1/* Common definitions for pread and pwrite.
2 Copyright (C) 2016-2022 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 <errno.h>
20#include <error.h>
21#include <string.h>
22#include <unistd.h>
23#include <sys/stat.h>
24
25static void do_prepare (void);
26#define PREPARE(argc, argv) do_prepare ()
27static int do_test (void);
28#define TEST_FUNCTION do_test ()
29
30/* This defines the `main' function and some more. */
31#include <test-skeleton.c>
32
33/* These are for the temporary file we generate. */
34static char *name;
35static int fd;
36
37static void
38do_prepare (void)
39{
40 fd = create_temp_file (base: "tst-preadwrite.", filename: &name);
41 if (fd == -1)
42 error (EXIT_FAILURE, errno, format: "cannot create temporary file");
43}
44
45
46static ssize_t
47do_test_with_offset (off_t offset)
48{
49 char buf[1000];
50 char res[1000];
51 int i;
52 ssize_t ret;
53
54 memset (buf, '\0', sizeof (buf));
55 memset (res, '\xff', sizeof (res));
56
57 if (write (fd, buf, sizeof (buf)) != sizeof (buf))
58 error (EXIT_FAILURE, errno, format: "during write");
59
60 for (i = 100; i < 200; ++i)
61 buf[i] = i;
62 ret = pwrite (fd: fd, buf: buf + 100, n: 100, offset: offset + 100);
63 if (ret == -1)
64 error (EXIT_FAILURE, errno, format: "during pwrite");
65
66 for (i = 450; i < 600; ++i)
67 buf[i] = i;
68 ret = pwrite (fd: fd, buf: buf + 450, n: 150, offset: offset + 450);
69 if (ret == -1)
70 error (EXIT_FAILURE, errno, format: "during pwrite");
71
72 ret = pread (fd: fd, buf: res, nbytes: sizeof (buf) - 50, offset: offset + 50);
73 if (ret == -1)
74 error (EXIT_FAILURE, errno, format: "during pread");
75
76 if (memcmp (buf + 50, res, ret) != 0)
77 {
78 printf (format: "error: read of pread != write of pwrite\n");
79 return -1;
80 }
81
82 return ret;
83}
84

source code of glibc/posix/tst-preadwrite-common.c