diff options
Diffstat (limited to 'src/getfd.c')
-rw-r--r-- | src/getfd.c | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/src/getfd.c b/src/getfd.c new file mode 100644 index 0000000..9dbe15c --- /dev/null +++ b/src/getfd.c @@ -0,0 +1,52 @@ +#include <stdio.h> +#include <fcntl.h> +#include <errno.h> +#include <linux/kd.h> +#include <sys/ioctl.h> + +/* + * getfd.c + * + * Get an fd for use with kbd/console ioctls. + * We try several things because opening /dev/console will fail + * if someone else used X (which does a chown on /dev/console). + */ + +static int +is_a_console(int fd) { + char arg; + + arg = 0; + return (ioctl(fd, KDGKBTYPE, &arg) == 0 + && ((arg == KB_101) || (arg == KB_84))); +} + +static int +open_a_console(char *fnam) { + int fd; + + fd = open(fnam, O_RDONLY); + if (fd < 0 && errno == EACCES) + fd = open(fnam, O_WRONLY); + if (fd < 0 || ! is_a_console(fd)) + return -1; + return fd; +} + +int getfd() { + int fd; + + fd = open_a_console("/dev/tty"); + if (fd >= 0) + return fd; + + fd = open_a_console("/dev/console"); + if (fd >= 0) + return fd; + + for (fd = 0; fd < 3; fd++) + if (is_a_console(fd)) + return fd; + + return -1; +} |