1/* Test program for ungetc/fseekpos interaction.
2 Copyright (C) 2004-2022 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
21static void do_prepare (void);
22#define PREPARE(argc, argv) do_prepare ()
23static int do_test (void);
24#define TEST_FUNCTION do_test ()
25#include "../test-skeleton.c"
26
27static const char pattern[] = "abcdefghijklmnopqrstuvwxyz";
28static char *temp_file;
29
30static void
31do_prepare (void)
32{
33 int fd = create_temp_file (base: "bug-ungetc.", filename: &temp_file);
34 if (fd == -1)
35 {
36 printf (format: "cannot create temporary file: %m\n");
37 exit (1);
38 }
39 write (fd, pattern, sizeof (pattern) - 1);
40 close (fd: fd);
41}
42
43#define TEST_POS 5
44
45static int
46do_one_test (int mode)
47{
48 FILE *f = fopen (temp_file, "r");
49 if (f == NULL)
50 {
51 printf (format: "%d: could not open temporary file: %m\n", mode);
52 return 1;
53 }
54
55 int i;
56 for (i = 0; i < TEST_POS; ++i)
57 getc (stream: f);
58
59 fpos_t p;
60 if (fgetpos (f, &p) != 0)
61 {
62 printf (format: "%d: fgetpos failed: %m\n", mode);
63 return 1;
64 }
65
66 if (mode)
67 {
68 if (fseek (f, 0, SEEK_SET) != 0)
69 {
70 printf (format: "%d: fseek failed: %m\n", mode);
71 return 1;
72 }
73
74 for (i = 0; i < TEST_POS - (mode >= 2); ++i)
75 getc (stream: f);
76 }
77
78 if (mode != 2 && ungetc ('X', f) != 'X')
79 {
80 printf (format: "%d: ungetc failed\n", mode);
81 return 1;
82 }
83
84 if (mode == 3 && getc (stream: f) != 'X')
85 {
86 printf (format: "%d: getc after ungetc did not return X\n", mode);
87 return 1;
88 }
89
90 if (fsetpos (f, &p) != 0)
91 {
92 printf (format: "%d: fsetpos failed: %m\n", mode);
93 return 1;
94 }
95
96 if (getc (stream: f) != pattern[TEST_POS])
97 {
98 printf (format: "%d: getc did not return %c\n", mode, pattern[TEST_POS]);
99 return 1;
100 }
101
102 fclose (f);
103
104 return 0;
105}
106
107static int
108do_test (void)
109{
110 int mode, ret = 0;
111 for (mode = 0; mode <= 4; mode++)
112 ret |= do_one_test (mode);
113 return ret;
114}
115

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