blob: 68818e416180af66d6932e18a2c8dfca9a785118 [file] [log] [blame]
/*
* 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 <stdint.h>
#include <string.h>
#include <sys/mman.h>
#include <string>
#include <vector>
#include <compat/compat.h>
#include <unwindstack/Global.h>
#include <unwindstack/MapInfo.h>
#include <unwindstack/Maps.h>
#include <unwindstack/Memory.h>
namespace unwindstack {
Global::Global(std::shared_ptr<Memory>& memory) : memory_(memory) {}
Global::Global(std::shared_ptr<Memory>& memory, std::vector<std::string>& search_libs)
: memory_(memory), search_libs_(search_libs) {}
void Global::SetArch(ArchEnum arch) {
if (arch_ == ARCH_UNKNOWN) {
arch_ = arch;
ProcessArch();
}
}
bool Global::Searchable(const std::string& name) {
if (search_libs_.empty()) {
return true;
}
if (name.empty()) {
return false;
}
const char* base_name = compat_basename(name.c_str());
for (const std::string& lib : search_libs_) {
if (base_name == lib) {
return true;
}
}
return false;
}
void Global::FindAndReadVariable(Maps* maps, const char* var_str) {
std::string variable(var_str);
// When looking for global variables, do not arbitrarily search every
// readable map. Instead look for a specific pattern that must exist.
// The pattern should be a readable map, followed by a read-write
// map with a non-zero offset.
// For example:
// f0000-f1000 0 r-- /system/lib/libc.so
// f1000-f2000 1000 r-x /system/lib/libc.so
// f2000-f3000 2000 rw- /system/lib/libc.so
// This also works:
// f0000-f2000 0 r-- /system/lib/libc.so
// f2000-f3000 2000 rw- /system/lib/libc.so
// It is also possible to see empty maps after the read-only like so:
// f0000-f1000 0 r-- /system/lib/libc.so
// f1000-f2000 0 ---
// f2000-f3000 1000 r-x /system/lib/libc.so
// f3000-f4000 2000 rw- /system/lib/libc.so
MapInfo* map_zero = nullptr;
for (const auto& info : *maps) {
if (info->offset != 0 && (info->flags & (PROT_READ | PROT_WRITE)) == (PROT_READ | PROT_WRITE) &&
map_zero != nullptr && Searchable(info->name) && info->name == map_zero->name) {
Elf* elf = map_zero->GetElf(memory_, arch());
uint64_t ptr;
if (elf->GetGlobalVariableOffset(variable, &ptr) && ptr != 0) {
uint64_t offset_end = info->offset + info->end - info->start;
if (ptr >= info->offset && ptr < offset_end) {
ptr = info->start + ptr - info->offset;
if (ReadVariableData(ptr)) {
break;
}
}
}
} else if (info->offset == 0 && !info->name.empty()) {
map_zero = info.get();
}
}
}
} // namespace unwindstack