test/select/test14.c

   1 /*
   2  * Test name: test14.c
   3  *
   4  * Objetive: The purpose of this test is to make sure that select works
   5  * with ptys.
   6  *
   7  * Adapted from test11.c (pipe test).
   8  *
   9  * Ben Gras
  10  */
  11 #include <time.h>
  12 #include <sys/types.h>
  13 #include <sys/wait.h>
  14 #include <sys/asynchio.h>
  15 #include <fcntl.h>
  16 #include <unistd.h>
  17 #include <sys/select.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <limits.h>
  21 #include <string.h>
  22 #include <signal.h>
  23 #include <libutil.h>
  24 char name[100];
  25 void pipehandler(int sig)
  26 {
  27 }
  28 #define CHILDFD 1
  29 #define PARENTFD 0
  30 void do_child(int pty_fds[])
  31 {
  32         /* reads from pipe and prints out the data */
  33         char data[2048];
  34         int retval;
  35         fd_set fds_read;
  36         fd_set fds_exception;
  37         struct timeval timeout;
  38         signal(SIGPIPE, pipehandler);
  39         signal(SIGUSR1, pipehandler);
  40         /* first, close the write part, since it is not needed */
  41         close(pty_fds[PARENTFD]);
  42
  43         while(1) {
  44                 FD_ZERO(&fds_read);
  45                 FD_ZERO(&fds_exception);
  46                 FD_SET(pty_fds[CHILDFD], &fds_read);
  47                 FD_SET(pty_fds[CHILDFD], &fds_exception);
  48                 timeout.tv_sec = 5;
  49                 timeout.tv_usec = 0;
  50                 retval = select(pty_fds[CHILDFD]+2,  &fds_read, NULL, &fds_exception, &timeout);
  51                 if (retval == -1) {
  52                         perror("select");
  53                         fprintf(stderr, "child: Error in select\n");
  54                         continue;
  55                 } else printf("child select: %d\n", retval);
  56                 if (FD_ISSET(pty_fds[CHILDFD], &fds_exception)) {
  57                         printf("child: exception fd set. quitting.\n");
  58                         break;
  59                 }
  60                 if (FD_ISSET(pty_fds[CHILDFD], &fds_read)) {
  61                         printf("child: read fd set. reading.\n");
  62                         if ((retval = read(pty_fds[CHILDFD], data, sizeof(data))) < 0) {
  63                                 perror("read");
  64                                 fprintf(stderr, "child: couldn't read from pty\n");
  65                                 exit(-1);
  66                         }
  67                         if(retval == 0) {
  68                                 fprintf(stderr, "child: eof on pty\n");
  69                                 break;
  70                         }
  71                         data[retval] = '\0';
  72                         printf("pid %d pty reads (%d): %s\n", getpid(), retval, data);
  73                 } else printf("child: no fd set\n");
  74         }
  75
  76         exit(0);
  77 }
  78 void do_parent(int pty_fds[])
  79 {
  80         char data[1024];
  81         int retval;
  82         fd_set fds_write;
  83         signal(SIGPIPE, pipehandler);
  84         signal(SIGUSR1, pipehandler);
  85         /* first, close the read part of pty, since it is not needed */
  86         close(pty_fds[CHILDFD]);
  87         /* now enter a loop of read user input, and writing it to the pty */
  88         while (1) {
  89                 FD_ZERO(&fds_write);
  90                 FD_SET(pty_fds[PARENTFD], &fds_write);
  91                 printf("pid %d Waiting for pty ready to write on %s...\n",
  92                         getpid(), name);
  93                 retval = select(pty_fds[PARENTFD]+2, NULL, &fds_write, NULL, NULL);
  94                 if (retval == -1) {
  95                         perror("select");
  96                         fprintf(stderr, "Parent: Error in select\n");
  97                         exit(-1);
  98                 }
  99                 printf("Input data: ");
 100                 if(!gets(data)) {
 101                         printf("parent: eof; exiting\n");
 102                         break;
 103                 }
 104                 if (!strcmp(data, "exit"))
 105                         break;
 106                 if (!FD_ISSET(pty_fds[PARENTFD], &fds_write)) {
 107                         fprintf(stderr, "parent: write fd not set?! retrying\n");
 108                         continue;
 109                 }
 110                 retval = write(pty_fds[PARENTFD], data, 1024);
 111                 if (retval == -1) {
 112                         perror("write");
 113                         fprintf(stderr, "Error writing on pty\n");
 114                         exit(-1);
 115                 } else printf("wrote %d\n", retval);
 116         }
 117         /* got exit from user */
 118         close(pty_fds[PARENTFD]);       /* close pty, let child know we're done */
 119         wait(&retval);
 120         printf("Child exited with status: %d\n", retval);
 121         exit(0);
 122 }
 123 int main(int argc, char *argv[])
 124 {
 125         int ptys[2];
 126         int retval;
 127         int pid;
 128         if(openpty(&ptys[0], &ptys[1], name, NULL, NULL) < 0) {
 129                 perror("openpty");
 130                 return 1;
 131         }
 132         printf("Using %s\n", name);
 133         pid = fork();
 134         if (pid == -1) {
 135                 fprintf(stderr, "Error forking\n");
 136                 exit(-1);
 137         }
 138         if (pid == 0) /* child proc */
 139                 do_child(ptys);
 140         else
 141                 do_parent(ptys);
 142         /* not reached */
 143         return 0;
 144 }