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Bug 394692 - ASSERTION: read cursor is bad: 'mReadCursor != mWriteCursor', file xpcom/io/nsPipe3.cpp, line 539. Narrow the criteria used to decide whether to fire the assertion to deal with a particular (valid) pattern of memory allocations. r=biesi, a=bz

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This commit is contained in:
jwalden@mit.edu 2007-09-20 23:17:59 -07:00
parent 58ca3d4a2a
commit 08317171e2
4 changed files with 367 additions and 1 deletions
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24
xpcom/io/nsPipe3.cpp
View File

@ -536,7 +536,29 @@ nsPipe::AdvanceWriteCursor(PRUint32 bytesWritten)
mWriteCursor = newWriteCursor;
NS_ASSERTION(mReadCursor != mWriteCursor, "read cursor is bad");
// The only way mReadCursor == mWriteCursor is if:
//
// - mReadCursor is at the start of a segment (which, based on how
// nsSegmentedBuffer works, means that this segment is the "first"
// segment)
// - mWriteCursor points at the location past the end of the current
// write segment (so the current write filled the current write
// segment, so we've incremented mWriteCursor to point past the end
// of it)
// - the segment to which data has just been written is located
// exactly one segment's worth of bytes before the first segment
// where mReadCursor is located
//
// Consequently, the byte immediately after the end of the current
// write segment is the first byte of the first segment, so
// mReadCursor == mWriteCursor. (Another way to think about this is
// to consider the buffer architecture diagram above, but consider it
// with an arena allocator which allocates from the *end* of the
// arena to the *beginning* of the arena.)
NS_ASSERTION(mReadCursor != mWriteCursor ||
(mBuffer.GetSegment(0) == mReadCursor &&
mWriteCursor == mWriteLimit),
"read cursor is bad");
// update the writable flag on the output stream
if (mWriteCursor == mWriteLimit) {

7
xpcom/tests/Makefile.in
View File

@ -72,6 +72,7 @@ CPPSRCS = \
TestAutoPtr.cpp \
TestVersionComparator.cpp \
TestTextFormatter.cpp \
TestPipe.cpp \
$(NULL)
ifndef MOZ_ENABLE_LIBXUL
@ -123,6 +124,8 @@ ENABLE_CXX_EXCEPTIONS = 1
XPCSHELL_TESTS = unit
CPP_UNIT_TESTS = TestPipe
include $(topsrcdir)/config/rules.mk
LOCAL_INCLUDES = \
@ -141,3 +144,7 @@ check::
@$(PERL) -w $(srcdir)/TestVersionComparatorRunner.pl "$(RUN_TEST_PROGRAM) $(FINAL_TARGET)/TestVersionComparator$(BIN_SUFFIX)"
@echo "Running nsTextFormatter tests"
@$(RUN_TEST_PROGRAM) $(FINAL_TARGET)/TestTextFormatter$(BIN_SUFFIX)
@$(EXIT_ON_ERROR) \
for f in $(CPP_UNIT_TESTS); do \
XPCOM_DEBUG_BREAK=stack-and-abort $(RUN_TEST_PROGRAM) $(DIST)/bin/$$f; \
done

94
xpcom/tests/TestHarness.h Normal file
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@ -0,0 +1,94 @@
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Jeff Walden <jwalden+code@mit.edu>.
* Portions created by the Initial Developer are Copyright (C) 2007
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Test harness for XPCOM objects, providing a scoped XPCOM initializer,
* nsCOMPtr, nsRefPtr, and stdio.h/stdlib.h.
*/
#ifndef TestHarness_h__
#define TestHarness_h__
#include "nsIServiceManager.h"
#include "nsCOMPtr.h"
#include "nsAutoPtr.h"
#include <stdio.h>
#include <stdlib.h>
class ScopedXPCOM
{
public:
ScopedXPCOM(const char* testName)
{
mTestName = testName;
printf("Running %s tests...\n", mTestName);
nsresult rv = NS_InitXPCOM2(&mServMgr, NULL, NULL);
if (NS_FAILED(rv))
{
printf("FAIL NS_InitXPCOM2 returned failure code %x\n", rv);
mServMgr = NULL;
}
}
~ScopedXPCOM()
{
if (mServMgr)
{
NS_RELEASE(mServMgr);
nsresult rv = NS_ShutdownXPCOM(NULL);
if (NS_FAILED(rv))
{
printf("FAIL XPCOM shutdown failed with code %x\n", rv);
exit(1);
}
}
printf("Finished running %s tests.\n", mTestName);
}
PRBool failed()
{
return mServMgr == NULL;
}
private:
const char* mTestName;
nsIServiceManager* mServMgr;
};
#endif // TestHarness_h__

243
xpcom/tests/TestPipe.cpp Normal file
View File

@ -0,0 +1,243 @@
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Jeff Walden <jwalden+code@mit.edu>.
* Portions created by the Initial Developer are Copyright (C) 2007
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "TestHarness.h"
#include "nsIPipe.h"
#include "nsIMemory.h"
/**
* Allocator can allocate exactly count * size bytes, stored at mMemory;
* immediately after the end of this is a byte-map of 0/1 values indicating
* which <size>-byte locations in mMemory are empty and which are filled.
* Pretty stupid, but enough to test bug 394692.
*/
class BackwardsAllocator : public nsIMemory
{
public:
BackwardsAllocator()
: mMemory(0),
mIndex(0xFFFFFFFF),
mCount(0xFFFFFFFF),
mSize(0)
{ }
~BackwardsAllocator()
{
delete [] mMemory;
}
nsresult Init(PRUint32 count, size_t size);
NS_DECL_ISUPPORTS
NS_DECL_NSIMEMORY
private:
PRUint32 previous(PRUint32 i)
{
if (i == 0)
return mCount - 1;
return i - 1;
}
private:
PRUint8* mMemory;
PRUint32 mIndex;
PRUint32 mCount;
size_t mSize;
};
NS_IMPL_ISUPPORTS1(BackwardsAllocator, nsIMemory)
NS_IMETHODIMP BackwardsAllocator::Init(PRUint32 count, size_t size)
{
if (mMemory)
{
printf("FAIL allocator already initialized!\n");
return NS_ERROR_ALREADY_INITIALIZED;
}
mMemory = new PRUint8[count * size + count];
if (!mMemory)
{
printf("FAIL failed to allocate mMemory!\n");
return NS_ERROR_OUT_OF_MEMORY;
}
memset(mMemory, 0, count * size + count);
mIndex = 0;
mCount = count;
mSize = size;
return NS_OK;
}
NS_IMETHODIMP_(void*) BackwardsAllocator::Alloc(size_t size)
{
if (size != mSize)
{
NS_ERROR("umm, why would this be reached for this test?");
return NULL;
}
PRUint32 index = mIndex;
while ((index = previous(index)) != mIndex)
{
if (mMemory[mSize * mCount + index] == 1)
continue;
mMemory[mSize * mCount + index] = 1;
mIndex = index;
return &mMemory[mSize * index];
}
NS_ERROR("shouldn't reach here in this test");
return NULL;
}
NS_IMETHODIMP_(void*) BackwardsAllocator::Realloc(void* ptr, size_t newSize)
{
NS_ERROR("shouldn't reach here in this test");
return NULL;
}
NS_IMETHODIMP_(void) BackwardsAllocator::Free(void* ptr)
{
PRUint8* p = static_cast<PRUint8*>(ptr);
if (p)
mMemory[mCount * mSize + (p - mMemory) / mSize] = 0;
}
NS_IMETHODIMP BackwardsAllocator::HeapMinimize(PRBool immediate)
{
return NS_OK;
}
NS_IMETHODIMP BackwardsAllocator::IsLowMemory(PRBool* retval)
{
*retval = PR_FALSE;
return NS_OK;
}
nsresult TestBackwardsAllocator()
{
const PRUint32 SEGMENT_COUNT = 10;
const size_t SEGMENT_SIZE = 10;
nsRefPtr<BackwardsAllocator> allocator = new BackwardsAllocator();
if (!allocator)
{
printf("Allocation of BackwardsAllocator failed!\n");
return NS_ERROR_OUT_OF_MEMORY;
}
nsresult rv = allocator->Init(SEGMENT_COUNT, SEGMENT_SIZE);
if (NS_FAILED(rv))
return rv;
nsCOMPtr<nsIAsyncInputStream> input;
nsCOMPtr<nsIAsyncOutputStream> output;
rv = NS_NewPipe2(getter_AddRefs(input),
getter_AddRefs(output),
PR_FALSE,
PR_FALSE,
SEGMENT_SIZE, SEGMENT_COUNT, allocator);
if (NS_FAILED(rv))
{
printf("FAIL NS_NewPipe2 failed: %x\n", rv);
return rv;
}
const PRUint32 BUFFER_LENGTH = 100;
const char written[] =
"0123456789"
"1123456789"
"2123456789"
"3123456789"
"4123456789"
"5123456789"
"6123456789"
"7123456789"
"8123456789"
"9123456789"; // not just a memset, to ensure the allocator works correctly
if (sizeof(written) < BUFFER_LENGTH)
{
printf("FAIL test error with string size\n");
return NS_ERROR_FAILURE;
}
PRUint32 writeCount;
rv = output->Write(written, BUFFER_LENGTH, &writeCount);
if (NS_FAILED(rv) || writeCount != BUFFER_LENGTH)
{
printf("FAIL writing %d bytes (wrote %d bytes) to output failed: %x\n",
BUFFER_LENGTH, writeCount, rv);
return rv;
}
char read[BUFFER_LENGTH];
PRUint32 readCount;
rv = input->Read(read, BUFFER_LENGTH, &readCount);
if (NS_FAILED(rv) || readCount != BUFFER_LENGTH)
{
printf("FAIL reading %d bytes (got %d bytes) from input failed: %x\n",
BUFFER_LENGTH, readCount, rv);
return rv;
}
if (0 != memcmp(written, read, BUFFER_LENGTH))
{
printf("FAIL didn't read the written data correctly!\n");
return NS_ERROR_FAILURE;
}
printf("TestBackwardsAllocator PASSED!\n");
return NS_OK;
}
int main(int argc, char** argv)
{
ScopedXPCOM xpcom("nsPipe");
if (xpcom.failed())
return 1;
int rv = 0;
if (NS_FAILED(TestBackwardsAllocator()))
rv = 1;
return rv;
}