tests/test-freading.c

   1 /* Test of freading() function.
   2    Copyright (C) 2007-2020 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 "freading.h"
  25
  26 #include <stdio.h>
  27
  28 #include "macros.h"
  29
  30 #define TESTFILE "t-freading.tmp"
  31
  32 int
  33 main (void)
  34 {
  35   FILE *fp;
  36
  37   /* Create a file with some contents.  Write-only file is never reading.  */
  38   fp = fopen (TESTFILE, "w");
  39   ASSERT (fp);
  40   ASSERT (!freading (fp));
  41   ASSERT (fwrite ("foobarsh", 1, 8, fp) == 8);
  42   ASSERT (!freading (fp));
  43   ASSERT (fclose (fp) == 0);
  44
  45   /* Open it in read-only mode.  Read-only file is always reading.  */
  46   fp = fopen (TESTFILE, "r");
  47   ASSERT (fp);
  48   ASSERT (freading (fp));
  49   ASSERT (fgetc (fp) == 'f');
  50   ASSERT (freading (fp));
  51   ASSERT (fseek (fp, 2, SEEK_CUR) == 0);
  52   ASSERT (freading (fp));
  53   ASSERT (fgetc (fp) == 'b');
  54   ASSERT (freading (fp));
  55   fflush (fp);
  56   ASSERT (freading (fp));
  57   ASSERT (fgetc (fp) == 'a');
  58   ASSERT (freading (fp));
  59   ASSERT (fseek (fp, 0, SEEK_END) == 0);
  60   ASSERT (freading (fp));
  61   ASSERT (fclose (fp) == 0);
  62
  63   /* Open it in read-write mode.  POSIX requires a reposition (fseek,
  64      fsetpos, rewind) or EOF when transitioning from read to write;
  65      freading is only deterministic after input or output, but this
  66      test case should be portable even on open, after reposition, and
  67      at EOF.  */
  68   /* First a scenario with only fgetc, fseek, fputc.  */
  69   fp = fopen (TESTFILE, "r+");
  70   ASSERT (fp);
  71   ASSERT (!freading (fp));
  72   ASSERT (fgetc (fp) == 'f');
  73   ASSERT (freading (fp));
  74   ASSERT (fseek (fp, 2, SEEK_CUR) ==  0);
  75   /* freading (fp) is undefined here, but fwriting (fp) is false.  */
  76   ASSERT (fgetc (fp) == 'b');
  77   ASSERT (freading (fp));
  78   /* This fseek call is necessary when switching from reading to writing.
  79      See the description of fopen(), ISO C 99 7.19.5.3.(6).  */
  80   ASSERT (fseek (fp, 0, SEEK_CUR) == 0);
  81   /* freading (fp) is undefined here, but fwriting (fp) is false.  */
  82   ASSERT (fputc ('x', fp) == 'x');
  83   ASSERT (!freading (fp));
  84   ASSERT (fseek (fp, 0, SEEK_END) == 0);
  85   /* freading (fp) is undefined here, because on some implementations (e.g.
  86      glibc) fseek causes a buffer to be read.
  87      fwriting (fp) is undefined as well.  */
  88   ASSERT (fclose (fp) == 0);
  89
  90   /* Open it in read-write mode.  POSIX requires a reposition (fseek,
  91      fsetpos, rewind) or EOF when transitioning from read to write;
  92      freading is only deterministic after input or output, but this
  93      test case should be portable even on open, after reposition, and
  94      at EOF.  */
  95   /* Here a scenario that includes fflush.  */
  96   fp = fopen (TESTFILE, "r+");
  97   ASSERT (fp);
  98   ASSERT (!freading (fp));
  99   ASSERT (fgetc (fp) == 'f');
 100   ASSERT (freading (fp));
 101   ASSERT (fseek (fp, 2, SEEK_CUR) == 0);
 102   /* freading (fp) is undefined here, but fwriting (fp) is false.  */
 103   ASSERT (fgetc (fp) == 'b');
 104   ASSERT (freading (fp));
 105   fflush (fp);
 106   /* freading (fp) is undefined here, but fwriting (fp) is false.  */
 107   ASSERT (fgetc (fp) == 'x');
 108   ASSERT (freading (fp));
 109   /* This fseek call is necessary when switching from reading to writing.
 110      See the description of fopen(), ISO C 99 7.19.5.3.(6).  */
 111   ASSERT (fseek (fp, 0, SEEK_CUR) == 0);
 112   /* freading (fp) is undefined here, but fwriting (fp) is false.  */
 113   ASSERT (fputc ('z', fp) == 'z');
 114   ASSERT (!freading (fp));
 115   ASSERT (fseek (fp, 0, SEEK_END) == 0);
 116   /* freading (fp) is undefined here, because on some implementations (e.g.
 117      glibc) fseek causes a buffer to be read.
 118      fwriting (fp) is undefined as well.  */
 119   ASSERT (fclose (fp) == 0);
 120
 121   /* Open it in append mode.  Write-only file is never reading.  */
 122   fp = fopen (TESTFILE, "a");
 123   ASSERT (fp);
 124   ASSERT (!freading (fp));
 125   ASSERT (fwrite ("bla", 1, 3, fp) == 3);
 126   ASSERT (!freading (fp));
 127   ASSERT (fclose (fp) == 0);
 128   ASSERT (remove (TESTFILE) == 0);
 129   return 0;
 130 }