tests/test-fflush.c

   1 /* Test of POSIX compatible fflush() function.
   2    Copyright (C) 2007, 2009-2025 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Eric Blake, 2007.  */
  18
  19 #include <config.h>
  20
  21 /* None of the files accessed by this test are large, so disable the
  22    ftell link warning if we are not using the gnulib ftell module.  */
  23 #define _GL_NO_LARGE_FILES
  24 #include <stdio.h>
  25
  26 #include "signature.h"
  27 SIGNATURE_CHECK (fflush, int, (FILE *));
  28
  29 #include <errno.h>
  30 #include <unistd.h>
  31
  32 #include "macros.h"
  33
  34 int
  35 main (void)
  36 {
  37   FILE *f;
  38   char buffer[10];
  39   int fd;
  40
  41   /* Create test file.  */
  42   f = fopen ("test-fflush.txt", "w");
  43   if (!f || fwrite ("1234567890ABCDEFG", 1, 17, f) != 17 || fclose (f) != 0)
  44     {
  45       fputs ("Failed to create sample file.\n", stderr);
  46       unlink ("test-fflush.txt");
  47       return 1;
  48     }
  49
  50   /* Test fflush.  */
  51   f = fopen ("test-fflush.txt", "r");
  52   ASSERT (f != NULL);
  53   fd = fileno (f);
  54   if (!f || 0 > fd || fread (buffer, 1, 5, f) != 5)
  55     {
  56       fputs ("Failed initial read of sample file.\n", stderr);
  57       if (f)
  58         fclose (f);
  59       unlink ("test-fflush.txt");
  60       return 1;
  61     }
  62   /* For deterministic results, ensure f read a bigger buffer.
  63      This is not the case on BeOS, nor on uClibc.  */
  64 #if !(defined __BEOS__ || defined __UCLIBC__)
  65   if (lseek (fd, 0, SEEK_CUR) == 5)
  66     {
  67       fputs ("Sample file was not buffered after fread.\n", stderr);
  68       fclose (f);
  69       unlink ("test-fflush.txt");
  70       return 1;
  71     }
  72 #endif
  73   /* POSIX requires fflush-fseek to set file offset of fd.  */
  74   if (fflush (f) != 0 || fseeko (f, 0, SEEK_CUR) != 0)
  75     {
  76       fputs ("Failed to flush-fseek sample file.\n", stderr);
  77       fclose (f);
  78       unlink ("test-fflush.txt");
  79       return 1;
  80     }
  81   /* Check that offset is correct.  */
  82   if (lseek (fd, 0, SEEK_CUR) != 5)
  83     {
  84       fprintf (stderr, "File offset is wrong after fseek: %ld.\n",
  85                (long) lseek (fd, 0, SEEK_CUR));
  86       fclose (f);
  87       unlink ("test-fflush.txt");
  88       return 1;
  89     }
  90   if (ftell (f) != 5)
  91     {
  92       fprintf (stderr, "ftell result is wrong after fseek: %ld.\n",
  93                (long) ftell (f));
  94       fclose (f);
  95       unlink ("test-fflush.txt");
  96       return 1;
  97     }
  98   /* Check that file reading resumes at correct location.  */
  99   if (fgetc (f) != '6')
 100     {
 101       fputs ("Failed to read next byte after fseek.\n", stderr);
 102       fclose (f);
 103       unlink ("test-fflush.txt");
 104       return 1;
 105     }
 106   /* For deterministic results, ensure f read a bigger buffer.  */
 107   if (lseek (fd, 0, SEEK_CUR) == 6)
 108     {
 109       fputs ("Sample file was not buffered after fgetc.\n", stderr);
 110       fclose (f);
 111       unlink ("test-fflush.txt");
 112       return 1;
 113     }
 114   /* POSIX requires fflush-fseeko to set file offset of fd.  */
 115   if (fflush (f) != 0 || fseeko (f, 0, SEEK_CUR) != 0)
 116     {
 117       fputs ("Failed to flush-fseeko sample file.\n", stderr);
 118       fclose (f);
 119       unlink ("test-fflush.txt");
 120       return 1;
 121     }
 122   /* Check that offset is correct.  */
 123   if (lseek (fd, 0, SEEK_CUR) != 6)
 124     {
 125       fprintf (stderr, "File offset is wrong after fseeko: %ld.\n",
 126                (long) lseek (fd, 0, SEEK_CUR));
 127       fclose (f);
 128       unlink ("test-fflush.txt");
 129       return 1;
 130     }
 131   if (ftell (f) != 6)
 132     {
 133       fprintf (stderr, "ftell result is wrong after fseeko: %ld.\n",
 134                (long) ftell (f));
 135       fclose (f);
 136       unlink ("test-fflush.txt");
 137       return 1;
 138     }
 139   /* Check that file reading resumes at correct location.  */
 140   if (fgetc (f) != '7')
 141     {
 142       fputs ("Failed to read next byte after fseeko.\n", stderr);
 143       fclose (f);
 144       unlink ("test-fflush.txt");
 145       return 1;
 146     }
 147   fclose (f);
 148
 149   /* Test that fflush() sets errno if someone else closes the stream
 150      fd behind the back of stdio.  */
 151   #if !defined __ANDROID__ /* fdsan */
 152   {
 153     FILE *fp = fopen ("test-fflush.txt", "w");
 154     ASSERT (fp != NULL);
 155     fputc ('x', fp);
 156     ASSERT (close (fileno (fp)) == 0);
 157     errno = 0;
 158     ASSERT (fflush (fp) == EOF);
 159     ASSERT (errno == EBADF);
 160     fclose (fp);
 161   }
 162   #endif
 163
 164   /* Test that fflush() sets errno if the stream was constructed with
 165      an invalid file descriptor.  */
 166   {
 167     FILE *fp = fdopen (-1, "w");
 168     if (fp != NULL)
 169       {
 170         fputc ('x', fp);
 171         errno = 0;
 172         ASSERT (fflush (fp) == EOF);
 173         ASSERT (errno == EBADF);
 174       }
 175   }
 176   {
 177     FILE *fp;
 178     close (99);
 179     fp = fdopen (99, "w");
 180     if (fp != NULL)
 181       {
 182         fputc ('x', fp);
 183         errno = 0;
 184         ASSERT (fflush (fp) == EOF);
 185         ASSERT (errno == EBADF);
 186       }
 187   }
 188
 189   /* Clean up.  */
 190   unlink ("test-fflush.txt");
 191
 192   return test_exit_status;
 193 }