| 1 | /* |
| 2 | * write to another user |
| 3 | */ |
| 4 | |
| 5 | #include <stdio.h> |
| 6 | #include <sys/types.h> |
| 7 | #include <sys/stat.h> |
| 8 | #include <signal.h> |
| 9 | #include <utmp.h> |
| 10 | |
| 11 | char *strcat(); |
| 12 | char *strcpy(); |
| 13 | struct utmp ubuf; |
| 14 | int signum[] = {SIGHUP, SIGINT, SIGQUIT, 0}; |
| 15 | char me[10] = "???"; |
| 16 | char *him; |
| 17 | char *mytty; |
| 18 | char histty[32]; |
| 19 | char *histtya; |
| 20 | char *ttyname(); |
| 21 | char *rindex(), *index(); |
| 22 | int logcnt; |
| 23 | int eof(); |
| 24 | int timout(); |
| 25 | FILE *tf; |
| 26 | |
| 27 | main(argc, argv) |
| 28 | char *argv[]; |
| 29 | { |
| 30 | struct stat stbuf; |
| 31 | register i; |
| 32 | register FILE *uf; |
| 33 | int c1, c2; |
| 34 | |
| 35 | if(argc < 2) { |
| 36 | printf("usage: write user [ttyname]\n"); |
| 37 | exit(1); |
| 38 | } |
| 39 | him = argv[1]; |
| 40 | if(argc > 2) |
| 41 | histtya = argv[2]; |
| 42 | if ((uf = fopen("/etc/utmp", "r")) == NULL) { |
| 43 | printf("cannot open /etc/utmp\n"); |
| 44 | goto cont; |
| 45 | } |
| 46 | mytty = ttyname(2); |
| 47 | if (mytty == NULL) { |
| 48 | printf("Can't find your tty\n"); |
| 49 | exit(1); |
| 50 | } |
| 51 | mytty = index(mytty+1, '/') + 1; |
| 52 | if (histtya) { |
| 53 | strcpy(histty, "/dev/"); |
| 54 | strcat(histty, histtya); |
| 55 | } |
| 56 | while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) { |
| 57 | if (strcmp(ubuf.ut_line, mytty)==0) { |
| 58 | for(i=0; i<8; i++) { |
| 59 | c1 = ubuf.ut_name[i]; |
| 60 | if(c1 == ' ') |
| 61 | c1 = 0; |
| 62 | me[i] = c1; |
| 63 | if(c1 == 0) |
| 64 | break; |
| 65 | } |
| 66 | } |
| 67 | if(him[0] != '-' || him[1] != 0) |
| 68 | for(i=0; i<8; i++) { |
| 69 | c1 = him[i]; |
| 70 | c2 = ubuf.ut_name[i]; |
| 71 | if(c1 == 0) |
| 72 | if(c2 == 0 || c2 == ' ') |
| 73 | break; |
| 74 | if(c1 != c2) |
| 75 | goto nomat; |
| 76 | } |
| 77 | logcnt++; |
| 78 | if (histty[0]==0) { |
| 79 | strcpy(histty, "/dev/"); |
| 80 | strcat(histty, ubuf.ut_line); |
| 81 | } |
| 82 | nomat: |
| 83 | ; |
| 84 | } |
| 85 | cont: |
| 86 | if (logcnt==0 && histty[0]=='\0') { |
| 87 | printf("%s not logged in.\n", him); |
| 88 | exit(1); |
| 89 | } |
| 90 | fclose(uf); |
| 91 | if (histtya==0 && logcnt > 1) { |
| 92 | printf("%s logged more than once\nwriting to %s\n", him, histty+5); |
| 93 | } |
| 94 | if(histty[0] == 0) { |
| 95 | printf(him); |
| 96 | if(logcnt) |
| 97 | printf(" not on that tty\n"); else |
| 98 | printf(" not logged in\n"); |
| 99 | exit(1); |
| 100 | } |
| 101 | if (access(histty, 0) < 0) { |
| 102 | printf("%s: ", histty); |
| 103 | printf("No such tty\n"); |
| 104 | exit(1); |
| 105 | } |
| 106 | signal(SIGALRM, timout); |
| 107 | alarm(5); |
| 108 | if ((tf = fopen(histty, "w")) == NULL) |
| 109 | goto perm; |
| 110 | alarm(0); |
| 111 | if (fstat(fileno(tf), &stbuf) < 0) |
| 112 | goto perm; |
| 113 | if ((stbuf.st_mode&02) == 0) |
| 114 | goto perm; |
| 115 | sigs(eof); |
| 116 | fprintf(tf, "Message from "); |
| 117 | #ifdef interdata |
| 118 | fprintf(tf, "(Interdata) " ); |
| 119 | #endif |
| 120 | fprintf(tf, "%s %s...\n\a\a\a", me, mytty); |
| 121 | fflush(tf); |
| 122 | for(;;) { |
| 123 | char buf[128]; |
| 124 | i = read(0, buf, 128); |
| 125 | if(i <= 0) |
| 126 | eof(); |
| 127 | if(buf[0] == '!') { |
| 128 | buf[i] = 0; |
| 129 | ex(buf); |
| 130 | continue; |
| 131 | } |
| 132 | write(fileno(tf), buf, i); |
| 133 | } |
| 134 | |
| 135 | perm: |
| 136 | printf("Permission denied\n"); |
| 137 | exit(1); |
| 138 | } |
| 139 | |
| 140 | timout() |
| 141 | { |
| 142 | |
| 143 | printf("Timeout opening his tty\n"); |
| 144 | exit(1); |
| 145 | } |
| 146 | |
| 147 | eof() |
| 148 | { |
| 149 | |
| 150 | fprintf(tf, "EOF\n"); |
| 151 | exit(0); |
| 152 | } |
| 153 | |
| 154 | ex(bp) |
| 155 | char *bp; |
| 156 | { |
| 157 | register i; |
| 158 | |
| 159 | sigs(SIG_IGN); |
| 160 | i = fork(); |
| 161 | if(i < 0) { |
| 162 | printf("Try again\n"); |
| 163 | goto out; |
| 164 | } |
| 165 | if(i == 0) { |
| 166 | sigs((int (*)())0); |
| 167 | execl("/bin/sh", "sh", "-c", bp+1, 0); |
| 168 | exit(0); |
| 169 | } |
| 170 | while(wait((int *)NULL) != i) |
| 171 | ; |
| 172 | printf("!\n"); |
| 173 | out: |
| 174 | sigs(eof); |
| 175 | } |
| 176 | |
| 177 | sigs(sig) |
| 178 | int (*sig)(); |
| 179 | { |
| 180 | register i; |
| 181 | |
| 182 | for(i=0;signum[i];i++) |
| 183 | signal(signum[i],sig); |
| 184 | } |