tests/test-fwriting.c

   1 /* Test of fwriting() function.
   2    Copyright (C) 2007-2024 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 Bruno Haible <bruno@clisp.org>, 2007.  */
  18
  19 #include <config.h>
  20
  21 /* None of the files accessed by this test are large, so disable the
  22    fseek link warning if we are not using the gnulib fseek module.  */
  23 #define _GL_NO_LARGE_FILES
  24 #include "fwriting.h"
  25
  26 #include <stdio.h>
  27
  28 #include "macros.h"
  29
  30 #define TESTFILE "t-fwriting.tmp"
  31
  32 int
  33 main ()
  34 {
  35   FILE *fp;
  36
  37   /* Create a file with some contents.  Write-only file is always writing.  */
  38   fp = fopen (TESTFILE, "w");
  39   if (fp == NULL)
  40     goto skip;
  41   ASSERT (fwriting (fp));
  42   if (fwrite ("foobarsh", 1, 8, fp) < 8)
  43     goto skip;
  44   ASSERT (fwriting (fp));
  45   if (fclose (fp))
  46     goto skip;
  47
  48   /* Open it in read-only mode.  Read-only file is never writing.  */
  49   fp = fopen (TESTFILE, "r");
  50   if (fp == NULL)
  51     goto skip;
  52   ASSERT (!fwriting (fp));
  53   if (fgetc (fp) != 'f')
  54     goto skip;
  55   ASSERT (!fwriting (fp));
  56   if (fseek (fp, 2, SEEK_CUR))
  57     goto skip;
  58   ASSERT (!fwriting (fp));
  59   if (fgetc (fp) != 'b')
  60     goto skip;
  61   ASSERT (!fwriting (fp));
  62   fflush (fp);
  63   ASSERT (!fwriting (fp));
  64   if (fgetc (fp) != 'a')
  65     goto skip;
  66   ASSERT (!fwriting (fp));
  67   if (fseek (fp, 0, SEEK_END))
  68     goto skip;
  69   ASSERT (!fwriting (fp));
  70   if (fclose (fp))
  71     goto skip;
  72
  73   /* Open it in read-write mode.  POSIX requires a reposition (fseek,
  74      fsetpos, rewind) or fflush when transitioning from write to read,
  75      fwriting is only deterministic after input or output, but this
  76      test case should be portable even on open, after reposition, and
  77      after fflush.  */
  78   /* First a scenario with only fgetc, fseek, fputc.  */
  79   fp = fopen (TESTFILE, "r+");
  80   if (fp == NULL)
  81     goto skip;
  82   ASSERT (!fwriting (fp));
  83   if (fgetc (fp) != 'f')
  84     goto skip;
  85   ASSERT (!fwriting (fp));
  86   if (fseek (fp, 2, SEEK_CUR))
  87     goto skip;
  88   ASSERT (!fwriting (fp));
  89   if (fgetc (fp) != 'b')
  90     goto skip;
  91   ASSERT (!fwriting (fp));
  92   /* This fseek call is necessary when switching from reading to writing.
  93      See the description of fopen(), ISO C 99 7.19.5.3.(6).  */
  94   if (fseek (fp, 0, SEEK_CUR) != 0)
  95     goto skip;
  96   ASSERT (!fwriting (fp));
  97   if (fputc ('x', fp) != 'x')
  98     goto skip;
  99   ASSERT (fwriting (fp));
 100   if (fseek (fp, 0, SEEK_END))
 101     goto skip;
 102   /* freading (fp) is undefined here, because on some implementations (e.g.
 103      glibc) fseek causes a buffer to be read.
 104      fwriting (fp) is undefined as well.  */
 105   if (fclose (fp))
 106     goto skip;
 107
 108   /* Open it in read-write mode.  POSIX requires a reposition (fseek,
 109      fsetpos, rewind) or fflush when transitioning from write to read,
 110      fwriting is only deterministic after input or output, but this
 111      test case should be portable even on open, after reposition, and
 112      after fflush.  */
 113   /* Here a scenario that includes fflush.  */
 114   fp = fopen (TESTFILE, "r+");
 115   if (fp == NULL)
 116     goto skip;
 117   ASSERT (!fwriting (fp));
 118   if (fgetc (fp) != 'f')
 119     goto skip;
 120   ASSERT (!fwriting (fp));
 121   if (fseek (fp, 2, SEEK_CUR))
 122     goto skip;
 123   ASSERT (!fwriting (fp));
 124   if (fgetc (fp) != 'b')
 125     goto skip;
 126   ASSERT (!fwriting (fp));
 127   fflush (fp);
 128   ASSERT (!fwriting (fp));
 129   if (fgetc (fp) != 'x')
 130     goto skip;
 131   ASSERT (!fwriting (fp));
 132   /* This fseek call is necessary when switching from reading to writing.
 133      See the description of fopen(), ISO C 99 7.19.5.3.(6).  */
 134   if (fseek (fp, 0, SEEK_CUR) != 0)
 135     goto skip;
 136   ASSERT (!fwriting (fp));
 137   if (fputc ('z', fp) != 'z')
 138     goto skip;
 139   ASSERT (fwriting (fp));
 140   if (fseek (fp, 0, SEEK_END))
 141     goto skip;
 142   /* freading (fp) is undefined here, because on some implementations (e.g.
 143      glibc) fseek causes a buffer to be read.
 144      fwriting (fp) is undefined as well.  */
 145   if (fclose (fp))
 146     goto skip;
 147
 148   /* Open it in append mode.  */
 149   fp = fopen (TESTFILE, "a");
 150   if (fp == NULL)
 151     goto skip;
 152   ASSERT (fwriting (fp));
 153   if (fwrite ("bla", 1, 3, fp) < 3)
 154     goto skip;
 155   ASSERT (fwriting (fp));
 156   if (fclose (fp))
 157     goto skip;
 158
 159   return test_exit_status;
 160
 161  skip:
 162   if (test_exit_status != EXIT_SUCCESS)
 163     return test_exit_status;
 164   fprintf (stderr, "Skipping test: file operations failed.\n");
 165   return 77;
 166 }