pjs/netwerk/cache/nsCacheMetaData.cpp

198 строки
6.1 KiB
C++

/* -*- Mode: C++; tab-width: 4; 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 nsCacheMetaData.cpp, released
* February 22, 2001.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Gordon Sheridan <gordon@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either 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 "nsCacheMetaData.h"
#include "nsICacheEntryDescriptor.h"
#include "prmem.h"
const char *
nsCacheMetaData::GetElement(const char * key)
{
const char * data = mBuffer;
const char * limit = mBuffer + mMetaSize;
while (data < limit) {
// Point to the value part
const char * value = data + strlen(data) + 1;
NS_ABORT_IF_FALSE(value < limit, "Cache Metadata corrupted");
if (strcmp(data, key) == 0)
return value;
// Skip value part
data = value + strlen(value) + 1;
}
NS_ABORT_IF_FALSE(data == limit, "Metadata corrupted");
return nsnull;
}
nsresult
nsCacheMetaData::SetElement(const char * key,
const char * value)
{
const PRUint32 keySize = strlen(key) + 1;
char * pos = (char *)GetElement(key);
if (!value) {
// No value means remove the key/value pair completely, if existing
if (pos) {
PRUint32 oldValueSize = strlen(pos) + 1;
PRUint32 offset = pos - mBuffer;
PRUint32 remainder = mMetaSize - (offset + oldValueSize);
memmove(pos - keySize, pos + oldValueSize, remainder);
mMetaSize -= keySize + oldValueSize;
}
return NS_OK;
}
const PRUint32 valueSize = strlen(value) + 1;
PRUint32 newSize = mMetaSize + valueSize;
if (pos) {
const PRUint32 oldValueSize = strlen(pos) + 1;
const PRUint32 offset = pos - mBuffer;
const PRUint32 remainder = mMetaSize - (offset + oldValueSize);
// Update the value in place
newSize -= oldValueSize;
nsresult rv = EnsureBuffer(newSize);
NS_ENSURE_SUCCESS(rv, rv);
// Move the remainder to the right place
pos = mBuffer + offset;
memmove(pos + valueSize, pos + oldValueSize, remainder);
} else {
// allocate new meta data element
newSize += keySize;
nsresult rv = EnsureBuffer(newSize);
NS_ENSURE_SUCCESS(rv, rv);
// Add after last element
pos = mBuffer + mMetaSize;
memcpy(pos, key, keySize);
pos += keySize;
}
// Update value
memcpy(pos, value, valueSize);
mMetaSize = newSize;
return NS_OK;
}
nsresult
nsCacheMetaData::FlattenMetaData(char * buffer, PRUint32 bufSize)
{
if (mMetaSize > bufSize) {
NS_ERROR("buffer size too small for meta data.");
return NS_ERROR_OUT_OF_MEMORY;
}
memcpy(buffer, mBuffer, mMetaSize);
return NS_OK;
}
nsresult
nsCacheMetaData::UnflattenMetaData(const char * data, PRUint32 size)
{
if (data && size) {
// Check if the metadata ends with a zero byte.
if (data[size-1] != '\0') {
NS_ERROR("Cache MetaData is not null terminated");
return NS_ERROR_ILLEGAL_VALUE;
}
// Check that there are an even number of zero bytes
// to match the pattern { key \0 value \0 }
bool odd = false;
for (PRUint32 i = 0; i < size; i++) {
if (data[i] == '\0')
odd = !odd;
}
if (odd) {
NS_ERROR("Cache MetaData is malformed");
return NS_ERROR_ILLEGAL_VALUE;
}
nsresult rv = EnsureBuffer(size);
NS_ENSURE_SUCCESS(rv, rv);
memcpy(mBuffer, data, size);
mMetaSize = size;
}
return NS_OK;
}
nsresult
nsCacheMetaData::VisitElements(nsICacheMetaDataVisitor * visitor)
{
const char * data = mBuffer;
const char * limit = mBuffer + mMetaSize;
while (data < limit) {
const char * key = data;
// Skip key part
data += strlen(data) + 1;
NS_ABORT_IF_FALSE(data < limit, "Metadata corrupted");
bool keepGoing;
nsresult rv = visitor->VisitMetaDataElement(key, data, &keepGoing);
if (NS_FAILED(rv) || !keepGoing)
return NS_OK;
// Skip value part
data += strlen(data) + 1;
}
NS_ABORT_IF_FALSE(data == limit, "Metadata corrupted");
return NS_OK;
}
nsresult
nsCacheMetaData::EnsureBuffer(PRUint32 bufSize)
{
if (mBufferSize < bufSize) {
char * buf = (char *)PR_REALLOC(mBuffer, bufSize);
if (!buf) {
return NS_ERROR_OUT_OF_MEMORY;
}
mBuffer = buf;
mBufferSize = bufSize;
}
return NS_OK;
}