gecko-dev/mozglue/linker/Mappable.cpp

455 строки
14 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <string>
#include "Mappable.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/UniquePtr.h"
#ifdef ANDROID
#include <linux/ashmem.h>
#endif
#include <sys/stat.h>
#include <errno.h>
#include "ElfLoader.h"
#include "XZStream.h"
#include "Logging.h"
using mozilla::MakeUnique;
using mozilla::UniquePtr;
class CacheValidator
{
public:
CacheValidator(const char* aCachedLibPath, Zip* aZip, Zip::Stream* aStream)
: mCachedLibPath(aCachedLibPath)
{
static const char kChecksumSuffix[] = ".crc";
mCachedChecksumPath =
MakeUnique<char[]>(strlen(aCachedLibPath) + sizeof(kChecksumSuffix));
sprintf(mCachedChecksumPath.get(), "%s%s", aCachedLibPath, kChecksumSuffix);
DEBUG_LOG("mCachedChecksumPath: %s", mCachedChecksumPath.get());
mChecksum = aStream->GetCRC32();
DEBUG_LOG("mChecksum: %x", mChecksum);
}
// Returns whether the cache is valid and up-to-date.
bool IsValid() const
{
// Validate based on checksum.
RefPtr<Mappable> checksumMap = MappableFile::Create(mCachedChecksumPath.get());
if (!checksumMap) {
// Force caching if checksum is missing in cache.
return false;
}
DEBUG_LOG("Comparing %x with %s", mChecksum, mCachedChecksumPath.get());
MappedPtr checksumBuf = checksumMap->mmap(nullptr, checksumMap->GetLength(),
PROT_READ, MAP_PRIVATE, 0);
if (checksumBuf == MAP_FAILED) {
WARN("Couldn't map %s to validate checksum", mCachedChecksumPath.get());
return false;
}
if (memcmp(checksumBuf, &mChecksum, sizeof(mChecksum))) {
return false;
}
return !access(mCachedLibPath.c_str(), R_OK);
}
// Caches the APK-provided checksum used in future cache validations.
void CacheChecksum() const
{
AutoCloseFD fd(open(mCachedChecksumPath.get(),
O_TRUNC | O_RDWR | O_CREAT | O_NOATIME,
S_IRUSR | S_IWUSR));
if (fd == -1) {
WARN("Couldn't open %s to update checksum", mCachedChecksumPath.get());
return;
}
DEBUG_LOG("Updating checksum %s", mCachedChecksumPath.get());
const size_t size = sizeof(mChecksum);
size_t written = 0;
while (written < size) {
ssize_t ret = write(fd,
reinterpret_cast<const uint8_t*>(&mChecksum) + written,
size - written);
if (ret >= 0) {
written += ret;
} else if (errno != EINTR) {
WARN("Writing checksum %s failed with errno %d",
mCachedChecksumPath.get(), errno);
break;
}
}
}
private:
const std::string mCachedLibPath;
UniquePtr<char[]> mCachedChecksumPath;
uint32_t mChecksum;
};
Mappable *
MappableFile::Create(const char *path)
{
int fd = open(path, O_RDONLY);
if (fd != -1)
return new MappableFile(fd);
return nullptr;
}
MemoryRange
MappableFile::mmap(const void *addr, size_t length, int prot, int flags,
off_t offset)
{
MOZ_ASSERT(fd != -1);
MOZ_ASSERT(!(flags & MAP_SHARED));
flags |= MAP_PRIVATE;
return MemoryRange::mmap(const_cast<void *>(addr), length, prot, flags,
fd, offset);
}
void
MappableFile::finalize()
{
/* Close file ; equivalent to close(fd.forget()) */
fd = -1;
}
size_t
MappableFile::GetLength() const
{
struct stat st;
return fstat(fd, &st) ? 0 : st.st_size;
}
Mappable *
MappableExtractFile::Create(const char *name, Zip *zip, Zip::Stream *stream)
{
MOZ_ASSERT(zip && stream);
const char *cachePath = getenv("MOZ_LINKER_CACHE");
if (!cachePath || !*cachePath) {
WARN("MOZ_LINKER_EXTRACT is set, but not MOZ_LINKER_CACHE; "
"not extracting");
return nullptr;
}
// Ensure that the cache dir is private.
chmod(cachePath, 0770);
UniquePtr<char[]> path =
MakeUnique<char[]>(strlen(cachePath) + strlen(name) + 2);
sprintf(path.get(), "%s/%s", cachePath, name);
CacheValidator validator(path.get(), zip, stream);
if (validator.IsValid()) {
DEBUG_LOG("Reusing %s", static_cast<char *>(path.get()));
return MappableFile::Create(path.get());
}
DEBUG_LOG("Extracting to %s", static_cast<char *>(path.get()));
AutoCloseFD fd;
fd = open(path.get(), O_TRUNC | O_RDWR | O_CREAT | O_NOATIME,
S_IRUSR | S_IWUSR);
if (fd == -1) {
ERROR("Couldn't open %s to decompress library", path.get());
return nullptr;
}
AutoUnlinkFile file(path.release());
if (stream->GetType() == Zip::Stream::DEFLATE) {
if (ftruncate(fd, stream->GetUncompressedSize()) == -1) {
ERROR("Couldn't ftruncate %s to decompress library", file.get());
return nullptr;
}
/* Map the temporary file for use as inflate buffer */
MappedPtr buffer(MemoryRange::mmap(nullptr, stream->GetUncompressedSize(),
PROT_WRITE, MAP_SHARED, fd, 0));
if (buffer == MAP_FAILED) {
ERROR("Couldn't map %s to decompress library", file.get());
return nullptr;
}
zxx_stream zStream = stream->GetZStream(buffer);
/* Decompress */
if (inflateInit2(&zStream, -MAX_WBITS) != Z_OK) {
ERROR("inflateInit failed: %s", zStream.msg);
return nullptr;
}
if (inflate(&zStream, Z_FINISH) != Z_STREAM_END) {
ERROR("inflate failed: %s", zStream.msg);
return nullptr;
}
if (inflateEnd(&zStream) != Z_OK) {
ERROR("inflateEnd failed: %s", zStream.msg);
return nullptr;
}
if (zStream.total_out != stream->GetUncompressedSize()) {
ERROR("File not fully uncompressed! %ld / %d", zStream.total_out,
static_cast<unsigned int>(stream->GetUncompressedSize()));
return nullptr;
}
} else if (XZStream::IsXZ(stream->GetBuffer(), stream->GetSize())) {
XZStream xzStream(stream->GetBuffer(), stream->GetSize());
if (!xzStream.Init()) {
ERROR("Couldn't initialize XZ decoder");
return nullptr;
}
DEBUG_LOG("XZStream created, compressed=%" PRIuPTR
", uncompressed=%" PRIuPTR,
xzStream.Size(), xzStream.UncompressedSize());
if (ftruncate(fd, xzStream.UncompressedSize()) == -1) {
ERROR("Couldn't ftruncate %s to decompress library", file.get());
return nullptr;
}
MappedPtr buffer(MemoryRange::mmap(nullptr, xzStream.UncompressedSize(),
PROT_WRITE, MAP_SHARED, fd, 0));
if (buffer == MAP_FAILED) {
ERROR("Couldn't map %s to decompress library", file.get());
return nullptr;
}
const size_t written = xzStream.Decode(buffer, buffer.GetLength());
DEBUG_LOG("XZStream decoded %" PRIuPTR, written);
if (written != buffer.GetLength()) {
ERROR("Error decoding XZ file %s", file.get());
return nullptr;
}
} else {
return nullptr;
}
validator.CacheChecksum();
return new MappableExtractFile(fd.forget(), file.release());
}
/**
* _MappableBuffer is a buffer which content can be mapped at different
* locations in the virtual address space.
* On Linux, uses a (deleted) temporary file on a tmpfs for sharable content.
* On Android, uses ashmem.
*/
class _MappableBuffer: public MappedPtr
{
public:
/**
* Returns a _MappableBuffer instance with the given name and the given
* length.
*/
static _MappableBuffer *Create(const char *name, size_t length)
{
AutoCloseFD fd;
#ifdef ANDROID
/* On Android, initialize an ashmem region with the given length */
fd = open("/" ASHMEM_NAME_DEF, O_RDWR, 0600);
if (fd == -1)
return nullptr;
char str[ASHMEM_NAME_LEN];
strlcpy(str, name, sizeof(str));
ioctl(fd, ASHMEM_SET_NAME, str);
if (ioctl(fd, ASHMEM_SET_SIZE, length))
return nullptr;
/* The Gecko crash reporter is confused by adjacent memory mappings of
* the same file and chances are we're going to map from the same file
* descriptor right away. To avoid problems with the crash reporter,
* create an empty anonymous page before or after the ashmem mapping,
* depending on how mappings grow in the address space.
*/
#if defined(__arm__)
// Address increases on ARM.
void *buf = ::mmap(nullptr, length + PAGE_SIZE, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (buf != MAP_FAILED) {
::mmap(AlignedEndPtr(reinterpret_cast<char *>(buf) + length, PAGE_SIZE),
PAGE_SIZE, PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
DEBUG_LOG("Decompression buffer of size 0x%" PRIxPTR
" in ashmem \"%s\", mapped @%p",
length, str, buf);
return new _MappableBuffer(fd.forget(), buf, length);
}
#elif defined(__i386__) || defined(__aarch64__)
// Address decreases on x86 and AArch64.
size_t anon_mapping_length = length + PAGE_SIZE;
void *buf = ::mmap(nullptr, anon_mapping_length, PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (buf != MAP_FAILED) {
char *first_page = reinterpret_cast<char *>(buf);
char *map_page = first_page + PAGE_SIZE;
void *actual_buf = ::mmap(map_page, length, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, fd, 0);
if (actual_buf == MAP_FAILED) {
::munmap(buf, anon_mapping_length);
DEBUG_LOG("Fixed allocation of decompression buffer at %p failed", map_page);
return nullptr;
}
DEBUG_LOG("Decompression buffer of size 0x%" PRIxPTR
" in ashmem \"%s\", mapped @%p", length, str, actual_buf);
return new _MappableBuffer(fd.forget(), actual_buf, length);
}
#else
#error need to add a case for your CPU
#endif
#else
/* On Linux, use /dev/shm as base directory for temporary files, assuming
* it's on tmpfs */
/* TODO: check that /dev/shm is tmpfs */
char path[256];
sprintf(path, "/dev/shm/%s.XXXXXX", name);
fd = mkstemp(path);
if (fd == -1)
return nullptr;
unlink(path);
ftruncate(fd, length);
void *buf = ::mmap(nullptr, length, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (buf != MAP_FAILED) {
DEBUG_LOG("Decompression buffer of size %ld in \"%s\", mapped @%p",
length, path, buf);
return new _MappableBuffer(fd.forget(), buf, length);
}
#endif
return nullptr;
}
void *mmap(const void *addr, size_t length, int prot, int flags, off_t offset)
{
MOZ_ASSERT(fd != -1);
#ifdef ANDROID
/* Mapping ashmem MAP_PRIVATE is like mapping anonymous memory, even when
* there is content in the ashmem */
if (flags & MAP_PRIVATE) {
flags &= ~MAP_PRIVATE;
flags |= MAP_SHARED;
}
#endif
return ::mmap(const_cast<void *>(addr), length, prot, flags, fd, offset);
}
#ifdef ANDROID
~_MappableBuffer() {
/* Free the additional page we allocated. See _MappableBuffer::Create */
#if defined(__arm__)
::munmap(AlignedEndPtr(*this + GetLength(), PAGE_SIZE), PAGE_SIZE);
#elif defined(__i386__) || defined(__aarch64__)
::munmap(*this - PAGE_SIZE, GetLength() + PAGE_SIZE);
#else
#error need to add a case for your CPU
#endif
}
#endif
private:
_MappableBuffer(int fd, void *buf, size_t length)
: MappedPtr(buf, length), fd(fd) { }
/* File descriptor for the temporary file or ashmem */
AutoCloseFD fd;
};
Mappable *
MappableDeflate::Create(const char *name, Zip *zip, Zip::Stream *stream)
{
MOZ_ASSERT(stream->GetType() == Zip::Stream::DEFLATE);
_MappableBuffer *buf = _MappableBuffer::Create(name, stream->GetUncompressedSize());
if (buf)
return new MappableDeflate(buf, zip, stream);
return nullptr;
}
MappableDeflate::MappableDeflate(_MappableBuffer *buf, Zip *zip,
Zip::Stream *stream)
: zip(zip), buffer(buf), zStream(stream->GetZStream(*buf)) { }
MappableDeflate::~MappableDeflate() { }
MemoryRange
MappableDeflate::mmap(const void *addr, size_t length, int prot, int flags, off_t offset)
{
MOZ_ASSERT(buffer);
MOZ_ASSERT(!(flags & MAP_SHARED));
flags |= MAP_PRIVATE;
/* The deflate stream is uncompressed up to the required offset + length, if
* it hasn't previously been uncompressed */
ssize_t missing = offset + length + zStream.avail_out - buffer->GetLength();
if (missing > 0) {
uInt avail_out = zStream.avail_out;
zStream.avail_out = missing;
if ((*buffer == zStream.next_out) &&
(inflateInit2(&zStream, -MAX_WBITS) != Z_OK)) {
ERROR("inflateInit failed: %s", zStream.msg);
return MemoryRange(MAP_FAILED, 0);
}
int ret = inflate(&zStream, Z_SYNC_FLUSH);
if (ret < 0) {
ERROR("inflate failed: %s", zStream.msg);
return MemoryRange(MAP_FAILED, 0);
}
if (ret == Z_NEED_DICT) {
ERROR("zstream requires a dictionary. %s", zStream.msg);
return MemoryRange(MAP_FAILED, 0);
}
zStream.avail_out = avail_out - missing + zStream.avail_out;
if (ret == Z_STREAM_END) {
if (inflateEnd(&zStream) != Z_OK) {
ERROR("inflateEnd failed: %s", zStream.msg);
return MemoryRange(MAP_FAILED, 0);
}
if (zStream.total_out != buffer->GetLength()) {
ERROR("File not fully uncompressed! %ld / %d", zStream.total_out,
static_cast<unsigned int>(buffer->GetLength()));
return MemoryRange(MAP_FAILED, 0);
}
}
}
#if defined(ANDROID) && defined(__arm__)
if (prot & PROT_EXEC) {
/* We just extracted data that may be executed in the future.
* We thus need to ensure Instruction and Data cache coherency. */
DEBUG_LOG("cacheflush(%p, %p)", *buffer + offset, *buffer + (offset + length));
cacheflush(reinterpret_cast<uintptr_t>(*buffer + offset),
reinterpret_cast<uintptr_t>(*buffer + (offset + length)), 0);
}
#endif
return MemoryRange(buffer->mmap(addr, length, prot, flags, offset), length);
}
void
MappableDeflate::finalize()
{
/* Free zlib internal buffers */
inflateEnd(&zStream);
/* Free decompression buffer */
buffer = nullptr;
/* Remove reference to Zip archive */
zip = nullptr;
}
size_t
MappableDeflate::GetLength() const
{
return buffer->GetLength();
}