1/* Test program for ungetc/fseekpos interaction.
2 Copyright (C) 2004-2024 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
23static void do_prepare (void);
24#define PREPARE(argc, argv) do_prepare ()
25static int do_test (void);
26#define TEST_FUNCTION do_test ()
27#include "../test-skeleton.c"
28
29static const char pattern[] = "abcdefghijklmnopqrstuvwxyz";
30static char *temp_file;
31
32static void
33do_prepare (void)
34{
35 int fd = create_temp_file (base: "bug-ungetc.", filename: &temp_file);
36 if (fd == -1)
37 {
38 printf (format: "cannot create temporary file: %m\n");
39 exit (1);
40 }
41 xwrite (fd, pattern, sizeof (pattern) - 1);
42 close (fd: fd);
43}
44
45#define TEST_POS 5
46
47static int
48do_one_test (int mode)
49{
50 FILE *f = fopen (temp_file, "r");
51 if (f == NULL)
52 {
53 printf (format: "%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 (stream: f);
60
61 fpos_t p;
62 if (fgetpos (f, &p) != 0)
63 {
64 printf (format: "%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 (format: "%d: fseek failed: %m\n", mode);
73 return 1;
74 }
75
76 for (i = 0; i < TEST_POS - (mode >= 2); ++i)
77 getc (stream: f);
78 }
79
80 if (mode != 2 && ungetc ('X', f) != 'X')
81 {
82 printf (format: "%d: ungetc failed\n", mode);
83 return 1;
84 }
85
86 if (mode == 3 && getc (stream: f) != 'X')
87 {
88 printf (format: "%d: getc after ungetc did not return X\n", mode);
89 return 1;
90 }
91
92 if (fsetpos (f, &p) != 0)
93 {
94 printf (format: "%d: fsetpos failed: %m\n", mode);
95 return 1;
96 }
97
98 if (getc (stream: f) != pattern[TEST_POS])
99 {
100 printf (format: "%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
109static int
110do_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}
117

source code of glibc/libio/bug-ungetc4.c