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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* 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 "nsCacheMetaData.h"
#include "nsICacheEntryDescriptor.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;
MOZ_ASSERT(value < limit, "Cache Metadata corrupted");
if (strcmp(data, key) == 0) return value;
// Skip value part
data = value + strlen(value) + 1;
}
MOZ_ASSERT(data == limit, "Metadata corrupted");
return nullptr;
}
nsresult nsCacheMetaData::SetElement(const char* key, const char* value) {
const uint32_t keySize = strlen(key) + 1;
char* pos = (char*)GetElement(key);
if (!value) {
// No value means remove the key/value pair completely, if existing
if (pos) {
uint32_t oldValueSize = strlen(pos) + 1;
uint32_t offset = pos - mBuffer;
uint32_t remainder = mMetaSize - (offset + oldValueSize);
memmove(pos - keySize, pos + oldValueSize, remainder);
mMetaSize -= keySize + oldValueSize;
}
return NS_OK;
}
const uint32_t valueSize = strlen(value) + 1;
uint32_t newSize = mMetaSize + valueSize;
if (pos) {
const uint32_t oldValueSize = strlen(pos) + 1;
const uint32_t offset = pos - mBuffer;
const uint32_t 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, uint32_t bufSize) {
if (mMetaSize > bufSize) {
NS_ERROR("buffer size too small for meta data.");
return NS_ERROR_OUT_OF_MEMORY;
}
if (!mBuffer) {
MOZ_ASSERT(mMetaSize == 0);
MOZ_ASSERT(bufSize == 0);
return NS_OK;
}
memcpy(buffer, mBuffer, mMetaSize);
return NS_OK;
}
nsresult nsCacheMetaData::UnflattenMetaData(const char* data, uint32_t 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 (uint32_t 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;
MOZ_ASSERT(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;
}
MOZ_ASSERT(data == limit, "Metadata corrupted");
return NS_OK;
}
nsresult nsCacheMetaData::EnsureBuffer(uint32_t bufSize) {
if (mBufferSize < bufSize) {
char* buf = (char*)realloc(mBuffer, bufSize);
if (!buf) {
return NS_ERROR_OUT_OF_MEMORY;
}
mBuffer = buf;
mBufferSize = bufSize;
}
return NS_OK;
}
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