platform_system_vold/fs/Exfat.cpp
Jeff Sharkey 37ba125205 Add basic exFAT support.
Several partners have been requesting exFAT support.  Android doesn't
natively support exFAT, but we're at least willing to try mounting an
exFAT filesystem if we detect the Linux kernel supports it, and if
helper binaries are present.

This CL is simple scaffolding, and it provides no actual
implementation of exFAT.

Test: builds, boots
Bug: 67822822
Change-Id: Id4f8ec3967b32de6e1c0e3c4b47fe6e43a6291ab
2018-01-19 11:58:43 +09:00

97 lines
2.7 KiB
C++

/*
* Copyright (C) 2018 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 specific language governing permissions and
* limitations under the License.
*/
#include <sys/mount.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
#include <logwrap/logwrap.h>
#include "Exfat.h"
#include "Utils.h"
using android::base::StringPrintf;
namespace android {
namespace vold {
namespace exfat {
static const char* kMkfsPath = "/system/bin/mkfs.exfat";
static const char* kFsckPath = "/system/bin/fsck.exfat";
bool IsSupported() {
return access(kMkfsPath, X_OK) == 0 && access(kFsckPath, X_OK) == 0 &&
IsFilesystemSupported("exfat");
}
status_t Check(const std::string& source) {
std::vector<std::string> cmd;
cmd.push_back(kFsckPath);
cmd.push_back(source);
int rc = ForkExecvp(cmd, sFsckUntrustedContext);
if (rc == 0) {
LOG(INFO) << "Check OK";
return 0;
} else {
LOG(ERROR) << "Check failed (code " << rc << ")";
errno = EIO;
return -1;
}
}
status_t Mount(const std::string& source, const std::string& target, int ownerUid, int ownerGid,
int permMask) {
int mountFlags = MS_NODEV | MS_NOSUID | MS_DIRSYNC | MS_NOATIME | MS_NOEXEC;
auto mountData = android::base::StringPrintf("uid=%d,gid=%d,fmask=%o,dmask=%o", ownerUid,
ownerGid, permMask, permMask);
if (mount(source.c_str(), target.c_str(), "exfat", mountFlags, mountData.c_str()) == 0) {
return 0;
}
PLOG(ERROR) << "Mount failed; attempting read-only";
mountFlags |= MS_RDONLY;
if (mount(source.c_str(), target.c_str(), "exfat", mountFlags, mountData.c_str()) == 0) {
return 0;
}
return -1;
}
status_t Format(const std::string& source) {
std::vector<std::string> cmd;
cmd.push_back(kMkfsPath);
cmd.push_back("-n");
cmd.push_back("android");
cmd.push_back(source);
int rc = ForkExecvp(cmd);
if (rc == 0) {
LOG(INFO) << "Format OK";
return 0;
} else {
LOG(ERROR) << "Format failed (code " << rc << ")";
errno = EIO;
return -1;
}
return 0;
}
} // namespace exfat
} // namespace vold
} // namespace android