packages/MtpDocumentsProvider/jni/com_android_mtp_AppFuse.cpp - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2015 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.
  */

 #define LOG_NDEBUG 0
 #define LOG_TAG "AppFuseJNI"
 #include "utils/Log.h"

 #include <assert.h>
 #include <dirent.h>
 #include <inttypes.h>

 #include <linux/fuse.h>
 #include <sys/stat.h>

 #include <map>

 #include "jni.h"
 #include "JNIHelp.h"
 #include "android_runtime/AndroidRuntime.h"

 namespace {

 constexpr int min(int a, int b) {
     return a < b ? a : b;
 }

 // Maximum number of bytes to write in one request.
 constexpr size_t MAX_WRITE = 256 * 1024;

 // Largest possible request.
 // The request size is bounded by the maximum size of a FUSE_WRITE request
 // because it has the largest possible data payload.
 constexpr size_t MAX_REQUEST_SIZE = sizeof(struct fuse_in_header) +
         sizeof(struct fuse_write_in) + MAX_WRITE;

 static jclass app_fuse_class;

 struct FuseRequest {
     char buffer[MAX_REQUEST_SIZE];
     FuseRequest() {}
     const struct fuse_in_header& header() const {
         return *(const struct fuse_in_header*) buffer;
     }
     const void* data() const {
         return (buffer + sizeof(struct fuse_in_header));
     }
     size_t data_length() const {
         return header().len - sizeof(struct fuse_in_header);
     }
 };

 class ScopedFd {
     int mFd;

 public:
     explicit ScopedFd(int fd) : mFd(fd) {}
     ~ScopedFd() {
         close(mFd);
     }
     operator int() {
         return mFd;
     }
 };

 /**
  * The class is used to access AppFuse class in Java from fuse handlers.
  */
 class AppFuse {
 public:
     AppFuse(JNIEnv* /*env*/, jobject /*self*/) {
     }

     bool handle_fuse_request(int fd, const FuseRequest& req) {
         ALOGV("Request op=%d", req.header().opcode);
         switch (req.header().opcode) {
             // TODO: Handle more operations that are enough to provide seekable
             // FD.
             case FUSE_INIT:
                 invoke_handler(fd, req, &AppFuse::handle_fuse_init);
                 return true;
             case FUSE_GETATTR:
                 invoke_handler(fd, req, &AppFuse::handle_fuse_getattr);
                 return true;
             case FUSE_FORGET:
                 return false;
             default: {
                 ALOGV("NOTIMPL op=%d uniq=%" PRIx64 " nid=%" PRIx64 "\n",
                       req.header().opcode,
                       req.header().unique,
                       req.header().nodeid);
                 fuse_reply(fd, req.header().unique, -ENOSYS, NULL, 0);
                 return true;
             }
         }
     }

 private:
     int handle_fuse_init(const fuse_in_header&,
                          const fuse_init_in* in,
                          fuse_init_out* out,
                          size_t* reply_size) {
         // 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) {
             ALOGE("Fuse kernel version mismatch: Kernel version %d.%d, "
                   "Expected at least %d.6",
                   in->major, in->minor, FUSE_KERNEL_VERSION);
             return -1;
         }

         // We limit ourselves to 15 because we don't handle BATCH_FORGET yet
         out->minor = min(in->minor, 15);
 #if defined(FUSE_COMPAT_22_INIT_OUT_SIZE)
         // FUSE_KERNEL_VERSION >= 23.

         // If the kernel only works on minor revs older than or equal to 22,
         // then use the older structure size since this code only uses the 7.22
         // version of the structure.
         if (in->minor <= 22) {
             *reply_size = FUSE_COMPAT_22_INIT_OUT_SIZE;
         }
 #else
         // Don't drop this line to prevent an 'unused' compile error.
         *reply_size = sizeof(fuse_init_out);
 #endif

         out->major = FUSE_KERNEL_VERSION;
         out->max_readahead = in->max_readahead;
         out->flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES;
         out->max_background = 32;
         out->congestion_threshold = 32;
         out->max_write = MAX_WRITE;

         return 0;
     }

     int handle_fuse_getattr(const fuse_in_header& header,
                             const fuse_getattr_in* /* in */,
                             fuse_attr_out* out,
                             size_t* /*unused*/) {
         if (header.nodeid != 1) {
             return -ENOENT;
         }
         out->attr_valid = 1000 * 60 * 10;
         out->attr.ino = header.nodeid;
         out->attr.mode = S_IFDIR | 0777;
         out->attr.size = 0;
         return 0;
     }

     template <typename T, typename S>
     void invoke_handler(int fd,
                         const FuseRequest& request,
                         int (AppFuse::*handler)(const fuse_in_header&,
                                                 const T*,
                                                 S*,
                                                 size_t*),
                         size_t reply_size = sizeof(S)) {
         char reply_data[reply_size];
         memset(reply_data, 0, reply_size);
         const int reply_code = (this->*handler)(
                 request.header(),
                 static_cast<const T*>(request.data()),
                 reinterpret_cast<S*>(reply_data),
                 &reply_size);
         fuse_reply(
                 fd,
                 request.header().unique,
                 reply_code,
                 reply_data,
                 reply_size);
     }

     static void fuse_reply(int fd, int unique, int reply_code, void* reply_data,
                            size_t reply_size) {
         // Don't send any data for error case.
         if (reply_code != 0) {
             reply_size = 0;
         }

         struct fuse_out_header hdr;
         hdr.len = reply_size + sizeof(hdr);
         hdr.error = reply_code;
         hdr.unique = unique;

         struct iovec vec[2];
         vec[0].iov_base = &hdr;
         vec[0].iov_len = sizeof(hdr);
         vec[1].iov_base = reply_data;
         vec[1].iov_len = reply_size;

         const int res = writev(fd, vec, reply_size != 0 ? 2 : 1);
         if (res < 0) {
             ALOGE("*** REPLY FAILED *** %d\n", errno);
         }
     }
 };

 jboolean com_android_mtp_AppFuse_start_app_fuse_loop(
         JNIEnv* env, jobject self, jint jfd) {
     ScopedFd fd(dup(static_cast<int>(jfd)));
     AppFuse appfuse(env, self);

     ALOGD("Start fuse loop.");
     while (true) {
         FuseRequest request;
         const ssize_t result = TEMP_FAILURE_RETRY(
                 read(fd, request.buffer, sizeof(request.buffer)));
         if (result < 0) {
             if (errno == ENODEV) {
                 ALOGE("Someone stole our marbles!\n");
                 return JNI_FALSE;
             }
             ALOGE("Failed to read bytes from FD: errno=%d\n", errno);
             continue;
         }

         const size_t length = static_cast<size_t>(result);
         if (length < sizeof(struct fuse_in_header)) {
             ALOGE("request too short: len=%zu\n", length);
             continue;
         }

         if (request.header().len != length) {
             ALOGE("malformed header: len=%zu, hdr->len=%u\n",
                   length, request.header().len);
             continue;
         }

         if (!appfuse.handle_fuse_request(fd, request)) {
             return JNI_TRUE;
         }
     }
 }

 static const JNINativeMethod gMethods[] = {
     {
         "native_start_app_fuse_loop",
         "(I)Z",
         (void *) com_android_mtp_AppFuse_start_app_fuse_loop
     }
 };

 }

 jint JNI_OnLoad(JavaVM* vm, void* /* reserved */) {
     JNIEnv* env = nullptr;
     if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
         ALOGE("ERROR: GetEnv failed\n");
         return -1;

     }
     assert(env != nullptr);

     jclass clazz = env->FindClass("com/android/mtp/AppFuse");
     if (clazz == nullptr) {
         ALOGE("Can't find com/android/mtp/AppFuse");
         return -1;
     }
     app_fuse_class = static_cast<jclass>(env->NewGlobalRef(clazz));
     if (app_fuse_class == nullptr) {
         ALOGE("Can't obtain global reference for com/android/mtp/AppFuse");
         return -1;
     }

     const int result = android::AndroidRuntime::registerNativeMethods(
             env, "com/android/mtp/AppFuse", gMethods, NELEM(gMethods));
     if (result < 0) {
         return -1;
     }

     return JNI_VERSION_1_4;
 }
	/*
	* Copyright (C) 2015 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.
	*/

	#define LOG_NDEBUG 0
	#define LOG_TAG "AppFuseJNI"
	#include "utils/Log.h"

	#include <assert.h>
	#include <dirent.h>
	#include <inttypes.h>

	#include <linux/fuse.h>
	#include <sys/stat.h>

	#include <map>

	#include "jni.h"
	#include "JNIHelp.h"
	#include "android_runtime/AndroidRuntime.h"

	namespace {

	constexpr int min(int a, int b) {
	return a < b ? a : b;
	}

	// Maximum number of bytes to write in one request.
	constexpr size_t MAX_WRITE = 256 * 1024;

	// Largest possible request.
	// The request size is bounded by the maximum size of a FUSE_WRITE request
	// because it has the largest possible data payload.
	constexpr size_t MAX_REQUEST_SIZE = sizeof(struct fuse_in_header) +
	sizeof(struct fuse_write_in) + MAX_WRITE;

	static jclass app_fuse_class;

	struct FuseRequest {
	char buffer[MAX_REQUEST_SIZE];
	FuseRequest() {}
	const struct fuse_in_header& header() const {
	return (const struct fuse_in_header) buffer;
	}
	const void* data() const {
	return (buffer + sizeof(struct fuse_in_header));
	}
	size_t data_length() const {
	return header().len - sizeof(struct fuse_in_header);
	}
	};

	class ScopedFd {
	int mFd;

	public:
	explicit ScopedFd(int fd) : mFd(fd) {}
	~ScopedFd() {
	close(mFd);
	}
	operator int() {
	return mFd;
	}
	};

	/**
	* The class is used to access AppFuse class in Java from fuse handlers.
	*/
	class AppFuse {
	public:
	AppFuse(JNIEnv* /env/, jobject /self/) {
	}

	bool handle_fuse_request(int fd, const FuseRequest& req) {
	ALOGV("Request op=%d", req.header().opcode);
	switch (req.header().opcode) {
	// TODO: Handle more operations that are enough to provide seekable
	// FD.
	case FUSE_INIT:
	invoke_handler(fd, req, &AppFuse::handle_fuse_init);
	return true;
	case FUSE_GETATTR:
	invoke_handler(fd, req, &AppFuse::handle_fuse_getattr);
	return true;
	case FUSE_FORGET:
	return false;
	default: {
	ALOGV("NOTIMPL op=%d uniq=%" PRIx64 " nid=%" PRIx64 "\n",
	req.header().opcode,
	req.header().unique,
	req.header().nodeid);
	fuse_reply(fd, req.header().unique, -ENOSYS, NULL, 0);
	return true;
	}
	}
	}

	private:
	int handle_fuse_init(const fuse_in_header&,
	const fuse_init_in* in,
	fuse_init_out* out,
	size_t* reply_size) {
	// 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) {
	ALOGE("Fuse kernel version mismatch: Kernel version %d.%d, "
	"Expected at least %d.6",
	in->major, in->minor, FUSE_KERNEL_VERSION);
	return -1;
	}

	// We limit ourselves to 15 because we don't handle BATCH_FORGET yet
	out->minor = min(in->minor, 15);
	#if defined(FUSE_COMPAT_22_INIT_OUT_SIZE)
	// FUSE_KERNEL_VERSION >= 23.

	// If the kernel only works on minor revs older than or equal to 22,
	// then use the older structure size since this code only uses the 7.22
	// version of the structure.
	if (in->minor <= 22) {
	*reply_size = FUSE_COMPAT_22_INIT_OUT_SIZE;
	}
	#else
	// Don't drop this line to prevent an 'unused' compile error.
	*reply_size = sizeof(fuse_init_out);
	#endif

	out->major = FUSE_KERNEL_VERSION;
	out->max_readahead = in->max_readahead;
	out->flags = FUSE_ATOMIC_O_TRUNC \| FUSE_BIG_WRITES;
	out->max_background = 32;
	out->congestion_threshold = 32;
	out->max_write = MAX_WRITE;

	return 0;
	}

	int handle_fuse_getattr(const fuse_in_header& header,
	const fuse_getattr_in* /* in */,
	fuse_attr_out* out,
	size_t* /unused/) {
	if (header.nodeid != 1) {
	return -ENOENT;
	}
	out->attr_valid = 1000 * 60 * 10;
	out->attr.ino = header.nodeid;
	out->attr.mode = S_IFDIR \| 0777;
	out->attr.size = 0;
	return 0;
	}

	template <typename T, typename S>
	void invoke_handler(int fd,
	const FuseRequest& request,
	int (AppFuse::*handler)(const fuse_in_header&,
	const T*,
	S*,
	size_t*),
	size_t reply_size = sizeof(S)) {
	char reply_data[reply_size];
	memset(reply_data, 0, reply_size);
	const int reply_code = (this->*handler)(
	request.header(),
	static_cast<const T*>(request.data()),
	reinterpret_cast<S*>(reply_data),
	&reply_size);
	fuse_reply(
	fd,
	request.header().unique,
	reply_code,
	reply_data,
	reply_size);
	}

	static void fuse_reply(int fd, int unique, int reply_code, void* reply_data,
	size_t reply_size) {
	// Don't send any data for error case.
	if (reply_code != 0) {
	reply_size = 0;
	}

	struct fuse_out_header hdr;
	hdr.len = reply_size + sizeof(hdr);
	hdr.error = reply_code;
	hdr.unique = unique;

	struct iovec vec[2];
	vec[0].iov_base = &hdr;
	vec[0].iov_len = sizeof(hdr);
	vec[1].iov_base = reply_data;
	vec[1].iov_len = reply_size;

	const int res = writev(fd, vec, reply_size != 0 ? 2 : 1);
	if (res < 0) {
	ALOGE("* REPLY FAILED * %d\n", errno);
	}
	}
	};

	jboolean com_android_mtp_AppFuse_start_app_fuse_loop(
	JNIEnv* env, jobject self, jint jfd) {
	ScopedFd fd(dup(static_cast<int>(jfd)));
	AppFuse appfuse(env, self);

	ALOGD("Start fuse loop.");
	while (true) {
	FuseRequest request;
	const ssize_t result = TEMP_FAILURE_RETRY(
	read(fd, request.buffer, sizeof(request.buffer)));
	if (result < 0) {
	if (errno == ENODEV) {
	ALOGE("Someone stole our marbles!\n");
	return JNI_FALSE;
	}
	ALOGE("Failed to read bytes from FD: errno=%d\n", errno);
	continue;
	}

	const size_t length = static_cast<size_t>(result);
	if (length < sizeof(struct fuse_in_header)) {
	ALOGE("request too short: len=%zu\n", length);
	continue;
	}

	if (request.header().len != length) {
	ALOGE("malformed header: len=%zu, hdr->len=%u\n",
	length, request.header().len);
	continue;
	}

	if (!appfuse.handle_fuse_request(fd, request)) {
	return JNI_TRUE;
	}
	}
	}

	static const JNINativeMethod gMethods[] = {
	{
	"native_start_app_fuse_loop",
	"(I)Z",
	(void *) com_android_mtp_AppFuse_start_app_fuse_loop
	}
	};

	}

	jint JNI_OnLoad(JavaVM* vm, void* /* reserved */) {
	JNIEnv* env = nullptr;
	if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
	ALOGE("ERROR: GetEnv failed\n");
	return -1;

	}
	assert(env != nullptr);

	jclass clazz = env->FindClass("com/android/mtp/AppFuse");
	if (clazz == nullptr) {
	ALOGE("Can't find com/android/mtp/AppFuse");
	return -1;
	}
	app_fuse_class = static_cast<jclass>(env->NewGlobalRef(clazz));
	if (app_fuse_class == nullptr) {
	ALOGE("Can't obtain global reference for com/android/mtp/AppFuse");
	return -1;
	}

	const int result = android::AndroidRuntime::registerNativeMethods(
	env, "com/android/mtp/AppFuse", gMethods, NELEM(gMethods));
	if (result < 0) {
	return -1;
	}

	return JNI_VERSION_1_4;
	}