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/* Copyright (c) 2012 The Chromium Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "nacl_mounts/kernel_object.h"
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <algorithm>
#include <map>
#include <string>
#include <vector>
#include "nacl_mounts/kernel_handle.h"
#include "nacl_mounts/mount.h"
#include "nacl_mounts/mount_node.h"
#include "utils/auto_lock.h"
KernelObject::KernelObject() {
pthread_mutex_init(&lock_, NULL);
}
KernelObject::~KernelObject() {
pthread_mutex_destroy(&lock_);
}
// Uses longest prefix to find the mount for the give path, then
// acquires the mount and returns it with a relative path.
Mount* KernelObject::AcquireMountAndPath(const std::string& relpath,
Path* out_path) {
AutoLock lock(&lock_);
Mount* mount = NULL;
Path abs_path = GetAbsPathLocked(relpath);
// Find longest prefix
size_t max = abs_path.Size();
for (size_t len = 0; len < abs_path.Size(); len++) {
MountMap_t::iterator it = mounts_.find(abs_path.Range(0, max - len));
if (it != mounts_.end()) {
out_path->Set("/");
out_path->Append(abs_path.Range(max - len, max));
mount = it->second;
break;
}
}
if (NULL == mount) {
errno = ENOTDIR;
return NULL;
}
// Acquire the mount while we hold the proxy lock
mount->Acquire();
return mount;
}
void KernelObject::ReleaseMount(Mount* mnt) {
AutoLock lock(&lock_);
mnt->Release();
}
KernelHandle* KernelObject::AcquireHandle(int fd) {
AutoLock lock(&lock_);
if (fd < 0 || fd >= static_cast<int>(handle_map_.size())) {
errno = EBADF;
return NULL;
}
KernelHandle* handle = handle_map_[fd];
if (NULL == handle) {
errno = EBADF;
return NULL;
}
// Ref count while holding parent mutex
handle->Acquire();
lock.Unlock();
if (handle->node_) handle->mount_->AcquireNode(handle->node_);
return handle;
}
void KernelObject::ReleaseHandle(KernelHandle* handle) {
// The handle must already be held before taking the
// kernel lock.
if (handle->node_) handle->mount_->ReleaseNode(handle->node_);
AutoLock lock(&lock_);
handle->Release();
}
// Helper function to properly sort FD order in the heap, forcing
// lower numberd FD to be available first.
static bool FdOrder(int i, int j) {
return i > j;
}
int KernelObject::AllocateFD(KernelHandle* handle) {
AutoLock lock(&lock_);
int id;
// Acquire then handle and it's mount since we are about
// to track them with this FD.
handle->Acquire();
handle->mount_->Acquire();
// If we can recycle and FD, use that first
if (free_fds_.size()) {
id = free_fds_.front();
std::pop_heap(free_fds_.begin(), free_fds_.end(), FdOrder);
free_fds_.pop_back();
handle_map_[id] = handle;
} else {
id = handle_map_.size();
handle_map_.push_back(handle);
}
return id;
}
void KernelObject::FreeFD(int fd) {
AutoLock lock(&lock_);
// Release the mount and handle since we no longer
// track them with this FD.
KernelHandle* handle = handle_map_[fd];
handle->mount_->Release();
handle->Release();
handle_map_[fd] = NULL;
free_fds_.push_back(fd);
std::push_heap(free_fds_.begin(), free_fds_.end(), FdOrder);
}
Path KernelObject::GetAbsPathLocked(const std::string& path) {
// Generate absolute path
Path abs_path(cwd_);
if (path[0] == '/') {
abs_path = path;
} else {
abs_path = cwd_;
abs_path.Append(path);
}
return abs_path;
}
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