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/*
* Copyright (C) 2017 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 "FileDeviceUtils.h"
#include <errno.h>
#include <fcntl.h>
#include <linux/fiemap.h>
#include <linux/fs.h>
#include <mntent.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/unique_fd.h>
namespace {
std::unique_ptr<struct fiemap> alloc_fiemap(uint32_t extent_count);
}
namespace android {
namespace vold {
// Given a file path, look for the corresponding block device in /proc/mount
std::string BlockDeviceForPath(const std::string& path) {
std::unique_ptr<FILE, int (*)(FILE*)> mnts(setmntent("/proc/mounts", "re"), endmntent);
if (!mnts) {
PLOG(ERROR) << "Unable to open /proc/mounts";
return "";
}
std::string result;
size_t best_length = 0;
struct mntent* mnt; // getmntent returns a thread local, so it's safe.
while ((mnt = getmntent(mnts.get())) != nullptr) {
auto l = strlen(mnt->mnt_dir);
if (l > best_length && path.size() > l && path[l] == '/' &&
path.compare(0, l, mnt->mnt_dir) == 0) {
result = mnt->mnt_fsname;
best_length = l;
}
}
if (result.empty()) {
LOG(ERROR) << "Didn't find a mountpoint to match path " << path;
return "";
}
return result;
}
std::unique_ptr<struct fiemap> PathFiemap(const std::string& path, uint32_t extent_count) {
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path.c_str(), O_RDONLY | O_CLOEXEC, 0)));
if (fd == -1) {
if (errno == ENOENT) {
PLOG(DEBUG) << "Unable to open " << path;
} else {
PLOG(ERROR) << "Unable to open " << path;
}
return nullptr;
}
auto fiemap = alloc_fiemap(extent_count);
if (ioctl(fd.get(), FS_IOC_FIEMAP, fiemap.get()) != 0) {
PLOG(ERROR) << "Unable to FIEMAP " << path;
return nullptr;
}
auto mapped = fiemap->fm_mapped_extents;
if (mapped < 1 || mapped > extent_count) {
LOG(ERROR) << "Extent count not in bounds 1 <= " << mapped << " <= " << extent_count
<< " in " << path;
return nullptr;
}
return fiemap;
}
} // namespace vold
} // namespace android
namespace {
std::unique_ptr<struct fiemap> alloc_fiemap(uint32_t extent_count) {
size_t allocsize = offsetof(struct fiemap, fm_extents[extent_count]);
std::unique_ptr<struct fiemap> res(new (::operator new(allocsize)) struct fiemap);
memset(res.get(), 0, allocsize);
res->fm_start = 0;
res->fm_length = UINT64_MAX;
res->fm_flags = 0;
res->fm_extent_count = extent_count;
res->fm_mapped_extents = 0;
return res;
}
} // namespace
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