1/* Test setvbuf on readonly fopen (using mmap stdio).
2 Copyright (C) 2002-2024 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#include <stdlib.h>
21#include <string.h>
22#include <unistd.h>
23
24int main (void)
25{
26 char name[] = "/tmp/tst-mmap-setvbuf.XXXXXX";
27 char buf[4096];
28 const char * const test = "Let's see if mmap stdio works with setvbuf.\n";
29 char temp[strlen (test) + 1];
30 int fd = mkstemp (template: name);
31 FILE *f;
32
33 if (fd == -1)
34 {
35 printf (format: "%u: cannot open temporary file: %m\n", __LINE__);
36 exit (1);
37 }
38
39 f = fdopen (fd, "w");
40 if (f == NULL)
41 {
42 printf (format: "%u: cannot fdopen temporary file: %m\n", __LINE__);
43 exit (1);
44 }
45
46 fputs (test, f);
47 fclose (f);
48
49 f = fopen (name, "rm");
50 if (f == NULL)
51 {
52 printf (format: "%u: cannot fopen temporary file: %m\n", __LINE__);
53 exit (1);
54 }
55
56 if (setvbuf (stream: f, buf: buf, _IOFBF, n: sizeof buf))
57 {
58 printf (format: "%u: setvbuf failed: %m\n", __LINE__);
59 exit (1);
60 }
61
62 if (fread (ptr: temp, size: 1, n: strlen (test), stream: f) != strlen (test))
63 {
64 printf (format: "%u: couldn't read the file back: %m\n", __LINE__);
65 exit (1);
66 }
67 temp [strlen (test)] = '\0';
68
69 if (strcmp (test, temp))
70 {
71 printf (format: "%u: read different string than was written:\n%s%s",
72 __LINE__, test, temp);
73 exit (1);
74 }
75
76 fclose (f);
77
78 unlink (name: name);
79 exit (0);
80}
81

source code of glibc/libio/tst-mmap-setvbuf.c