safe_readlink.h - mozsearch

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// Copyright (c) 2011, Google Inc.

// All rights reserved.

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

//     * Neither the name of Google Inc. nor the names of its

// contributors may be used to endorse or promote products derived from

// this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// safe_readlink.h: Define the google_breakpad::SafeReadLink function,

// which wraps sys_readlink and gurantees the result is NULL-terminated.

#ifndef COMMON_LINUX_SAFE_READLINK_H_

#define COMMON_LINUX_SAFE_READLINK_H_

#include <stddef.h>

namespace google_breakpad {

// This function wraps sys_readlink() and performs the same functionalty,

// but guarantees |buffer| is NULL-terminated if sys_readlink() returns

// no error. It takes the same arguments as sys_readlink(), but unlike

// sys_readlink(), it returns true on success.

//

// |buffer_size| specifies the size of |buffer| in bytes. As this function

// always NULL-terminates |buffer| on success, |buffer_size| should be

// at least one byte longer than the expected path length (e.g. PATH_MAX,

// which is typically defined as the maximum length of a path name

// including the NULL byte).

//

// The implementation of this function calls sys_readlink() instead of

// readlink(), it can thus be used in the context where calling to libc

// functions is discouraged.

bool SafeReadLink(const char* path, char* buffer, size_t buffer_size);

// Same as the three-argument version of SafeReadLink() but deduces the

// size of |buffer| if it is a char array of known size.

template <size_t N>

bool SafeReadLink(const char* path, char (&buffer)[N]) {

  return SafeReadLink(path, buffer, sizeof(buffer));

}  // namespace google_breakpad

#endif  // COMMON_LINUX_SAFE_READLINK_H_