test/select/test09.c

   1 /*
   2  * Test name: test09.c
   3  *
   4  * Objetive: The purpose of this test is to make sure that select works
   5  * when working with the terminal.
   6  *
   7  * Description:  This tests wait entry from stdin using select and displays
   8  * it again in stdout when it is ready to write (which is always)
   9  *
  10  * Jose M. Gomez
  11  */
  12
  13 #include <sys/types.h>
  14 #include <fcntl.h>
  15 #include <unistd.h>
  16 #include <sys/select.h>
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <limits.h>
  21
  22 void main(void) {
  23         fd_set fds_read, fds_write;
  24         int retval;
  25         char data[1024];
  26
  27         FD_ZERO(&fds_read);
  28         FD_ZERO(&fds_write);
  29         FD_SET(0, &fds_read);           /* stdin */
  30         FD_SET(1, &fds_write);          /* stdout */
  31
  32         while(1) {
  33                 printf("Input some data: ");
  34                 fflush(stdout);
  35                 retval=select(3, &fds_read, NULL, NULL, NULL);
  36                 if (retval < 0) {
  37                         fprintf(stderr, "Error while executing select\n");
  38                         exit(-1);
  39                 }
  40                 printf("select retval: %d\n", retval);
  41                 if (!FD_ISSET(0, &fds_read)) {
  42                         fprintf(stderr, "Error: stdin not ready (?)\n");
  43                         exit(-1);
  44                 }
  45                 printf("gets..\n");
  46                 gets(data);
  47                 printf("gets done..\n");
  48                 if (!strcmp(data, "exit"))
  49                         exit(0);
  50                 printf("Try to write it back\n");
  51                 retval=select(3, NULL, &fds_write, NULL, NULL);
  52                 if (retval < 0) {
  53                         fprintf(stderr, "Error while executing select\n");
  54                         exit(-1);
  55                 }
  56                 if (!FD_ISSET(1, &fds_write)) {
  57                         fprintf(stderr, "Error: stdout not ready (?)\n");
  58                         exit(-1);
  59                 }
  60                 printf("Data: %s\n", data);
  61         }
  62 }