libio/bug-ungetc4.c

   1 /* Test program for ungetc/fseekpos interaction.
   2    Copyright (C) 2004-2023 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
  21 #include <support/xunistd.h>
  22
  23 static void do_prepare (void);
  24 #define PREPARE(argc, argv) do_prepare ()
  25 static int do_test (void);
  26 #define TEST_FUNCTION do_test ()
  27 #include "../test-skeleton.c"
  28
  29 static const char pattern[] = "abcdefghijklmnopqrstuvwxyz";
  30 static char *temp_file;
  31
  32 static void
  33 do_prepare (void)
  34 {
  35   int fd = create_temp_file ("bug-ungetc.", &temp_file);
  36   if (fd == -1)
  37     {
  38       printf ("cannot create temporary file: %m\n");
  39       exit (1);
  40     }
  41   xwrite (fd, pattern, sizeof (pattern) - 1);
  42   close (fd);
  43 }
  44
  45 #define TEST_POS 5
  46
  47 static int
  48 do_one_test (int mode)
  49 {
  50   FILE *f = fopen (temp_file, "r");
  51   if (f == NULL)
  52     {
  53       printf ("%d: could not open temporary file: %m\n", mode);
  54       return 1;
  55     }
  56
  57   int i;
  58   for (i = 0; i < TEST_POS; ++i)
  59     getc (f);
  60
  61   fpos_t p;
  62   if (fgetpos (f, &p) != 0)
  63     {
  64       printf ("%d: fgetpos failed: %m\n", mode);
  65       return 1;
  66     }
  67
  68   if (mode)
  69     {
  70       if (fseek (f, 0, SEEK_SET) != 0)
  71         {
  72           printf ("%d: fseek failed: %m\n", mode);
  73           return 1;
  74         }
  75
  76       for (i = 0; i < TEST_POS - (mode >= 2); ++i)
  77         getc (f);
  78     }
  79
  80   if (mode != 2 && ungetc ('X', f) != 'X')
  81     {
  82       printf ("%d: ungetc failed\n", mode);
  83       return 1;
  84     }
  85
  86   if (mode == 3 && getc (f) != 'X')
  87     {
  88       printf ("%d: getc after ungetc did not return X\n", mode);
  89       return 1;
  90     }
  91
  92   if (fsetpos (f, &p) != 0)
  93     {
  94       printf ("%d: fsetpos failed: %m\n", mode);
  95       return 1;
  96     }
  97
  98   if (getc (f) != pattern[TEST_POS])
  99     {
 100       printf ("%d: getc did not return %c\n", mode, pattern[TEST_POS]);
 101       return 1;
 102     }
 103
 104   fclose (f);
 105
 106   return 0;
 107 }
 108
 109 static int
 110 do_test (void)
 111 {
 112   int mode, ret = 0;
 113   for (mode = 0; mode <= 4; mode++)
 114     ret |= do_one_test (mode);
 115   return ret;
 116 }