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       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>
      59           0 : bool SafeReadLink(const char* path, char (&buffer)[N]) {
      60           0 :   return SafeReadLink(path, buffer, sizeof(buffer));
      61             : }
      62             : 
      63             : }  // namespace google_breakpad
      64             : 
      65             : #endif  // COMMON_LINUX_SAFE_READLINK_H_