components/nacl/loader/nonsfi/irt_util.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_NACL_LOADER_NONSFI_IRT_UTIL_H_
   6 #define COMPONENTS_NACL_LOADER_NONSFI_IRT_UTIL_H_
   7
   8 #include <errno.h>
   9
  10 namespace nacl {
  11 namespace nonsfi {
  12
  13 // For IRT implementation, the following simple pattern is commonly used.
  14 //
  15 //   if (syscall(...) < 0)
  16 //     return errno;
  17 //   return 0;
  18 //
  19 // This function is a utility to write it in a line as follows:
  20 //
  21 //   return CheckError(syscall(...));
  22 inline int CheckError(int result) {
  23   return result < 0 ? errno : 0;
  24 }
  25
  26 // For IRT implementation, another but a similar pattern is also commonly used.
  27 //
  28 //   T result = syscall(...);
  29 //   if (result < 0)
  30 //     return errno;
  31 //   *output = result;
  32 //   return 0;
  33 //
  34 // This function is a utility to write it in a line as follows:
  35 //
  36 //   retrun CheckErrorWithResult(syscall(...), output);
  37 //
  38 // Here, T1 must be a signed integer value, and T2 must be convertible from
  39 // T1.
  40 template<typename T1, typename T2>
  41 int CheckErrorWithResult(const T1& result, T2* out) {
  42   if (result < 0)
  43     return errno;
  44
  45   *out = result;
  46   return 0;
  47 }
  48
  49 }  // namespace nonsfi
  50 }  // namespace nacl
  51
  52 #endif  // COMPONENTS_NACL_LOADER_NONSFI_IRT_UTIL_H_