test/select/test03.c

   1 /*
   2  * Test name: test03.c
   3  *
   4  * Objetive: The purpose of this test is to make sure that select works
   5  * when working with files.
   6  *
   7  * Description: This test shows more cases than in test02.c, where every
   8  * descriptor is ready. Here in one select call only half of the fd's will
   9  * be ready and in the next one none of them will be ready.
  10  *
  11  * Jose M. Gomez
  12  */
  13
  14 #include <sys/types.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 <sys/time.h>
  22
  23 void dump_fdset(fd_set *set) {
  24         int i;
  25         for (i = 0; i < OPEN_MAX; i++)
  26         if (FD_ISSET(i, set))
  27                 printf(" %d ", i);
  28         printf("\n");
  29 }
  30
  31 int main(int argc, char *argv[])
  32 {
  33         int fd1, fd2, fd3, fd4, fd5, fd6;       /* file descriptors of files */
  34         fd_set fds_read, fds_write;             /* bit maps */
  35         struct timeval timeout;                 /* timeout */
  36         int retval;                             /* ret value */
  37
  38         /* Creates the dummy files with different modes */
  39         fd1 = open("dummy1.txt", O_CREAT | O_RDONLY);
  40         if (fd1 < 0) {
  41                 perror("Error opening file");
  42                 exit(-1);
  43         }
  44
  45         fd2 = open("dummy2.txt", O_CREAT | O_RDONLY);
  46         if (fd2 < 0) {
  47                 perror("Error opening file");
  48                 exit(-1);
  49         }
  50
  51         fd3 = open("dummy3.txt", O_CREAT | O_WRONLY);
  52         if (fd3 < 0) {
  53                 perror("Error opening file");
  54                 exit(-1);
  55         }
  56
  57         fd4 = open("dummy4.txt", O_CREAT | O_WRONLY);
  58         if (fd4 < 0) {
  59                 perror("Error opening file");
  60                 exit(-1);
  61         }
  62
  63         fd5 = open("dummy5.txt", O_CREAT | O_RDWR);
  64         if (fd5 < 0) {
  65                 perror("Error opening file");
  66                 exit(-1);
  67         }
  68
  69         fd6 = open("dummy6.txt", O_CREAT | O_RDWR);
  70         if (fd6 < 0) {
  71                 perror("Error opening file");
  72                 exit(-1);
  73         }
  74
  75         /* Create the fd_set structures */
  76         FD_ZERO(&fds_read);
  77         FD_ZERO(&fds_write);
  78         FD_SET(fd1, &fds_write);        /* fd1 => O_RDONLY */
  79         FD_SET(fd2, &fds_write);        /* fd2 => O_RDONLY */
  80         FD_SET(fd3, &fds_read);         /* fd3 => O_WRONLY */
  81         FD_SET(fd4, &fds_read);         /* fd4 => O_WRONLY */
  82         FD_SET(fd5, &fds_read);         /* fd5 => O_RDWR */
  83         FD_SET(fd5, &fds_write);        /* fd5 => O_RDWR */
  84         FD_SET(fd6, &fds_read);         /* fd6 => O_RDWR */
  85         FD_SET(fd6, &fds_write);        /* fd6 => O_RDWR */
  86
  87         printf("* Dump INPUT fds_read:\n");
  88         dump_fdset(&fds_read);
  89         printf("* Dump INPUT fds_write:\n");
  90         dump_fdset(&fds_write);
  91
  92         retval=select(9, &fds_read, &fds_write, NULL, NULL);
  93         printf("\n***********************\n");
  94         printf("After select: \n");
  95         printf("Return value: %d\n", retval);
  96         printf("* Dump RESULTING fds_read:\n");
  97         dump_fdset(&fds_read);
  98         printf("* Dump RESULTING fds_write:\n");
  99         dump_fdset(&fds_write);
 100
 101         /* make a select call where none of them are ready (don't use fd5 and fd6) */
 102
 103         FD_ZERO(&fds_read);
 104         FD_ZERO(&fds_write);
 105         FD_SET(fd1, &fds_write);        /* fd1 => O_RDONLY */
 106         FD_SET(fd2, &fds_write);        /* fd2 => O_RDONLY */
 107         FD_SET(fd3, &fds_read);         /* fd3 => O_WRONLY */
 108         FD_SET(fd4, &fds_read);         /* fd4 => O_WRONLY */
 109
 110         /* make a select call where none of them are ready (don't use fd5 and fd6) */
 111         /* create a timeout as well */
 112         timeout.tv_sec = 5;
 113         timeout.tv_usec = 0;
 114         retval=select(7, &fds_read, &fds_write, NULL, NULL);
 115         printf("\n***********************\n");
 116         printf("After select: \n");
 117         printf("Return value: %d\n", retval);
 118         printf("* Dump RESULTING fds_read:\n");
 119         dump_fdset(&fds_read);
 120         printf("* Dump RESULTING fds_write:\n");
 121         dump_fdset(&fds_write);
 122
 123         /* close and delete dummy files */
 124         close(fd1);
 125         close(fd2);
 126         close(fd3);
 127         close(fd4);
 128         close(fd5);
 129         close(fd6);
 130         unlink("dummy1.txt");
 131         unlink("dummy2.txt");
 132         unlink("dummy3.txt");
 133         unlink("dummy4.txt");
 134         unlink("dummy5.txt");
 135         unlink("dummy6.txt");
 136         return 0;
 137 }