libcryfs/impl/DirBlock.cpp
2015-02-17 01:02:15 +01:00

123 lines
3.4 KiB
C++

#include "DirBlock.h"
#include <cassert>
//TODO Remove and replace with exception hierarchy
#include "messmer/fspp/fuse/FuseErrnoException.h"
#include "MagicNumbers.h"
using std::unique_ptr;
using std::make_unique;
using std::vector;
using std::string;
using blockstore::Block;
using blockstore::Key;
namespace cryfs {
DirBlock::DirBlock(unique_ptr<Block> block)
: _block(std::move(block)) {
}
DirBlock::~DirBlock() {
}
void DirBlock::InitializeEmptyDir() {
*magicNumber() = MagicNumbers::DIR;
*entryCounter() = 0;
}
unsigned char *DirBlock::magicNumber() {
return const_cast<unsigned char*>(magicNumber(const_cast<const Block&>(*_block)));
}
const unsigned char *DirBlock::magicNumber(const blockstore::Block &block) {
return (unsigned char*)block.data();
}
bool DirBlock::IsDir(const blockstore::Block &block) {
return *magicNumber(block) == MagicNumbers::DIR;
}
unique_ptr<vector<string>> DirBlock::GetChildren() const {
auto result = make_unique<vector<string>>();
unsigned int entryCount = *entryCounter();
result->reserve(entryCount);
const char *pos = entriesBegin();
for (unsigned int i = 0; i < entryCount; ++i) {
pos = readAndAddNextChild(pos, result.get());
}
return result;
}
const char *DirBlock::readAndAddNextChild(const char *pos, vector<string> *result) const {
size_t length = strlen(pos);
result->emplace_back(pos, length);
const char *posAfterName = pos + length + 1;
const char *posAfterKey = posAfterName + strlen(posAfterName) + 1;
return posAfterKey;
}
void DirBlock::AddChild(const std::string &name, const Key &blockKey) {
string blockKeyStr = blockKey.ToString();
char *insertPos = entriesEnd();
assertEnoughSpaceLeft(insertPos, name.size() + 1 + blockKeyStr.size() + 1);
memcpy(insertPos, name.c_str(), name.size()+1);
memcpy(insertPos + name.size()+1, blockKeyStr.c_str(), blockKeyStr.size()+1);
++(*entryCounter());
}
void DirBlock::assertEnoughSpaceLeft(char *insertPos, size_t insertSize) const {
size_t usedSize = insertPos - (char*)_block->data();
assert(usedSize + insertSize <= _block->size());
}
Key DirBlock::GetBlockKeyForName(const string &name) const {
unsigned int entryCount = *entryCounter();
const char *pos = entriesBegin();
for(unsigned int i = 0; i < entryCount; ++i) {
size_t name_length = strlen(pos);
if (name_length == name.size() && 0==std::memcmp(pos, name.c_str(), name_length)) {
pos += strlen(pos) + 1; // Skip name
return Key::FromString(pos); // Return key
}
pos += strlen(pos) + 1; // Skip name
pos += strlen(pos) + 1; // Skip key
}
throw fspp::fuse::FuseErrnoException(ENOENT);
}
unsigned int *DirBlock::entryCounter() {
return const_cast<unsigned int*>(const_cast<const DirBlock*>(this)->entryCounter());
}
const unsigned int *DirBlock::entryCounter() const {
return (unsigned int*)((char*)_block->data() + sizeof(unsigned char));
}
char *DirBlock::entriesBegin() {
return const_cast<char*>(const_cast<const DirBlock*>(this)->entriesBegin());
}
const char *DirBlock::entriesBegin() const {
return (char *)(_block->data())+sizeof(unsigned char) + sizeof(unsigned int);
}
char *DirBlock::entriesEnd() {
unsigned int entryCount = *entryCounter();
char *pos = entriesBegin();
for(unsigned int i = 0; i < entryCount; ++i) {
pos += strlen(pos) + 1; // Skip entry name
pos += strlen(pos) + 1; // Skip entry key
}
return pos;
}
}