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Commit 0d97be4d authored by Daichi Hirono's avatar Daichi Hirono
Browse files

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

Bug: 32260320
Test: libappfuse_test
Change-Id: I6430c11fdeb2405996410c97044b4260c25209b8
parent a0aecda1

libappfuse/FuseBuffer.cc

+19 −11
Original line number Diff line number Diff line
@@ -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) {

libappfuse/include/libappfuse/FuseBuffer.h

+7 −5
Original line number Diff line number Diff line
@@ -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;