diff options
| -rw-r--r-- | tdekbdledsync/main.cpp | 69 |
1 files changed, 64 insertions, 5 deletions
diff --git a/tdekbdledsync/main.cpp b/tdekbdledsync/main.cpp index e48af2f53..a439ebd41 100644 --- a/tdekbdledsync/main.cpp +++ b/tdekbdledsync/main.cpp @@ -33,6 +33,7 @@ License along with tdekbdledsync. If not, see http://www.gnu.org/licenses/. #include <linux/vt.h> #include <linux/input.h> #include <linux/uinput.h> +#include <sys/file.h> #include <sys/types.h> #include <sys/stat.h> #include <sys/select.h> @@ -71,6 +72,9 @@ int keyboard_fds[MAX_KEYBOARDS]; Display* display = NULL; +int lockfd = -1; +char lockFileName[256]; + // -------------------------------------------------------------------------------------- // Useful function from Stack Overflow // http://stackoverflow.com/questions/874134/find-if-string-endswith-another-string-in-c @@ -92,6 +96,34 @@ int str_ends_with(const char * str, const char * suffix) { // -------------------------------------------------------------------------------------- // -------------------------------------------------------------------------------------- +// Useful function from Stack Overflow +// http://stackoverflow.com/questions/1599459/optimal-lock-file-method +// -------------------------------------------------------------------------------------- +int tryGetLock(char const *lockName) { + mode_t m = umask( 0 ); + int fd = open( lockName, O_RDWR|O_CREAT, 0666 ); + umask( m ); + if( fd >= 0 && flock( fd, LOCK_EX | LOCK_NB ) < 0 ) { + close( fd ); + fd = -1; + } + return fd; +} + +// -------------------------------------------------------------------------------------- +// Useful function from Stack Overflow +// http://stackoverflow.com/questions/1599459/optimal-lock-file-method +// -------------------------------------------------------------------------------------- +void releaseLock(int fd, char const *lockName) { + if( fd < 0 ) { + return; + } + remove( lockName ); + close( fd ); +} + + +// -------------------------------------------------------------------------------------- // Get the VT number X is running on // (code taken from GDM, daemon/getvt.c, GPLv2+) // -------------------------------------------------------------------------------------- @@ -254,6 +286,13 @@ int find_keyboards() { return 0; } +void handle_sigterm(int signum) { + if (lockfd >= 0) { + releaseLock(lockfd, lockFileName); + } + exit(0); +} + int main() { int current_keyboard; char name[256] = "Unknown"; @@ -276,6 +315,12 @@ int main() { int evBase; int errBase; + // Register cleanup handlers + struct sigaction action; + memset(&action, 0, sizeof(struct sigaction)); + action.sa_handler = handle_sigterm; + sigaction(SIGTERM, &action, NULL); + // Open X11 display display = XOpenDisplay(NULL); if (!display) { @@ -283,13 +328,22 @@ int main() { return -1; } + // Ensure only one process is running on a given display + sprintf(lockFileName, "/var/lock/tdekbdledsync-%s.lock", XDisplayString(display)); + lockfd = tryGetLock(lockFileName); + if (lockfd < 0) { + printf ("[tdekbdledsync] Another instance of this program is already running on this X11 display!\n[tdekbdledsync] Lockfile detected at '%s'\n", lockFileName); + return -2; + } + // Set up Xkb extension int i1, mn, mj; mj = XkbMajorVersion; mn = XkbMinorVersion; if (!XkbQueryExtension(display, &i1, &evBase, &errBase, &mj, &mn)) { printf("[tdekbdledsync] Server doesn't support a compatible XKB\n"); - return -2; + releaseLock(lockfd, lockFileName); + return -3; } XkbSelectEvents(display, XkbUseCoreKbd, XkbStateNotifyMask, XkbStateNotifyMask); @@ -309,7 +363,8 @@ int main() { udev = udev_new(); if (!udev) { printf("[tdekbdledsync] Cannot connect to udev interface\n"); - return -3; + releaseLock(lockfd, lockFileName); + return -4; } // Set up a udev monitor to monitor input devices @@ -327,7 +382,8 @@ int main() { find_keyboards(); if (keyboard_fd_num == 0) { printf ("[tdekbdledsync] Could not find any usable keyboard(s)!\n"); - return -4; + releaseLock(lockfd, lockFileName); + return -5; } else { fprintf(stderr, "[tdekbdledsync] Found %d keyboard(s)\n", keyboard_fd_num); @@ -342,14 +398,16 @@ int main() { // Get current active VT if (ioctl(vt_fd, VT_GETSTATE, &vtstat)) { fprintf(stderr, "[tdekbdledsync] Unable to get current VT!\n"); - return -5; + releaseLock(lockfd, lockFileName); + return -6; } if (x11_vt_num == vtstat.v_active) { // Get Virtual Core keyboard status if (XkbGetIndicatorState(display, XkbUseCoreKbd, &states) != Success) { fprintf(stderr, "[tdekbdledsync] Unable to query X11 Virtual Core keyboard!\n"); - return -6; + releaseLock(lockfd, lockFileName); + return -7; } XkbGetState(display, XkbUseCoreKbd, &state); @@ -440,5 +498,6 @@ int main() { } } + releaseLock(lockfd, lockFileName); return 0; } |