Initial commit.

hid_apple_fn_lock.c

@@ -0,0 +1,149 @@
+#include <unistd.h> /* access */
+#include <stdlib.h> /* exit */
+#include <syslog.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <errno.h>
+#include <string.h> /* strcmp */
+
+/* Kernel module entry for the Apple Human Interface Device driver. */
+#define APPLE_HID_PATH "/sys/module/hid_apple"
+
+char file_exists(const char *filename)
+{
+    return access(filename, F_OK) != -1;
+}
+
+int init_apple_hid_module()
+{
+    int fd;
+
+    if(!file_exists(APPLE_HID_PATH)) {
+        syslog(LOG_WARNING, "Apple hid module is unloaded.");
+        return -1;
+    }
+
+    fd = open(APPLE_HID_PATH"/parameters/fnmode", O_RDWR);
+    if(fd == -1) {
+        syslog(LOG_WARNING, "Failed to open %s.",
+               APPLE_HID_PATH"/parameters/fnmode");
+        return -1;
+    }
+
+    return fd;
+}
+
+int get_fn_lock()
+{
+    int fd;
+    char state;
+
+    fd = init_apple_hid_module();
+    if(fd != -1) {
+        if(read(fd, &state, 1) != 1)
+            state = '0';
+        close(fd);
+    }
+
+    return state == '2';
+}
+
+void set_fn_lock_on()
+{
+    int fd;
+
+    fd = init_apple_hid_module();
+    if(fd != -1) {
+        if(write(fd, "2", 1) != 1)
+            syslog(LOG_WARNING, "Failed to write to Apple HID driver.");
+        else
+            syslog(LOG_INFO, "Fn lock is on.");
+        close(fd);
+    }
+}
+
+void set_fn_lock_off()
+{
+    int fd = init_apple_hid_module();
+    if(fd != -1) {
+        if(write(fd, "1", 1) != 1)
+            syslog(LOG_WARNING, "Failed to write Apple HID driver.");
+        else
+            syslog(LOG_INFO, "Fn lock is off.");
+        close(fd);
+    }
+}
+
+void daemonize()
+{
+    close(0);
+    close(1);
+    close(2);
+    open("/dev/null", O_RDONLY); /* stdin */
+    open("/dev/null", O_WRONLY); /* stdout */
+    open("/dev/null", O_WRONLY); /* stderr */
+    chdir("/");
+    int pid = fork();
+    if(pid > 0)
+        exit(0);
+    setsid();
+    pid = fork();
+    if(pid > 0)
+        exit(0);
+}
+
+#if 1
+static volatile sig_atomic_t n = 0;
+
+void usr1hdl(int sig)
+{
+    int save_errno = errno;
+    signal(SIGUSR1, usr1hdl);
+    n = 0;
+    errno = save_errno;
+}
+
+void termhdl(int sig)
+{
+    int save_errno = errno;
+    signal(SIGTERM, termhdl);
+    n = 1;
+    errno = save_errno;
+}
+#endif
+
+int main(int argc, char *argv[])
+{
+    /*daemonize();*/
+
+    signal(SIGUSR1, usr1hdl);
+    signal(SIGTERM, termhdl);
+
+    openlog("hid_apple_fn_lock", 0, LOG_USER);
+    syslog(LOG_INFO, "Daemon started, pid == %d", getpid());
+
+    uid_t euid = geteuid();
+    if(euid != 0) {
+        syslog(LOG_WARNING, "Must have root priviliges. Quitting...");
+        return 1;
+    }
+
+    for(;;) {
+        pause();
+        if(n == 0) {
+            if(get_fn_lock())
+                set_fn_lock_off();
+            else
+                set_fn_lock_on();
+        } else if(n == 1) {
+            syslog(LOG_INFO, "Shutting down...");
+            break;
+        } else {
+            /* ignore */
+        }
+    }
+
+    closelog();
+
+    return 0;
+}