commands/simple/modem.c

   1 /* modem - Put modem into DIALIN or DIALOUT mode.       Author: F. van Kempen */
   2
   3 /* Exit:        0       OK, suspended/restarted GETTY
   4  *              1       UNIX error
   5  *              2       Process busy
   6  * Version:     1.3     12/30/89
   7  *
   8  * Author:      F. van Kempen, MicroWalt Corporation
   9  *
  10  * All fancy stuff removed, see getty.c.        Kees J. Bot.
  11  *
  12  */
  13
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18 #include <sys/wait.h>
  19 #include <fcntl.h>
  20 #include <signal.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <utmp.h>
  24 #include <errno.h>
  25
  26 #include <minix/paths.h>
  27
  28 char PATH_UTMP[] = _PATH_UTMP;                  /* current logins */
  29
  30 _PROTOTYPE(void usage , (void));
  31 _PROTOTYPE(int main , (int argc , char *argv []));
  32 _PROTOTYPE(void sendcodes , (char *tty, char *codes));
  33
  34
  35 void usage()
  36 {
  37   fprintf(stderr,
  38 "Usage: modem [-sio] [-I in-codes] [-O out-codes] line [command args ...]\n");
  39   exit(1);
  40 }
  41
  42
  43 main(argc, argv)
  44 int argc;
  45 char *argv[];
  46 {
  47   struct utmp entry;
  48   char devtty[1024], *tty;
  49   char **command;
  50   int ex_code = 0;
  51   int fd, i, slot, getty;
  52   struct stat st;
  53   enum { TOGGLE, DIALIN, DIALOUT } mode= TOGGLE;
  54   int silent = 0;
  55   _PROTOTYPE(void (*hsig), (int));
  56   _PROTOTYPE(void (*isig), (int));
  57   _PROTOTYPE(void (*qsig), (int));
  58   _PROTOTYPE(void (*tsig), (int));
  59   pid_t pid;
  60   int r, status;
  61   uid_t uid = getuid();
  62   gid_t gid = getgid();
  63   char *in_codes, *out_codes;
  64
  65   i = 1;
  66   while (i < argc && argv[i][0] == '-') {
  67         char *opt = argv[i++] + 1;
  68
  69         if (opt[0] == '-' && opt[1] == 0) break;
  70
  71         while (*opt != 0) {
  72                 switch (*opt++) {
  73                     case 's':   /* silent mode */
  74                         silent = 1;
  75                         break;
  76                     case 'i':   /* DIAL-IN mode: suspend GETTY */
  77                         mode = DIALIN;
  78                         break;
  79                     case 'o':   /* DIAL-OUT mode: restart GETTY */
  80                         mode = DIALOUT;
  81                         break;
  82                     case 'I':   /* code to switch modem to dial-in */
  83                         if (*opt == 0) {
  84                                 if (i == argc) usage();
  85                                 opt = argv[i++];
  86                         }
  87                         in_codes = opt;
  88                         opt = "";
  89                         break;
  90                     case 'O':   /* code to switch modem to dial-out */
  91                         if (*opt == 0) {
  92                                 if (i == argc) usage();
  93                                 opt = argv[i++];
  94                         }
  95                         out_codes = opt;
  96                         opt = "";
  97                         break;
  98                     default:
  99                         usage();
 100                 }
 101         }
 102   }
 103
 104   if (i == argc) usage();
 105   tty = argv[i++];              /* Modem line */
 106
 107   if (mode != TOGGLE && i != argc) usage();
 108   command = argv + i;           /* Command to execute (if any). */
 109
 110   if (strchr(tty, '/') == NULL) {
 111         strcpy(devtty, "/dev/");
 112         strncat(devtty, tty, 1024 - 6);
 113         tty = devtty;
 114   }
 115
 116   if (stat(tty, &st) < 0) {
 117         fprintf(stderr, "modem: %s: %s\n", tty, strerror(errno));
 118         exit(1);
 119   }
 120
 121   if (!S_ISCHR(st.st_mode)) {
 122         fprintf(stderr, "%s is not a tty\n", tty);
 123         exit(1);
 124   }
 125
 126   /* Find the utmp slot number for the line. */
 127   if ((fd= open(tty, O_RDONLY)) < 0 || (slot= fttyslot(fd)) == 0) {
 128         fprintf(stderr, "modem: %s: %s\n", tty, strerror(errno));
 129         exit(1);
 130   }
 131   close(fd);
 132
 133   /* Read the UTMP file to find out the PID and STATUS of the GETTY. */
 134   entry.ut_type= 0;
 135   if ((fd = open(PATH_UTMP, O_RDONLY)) < 0
 136         || lseek(fd, (off_t) slot * sizeof(entry), SEEK_SET) < 0
 137         || read(fd, &entry, sizeof(entry)) < 0
 138   ) {
 139         fprintf(stderr, "modem: cannot read UTMP !\n");
 140         exit(1);
 141   }
 142   close(fd);
 143
 144   hsig= signal(SIGHUP, SIG_IGN);
 145   isig= signal(SIGINT, SIG_IGN);
 146   qsig= signal(SIGQUIT, SIG_IGN);
 147   tsig= signal(SIGTERM, SIG_IGN);
 148
 149   /* Process the terminal entry if we got one. */
 150   switch (entry.ut_type) {
 151   case LOGIN_PROCESS:           /* getty waiting for a call */
 152         getty = 1;
 153         break;
 154   case USER_PROCESS:            /* login or user-shell */
 155         if (!silent) fprintf(stderr, "modem: line is busy.\n");
 156         exit(2);
 157         break;
 158   default:
 159         getty = 0;
 160   }
 161
 162   for (i = (mode == TOGGLE) ? 0 : 1; i < 2; i++) {
 163         /* Now perform the desired action (DIALIN or DIALOUT). */
 164         switch (mode) {
 165         case DIALOUT:
 166         case TOGGLE:
 167                 if (getty) kill(entry.ut_pid, SIGUSR1);  /* suspend getty */
 168                 chown(tty, uid, st.st_gid);     /* give line to user */
 169                 chmod(tty, 0600);
 170                 if (out_codes != NULL) sendcodes(tty, out_codes);
 171                 if (!silent) printf("modem on %s set for dialout.\n", tty);
 172                 break;
 173         case DIALIN:
 174                 if (in_codes != NULL) sendcodes(tty, in_codes);
 175                 chown(tty, 0, st.st_gid);               /* revoke access */
 176                 chmod(tty, 0600);
 177                 if (getty) kill(entry.ut_pid, SIGUSR2); /* restart getty */
 178                 if (!silent) printf("modem on %s set for dialin.\n", tty);
 179         }
 180         if (mode == TOGGLE) {
 181                 /* Start the command to run */
 182                 pid_t pid;
 183                 int status;
 184
 185                 switch ((pid = fork())) {
 186                 case -1:
 187                         fprintf(stderr, "modem: fork(): %s\n", strerror(errno));
 188                         ex_code= 1;
 189                         break;
 190                 case 0:
 191                         setgid(gid);
 192                         setuid(uid);
 193                         (void) signal(SIGHUP, hsig);
 194                         (void) signal(SIGINT, isig);
 195                         (void) signal(SIGQUIT, qsig);
 196                         (void) signal(SIGTERM, tsig);
 197                         execvp(command[0], command);
 198                         fprintf(stderr, "modem: %s: %s\n",
 199                                         command[0], strerror(errno));
 200                         _exit(127);
 201                 default:
 202                         while ((r= wait(&status)) != pid) {
 203                                 if (r == -1 && errno != EINTR) break;
 204                         }
 205                         if (r == -1 || status != 0) ex_code = 1;
 206                 }
 207                 mode = DIALIN;
 208         }
 209   }
 210   exit(ex_code);
 211 }
 212
 213 void sendcodes(tty, codes)
 214 char *tty, *codes;
 215 {
 216         int fd;
 217         int c;
 218         char buf[1024], *bp = buf;
 219
 220         if ((fd = open(tty, O_RDWR|O_NONBLOCK)) < 0) {
 221                 fprintf(stderr, "modem: can't send codes to %s: %s\n",
 222                         tty, strerror(errno));
 223                 return;
 224         }
 225         while ((c = *codes++) != 0) {
 226 fprintf(stderr, "%d\n", __LINE__);
 227                 if (c == '\\') {
 228                         if ((c = *codes++) == 0) break;
 229                         if (c == 'r') c= '\r';
 230                         if (c == 'n') c= '\n';
 231                 }
 232                 *bp++ = c;
 233                 if (bp == buf + sizeof(buf) || c == '\r' || c == '\n') {
 234 fprintf(stderr, "%d\n", __LINE__);
 235                         write(fd, buf, bp - buf);
 236 fprintf(stderr, "%d\n", __LINE__);
 237                         do {sleep(1);
 238 fprintf(stderr, "%d\n", __LINE__);
 239                         fprintf(stderr, "%d\n", read(fd, buf, sizeof(buf)));
 240                         }while (read(fd, buf, sizeof(buf)) > 0);
 241 fprintf(stderr, "%d\n", __LINE__);
 242                         bp = buf;
 243                 }
 244         }
 245         if (bp > buf) {
 246 fprintf(stderr, "%d\n", __LINE__);
 247                 write(fd, buf, bp - buf);
 248 fprintf(stderr, "%d\n", __LINE__);
 249                 do sleep(1); while (read(fd, buf, sizeof(buf)) > 0);
 250 fprintf(stderr, "%d\n", __LINE__);
 251         }
 252         close(fd);
 253 }