1  #include <stdio_ext.h>
       2  #include <stdlib.h>
       3  #include <string.h>
       4  
       5  
       6  int
       7  main (void)
       8  {
       9    FILE *fp;
      10    const char teststring[] = "hello world";
      11    char buf[3072];
      12    int result = 0;
      13    char readbuf[256];
      14  
      15    /* Open a file.  */
      16    fp = tmpfile ();
      17  
      18    /* Set a buffer.  */
      19    if (setvbuf (fp, buf, _IOFBF, sizeof buf) == EOF)
      20      {
      21        printf ("setvbuf failed: %m\n");
      22        exit (1);
      23      }
      24  
      25    /* Get the buffer size.  */
      26    if (__fbufsize (fp) != sizeof buf)
      27      {
      28        printf ("__fbusize() reported a buffer size of %zd bytes;"
      29  	      " we installed a buffer with %zd bytes\n",
      30  	      __fbufsize (fp), sizeof buf);
      31        result = 1;
      32      }
      33  
      34    /* Write something and read it back.  */
      35    if (fputs (teststring, fp) == EOF)
      36      {
      37        printf ("writing to new stream failed: %m\n");
      38        exit (1);
      39      }
      40    rewind (fp);
      41    if (fgets (readbuf, sizeof readbuf, fp) == NULL)
      42      {
      43        printf ("reading from new stream failed: %m\n");
      44        exit (1);
      45      }
      46    if (strcmp (readbuf, teststring) != 0)
      47      {
      48        puts ("not the correct string read");
      49        exit (1);
      50      }
      51  
      52    /* The file must be opened for reading and writing.  */
      53    if (__freading (fp) == 0)
      54      {
      55        puts ("__freading() reported stream is not last read from");
      56        result = 1;
      57      }
      58    if (__fwriting (fp) != 0)
      59      {
      60        puts ("__fwriting() reported stream is write-only or last written to");
      61        result = 1;
      62      }
      63    rewind (fp);
      64    if (fputs (teststring, fp) == EOF)
      65      {
      66        printf ("writing(2) to new stream failed: %m\n");
      67        exit (1);
      68      }
      69    if (__fwriting (fp) == 0)
      70      {
      71        puts ("__fwriting() doe snot reported stream is last written to");
      72        result = 1;
      73      }
      74    if (__freading (fp) != 0)
      75      {
      76        puts ("__freading() reported stream is last read from");
      77        result = 1;
      78      }
      79  
      80    if (__freadable (fp) == 0)
      81      {
      82        puts ("__freading() reported stream is last readable");
      83        result = 1;
      84      }
      85    if (__fwritable (fp) == 0)
      86      {
      87        puts ("__freading() reported stream is last writable");
      88        result = 1;
      89      }
      90  
      91    /* The string we wrote above should still be in the buffer.  */
      92    if (__fpending (fp) != strlen (teststring))
      93      {
      94        printf ("__fpending() returned %zd; expected %zd\n",
      95  	      __fpending (fp), strlen (teststring));
      96        result = 1;
      97      }
      98    /* Discard all the output.  */
      99    __fpurge (fp);
     100    /* And check again.  */
     101    if (__fpending (fp) != 0)
     102      {
     103        printf ("__fpending() returned %zd; expected 0\n",
     104  	      __fpending (fp));
     105        result = 1;
     106      }
     107  
     108  
     109    /* Find out whether buffer is line buffered.  */
     110    if (__flbf (fp) != 0)
     111      {
     112        puts ("__flbf() reports line buffered but it is fully buffered");
     113        result = 1;
     114      }
     115  
     116    if (setvbuf (fp, buf, _IOLBF, sizeof buf) == EOF)
     117      {
     118        printf ("setvbuf(2) failed: %m\n");
     119        exit (1);
     120      }
     121    if (__flbf (fp) == 0)
     122      {
     123        puts ("__flbf() reports file is not line buffered");
     124        result = 1;
     125      }
     126  
     127    if (setvbuf (fp, NULL, _IONBF, 0) == EOF)
     128      {
     129        printf ("setvbuf(3) failed: %m\n");
     130        exit (1);
     131      }
     132    if (__flbf (fp) != 0)
     133      {
     134        puts ("__flbf() reports line buffered but it is not buffered");
     135        result = 1;
     136      }
     137  
     138    fclose (fp);
     139  
     140    return result;
     141  }