michael@0: /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
michael@0:  *
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsCacheMetaData.h"
michael@0: #include "nsICacheEntryDescriptor.h"
michael@0: 
michael@0: const char *
michael@0: nsCacheMetaData::GetElement(const char * key)
michael@0: {
michael@0:     const char * data = mBuffer;
michael@0:     const char * limit = mBuffer + mMetaSize;
michael@0: 
michael@0:     while (data < limit) {
michael@0:         // Point to the value part
michael@0:         const char * value = data + strlen(data) + 1;
michael@0:         NS_ABORT_IF_FALSE(value < limit, "Cache Metadata corrupted");
michael@0:         if (strcmp(data, key) == 0)
michael@0:             return value;
michael@0: 
michael@0:         // Skip value part
michael@0:         data = value + strlen(value) + 1;
michael@0:     }
michael@0:     NS_ABORT_IF_FALSE(data == limit, "Metadata corrupted");
michael@0:     return nullptr;
michael@0: }
michael@0: 
michael@0: 
michael@0: nsresult
michael@0: nsCacheMetaData::SetElement(const char * key,
michael@0:                             const char * value)
michael@0: {
michael@0:     const uint32_t keySize = strlen(key) + 1;
michael@0:     char * pos = (char *)GetElement(key);
michael@0: 
michael@0:     if (!value) {
michael@0:         // No value means remove the key/value pair completely, if existing
michael@0:         if (pos) {
michael@0:             uint32_t oldValueSize = strlen(pos) + 1;
michael@0:             uint32_t offset = pos - mBuffer;
michael@0:             uint32_t remainder = mMetaSize - (offset + oldValueSize);
michael@0: 
michael@0:             memmove(pos - keySize, pos + oldValueSize, remainder);
michael@0:             mMetaSize -= keySize + oldValueSize;
michael@0:         }
michael@0:         return NS_OK;
michael@0:     }
michael@0: 
michael@0:     const uint32_t valueSize = strlen(value) + 1;
michael@0:     uint32_t newSize = mMetaSize + valueSize;
michael@0:     if (pos) {
michael@0:         const uint32_t oldValueSize = strlen(pos) + 1;
michael@0:         const uint32_t offset = pos - mBuffer;
michael@0:         const uint32_t remainder = mMetaSize - (offset + oldValueSize);
michael@0: 
michael@0:         // Update the value in place
michael@0:         newSize -= oldValueSize;
michael@0:         nsresult rv = EnsureBuffer(newSize);
michael@0:         NS_ENSURE_SUCCESS(rv, rv);
michael@0: 
michael@0:         // Move the remainder to the right place
michael@0:         pos = mBuffer + offset;
michael@0:         memmove(pos + valueSize, pos + oldValueSize, remainder);
michael@0:     } else {
michael@0:         // allocate new meta data element
michael@0:         newSize += keySize;
michael@0:         nsresult rv = EnsureBuffer(newSize);
michael@0:         NS_ENSURE_SUCCESS(rv, rv);
michael@0: 
michael@0:         // Add after last element
michael@0:         pos = mBuffer + mMetaSize;
michael@0:         memcpy(pos, key, keySize);
michael@0:         pos += keySize;
michael@0:     }
michael@0: 
michael@0:     // Update value
michael@0:     memcpy(pos, value, valueSize);
michael@0:     mMetaSize = newSize;
michael@0: 
michael@0:     return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult
michael@0: nsCacheMetaData::FlattenMetaData(char * buffer, uint32_t bufSize)
michael@0: {
michael@0:     if (mMetaSize > bufSize) {
michael@0:         NS_ERROR("buffer size too small for meta data.");
michael@0:         return NS_ERROR_OUT_OF_MEMORY;
michael@0:     }
michael@0: 
michael@0:     memcpy(buffer, mBuffer, mMetaSize);
michael@0:     return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult
michael@0: nsCacheMetaData::UnflattenMetaData(const char * data, uint32_t size)
michael@0: {
michael@0:     if (data && size) {
michael@0:         // Check if the metadata ends with a zero byte.
michael@0:         if (data[size-1] != '\0') {
michael@0:             NS_ERROR("Cache MetaData is not null terminated");
michael@0:             return NS_ERROR_ILLEGAL_VALUE;
michael@0:         }
michael@0:         // Check that there are an even number of zero bytes
michael@0:         // to match the pattern { key \0 value \0 }
michael@0:         bool odd = false;
michael@0:         for (uint32_t i = 0; i < size; i++) {
michael@0:             if (data[i] == '\0') 
michael@0:                 odd = !odd;
michael@0:         }
michael@0:         if (odd) {
michael@0:             NS_ERROR("Cache MetaData is malformed");
michael@0:             return NS_ERROR_ILLEGAL_VALUE;
michael@0:         }
michael@0: 
michael@0:         nsresult rv = EnsureBuffer(size);
michael@0:         NS_ENSURE_SUCCESS(rv, rv);
michael@0: 
michael@0:         memcpy(mBuffer, data, size);
michael@0:         mMetaSize = size;
michael@0:     }
michael@0:     return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult
michael@0: nsCacheMetaData::VisitElements(nsICacheMetaDataVisitor * visitor)
michael@0: {
michael@0:     const char * data = mBuffer;
michael@0:     const char * limit = mBuffer + mMetaSize;
michael@0: 
michael@0:     while (data < limit) {
michael@0:         const char * key = data;
michael@0:         // Skip key part
michael@0:         data += strlen(data) + 1;
michael@0:         NS_ABORT_IF_FALSE(data < limit, "Metadata corrupted");
michael@0:         bool keepGoing;
michael@0:         nsresult rv = visitor->VisitMetaDataElement(key, data, &keepGoing);
michael@0:         if (NS_FAILED(rv) || !keepGoing)
michael@0:             return NS_OK;
michael@0: 
michael@0:         // Skip value part
michael@0:         data += strlen(data) + 1;
michael@0:     }
michael@0:     NS_ABORT_IF_FALSE(data == limit, "Metadata corrupted");
michael@0:     return NS_OK;
michael@0: }
michael@0: 
michael@0: nsresult
michael@0: nsCacheMetaData::EnsureBuffer(uint32_t bufSize)
michael@0: {
michael@0:     if (mBufferSize < bufSize) {
michael@0:         char * buf = (char *)moz_realloc(mBuffer, bufSize);
michael@0:         if (!buf) {
michael@0:             return NS_ERROR_OUT_OF_MEMORY;
michael@0:         }
michael@0:         mBuffer = buf;
michael@0:         mBufferSize = bufSize;
michael@0:     }
michael@0:     return NS_OK;
michael@0: }