libcryfs/impl/DirBlob.cpp

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#include "DirBlob.h"
#include <cassert>
//TODO Remove and replace with exception hierarchy
#include "messmer/fspp/fuse/FuseErrnoException.h"
#include <messmer/blockstore/utils/Data.h>
#include "MagicNumbers.h"
using std::unique_ptr;
using std::make_unique;
using std::vector;
using std::string;
using blobstore::Blob;
using blockstore::Key;
using blockstore::Data;
//TODO Refactor: Keep a parsed dir structure (list of entries and blob keys they're pointing to) in memory and serialize/deserialize it
namespace cryfs {
DirBlob::DirBlob(unique_ptr<Blob> blob)
: _blob(std::move(blob)) {
}
DirBlob::~DirBlob() {
}
void DirBlob::InitializeEmptyDir() {
_blob->resize(1);
unsigned char magicNumber = MagicNumbers::DIR;
_blob->write(&magicNumber, 0, 1);
}
unsigned char DirBlob::magicNumber() const {
return magicNumber(*_blob);
}
const unsigned char DirBlob::magicNumber(const blobstore::Blob &blob) {
unsigned char number;
blob.read(&number, 0, 1);
return number;
}
bool DirBlob::IsDir(const blobstore::Blob &blob) {
return magicNumber(blob) == MagicNumbers::DIR;
}
unique_ptr<vector<string>> DirBlob::GetChildren() const {
Data entries(_blob->size()-1);
_blob->read(entries.data(), 1, _blob->size()-1);
auto result = make_unique<vector<string>>();
const char *pos = (const char*)entries.data();
while(pos < (const char*)entries.data()+entries.size()) {
pos = readAndAddNextChild(pos, result.get());
}
return result;
}
const char *DirBlob::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 DirBlob::AddChild(const std::string &name, const Key &blobKey) {
//TODO blob.resize(blob.size()+X) has to traverse tree twice. Better would be blob.addSize(X) which returns old size
uint64_t oldBlobSize = _blob->size();
string blobKeyStr = blobKey.ToString();
_blob->resize(oldBlobSize + name.size() + 1 + blobKeyStr.size() + 1);
//Write entry name inclusive null terminator
_blob->write(name.c_str(), oldBlobSize, name.size()+1);
//Write blob key inclusive null terminator
_blob->write(blobKeyStr.c_str(), oldBlobSize + name.size() + 1, blobKeyStr.size()+1);
}
Key DirBlob::GetBlobKeyForName(const string &name) const {
auto result = make_unique<vector<string>>();
Data entries(_blob->size()-1);
_blob->read(entries.data(), 1, _blob->size()-1);
const char *pos = (const char*)entries.data();
while(pos < (const char*)entries.data()+entries.size()) {
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);
}
}