1  /* Test setvbuf on readonly fopen (using mmap stdio).
       2     Copyright (C) 2002-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <stdio.h>
      20  #include <stdlib.h>
      21  #include <string.h>
      22  #include <unistd.h>
      23  
      24  int main (void)
      25  {
      26    char name[] = "/tmp/tst-mmap-setvbuf.XXXXXX";
      27    char buf[4096];
      28    const char * const test = "Let's see if mmap stdio works with setvbuf.\n";
      29    char temp[strlen (test) + 1];
      30    int fd = mkstemp (name);
      31    FILE *f;
      32  
      33    if (fd == -1)
      34      {
      35        printf ("%u: cannot open temporary file: %m\n", __LINE__);
      36        exit (1);
      37      }
      38  
      39    f = fdopen (fd, "w");
      40    if (f == NULL)
      41      {
      42        printf ("%u: cannot fdopen temporary file: %m\n", __LINE__);
      43        exit (1);
      44      }
      45  
      46    fputs (test, f);
      47    fclose (f);
      48  
      49    f = fopen (name, "rm");
      50    if (f == NULL)
      51      {
      52        printf ("%u: cannot fopen temporary file: %m\n", __LINE__);
      53        exit (1);
      54      }
      55  
      56    if (setvbuf (f, buf, _IOFBF, sizeof buf))
      57      {
      58        printf ("%u: setvbuf failed: %m\n", __LINE__);
      59        exit (1);
      60      }
      61  
      62    if (fread (temp, 1, strlen (test), f) != strlen (test))
      63      {
      64        printf ("%u: couldn't read the file back: %m\n", __LINE__);
      65        exit (1);
      66      }
      67    temp [strlen (test)] = '\0';
      68  
      69    if (strcmp (test, temp))
      70      {
      71        printf ("%u: read different string than was written:\n%s%s",
      72  	      __LINE__, test, temp);
      73        exit (1);
      74      }
      75  
      76    fclose (f);
      77  
      78    unlink (name);
      79    exit (0);
      80  }