test/t40c.c

   1 /* t40c.c
   2  *
   3  * Test (pseudo) terminal devices
   4  *
   5  * Select works on regular files, (pseudo) terminal devices, streams-based
   6  * files, FIFOs, pipes, and sockets. This test verifies selecting for (pseudo)
   7  * terminal devices.
   8  *
   9  * This test is part of a bigger select test. It expects as argument which sub-
  10  * test it is.
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18 #include <fcntl.h>
  19 #include <sys/select.h>
  20 #include <errno.h>
  21 #include <sys/wait.h>
  22 #include <string.h>
  23
  24 #define TERMINALW "/dev/ttypf"
  25 #define TERMINALR "/dev/ptypf"
  26 #define SENDSTRING "minixrocks"
  27 #define MAX_ERROR 5
  28
  29 int errct = 0, subtest = -1;
  30
  31 void e(int n, char *s) {
  32   printf("Subtest %d, error %d, %s\n", subtest, n, s);
  33
  34   if (errct++ > MAX_ERROR) {
  35     printf("Too many errors; test aborted\n");
  36     exit(errct);
  37   }
  38 }
  39
  40 int do_child(void) {
  41   int fd, retval;
  42   struct timeval tv;
  43
  44   /* Opening master terminal for writing */
  45   if((fd = open(TERMINALW, O_WRONLY)) == -1) {
  46     printf("Error opening %s for writing, signalling parent to quit\n",
  47            TERMINALW);
  48     perror(NULL);
  49     printf("Please make sure that %s is not in use while running this test\n",
  50            TERMINALW);
  51     exit(-1);
  52   }
  53
  54   /* Going to sleep for two seconds to allow the parent proc to get ready */
  55   tv.tv_sec = 2;
  56   tv.tv_usec = 0;
  57   select(0, NULL, NULL, NULL, &tv);
  58
  59   /* Try to write. Doesn't matter how many bytes we actually send. */
  60   retval = write(fd, SENDSTRING, strlen(SENDSTRING));
  61   close(fd);
  62
  63   /* Wait for another second to allow the parent to process incoming data */
  64   tv.tv_usec = 1000000;
  65   retval = select(0,NULL, NULL, NULL, &tv);
  66   exit(0);
  67 }
  68
  69 int do_parent(int child) {
  70   int fd;
  71   fd_set fds_read, fds_write, fds_error;
  72   int retval;
  73
  74   /* Open slave terminal for reading */
  75   if((fd = open(TERMINALR, O_RDONLY)) == -1) {
  76     printf("Error opening %s for reading\n", TERMINALR);
  77     perror(NULL);
  78     printf("Please make sure that %s is not in use while running this test.\n",
  79            TERMINALR);
  80     waitpid(child, &retval, 0);
  81     exit(-1);
  82   }
  83
  84   /* Clear bit masks */
  85   FD_ZERO(&fds_read); FD_ZERO(&fds_write); FD_ZERO(&fds_error);
  86   /* Set read bits */
  87   FD_SET(fd, &fds_read);
  88   FD_SET(fd, &fds_write);
  89
  90   /* Test if we can read or write from/to fd. As fd is opened read only we
  91    * cannot actually write, so the select should return immediately with fd
  92    * set in fds_write, but not in fds_read. Note that the child waits two
  93    * seconds before sending data. This gives us the opportunity run this
  94    * sub-test as reading from fd is blocking at this point. */
  95   retval = select(fd+1, &fds_read, &fds_write, &fds_error, NULL);
  96
  97   if(retval != 1) e(1, "incorrect amount of ready file descriptors");
  98
  99
 100   if(FD_ISSET(fd, &fds_read)) e(2, "read should NOT be set");
 101   if(!FD_ISSET(fd, &fds_write)) e(3, "write should be set");
 102   if(FD_ISSET(fd, &fds_error)) e(4, "error should NOT be set");
 103
 104   /* Block until ready; until child wrote stuff */
 105   FD_ZERO(&fds_read); FD_ZERO(&fds_write); FD_ZERO(&fds_error);
 106   FD_SET(fd, &fds_read);
 107   retval = select(fd+1, &fds_read, NULL, &fds_error, NULL);
 108
 109   if(retval != 1) e(5, "incorrect amount of ready file descriptors");
 110   if(!FD_ISSET(fd, &fds_read)) e(6, "read should be set");
 111   if(FD_ISSET(fd, &fds_error)) e(7, "error should not be set");
 112
 113
 114   FD_ZERO(&fds_read); FD_ZERO(&fds_error);
 115   FD_SET(fd,&fds_write);
 116   retval = select(fd+1, NULL, &fds_write, NULL, NULL);
 117   /* As it is impossible to write to a read only fd, this select should return
 118    * immediately with fd set in fds_write. */
 119   if(retval != 1) e(8, "incorrect amount or ready file descriptors");
 120
 121   close(fd);
 122   waitpid(child, &retval, 0);
 123   exit(errct);
 124 }
 125
 126 int main(int argc, char **argv) {
 127   int forkres;
 128
 129   /* Get subtest number */
 130   if(argc != 2) {
 131     printf("Usage: %s subtest_no\n", argv[0]);
 132     exit(-1);
 133   } else if(sscanf(argv[1], "%d", &subtest) != 1) {
 134     printf("Usage: %s subtest_no\n", argv[0]);
 135     exit(-1);
 136   }
 137
 138   forkres = fork();
 139   if(forkres == 0) do_child();
 140   else if(forkres > 0)  do_parent(forkres);
 141   else { /* Fork failed */
 142     perror("Unable to fork");
 143     exit(-1);
 144   }
 145
 146   exit(-2); /* We're not supposed to get here. Both do_* routines should exit*/
 147
 148 }