1 /* Test the pread function.
2 Copyright (C) 2009 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* Written by Jim Meyering. */
25 #include <sys/types.h>
29 #define ASSERT(expr) \
34 fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
41 #define N (sizeof buf - 1)
46 char const *file = "in";
48 char buf[] = "0123456789";
53 fd = open (file, O_CREAT | O_WRONLY, 0600);
55 ASSERT (write (fd, buf, N) == N);
56 ASSERT (close (fd) == 0);
58 fd = open (file, O_RDONLY);
61 for (pos = 0; pos < 3; pos++)
64 off_t init_pos = lseek (fd, pos, SEEK_SET);
65 ASSERT (init_pos == pos);
67 for (i = 0; i < N; i++)
70 ASSERT (pread (fd, &byte_buf, 1, i) == 1);
71 ASSERT (byte_buf == buf[i]);
72 ASSERT (lseek (fd, 0, SEEK_CUR) == init_pos);
77 /* Invalid offset must evoke failure with EINVAL. */
79 ASSERT (pread (fd, &byte, 1, (off_t) -1) == -1);
80 ASSERT (errno == EINVAL);
83 ASSERT (close (fd) == 0);
87 /* Trying to operate on a pipe must evoke failure with ESPIPE.
88 This assumes that stdin is a pipe, and hence not seekable. */
89 ASSERT (pread (STDIN_FILENO, &byte, 1, 1) == -1);
90 ASSERT (errno == ESPIPE);