gecko-dev/devtools/shared/heapsnapshot/AutoMemMap.cpp
Nicholas Nethercote 34dcc7b852 Bug 1299384 - Use MOZ_MUST_USE with NS_warn_if_impl(). r=erahm.
This change avoids lots of false positives for Coverity's CHECKED_RETURN
warning, caused by NS_WARN_IF's current use in both statement-style and
expression-style.

In the case where the code within the NS_WARN_IF has side-effects, I made the
following change.

> NS_WARN_IF(NS_FAILED(FunctionWithSideEffects()));
> -->
> Unused << NS_WARN_IF(NS_FAILED(FunctionWithSideEffects()));

In the case where the code within the NS_WARN_IF lacks side-effects, I made the
following change.

> NS_WARN_IF(!condWithoutSideEffects);
> -->
> NS_WARNING_ASSERTION(condWithoutSideEffects, "msg");

This has two improvements.
- The condition is not evaluated in non-debug builds.
- The sense of the condition is inverted to the familiar "this condition should
  be true" sense used in assertions.

A common variation on the side-effect-free case is the following.

> nsresult rv = Fn();
> NS_WARN_IF_(NS_FAILED(rv));
> -->
> DebugOnly<nsresult rv> = Fn();
> NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Fn failed");

--HG--
extra : rebase_source : 58788245021096efa8372a9dc1d597a611d45611
2016-09-02 17:12:24 +10:00

65 lines
1.5 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "mozilla/devtools/AutoMemMap.h"
#include "mozilla/Unused.h"
#include "nsDebug.h"
namespace mozilla {
namespace devtools {
AutoMemMap::~AutoMemMap()
{
if (addr) {
Unused << NS_WARN_IF(PR_MemUnmap(addr, size()) != PR_SUCCESS);
addr = nullptr;
}
if (fileMap) {
Unused << NS_WARN_IF(PR_CloseFileMap(fileMap) != PR_SUCCESS);
fileMap = nullptr;
}
if (fd) {
Unused << NS_WARN_IF(PR_Close(fd) != PR_SUCCESS);
fd = nullptr;
}
}
nsresult
AutoMemMap::init(const char* filePath, int flags, int mode, PRFileMapProtect prot)
{
MOZ_ASSERT(!fd);
MOZ_ASSERT(!fileMap);
MOZ_ASSERT(!addr);
if (PR_GetFileInfo64(filePath, &fileInfo) != PR_SUCCESS)
return NS_ERROR_FILE_NOT_FOUND;
// Check if the file is too big to memmap.
if (fileInfo.size > int64_t(UINT32_MAX))
return NS_ERROR_INVALID_ARG;
auto length = uint32_t(fileInfo.size);
fd = PR_Open(filePath, flags, flags);
if (!fd)
return NS_ERROR_UNEXPECTED;
fileMap = PR_CreateFileMap(fd, fileInfo.size, prot);
if (!fileMap)
return NS_ERROR_UNEXPECTED;
addr = PR_MemMap(fileMap, 0, length);
if (!addr)
return NS_ERROR_UNEXPECTED;
return NS_OK;
}
} // namespace devtools
} // namespace mozilla