loadkmap.c

   1 #include <unistd.h>
   2 #include <fcntl.h>
   3 #include <sys/ioctl.h>
   4 #include <netinet/in.h>
   5
   6 #define KDGKBTYPE 0x4B33
   7 #define ARRAYSIZE(a) sizeof(a)/sizeof(a[0])
   8 static int console_fd(int mode) {
   9         const char devs[][16] = { "/dev/tty", "/dev/vc/0", "/dev/console" };
  10         size_t i = 0;
  11         int fd = -1;
  12         while(i < ARRAYSIZE(devs) && fd == -1) {
  13                 fd = open(devs[i++], mode);
  14                 if(fd != -1 && ioctl(fd, KDGKBTYPE, &(char){0})) {
  15                         close(fd);
  16                         fd = -1;
  17                 }
  18         }
  19         return fd;
  20 }
  21
  22 struct kbentry {
  23         unsigned char kb_table;
  24         unsigned char kb_index;
  25         unsigned short kb_value;
  26 };
  27
  28 #define KDSKBENT 0x4B47
  29 #define NR_KEYS 128
  30 #define MAX_NR_KEYMAPS 256
  31
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #ifdef USE_LIBULZ
  35 #include <ulz/stdio-repl.h>
  36 #endif
  37
  38 #define noret __attribute__((noreturn))
  39
  40 noret static void die_perror(const char* msg) {
  41         perror(msg);
  42         exit(1);
  43 }
  44
  45 noret static void usage(const char *arg0) {
  46         dprintf(2, "usage: %s < my.kmap\n"
  47                    "loads kmap from stdin.\n", arg0);
  48         exit(1);
  49 }
  50
  51 static void fetch(int fd, void* buf, size_t cnt) {
  52         if(read(fd, buf, cnt) != (ssize_t) cnt) die_perror("read");
  53 }
  54
  55 #include <errno.h>
  56 #include <string.h>
  57 int main(int argc, char** argv) {
  58         (void) argc;
  59         if(argv[1] || isatty(0)) usage(argv[0]);
  60         char flags[MAX_NR_KEYMAPS];
  61         fetch(0, flags, 7);
  62         if(memcmp(flags, "hcukmap", 7)) { errno = EINVAL; die_perror("invalid magic"); }
  63         fetch(0, flags, MAX_NR_KEYMAPS);
  64         int cfd = console_fd(O_WRONLY);
  65         if(cfd == -1) die_perror("could not get console fd");
  66         size_t i = 0, j;
  67         for(;i < MAX_NR_KEYMAPS; i++) if(flags[i]) {
  68                 short kmap[NR_KEYS];
  69                 fetch(0, kmap, sizeof kmap);
  70                 for(j=0; j < NR_KEYS; j++) {
  71                         struct kbentry ke = { .kb_index = j, .kb_table = i };
  72                         ke.kb_value = ntohs(kmap[j]);
  73                         if(ioctl(cfd, KDSKBENT, &ke))
  74                                 ;
  75                                 // some keymaps contain the value 638 in the first entry, which means K_ALLOCATED.
  76                                 // not sure how to deal with this best; it seems it can be ignored.
  77                                 /* dprintf(2, "warning: failed to set key slot %zu,%zu to %d, reason: %s\n",
  78                                         i, j, ke.kb_value, strerror(errno)); */
  79                 }
  80         }
  81         return 0;
  82 }