mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-12-24 09:27:39 +00:00
99 lines
3.0 KiB
C++
Vendored
99 lines
3.0 KiB
C++
Vendored
/*
|
|
* Copyright (C) 2008 The Android Open Source Project
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* * Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* * Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in
|
|
* the documentation and/or other materials provided with the
|
|
* distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
|
|
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*/
|
|
|
|
#include "system_properties/context_node.h"
|
|
|
|
#include <limits.h>
|
|
#include <unistd.h>
|
|
|
|
#include <async_safe/log.h>
|
|
|
|
#include "system_properties/system_properties.h"
|
|
|
|
// pthread_mutex_lock() calls into system_properties in the case of contention.
|
|
// This creates a risk of dead lock if any system_properties functions
|
|
// use pthread locks after system_property initialization.
|
|
//
|
|
// For this reason, the below three functions use a bionic Lock and static
|
|
// allocation of memory for each filename.
|
|
|
|
bool ContextNode::Open(bool access_rw, bool* fsetxattr_failed) {
|
|
lock_.lock();
|
|
if (pa_) {
|
|
lock_.unlock();
|
|
return true;
|
|
}
|
|
|
|
char filename[PROP_FILENAME_MAX];
|
|
int len = async_safe_format_buffer(filename, sizeof(filename), "%s/%s", filename_, context_);
|
|
if (len < 0 || len >= PROP_FILENAME_MAX) {
|
|
lock_.unlock();
|
|
return false;
|
|
}
|
|
|
|
if (access_rw) {
|
|
pa_ = prop_area::map_prop_area_rw(filename, context_, fsetxattr_failed);
|
|
} else {
|
|
pa_ = prop_area::map_prop_area(filename);
|
|
}
|
|
lock_.unlock();
|
|
return pa_;
|
|
}
|
|
|
|
bool ContextNode::CheckAccessAndOpen() {
|
|
if (!pa_ && !no_access_) {
|
|
if (!CheckAccess() || !Open(false, nullptr)) {
|
|
no_access_ = true;
|
|
}
|
|
}
|
|
return pa_;
|
|
}
|
|
|
|
void ContextNode::ResetAccess() {
|
|
if (!CheckAccess()) {
|
|
Unmap();
|
|
no_access_ = true;
|
|
} else {
|
|
no_access_ = false;
|
|
}
|
|
}
|
|
|
|
bool ContextNode::CheckAccess() {
|
|
char filename[PROP_FILENAME_MAX];
|
|
int len = async_safe_format_buffer(filename, sizeof(filename), "%s/%s", filename_, context_);
|
|
if (len < 0 || len >= PROP_FILENAME_MAX) {
|
|
return false;
|
|
}
|
|
|
|
return access(filename, R_OK) == 0;
|
|
}
|
|
|
|
void ContextNode::Unmap() {
|
|
prop_area::unmap_prop_area(&pa_);
|
|
}
|