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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specic language governing permissions and
* limitations under the License.
*/
#include "libappfuse/FuseBuffer.h"
#include <inttypes.h>
#include <string.h>
#include <unistd.h>
#include <algorithm>
#include <type_traits>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/macros.h>
namespace android {
namespace fuse {
static_assert(
std::is_standard_layout<FuseBuffer>::value,
"FuseBuffer must be standard layout union.");
template <typename T>
bool FuseMessage<T>::CheckHeaderLength(const char* name) const {
const auto& header = static_cast<const T*>(this)->header;
if (header.len >= sizeof(header) && header.len <= sizeof(T)) {
return true;
} else {
LOG(ERROR) << "Invalid header length is found in " << name << ": " <<
header.len;
return false;
}
}
template <typename T>
bool FuseMessage<T>::Read(int fd) {
char* const buf = reinterpret_cast<char*>(this);
const ssize_t result = TEMP_FAILURE_RETRY(::read(fd, buf, sizeof(T)));
if (result < 0) {
PLOG(ERROR) << "Failed to read a FUSE message";
return false;
}
const auto& header = static_cast<const T*>(this)->header;
if (result < static_cast<ssize_t>(sizeof(header))) {
LOG(ERROR) << "Read bytes " << result << " are shorter than header size " <<
sizeof(header);
return false;
}
if (!CheckHeaderLength("Read")) {
return false;
}
if (static_cast<uint32_t>(result) > header.len) {
LOG(ERROR) << "Read bytes " << result << " are longer than header.len " <<
header.len;
return false;
}
if (!base::ReadFully(fd, buf + result, header.len - result)) {
PLOG(ERROR) << "ReadFully failed";
return false;
}
return true;
}
template <typename T>
bool FuseMessage<T>::Write(int fd) const {
if (!CheckHeaderLength("Write")) {
return false;
}
const char* const buf = reinterpret_cast<const char*>(this);
const auto& header = static_cast<const T*>(this)->header;
if (!base::WriteFully(fd, buf, header.len)) {
PLOG(ERROR) << "WriteFully failed";
return false;
}
return true;
}
template class FuseMessage<FuseRequest>;
template class FuseMessage<FuseResponse>;
void FuseRequest::Reset(
uint32_t data_length, uint32_t opcode, uint64_t unique) {
memset(this, 0, sizeof(fuse_in_header) + data_length);
header.len = sizeof(fuse_in_header) + data_length;
header.opcode = opcode;
header.unique = unique;
}
void FuseResponse::ResetHeader(
uint32_t data_length, int32_t error, uint64_t unique) {
CHECK_LE(error, 0) << "error should be zero or negative.";
header.len = sizeof(fuse_out_header) + data_length;
header.error = error;
header.unique = unique;
}
void FuseResponse::Reset(uint32_t data_length, int32_t error, uint64_t unique) {
memset(this, 0, sizeof(fuse_out_header) + data_length);
ResetHeader(data_length, error, unique);
}
void FuseBuffer::HandleInit() {
const fuse_init_in* const in = &request.init_in;
// Before writing |out|, we need to copy data from |in|.
const uint64_t unique = request.header.unique;
const uint32_t minor = in->minor;
const uint32_t max_readahead = in->max_readahead;
// Kernel 2.6.16 is the first stable kernel with struct fuse_init_out
// defined (fuse version 7.6). The structure is the same from 7.6 through
// 7.22. Beginning with 7.23, the structure increased in size and added
// new parameters.
if (in->major != FUSE_KERNEL_VERSION || in->minor < 6) {
LOG(ERROR) << "Fuse kernel version mismatch: Kernel version " << in->major
<< "." << in->minor << " Expected at least " << FUSE_KERNEL_VERSION
<< ".6";
response.Reset(0, -EPERM, unique);
return;
}
// We limit ourselves to minor=15 because we don't handle BATCH_FORGET yet.
// Thus we need to use FUSE_COMPAT_22_INIT_OUT_SIZE.
#if defined(FUSE_COMPAT_22_INIT_OUT_SIZE)
// FUSE_KERNEL_VERSION >= 23.
const size_t response_size = FUSE_COMPAT_22_INIT_OUT_SIZE;
#else
const size_t response_size = sizeof(fuse_init_out);
#endif
response.Reset(response_size, kFuseSuccess, unique);
fuse_init_out* const out = &response.init_out;
out->major = FUSE_KERNEL_VERSION;
out->minor = std::min(minor, 15u);
out->max_readahead = max_readahead;
out->flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES;
out->max_background = 32;
out->congestion_threshold = 32;
out->max_write = kFuseMaxWrite;
}
void FuseBuffer::HandleNotImpl() {
LOG(VERBOSE) << "NOTIMPL op=" << request.header.opcode << " uniq="
<< request.header.unique << " nid=" << request.header.nodeid;
const uint64_t unique = request.header.unique;
response.Reset(0, -ENOSYS, unique);
}
} // namespace fuse
} // namespace android
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