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
38 namespace 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.
54 bool 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.
58 template <size_t N>
SafeReadLink(const char * path,char (& buffer)[N])59 bool 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