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/*
* Copyright (C) 2020 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.
*/
#include "node-inl.h"
static std::vector<std::string> GetPathSegments(int segment_start, const std::string& path) {
std::vector<std::string> segments;
int segment_end = path.find_first_of('/', segment_start);
while (segment_end != std::string::npos) {
if (segment_end == segment_start) {
// First character is '/' ignore
segment_end = path.find_first_of('/', ++segment_start);
continue;
}
segments.push_back(path.substr(segment_start, segment_end - segment_start));
segment_start = segment_end + 1;
segment_end = path.find_first_of('/', segment_start);
}
if (segment_start < path.size()) {
segments.push_back(path.substr(segment_start));
}
return segments;
}
namespace mediaprovider {
namespace fuse {
// Assumes that |node| has at least one child.
void node::BuildPathForNodeRecursive(bool safe, const node* node, std::stringstream* path) const {
if (node->parent_) {
BuildPathForNodeRecursive(safe, node->parent_, path);
}
if (safe && node->parent_) {
(*path) << reinterpret_cast<uintptr_t>(node);
} else {
(*path) << node->GetName();
}
if (node != this) {
// Must not add a '/' to the last segment
(*path) << "/";
}
}
std::string node::BuildPath() const {
std::lock_guard<std::recursive_mutex> guard(*lock_);
std::stringstream path;
BuildPathForNodeRecursive(false, this, &path);
return path.str();
}
std::string node::BuildSafePath() const {
std::lock_guard<std::recursive_mutex> guard(*lock_);
std::stringstream path;
BuildPathForNodeRecursive(true, this, &path);
return path.str();
}
const node* node::LookupAbsolutePath(const node* root, const std::string& absolute_path) {
if (absolute_path.find(root->GetName()) != 0) {
return nullptr;
}
std::vector<std::string> segments = GetPathSegments(root->GetName().size(), absolute_path);
std::lock_guard<std::recursive_mutex> guard(*root->lock_);
const node* node = root;
for (const std::string& segment : segments) {
node = node->LookupChildByName(segment, false /* acquire */);
if (!node) {
return nullptr;
}
}
return node;
}
const node* node::LookupInode(const node* root, ino_t ino) {
CHECK(root);
std::lock_guard<std::recursive_mutex> guard(*root->lock_);
if ((root->ino_ == ino) && !root->deleted_ && !(root->handles_.empty())) {
return root;
}
for (node* child : root->children_) {
const node* node = LookupInode(child, ino);
if (node) {
return node;
}
}
return nullptr;
}
void node::DeleteTree(node* tree) {
std::lock_guard<std::recursive_mutex> guard(*tree->lock_);
if (tree) {
// Guarantee this node not be released while deleting its children.
// pf_forget could be called for a parent node first not its children
// when evicting file system inodes by shrinker, so the parent node
// could exist without its own reference but having a children node.
// In this case, this node could be deleted during executing
// DeleteTree(child), and it causes double free for the node.
tree->Acquire();
// Make a copy of the list of children because calling Delete tree
// will modify the list of children, which will cause issues while
// iterating over them.
std::vector<node*> children(tree->children_.begin(), tree->children_.end());
for (node* child : children) {
DeleteTree(child);
}
CHECK(tree->children_.empty());
delete tree;
}
}
} // namespace fuse
} // namespace mediaprovider
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