| 1 | /* |
| 2 | * mesg -- set current tty to accept or |
| 3 | * forbid write permission. |
| 4 | * |
| 5 | * mesg [y] [n] |
| 6 | * y allow messages |
| 7 | * n forbid messages |
| 8 | */ |
| 9 | |
| 10 | #include <stdio.h> |
| 11 | #include <sys/types.h> |
| 12 | #include <sys/stat.h> |
| 13 | |
| 14 | struct stat sbuf; |
| 15 | |
| 16 | char *tty; |
| 17 | char *ttyname(); |
| 18 | |
| 19 | main(argc, argv) |
| 20 | char *argv[]; |
| 21 | { |
| 22 | int r=0; |
| 23 | tty = ttyname(2); |
| 24 | if(stat(tty, &sbuf) < 0) error("cannot stat"); |
| 25 | if(argc < 2) { |
| 26 | if(sbuf.st_mode & 02) |
| 27 | fprintf(stderr,"is y\n"); |
| 28 | else { r=1; |
| 29 | fprintf(stderr,"is n\n"); |
| 30 | } |
| 31 | } else switch(*argv[1]) { |
| 32 | case 'y': |
| 33 | newmode(0622); break; |
| 34 | |
| 35 | case 'n': |
| 36 | newmode(0600); r=1; break; |
| 37 | |
| 38 | default: |
| 39 | error("usage: mesg [y] [n]"); |
| 40 | } |
| 41 | exit(r); |
| 42 | } |
| 43 | |
| 44 | error(s) |
| 45 | char *s; |
| 46 | { |
| 47 | fprintf(stderr,"mesg: %s\n",s); |
| 48 | exit(-1); |
| 49 | } |
| 50 | |
| 51 | newmode(m) |
| 52 | { |
| 53 | if(chmod(tty,m)<0) |
| 54 | error("cannot change mode"); |
| 55 | } |