1 | /* Test of POSIX compatible fflush() function.
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2 | Copyright (C) 2008-2022 Free Software Foundation, Inc.
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3 |
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4 | This program is free software: you can redistribute it and/or modify
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5 | it under the terms of the GNU General Public License as published by
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6 | the Free Software Foundation, either version 3 of the License, or
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7 | (at your option) any later version.
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8 |
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9 | This program is distributed in the hope that it will be useful,
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10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 | GNU General Public License for more details.
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13 |
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14 | You should have received a copy of the GNU General Public License
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15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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16 |
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17 | #include <config.h>
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18 |
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19 | #include <stdio.h>
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20 |
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21 | #include "binary-io.h"
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22 | #include "macros.h"
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23 |
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24 | int
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25 | main (int argc, char **argv)
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26 | {
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27 | int c;
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28 |
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29 | /* Avoid the well-known bugs of fflush() on streams in O_TEXT mode
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30 | on native Windows platforms. */
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31 | set_binary_mode (0, O_BINARY);
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32 |
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33 | if (argc > 1)
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34 | switch (argv[1][0])
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35 | {
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36 | case '1':
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37 | /* Check fflush after a backup ungetc() call. This is case 1a in
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38 | terms of
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39 | <https://lists.gnu.org/r/bug-gnulib/2008-03/msg00131.html>,
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40 | according to the Austin Group's resolution on 2009-01-08. */
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41 |
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42 | c = fgetc (stdin);
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43 | ASSERT (c == '#');
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44 |
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45 | c = fgetc (stdin);
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46 | ASSERT (c == '!');
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47 |
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48 | /* Here the file-position indicator must be 2. */
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49 |
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50 | c = ungetc ('!', stdin);
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51 | ASSERT (c == '!');
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52 |
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53 | fflush (stdin);
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54 |
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55 | /* Here the file-position indicator must be 1. */
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56 |
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57 | c = fgetc (stdin);
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58 | ASSERT (c == '!');
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59 |
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60 | c = fgetc (stdin);
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61 | ASSERT (c == '/');
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62 |
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63 | return 0;
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64 |
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65 | case '2':
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66 | /* Check fflush after a non-backup ungetc() call. This is case 2a in
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67 | terms of
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68 | <https://lists.gnu.org/r/bug-gnulib/2008-03/msg00131.html>,
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69 | according to the Austin Group's resolution on 2009-01-08. */
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70 | /* Check that fflush after a non-backup ungetc() call discards the
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71 | ungetc buffer. This is mandated by POSIX
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72 | <https://pubs.opengroup.org/onlinepubs/9699919799/functions/fflush.html>:
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73 | "...any characters pushed back onto the stream by ungetc()
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74 | or ungetwc() that have not subsequently been read from the
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75 | stream shall be discarded..." */
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76 |
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77 | c = fgetc (stdin);
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78 | ASSERT (c == '#');
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79 |
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80 | c = fgetc (stdin);
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81 | ASSERT (c == '!');
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82 |
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83 | /* Here the file-position indicator must be 2. */
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84 |
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85 | c = ungetc ('@', stdin);
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86 | ASSERT (c == '@');
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87 |
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88 | fflush (stdin);
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89 |
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90 | /* Here the file-position indicator must be 1. */
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91 |
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92 | c = fgetc (stdin);
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93 | ASSERT (c == '!');
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94 |
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95 | c = fgetc (stdin);
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96 | ASSERT (c == '/');
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97 |
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98 | return 0;
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99 | }
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100 |
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101 | return 1;
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102 | }
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