm/i3-dump-log/main.c

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/*
* vim:ts=4:sw=4:expandtab
*
* i3 - an improved dynamic tiling window manager
* © 2009-2012 Michael Stapelberg and contributors (see also: LICENSE)
*
* i3-dump-log/main.c: Dumps the i3 SHM log to stdout.
*
*/
#include <stdio.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <err.h>
#include <stdint.h>
#include <getopt.h>
#include <limits.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include "libi3.h"
#include "shmlog.h"
#include <i3/ipc.h>
static uint32_t offset_next_write,
wrap_count;
static i3_shmlog_header *header;
static char *logbuffer,
*walk;
static int check_for_wrap(void) {
if (wrap_count == header->wrap_count)
return 0;
/* The log wrapped. Print the remaining content and reset walk to the top
* of the log. */
wrap_count = header->wrap_count;
const int len = (logbuffer + header->offset_last_wrap) - walk;
if (write(STDOUT_FILENO, walk, len) != len)
err(EXIT_FAILURE, "write()");
walk = logbuffer + sizeof(i3_shmlog_header);
return 1;
}
static void print_till_end(void) {
check_for_wrap();
const int len = (logbuffer + header->offset_next_write) - walk;
const int n = write(STDOUT_FILENO, walk, len);
if (len != n)
err(EXIT_FAILURE, "write()");
if (n > 0) {
walk += n;
}
}
int main(int argc, char *argv[]) {
int o, option_index = 0;
bool verbose = false,
follow = false;
static struct option long_options[] = {
{"version", no_argument, 0, 'v'},
{"verbose", no_argument, 0, 'V'},
{"follow", no_argument, 0, 'f'},
{"help", no_argument, 0, 'h'},
{0, 0, 0, 0}};
char *options_string = "s:vfVh";
while ((o = getopt_long(argc, argv, options_string, long_options, &option_index)) != -1) {
if (o == 'v') {
printf("i3-dump-log " I3_VERSION "\n");
return 0;
} else if (o == 'V') {
verbose = true;
} else if (o == 'f') {
follow = true;
} else if (o == 'h') {
printf("i3-dump-log " I3_VERSION "\n");
printf("i3-dump-log [-f] [-s <socket>]\n");
return 0;
}
}
char *shmname = root_atom_contents("I3_SHMLOG_PATH", NULL, 0);
if (shmname == NULL) {
/* Something failed. Lets invest a little effort to find out what it
* is. This is hugely helpful for users who want to debug i3 but are
* not used to the procedure yet. */
xcb_connection_t *conn;
int screen;
if ((conn = xcb_connect(NULL, &screen)) == NULL ||
xcb_connection_has_error(conn)) {
fprintf(stderr, "i3-dump-log: ERROR: Cannot connect to X11.\n\n");
if (getenv("DISPLAY") == NULL) {
fprintf(stderr, "Your DISPLAY environment variable is not set.\n");
fprintf(stderr, "Are you running i3-dump-log via SSH or on a virtual console?\n");
fprintf(stderr, "Try DISPLAY=:0 i3-dump-log\n");
exit(1);
}
fprintf(stderr, "FYI: The DISPLAY environment variable is set to \"%s\".\n", getenv("DISPLAY"));
exit(1);
}
if (root_atom_contents("I3_CONFIG_PATH", conn, screen) != NULL) {
fprintf(stderr, "i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled.\n\n");
if (!is_debug_build()) {
fprintf(stderr, "You seem to be using a release version of i3:\n %s\n\n", I3_VERSION);
fprintf(stderr, "Release versions do not use SHM logging by default,\ntherefore i3-dump-log does not work.\n\n");
fprintf(stderr, "Please follow this guide instead:\nhttp://i3wm.org/docs/debugging-release-version.html\n");
exit(1);
}
}
errx(EXIT_FAILURE, "Cannot get I3_SHMLOG_PATH atom contents. Is i3 running on this display?");
}
if (*shmname == '\0')
errx(EXIT_FAILURE, "Cannot dump log: SHM logging is disabled in i3.");
struct stat statbuf;
/* NB: While we must never write, we need O_RDWR for the pthread condvar. */
int logbuffer_shm = shm_open(shmname, O_RDWR, 0);
if (logbuffer_shm == -1)
err(EXIT_FAILURE, "Could not shm_open SHM segment for the i3 log (%s)", shmname);
if (fstat(logbuffer_shm, &statbuf) != 0)
err(EXIT_FAILURE, "stat(%s)", shmname);
/* NB: While we must never write, we need PROT_WRITE for the pthread condvar. */
logbuffer = mmap(NULL, statbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, logbuffer_shm, 0);
if (logbuffer == MAP_FAILED)
err(EXIT_FAILURE, "Could not mmap SHM segment for the i3 log");
header = (i3_shmlog_header *)logbuffer;
if (verbose)
printf("next_write = %d, last_wrap = %d, logbuffer_size = %d, shmname = %s\n",
header->offset_next_write, header->offset_last_wrap, header->size, shmname);
walk = logbuffer + header->offset_next_write;
/* We first need to print old content in case there was at least one
* wrapping already. */
if (*walk != '\0') {
/* In case there was a write to the buffer already, skip the first
* old line, it very likely is mangled. Not a problem, though, the log
* is chatty enough to have plenty lines left. */
while (*walk != '\n')
walk++;
walk++;
}
/* In case there was no wrapping, this is a no-op, otherwise it prints the
* old lines. */
wrap_count = 0;
check_for_wrap();
/* Then start from the beginning and print the newer lines */
walk = logbuffer + sizeof(i3_shmlog_header);
print_till_end();
if (follow) {
/* Since pthread_cond_wait() expects a mutex, we need to provide one.
* To not lock i3 (thats bad, mhkay?) we just define one outside of
* the shared memory. */
pthread_mutex_t dummy_mutex = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_lock(&dummy_mutex);
while (1) {
pthread_cond_wait(&(header->condvar), &dummy_mutex);
/* If this was not a spurious wakeup, print the new lines. */
if (header->offset_next_write != offset_next_write) {
offset_next_write = header->offset_next_write;
print_till_end();
}
}
}
return 0;
}