1// Copyright (c) 2011, Google Inc.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8// * Redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer.
10// * Redistributions in binary form must reproduce the above
11// copyright notice, this list of conditions and the following disclaimer
12// in the documentation and/or other materials provided with the
13// distribution.
14// * Neither the name of Google Inc. nor the names of its
15// contributors may be used to endorse or promote products derived from
16// this software without specific prior written permission.
17//
18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30// safe_readlink.h: Define the google_breakpad::SafeReadLink function,
31// which wraps sys_readlink and gurantees the result is NULL-terminated.
32
33#ifndef COMMON_LINUX_SAFE_READLINK_H_
34#define COMMON_LINUX_SAFE_READLINK_H_
35
36#include <stddef.h>
37
38namespace google_breakpad {
39
40// This function wraps sys_readlink() and performs the same functionalty,
41// but guarantees |buffer| is NULL-terminated if sys_readlink() returns
42// no error. It takes the same arguments as sys_readlink(), but unlike
43// sys_readlink(), it returns true on success.
44//
45// |buffer_size| specifies the size of |buffer| in bytes. As this function
46// always NULL-terminates |buffer| on success, |buffer_size| should be
47// at least one byte longer than the expected path length (e.g. PATH_MAX,
48// which is typically defined as the maximum length of a path name
49// including the NULL byte).
50//
51// The implementation of this function calls sys_readlink() instead of
52// readlink(), it can thus be used in the context where calling to libc
53// functions is discouraged.
54bool SafeReadLink(const char* path, char* buffer, size_t buffer_size);
55
56// Same as the three-argument version of SafeReadLink() but deduces the
57// size of |buffer| if it is a char array of known size.
58template <size_t N>
59bool SafeReadLink(const char* path, char (&buffer)[N]) {
60 return SafeReadLink(path, buffer, sizeof(buffer));
61}
62
63} // namespace google_breakpad
64
65#endif // COMMON_LINUX_SAFE_READLINK_H_
66