test/t40b.c

   1 /* t40b.c
   2  *
   3  * Test regular files
   4  *
   5  * Select works on regular files, (pseudo) terminal devices, streams-based
   6  * files, FIFOs, pipes, and sockets. This test verifies selecting for regular
   7  * file descriptors. "File descriptors associated with regular files shall
   8  * always select true for ready to read, ready to write, and error conditions"
   9  * - Open Group. Although we set a timeout, the select should return
  10  * immediately.
  11  *
  12  * This test is part of a bigger select test. It expects as argument which sub-
  13  * test it is.
  14  */
  15
  16 #include <stdio.h>
  17 #include <stdlib.h>
  18 #include <unistd.h>
  19 #include <sys/types.h>
  20 #include <sys/stat.h>
  21 #include <fcntl.h>
  22 #include <sys/select.h>
  23 #include <errno.h>
  24 #include <time.h>
  25
  26 #include "common.h"
  27
  28 #define FILE1 "selecttestb-1"
  29 #define FILES 2
  30 #define TIME 3
  31
  32 #define MAX_ERROR 10
  33
  34 char errorbuf[1000];
  35
  36 int main(int argc, char **argv) {
  37   int fd1, fd2, retval;
  38   fd_set fds_read, fds_write, fds_error;
  39   struct timeval tv;
  40   time_t start, end;
  41
  42   /* Get subtest number */
  43   if(argc != 2) {
  44     printf("Usage: %s subtest_no\n", argv[0]);
  45     exit(-1);
  46   } else if(sscanf(argv[1], "%d", &subtest) != 1) {
  47     printf("Usage: %s subtest_no\n", argv[0]);
  48     exit(-1);
  49   }
  50
  51   /* Set timeout */
  52   tv.tv_sec = TIME;
  53   tv.tv_usec = 0;
  54
  55   /* Open a file for writing */
  56   if((fd1 = open(FILE1, O_WRONLY|O_CREAT, 0644)) == -1) {
  57     snprintf(errorbuf, sizeof(errorbuf), "failed to open file %s for writing",
  58              FILE1);
  59     em(1, errorbuf);
  60     perror(NULL);
  61     exit(1);
  62   }
  63
  64   /* Open the same file for reading */
  65   if((fd2 = open(FILE1, O_RDONLY)) == -1) {
  66     snprintf(errorbuf, sizeof(errorbuf), "failed to open file %s for reading",
  67              FILE1);
  68     em(2, errorbuf);
  69     perror(NULL);
  70     exit(1);
  71   }
  72
  73   /* Clear file descriptor bit masks */
  74   FD_ZERO(&fds_read); FD_ZERO(&fds_write); FD_ZERO(&fds_error);
  75
  76   /* Fill bit mask */
  77   FD_SET(fd1, &fds_write);
  78   FD_SET(fd2, &fds_read);
  79   FD_SET(fd1, &fds_error);
  80   FD_SET(fd2, &fds_error);
  81
  82   /* Do the select and time how long it takes */
  83   start = time(NULL);
  84   retval =  select(fd2+1, &fds_read, &fds_write, &fds_error, &tv);
  85   end = time(NULL);
  86
  87   /* Correct amount of ready file descriptors? 1 read + 1 write + 2 errors */
  88   if(retval != 4) {
  89     em(3, "four fds should be set");
  90   }
  91
  92   /* Test resulting bit masks */
  93   if(!FD_ISSET(fd1, &fds_write)) em(4, "write should be set");
  94   if(!FD_ISSET(fd2, &fds_read)) em(5, "read should be set");
  95   if(!FD_ISSET(fd1, &fds_error)) em(6, "error should be set");
  96   if(!FD_ISSET(fd2, &fds_error)) em(7, "error should be set");
  97
  98   /* Was it instantaneous? */
  99   if(end-start != TIME - TIME) {
 100     snprintf(errorbuf,sizeof(errorbuf),"time spent blocking is not %d, but %ld",
 101              TIME - TIME, (long int) (end-start));
 102     em(8, errorbuf);
 103   }
 104
 105   /* Wait for read to become ready on O_WRONLY. This should fail immediately. */
 106   FD_ZERO(&fds_read); FD_ZERO(&fds_write); FD_ZERO(&fds_error);
 107   FD_SET(fd1, &fds_read);
 108   FD_SET(fd1, &fds_error);
 109   FD_SET(fd2, &fds_error);
 110   tv.tv_sec = TIME;
 111   tv.tv_usec = 0;
 112   retval = select(fd2+1, &fds_read, NULL, &fds_error, &tv);
 113
 114   /* Correct amount of ready file descriptors? 1 read + 2 error */
 115   if(retval != 3) em(9, "incorrect amount of ready file descriptors");
 116   if(!FD_ISSET(fd1, &fds_read)) em(10, "read should be set");
 117   if(!FD_ISSET(fd1, &fds_error)) em(11, "error should be set");
 118   if(!FD_ISSET(fd2, &fds_error)) em(12, "error should be set");
 119
 120   /* Try again as above, bit this time with O_RDONLY in the write set */
 121   FD_ZERO(&fds_error);
 122   FD_SET(fd2, &fds_write);
 123   FD_SET(fd1, &fds_error);
 124   FD_SET(fd2, &fds_error);
 125   tv.tv_sec = TIME;
 126   tv.tv_usec = 0;
 127   retval = select(fd2+1, NULL, &fds_write, &fds_error, &tv);
 128
 129   /* Correct amount of ready file descriptors? 1 write + 2 errors */
 130   if(retval != 3) em(13, "incorrect amount of ready file descriptors");
 131   if(!FD_ISSET(fd2, &fds_write)) em(14, "write should be set");
 132   if(!FD_ISSET(fd1, &fds_error)) em(15, "error should be set");
 133   if(!FD_ISSET(fd2, &fds_error)) em(16, "error should be set");
 134
 135   close(fd1);
 136   close(fd2);
 137   unlink(FILE1);
 138
 139   exit(errct);
 140 }