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Add static assert to check if FuseBuffer is standard layout union.

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Bug: 32260320
Test: libappfuse_test
Change-Id: I6430c11fdeb2405996410c97044b4260c25209b8
This commit is contained in:
Daichi Hirono 2016-11-10 09:17:17 +09:00
parent a0aecda12b
commit 0d97be4d7d
2 changed files with 26 additions and 16 deletions
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30
libappfuse/FuseBuffer.cc
View file

@ -21,6 +21,7 @@
#include <unistd.h>
#include <algorithm>
#include <type_traits>
#include <android-base/logging.h>
#include <android-base/macros.h>
@ -28,9 +29,14 @@
namespace android {
namespace fuse {
template <typename T, typename Header>
bool FuseMessage<T, Header>::CheckHeaderLength() const {
if (sizeof(Header) <= header.len && header.len <= sizeof(T)) {
static_assert(
std::is_standard_layout<FuseBuffer>::value,
"FuseBuffer must be standard layout union.");
template <typename T>
bool FuseMessage<T>::CheckHeaderLength() const {
const auto& header = static_cast<const T*>(this)->header;
if (sizeof(header) <= header.len && header.len <= sizeof(T)) {
return true;
} else {
LOG(ERROR) << "Packet size is invalid=" << header.len;
@ -38,9 +44,10 @@ bool FuseMessage<T, Header>::CheckHeaderLength() const {
}
}
template <typename T, typename Header>
bool FuseMessage<T, Header>::CheckResult(
template <typename T>
bool FuseMessage<T>::CheckResult(
int result, const char* operation_name) const {
const auto& header = static_cast<const T*>(this)->header;
if (result >= 0 && static_cast<uint32_t>(result) == header.len) {
return true;
} else {
@ -51,14 +58,15 @@ bool FuseMessage<T, Header>::CheckResult(
}
}
template <typename T, typename Header>
bool FuseMessage<T, Header>::Read(int fd) {
template <typename T>
bool FuseMessage<T>::Read(int fd) {
const ssize_t result = TEMP_FAILURE_RETRY(::read(fd, this, sizeof(T)));
return CheckHeaderLength() && CheckResult(result, "read");
}
template <typename T, typename Header>
bool FuseMessage<T, Header>::Write(int fd) const {
template <typename T>
bool FuseMessage<T>::Write(int fd) const {
const auto& header = static_cast<const T*>(this)->header;
if (!CheckHeaderLength()) {
return false;
}
@ -66,8 +74,8 @@ bool FuseMessage<T, Header>::Write(int fd) const {
return CheckResult(result, "write");
}
template struct FuseMessage<FuseRequest, fuse_in_header>;
template struct FuseMessage<FuseResponse, fuse_out_header>;
template class FuseMessage<FuseRequest>;
template class FuseMessage<FuseResponse>;
void FuseRequest::Reset(
uint32_t data_length, uint32_t opcode, uint64_t unique) {

12
libappfuse/include/libappfuse/FuseBuffer.h
View file

@ -28,9 +28,9 @@ constexpr size_t kFuseMaxWrite = 256 * 1024;
constexpr size_t kFuseMaxRead = 128 * 1024;
constexpr int32_t kFuseSuccess = 0;
template<typename T, typename Header>
struct FuseMessage {
Header header;
template<typename T>
class FuseMessage {
public:
bool Read(int fd);
bool Write(int fd) const;
private:
@ -40,7 +40,8 @@ struct FuseMessage {
// FuseRequest represents file operation requests from /dev/fuse. It starts
// from fuse_in_header. The body layout depends on the operation code.
struct FuseRequest final : public FuseMessage<FuseRequest, fuse_in_header> {
struct FuseRequest : public FuseMessage<FuseRequest> {
fuse_in_header header;
union {
// for FUSE_WRITE
struct {
@ -61,7 +62,8 @@ struct FuseRequest final : public FuseMessage<FuseRequest, fuse_in_header> {
// FuseResponse represents file operation responses to /dev/fuse. It starts
// from fuse_out_header. The body layout depends on the operation code.
struct FuseResponse final : public FuseMessage<FuseResponse, fuse_out_header> {
struct FuseResponse : public FuseMessage<FuseResponse> {
fuse_out_header header;
union {
// for FUSE_INIT
fuse_init_out init_out;