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 /* 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 "Mappable.h"

 #ifdef ANDROID

 #include <linux/ashmem.h>

 #endif

 #include <sys/stat.h>

 #include <errno.h>

 #include "ElfLoader.h"

 #include "SeekableZStream.h"

 #include "Logging.h"

 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)

 {

   const char *cachePath = getenv("MOZ_LINKER_CACHE");

   if (!cachePath || !*cachePath) {

     LOG("Warning: MOZ_LINKER_EXTRACT is set, but not MOZ_LINKER_CACHE; "

         "not extracting");

     return nullptr;

   }

   mozilla::ScopedDeleteArray<char> path;

   path = new char[strlen(cachePath) + strlen(name) + 2];

   sprintf(path, "%s/%s", cachePath, name);

   struct stat cacheStat;

   if (stat(path, &cacheStat) == 0) {

     struct stat zipStat;

     stat(zip->GetName(), &zipStat);

     if (cacheStat.st_mtime > zipStat.st_mtime) {

       DEBUG_LOG("Reusing %s", static_cast<char *>(path));

       return MappableFile::Create(path);

     }

   }

   DEBUG_LOG("Extracting to %s", static_cast<char *>(path));

   AutoCloseFD fd;

   fd = open(path, O_TRUNC | O_RDWR | O_CREAT | O_NOATIME,

                   S_IRUSR | S_IWUSR);

   if (fd == -1) {

     LOG("Couldn't open %s to decompress library", path.get());

     return nullptr;

   }

   AutoUnlinkFile file;

   file = path.forget();

   if (stream->GetType() == Zip::Stream::DEFLATE) {

     if (ftruncate(fd, stream->GetUncompressedSize()) == -1) {

       LOG("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) {

       LOG("Couldn't map %s to decompress library", file.get());

       return nullptr;

     }

     z_stream zStream = stream->GetZStream(buffer);

     /* Decompress */

     if (inflateInit2(&zStream, -MAX_WBITS) != Z_OK) {

       LOG("inflateInit failed: %s", zStream.msg);

       return nullptr;

     }

     if (inflate(&zStream, Z_FINISH) != Z_STREAM_END) {

       LOG("inflate failed: %s", zStream.msg);

       return nullptr;

     }

     if (inflateEnd(&zStream) != Z_OK) {

       LOG("inflateEnd failed: %s", zStream.msg);

       return nullptr;

     }

     if (zStream.total_out != stream->GetUncompressedSize()) {

       LOG("File not fully uncompressed! %ld / %d", zStream.total_out,

           static_cast<unsigned int>(stream->GetUncompressedSize()));

       return nullptr;

     }

   } else if (stream->GetType() == Zip::Stream::STORE) {

     SeekableZStream zStream;

     if (!zStream.Init(stream->GetBuffer(), stream->GetSize())) {

       LOG("Couldn't initialize SeekableZStream for %s", name);

       return nullptr;

     }

     if (ftruncate(fd, zStream.GetUncompressedSize()) == -1) {

       LOG("Couldn't ftruncate %s to decompress library", file.get());

       return nullptr;

     }

     MappedPtr buffer(MemoryRange::mmap(nullptr, zStream.GetUncompressedSize(),

                                        PROT_WRITE, MAP_SHARED, fd, 0));

     if (buffer == MAP_FAILED) {

       LOG("Couldn't map %s to decompress library", file.get());

       return nullptr;

     }

     if (!zStream.Decompress(buffer, 0, zStream.GetUncompressedSize())) {

       LOG("%s: failed to decompress", name);

       return nullptr;

     }

   } else {

     return nullptr;

   }

   return new MappableExtractFile(fd.forget(), file.forget());

 }

 MappableExtractFile::~MappableExtractFile()

 {

   /* When destroying from a forked process, we don't want the file to be

    * removed, as the main process is still using the file. Although it

    * doesn't really matter, it helps e.g. valgrind that the file is there.

    * The string still needs to be delete[]d, though */

   if (pid != getpid())

     delete [] path.forget();

 }

 /**

  * _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__)

     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%x in ashmem \"%s\", mapped @%p",

                 length, str, buf);

       return new _MappableBuffer(fd.forget(), buf, length);

     }

 #elif defined(__i386__)

     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%x 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__)

     ::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)) {

       LOG("inflateInit failed: %s", zStream.msg);

       return MemoryRange(MAP_FAILED, 0);

     }

     int ret = inflate(&zStream, Z_SYNC_FLUSH);

     if (ret < 0) {

       LOG("inflate failed: %s", zStream.msg);

       return MemoryRange(MAP_FAILED, 0);

     }

     if (ret == Z_NEED_DICT) {

       LOG("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) {

         LOG("inflateEnd failed: %s", zStream.msg);

         return MemoryRange(MAP_FAILED, 0);

       }

       if (zStream.total_out != buffer->GetLength()) {

         LOG("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();

 }

 Mappable *

 MappableSeekableZStream::Create(const char *name, Zip *zip,

                                 Zip::Stream *stream)

 {

   MOZ_ASSERT(stream->GetType() == Zip::Stream::STORE);

   mozilla::ScopedDeletePtr<MappableSeekableZStream> mappable;

   mappable = new MappableSeekableZStream(zip);

   pthread_mutexattr_t recursiveAttr;

   pthread_mutexattr_init(&recursiveAttr);

   pthread_mutexattr_settype(&recursiveAttr, PTHREAD_MUTEX_RECURSIVE);

   if (pthread_mutex_init(&mappable->mutex, &recursiveAttr))

     return nullptr;

   if (!mappable->zStream.Init(stream->GetBuffer(), stream->GetSize()))

     return nullptr;

   mappable->buffer = _MappableBuffer::Create(name,

                               mappable->zStream.GetUncompressedSize());

   if (!mappable->buffer)

     return nullptr;

   mappable->chunkAvail = new unsigned char[mappable->zStream.GetChunksNum()];

   memset(mappable->chunkAvail, 0, mappable->zStream.GetChunksNum());

   return mappable.forget();

 }

 MappableSeekableZStream::MappableSeekableZStream(Zip *zip)

 : zip(zip), chunkAvailNum(0) { }

 MappableSeekableZStream::~MappableSeekableZStream()

 {

   pthread_mutex_destroy(&mutex);

 }

 MemoryRange

 MappableSeekableZStream::mmap(const void *addr, size_t length, int prot,

                               int flags, off_t offset)

 {

   /* Map with PROT_NONE so that accessing the mapping would segfault, and

    * bring us to ensure() */

   void *res = buffer->mmap(addr, length, PROT_NONE, flags, offset);

   if (res == MAP_FAILED)

     return MemoryRange(MAP_FAILED, 0);

   /* Store the mapping, ordered by offset and length */

   std::vector<LazyMap>::reverse_iterator it;

   for (it = lazyMaps.rbegin(); it < lazyMaps.rend(); ++it) {

     if ((it->offset < offset) ||

         ((it->offset == offset) && (it->length < length)))

       break;

   }

   LazyMap map = { res, length, prot, offset };

   lazyMaps.insert(it.base(), map);

   return MemoryRange(res, length);

 }

 void

 MappableSeekableZStream::munmap(void *addr, size_t length)

 {

   std::vector<LazyMap>::iterator it;

   for (it = lazyMaps.begin(); it < lazyMaps.end(); ++it)

     if ((it->addr = addr) && (it->length == length)) {

       lazyMaps.erase(it);

       ::munmap(addr, length);

       return;

     }

   MOZ_CRASH("munmap called with unknown mapping");

 }

 void

 MappableSeekableZStream::finalize() { }

 class AutoLock {

 public:

   AutoLock(pthread_mutex_t *mutex): mutex(mutex)

   {

     if (pthread_mutex_lock(mutex))

       MOZ_CRASH("pthread_mutex_lock failed");

   }

   ~AutoLock()

   {

     if (pthread_mutex_unlock(mutex))

       MOZ_CRASH("pthread_mutex_unlock failed");

   }

 private:

   pthread_mutex_t *mutex;

 };

 bool

 MappableSeekableZStream::ensure(const void *addr)

 {

   DEBUG_LOG("ensure @%p", addr);

   const void *addrPage = PageAlignedPtr(addr);

   /* Find the mapping corresponding to the given page */

   std::vector<LazyMap>::iterator map;

   for (map = lazyMaps.begin(); map < lazyMaps.end(); ++map) {

     if (map->Contains(addrPage))

       break;

   }

   if (map == lazyMaps.end())

     return false;

   /* Find corresponding chunk */

   off_t mapOffset = map->offsetOf(addrPage);

   off_t chunk = mapOffset / zStream.GetChunkSize();

   /* In the typical case, we just need to decompress the chunk entirely. But

    * when the current mapping ends in the middle of the chunk, we want to

    * stop at the end of the corresponding page.

    * However, if another mapping needs the last part of the chunk, we still

    * need to continue. As mappings are ordered by offset and length, we don't

    * need to scan the entire list of mappings.

    * It is safe to run through lazyMaps here because the linker is never

    * going to call mmap (which adds lazyMaps) while this function is

    * called. */

   size_t length = zStream.GetChunkSize(chunk);

   off_t chunkStart = chunk * zStream.GetChunkSize();

   off_t chunkEnd = chunkStart + length;

   std::vector<LazyMap>::iterator it;

   for (it = map; it < lazyMaps.end(); ++it) {

     if (chunkEnd <= it->endOffset())

       break;

   }

   if ((it == lazyMaps.end()) || (chunkEnd > it->endOffset())) {

     /* The mapping "it" points at now is past the interesting one */

     --it;

     length = it->endOffset() - chunkStart;

   }

   length = PageAlignedSize(length);

   /* The following lock can be re-acquired by the thread holding it.

    * If this happens, it means the following code is interrupted somehow by

    * some signal, and ends up retriggering a chunk decompression for the

    * same MappableSeekableZStream.

    * If the chunk to decompress is different the second time, then everything

    * is safe as the only common data touched below is chunkAvailNum, and it is

    * atomically updated (leaving out any chance of an interruption while it is

    * updated affecting the result). If the chunk to decompress is the same, the

    * worst thing that can happen is chunkAvailNum being incremented one too

    * many times, which doesn't affect functionality. The chances of it

    * happening being pretty slim, and the effect being harmless, we can just

    * ignore the issue. Other than that, we'd just be wasting time decompressing

    * the same chunk twice. */

   AutoLock lock(&mutex);

   /* The very first page is mapped and accessed separately of the rest, and

    * as such, only the first page of the first chunk is decompressed this way.

    * When we fault in the remaining pages of that chunk, we want to decompress

    * the complete chunk again. Short of doing that, we would end up with

    * no data between PageSize() and chunkSize, which would effectively corrupt

    * symbol resolution in the underlying library. */

   if (chunkAvail[chunk] < PageNumber(length)) {

     if (!zStream.DecompressChunk(*buffer + chunkStart, chunk, length))

       return false;

 #if defined(ANDROID) && defined(__arm__)

     if (map->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 + chunkStart, *buffer + (chunkStart + length));

       cacheflush(reinterpret_cast<uintptr_t>(*buffer + chunkStart),

                  reinterpret_cast<uintptr_t>(*buffer + (chunkStart + length)), 0);

     }

 #endif

     /* Only count if we haven't already decompressed parts of the chunk */

     if (chunkAvail[chunk] == 0)

       chunkAvailNum++;

     chunkAvail[chunk] = PageNumber(length);

   }

   /* Flip the chunk mapping protection to the recorded flags. We could

    * also flip the protection for other mappings of the same chunk,

    * but it's easier to skip that and let further segfaults call

    * ensure again. */

   const void *chunkAddr = reinterpret_cast<const void *>

                           (reinterpret_cast<uintptr_t>(addrPage)

                            - mapOffset % zStream.GetChunkSize());

   const void *chunkEndAddr = reinterpret_cast<const void *>

                              (reinterpret_cast<uintptr_t>(chunkAddr) + length);

   const void *start = std::max(map->addr, chunkAddr);

   const void *end = std::min(map->end(), chunkEndAddr);

   length = reinterpret_cast<uintptr_t>(end)

            - reinterpret_cast<uintptr_t>(start);

   if (mprotect(const_cast<void *>(start), length, map->prot) == 0) {

     DEBUG_LOG("mprotect @%p, 0x%" PRIxSize ", 0x%x", start, length, map->prot);

     return true;

   }

   LOG("mprotect @%p, 0x%" PRIxSize ", 0x%x failed with errno %d",

       start, length, map->prot, errno);

   LOG("mprotect failed");

   return false;

 }

 void

 MappableSeekableZStream::stats(const char *when, const char *name) const

 {

   size_t nEntries = zStream.GetChunksNum();

   DEBUG_LOG("%s: %s; %" PRIdSize "/%" PRIdSize " chunks decompressed",

             name, when, static_cast<size_t>(chunkAvailNum), nEntries);

   size_t len = 64;

   mozilla::ScopedDeleteArray<char> map;

   map = new char[len + 3];

   map[0] = '[';

   for (size_t i = 0, j = 1; i < nEntries; i++, j++) {

     map[j] = chunkAvail[i] ? '*' : '_';

     if ((j == len) || (i == nEntries - 1)) {

       map[j + 1] = ']';

       map[j + 2] = '\0';

       DEBUG_LOG("%s", static_cast<char *>(map));

       j = 0;

     }

   }

 }

 size_t

 MappableSeekableZStream::GetLength() const

 {

   return buffer->GetLength();

 }