Magisk/native/jni/daemon/log_daemon.c
2018-09-27 18:26:41 -04:00

189 lines
4.6 KiB
C

/* log_daemon.c - A dedicated daemon to monitor logcat
*
* A universal logcat monitor for many usages. Add listeners to the list,
* and the new log line will be sent through sockets to trigger
* asynchronous events without polling
*/
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <fcntl.h>
#include "magisk.h"
#include "utils.h"
#include "daemon.h"
#include "flags.h"
static int loggable = 0;
static struct vector log_cmd, clear_cmd;
static int sockfd;
static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
enum {
HIDE_EVENT,
LOG_EVENT
};
struct log_listener {
int fd;
int (*filter) (const char*);
};
static int am_proc_start_filter(const char *log) {
return strstr(log, "am_proc_start") != NULL;
}
static int magisk_log_filter(const char *log) {
return !am_proc_start_filter(log);
}
static struct log_listener events[] = {
{ /* HIDE_EVENT */
.fd = -1,
.filter = am_proc_start_filter
},
{ /* LOG_EVENT */
.fd = -1,
.filter = magisk_log_filter
}
};
#define EVENT_NUM (sizeof(events) / sizeof(struct log_listener))
static void sigpipe_handler(int sig) {
close(events[HIDE_EVENT].fd);
events[HIDE_EVENT].fd = -1;
}
static void *monitor_thread(void *args) {
// Block SIGPIPE to prevent interruption
sigset_t block_set;
sigemptyset(&block_set);
sigaddset(&block_set, SIGPIPE);
pthread_sigmask(SIG_SETMASK, &block_set, NULL);
// Give the main daemon some time before we monitor it
sleep(5);
int fd;
char b;
while (1) {
fd = connect_daemon();
write_int(fd, HANDSHAKE);
// This should hold unless the daemon is killed
read(fd, &b, sizeof(b));
// The main daemon crashed, spawn a new one
close(fd);
}
}
static void *logcat_thread(void *args) {
int log_fd = -1, log_pid;
char line[4096];
while (1) {
// Start logcat
log_pid = exec_array(0, &log_fd, NULL, (char **) vec_entry(&log_cmd));
FILE *logs = fdopen(log_fd, "r");
while (fgets(line, sizeof(line), logs)) {
if (line[0] == '-')
continue;
size_t len = strlen(line);
pthread_mutex_lock(&lock);
for (int i = 0; i < EVENT_NUM; ++i) {
if (events[i].fd > 0 && events[i].filter(line))
write(events[i].fd, line, len);
}
pthread_mutex_unlock(&lock);
}
fclose(logs);
log_fd = -1;
kill(log_pid, SIGTERM);
waitpid(log_pid, NULL, 0);
LOGI("magisklogd: logcat output EOF");
// Clear buffer
log_pid = exec_array(0, NULL, NULL, (char **) vec_entry(&clear_cmd));
waitpid(log_pid, NULL, 0);
}
}
int check_and_start_logger() {
if (!loggable) {
int fd;
loggable = exec_command_sync("/system/bin/logcat", "-d", "-f", "/dev/null", NULL) == 0;
chmod("/dev/null", 0666);
if (loggable) {
connect_daemon2(LOG_DAEMON, &fd);
write_int(fd, HANDSHAKE);
close(fd);
}
}
return loggable;
}
void log_daemon() {
setsid();
struct sockaddr_un sun;
socklen_t len = setup_sockaddr(&sun, LOG_DAEMON);
sockfd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
if (xbind(sockfd, (struct sockaddr*) &sun, len))
exit(1);
xlisten(sockfd, 10);
LOGI("Magisk v" xstr(MAGISK_VERSION) "(" xstr(MAGISK_VER_CODE) ") logger started\n");
strcpy(argv0, "magisklogd");
// Set SIGPIPE handler
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = sigpipe_handler;
sigaction(SIGPIPE, &act, NULL);
// Setup log dumps
rename(LOGFILE, LOGFILE ".bak");
events[LOG_EVENT].fd = xopen(LOGFILE, O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC | O_APPEND, 0644);
// Construct cmdline
vec_init(&log_cmd);
vec_push_back(&log_cmd, "/system/bin/logcat");
// Test whether these buffers actually works
const char* b[] = { "main", "events", "crash" };
for (int i = 0; i < 3; ++i) {
if (exec_command_sync("/system/bin/logcat", "-b", b[i], "-d", "-f", "/dev/null", NULL) == 0)
vec_push_back_all(&log_cmd, "-b", b[i], NULL);
}
chmod("/dev/null", 0666);
vec_dup(&log_cmd, &clear_cmd);
vec_push_back_all(&log_cmd, "-v", "threadtime", "-s", "am_proc_start", "Magisk", NULL);
#ifdef MAGISK_DEBUG
vec_push_back(&log_cmd, "*:F");
#endif
vec_push_back(&log_cmd, NULL);
vec_push_back(&clear_cmd, "-c");
vec_push_back(&clear_cmd, NULL);
// Start worker threads
pthread_t thread;
pthread_create(&thread, NULL, monitor_thread, NULL);
pthread_detach(thread);
xpthread_create(&thread, NULL, logcat_thread, NULL);
pthread_detach(thread);
while(1) {
int fd = xaccept4(sockfd, NULL, NULL, SOCK_CLOEXEC);
switch(read_int(fd)) {
case HIDE_CONNECT:
pthread_mutex_lock(&lock);
close(events[HIDE_EVENT].fd);
events[HIDE_EVENT].fd = fd;
pthread_mutex_unlock(&lock);
break;
case HANDSHAKE:
default:
close(fd);
break;
}
}
}