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76 lines
1.3 KiB
76 lines
1.3 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <sys/ioctl.h>
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#include <linux/kd.h>
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#include "getfd.h"
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/*
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* getfd.c
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*
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* Get an fd for use with kbd/console ioctls.
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* We try several things because opening /dev/console will fail
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* if someone else used X (which does a chown on /dev/console).
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*/
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static int
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is_a_console(int fd) {
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char arg;
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arg = 0;
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return (ioctl(fd, KDGKBTYPE, &arg) == 0
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&& ((arg == KB_101) || (arg == KB_84)));
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}
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static int
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open_a_console(const char *fnam) {
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int fd;
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/*
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* For ioctl purposes we only need some fd and permissions
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* do not matter. But setfont:activatemap() does a write.
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*/
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fd = open(fnam, O_RDWR);
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if (fd < 0 && errno == EACCES)
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fd = open(fnam, O_WRONLY);
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if (fd < 0 && errno == EACCES)
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fd = open(fnam, O_RDONLY);
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if (fd < 0)
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return -1;
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if (!is_a_console(fd)) {
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close(fd);
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return -1;
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}
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return fd;
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}
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int getfd() {
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int fd;
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fd = open_a_console("/dev/tty");
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if (fd >= 0)
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return fd;
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fd = open_a_console("/dev/tty0");
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if (fd >= 0)
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return fd;
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fd = open_a_console("/dev/vc/0");
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if (fd >= 0)
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return fd;
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fd = open_a_console("/dev/console");
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if (fd >= 0)
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return fd;
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for (fd = 0; fd < 3; fd++)
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if (is_a_console(fd))
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return fd;
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// "Couldnt get a file descriptor referring to the console
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return -1;
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}
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