michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include <fcntl.h>
michael@0: #include <unistd.h>
michael@0: #include <sys/mman.h>
michael@0: #include <sys/stat.h>
michael@0: #include <cstring>
michael@0: #include <cstdlib>
michael@0: #include <cstdio>
michael@0: #include "Mappable.h"
michael@0: #ifdef ANDROID
michael@0: #include <linux/ashmem.h>
michael@0: #endif
michael@0: #include <sys/stat.h>
michael@0: #include <errno.h>
michael@0: #include "ElfLoader.h"
michael@0: #include "SeekableZStream.h"
michael@0: #include "Logging.h"
michael@0: 
michael@0: Mappable *
michael@0: MappableFile::Create(const char *path)
michael@0: {
michael@0:   int fd = open(path, O_RDONLY);
michael@0:   if (fd != -1)
michael@0:     return new MappableFile(fd);
michael@0:   return nullptr;
michael@0: }
michael@0: 
michael@0: MemoryRange
michael@0: MappableFile::mmap(const void *addr, size_t length, int prot, int flags,
michael@0:                    off_t offset)
michael@0: {
michael@0:   MOZ_ASSERT(fd != -1);
michael@0:   MOZ_ASSERT(!(flags & MAP_SHARED));
michael@0:   flags |= MAP_PRIVATE;
michael@0: 
michael@0:   return MemoryRange::mmap(const_cast<void *>(addr), length, prot, flags,
michael@0:                            fd, offset);
michael@0: }
michael@0: 
michael@0: void
michael@0: MappableFile::finalize()
michael@0: {
michael@0:   /* Close file ; equivalent to close(fd.forget()) */
michael@0:   fd = -1;
michael@0: }
michael@0: 
michael@0: size_t
michael@0: MappableFile::GetLength() const
michael@0: {
michael@0:   struct stat st;
michael@0:   return fstat(fd, &st) ? 0 : st.st_size;
michael@0: }
michael@0: 
michael@0: Mappable *
michael@0: MappableExtractFile::Create(const char *name, Zip *zip, Zip::Stream *stream)
michael@0: {
michael@0:   const char *cachePath = getenv("MOZ_LINKER_CACHE");
michael@0:   if (!cachePath || !*cachePath) {
michael@0:     LOG("Warning: MOZ_LINKER_EXTRACT is set, but not MOZ_LINKER_CACHE; "
michael@0:         "not extracting");
michael@0:     return nullptr;
michael@0:   }
michael@0:   mozilla::ScopedDeleteArray<char> path;
michael@0:   path = new char[strlen(cachePath) + strlen(name) + 2];
michael@0:   sprintf(path, "%s/%s", cachePath, name);
michael@0:   struct stat cacheStat;
michael@0:   if (stat(path, &cacheStat) == 0) {
michael@0:     struct stat zipStat;
michael@0:     stat(zip->GetName(), &zipStat);
michael@0:     if (cacheStat.st_mtime > zipStat.st_mtime) {
michael@0:       DEBUG_LOG("Reusing %s", static_cast<char *>(path));
michael@0:       return MappableFile::Create(path);
michael@0:     }
michael@0:   }
michael@0:   DEBUG_LOG("Extracting to %s", static_cast<char *>(path));
michael@0:   AutoCloseFD fd;
michael@0:   fd = open(path, O_TRUNC | O_RDWR | O_CREAT | O_NOATIME,
michael@0:                   S_IRUSR | S_IWUSR);
michael@0:   if (fd == -1) {
michael@0:     LOG("Couldn't open %s to decompress library", path.get());
michael@0:     return nullptr;
michael@0:   }
michael@0:   AutoUnlinkFile file;
michael@0:   file = path.forget();
michael@0:   if (stream->GetType() == Zip::Stream::DEFLATE) {
michael@0:     if (ftruncate(fd, stream->GetUncompressedSize()) == -1) {
michael@0:       LOG("Couldn't ftruncate %s to decompress library", file.get());
michael@0:       return nullptr;
michael@0:     }
michael@0:     /* Map the temporary file for use as inflate buffer */
michael@0:     MappedPtr buffer(MemoryRange::mmap(nullptr, stream->GetUncompressedSize(),
michael@0:                                        PROT_WRITE, MAP_SHARED, fd, 0));
michael@0:     if (buffer == MAP_FAILED) {
michael@0:       LOG("Couldn't map %s to decompress library", file.get());
michael@0:       return nullptr;
michael@0:     }
michael@0: 
michael@0:     z_stream zStream = stream->GetZStream(buffer);
michael@0: 
michael@0:     /* Decompress */
michael@0:     if (inflateInit2(&zStream, -MAX_WBITS) != Z_OK) {
michael@0:       LOG("inflateInit failed: %s", zStream.msg);
michael@0:       return nullptr;
michael@0:     }
michael@0:     if (inflate(&zStream, Z_FINISH) != Z_STREAM_END) {
michael@0:       LOG("inflate failed: %s", zStream.msg);
michael@0:       return nullptr;
michael@0:     }
michael@0:     if (inflateEnd(&zStream) != Z_OK) {
michael@0:       LOG("inflateEnd failed: %s", zStream.msg);
michael@0:       return nullptr;
michael@0:     }
michael@0:     if (zStream.total_out != stream->GetUncompressedSize()) {
michael@0:       LOG("File not fully uncompressed! %ld / %d", zStream.total_out,
michael@0:           static_cast<unsigned int>(stream->GetUncompressedSize()));
michael@0:       return nullptr;
michael@0:     }
michael@0:   } else if (stream->GetType() == Zip::Stream::STORE) {
michael@0:     SeekableZStream zStream;
michael@0:     if (!zStream.Init(stream->GetBuffer(), stream->GetSize())) {
michael@0:       LOG("Couldn't initialize SeekableZStream for %s", name);
michael@0:       return nullptr;
michael@0:     }
michael@0:     if (ftruncate(fd, zStream.GetUncompressedSize()) == -1) {
michael@0:       LOG("Couldn't ftruncate %s to decompress library", file.get());
michael@0:       return nullptr;
michael@0:     }
michael@0:     MappedPtr buffer(MemoryRange::mmap(nullptr, zStream.GetUncompressedSize(),
michael@0:                                        PROT_WRITE, MAP_SHARED, fd, 0));
michael@0:     if (buffer == MAP_FAILED) {
michael@0:       LOG("Couldn't map %s to decompress library", file.get());
michael@0:       return nullptr;
michael@0:     }
michael@0: 
michael@0:     if (!zStream.Decompress(buffer, 0, zStream.GetUncompressedSize())) {
michael@0:       LOG("%s: failed to decompress", name);
michael@0:       return nullptr;
michael@0:     }
michael@0:   } else {
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   return new MappableExtractFile(fd.forget(), file.forget());
michael@0: }
michael@0: 
michael@0: MappableExtractFile::~MappableExtractFile()
michael@0: {
michael@0:   /* When destroying from a forked process, we don't want the file to be
michael@0:    * removed, as the main process is still using the file. Although it
michael@0:    * doesn't really matter, it helps e.g. valgrind that the file is there.
michael@0:    * The string still needs to be delete[]d, though */
michael@0:   if (pid != getpid())
michael@0:     delete [] path.forget();
michael@0: }
michael@0: 
michael@0: /**
michael@0:  * _MappableBuffer is a buffer which content can be mapped at different
michael@0:  * locations in the virtual address space.
michael@0:  * On Linux, uses a (deleted) temporary file on a tmpfs for sharable content.
michael@0:  * On Android, uses ashmem.
michael@0:  */
michael@0: class _MappableBuffer: public MappedPtr
michael@0: {
michael@0: public:
michael@0:   /**
michael@0:    * Returns a _MappableBuffer instance with the given name and the given
michael@0:    * length.
michael@0:    */
michael@0:   static _MappableBuffer *Create(const char *name, size_t length)
michael@0:   {
michael@0:     AutoCloseFD fd;
michael@0: #ifdef ANDROID
michael@0:     /* On Android, initialize an ashmem region with the given length */
michael@0:     fd = open("/" ASHMEM_NAME_DEF, O_RDWR, 0600);
michael@0:     if (fd == -1)
michael@0:       return nullptr;
michael@0:     char str[ASHMEM_NAME_LEN];
michael@0:     strlcpy(str, name, sizeof(str));
michael@0:     ioctl(fd, ASHMEM_SET_NAME, str);
michael@0:     if (ioctl(fd, ASHMEM_SET_SIZE, length))
michael@0:       return nullptr;
michael@0: 
michael@0:     /* The Gecko crash reporter is confused by adjacent memory mappings of
michael@0:      * the same file and chances are we're going to map from the same file
michael@0:      * descriptor right away. To avoid problems with the crash reporter,
michael@0:      * create an empty anonymous page before or after the ashmem mapping,
michael@0:      * depending on how mappings grow in the address space.
michael@0:      */
michael@0: #if defined(__arm__)
michael@0:     void *buf = ::mmap(nullptr, length + PAGE_SIZE, PROT_READ | PROT_WRITE,
michael@0:                        MAP_SHARED, fd, 0);
michael@0:     if (buf != MAP_FAILED) {
michael@0:       ::mmap(AlignedEndPtr(reinterpret_cast<char *>(buf) + length, PAGE_SIZE),
michael@0:              PAGE_SIZE, PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
michael@0:       DEBUG_LOG("Decompression buffer of size 0x%x in ashmem \"%s\", mapped @%p",
michael@0:                 length, str, buf);
michael@0:       return new _MappableBuffer(fd.forget(), buf, length);
michael@0:     }
michael@0: #elif defined(__i386__)
michael@0:     size_t anon_mapping_length = length + PAGE_SIZE;
michael@0:     void *buf = ::mmap(nullptr, anon_mapping_length, PROT_NONE,
michael@0:                        MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
michael@0:     if (buf != MAP_FAILED) {
michael@0:       char *first_page = reinterpret_cast<char *>(buf);
michael@0:       char *map_page = first_page + PAGE_SIZE;
michael@0: 
michael@0:       void *actual_buf = ::mmap(map_page, length, PROT_READ | PROT_WRITE,
michael@0:                                 MAP_FIXED | MAP_SHARED, fd, 0);
michael@0:       if (actual_buf == MAP_FAILED) {
michael@0:         ::munmap(buf, anon_mapping_length);
michael@0:         DEBUG_LOG("Fixed allocation of decompression buffer at %p failed", map_page);
michael@0:         return nullptr;
michael@0:       }
michael@0: 
michael@0:       DEBUG_LOG("Decompression buffer of size 0x%x in ashmem \"%s\", mapped @%p",
michael@0:                 length, str, actual_buf);
michael@0:       return new _MappableBuffer(fd.forget(), actual_buf, length);
michael@0:     }
michael@0: #else
michael@0: #error need to add a case for your CPU
michael@0: #endif
michael@0: #else
michael@0:     /* On Linux, use /dev/shm as base directory for temporary files, assuming
michael@0:      * it's on tmpfs */
michael@0:     /* TODO: check that /dev/shm is tmpfs */
michael@0:     char path[256];
michael@0:     sprintf(path, "/dev/shm/%s.XXXXXX", name);
michael@0:     fd = mkstemp(path);
michael@0:     if (fd == -1)
michael@0:       return nullptr;
michael@0:     unlink(path);
michael@0:     ftruncate(fd, length);
michael@0: 
michael@0:     void *buf = ::mmap(nullptr, length, PROT_READ | PROT_WRITE,
michael@0:                        MAP_SHARED, fd, 0);
michael@0:     if (buf != MAP_FAILED) {
michael@0:       DEBUG_LOG("Decompression buffer of size %ld in \"%s\", mapped @%p",
michael@0:                 length, path, buf);
michael@0:       return new _MappableBuffer(fd.forget(), buf, length);
michael@0:     }
michael@0: #endif
michael@0:     return nullptr;
michael@0:   }
michael@0: 
michael@0:   void *mmap(const void *addr, size_t length, int prot, int flags, off_t offset)
michael@0:   {
michael@0:     MOZ_ASSERT(fd != -1);
michael@0: #ifdef ANDROID
michael@0:     /* Mapping ashmem MAP_PRIVATE is like mapping anonymous memory, even when
michael@0:      * there is content in the ashmem */
michael@0:     if (flags & MAP_PRIVATE) {
michael@0:       flags &= ~MAP_PRIVATE;
michael@0:       flags |= MAP_SHARED;
michael@0:     }
michael@0: #endif
michael@0:     return ::mmap(const_cast<void *>(addr), length, prot, flags, fd, offset);
michael@0:   }
michael@0: 
michael@0: #ifdef ANDROID
michael@0:   ~_MappableBuffer() {
michael@0:     /* Free the additional page we allocated. See _MappableBuffer::Create */
michael@0: #if defined(__arm__)
michael@0:     ::munmap(AlignedEndPtr(*this + GetLength(), PAGE_SIZE), PAGE_SIZE);
michael@0: #elif defined(__i386__)
michael@0:     ::munmap(*this - PAGE_SIZE, GetLength() + PAGE_SIZE);
michael@0: #else
michael@0: #error need to add a case for your CPU
michael@0: #endif
michael@0:   }
michael@0: #endif
michael@0: 
michael@0: private:
michael@0:   _MappableBuffer(int fd, void *buf, size_t length)
michael@0:   : MappedPtr(buf, length), fd(fd) { }
michael@0: 
michael@0:   /* File descriptor for the temporary file or ashmem */
michael@0:   AutoCloseFD fd;
michael@0: };
michael@0: 
michael@0: 
michael@0: Mappable *
michael@0: MappableDeflate::Create(const char *name, Zip *zip, Zip::Stream *stream)
michael@0: {
michael@0:   MOZ_ASSERT(stream->GetType() == Zip::Stream::DEFLATE);
michael@0:   _MappableBuffer *buf = _MappableBuffer::Create(name, stream->GetUncompressedSize());
michael@0:   if (buf)
michael@0:     return new MappableDeflate(buf, zip, stream);
michael@0:   return nullptr;
michael@0: }
michael@0: 
michael@0: MappableDeflate::MappableDeflate(_MappableBuffer *buf, Zip *zip,
michael@0:                                  Zip::Stream *stream)
michael@0: : zip(zip), buffer(buf), zStream(stream->GetZStream(*buf)) { }
michael@0: 
michael@0: MappableDeflate::~MappableDeflate() { }
michael@0: 
michael@0: MemoryRange
michael@0: MappableDeflate::mmap(const void *addr, size_t length, int prot, int flags, off_t offset)
michael@0: {
michael@0:   MOZ_ASSERT(buffer);
michael@0:   MOZ_ASSERT(!(flags & MAP_SHARED));
michael@0:   flags |= MAP_PRIVATE;
michael@0: 
michael@0:   /* The deflate stream is uncompressed up to the required offset + length, if
michael@0:    * it hasn't previously been uncompressed */
michael@0:   ssize_t missing = offset + length + zStream.avail_out - buffer->GetLength();
michael@0:   if (missing > 0) {
michael@0:     uInt avail_out = zStream.avail_out;
michael@0:     zStream.avail_out = missing;
michael@0:     if ((*buffer == zStream.next_out) &&
michael@0:         (inflateInit2(&zStream, -MAX_WBITS) != Z_OK)) {
michael@0:       LOG("inflateInit failed: %s", zStream.msg);
michael@0:       return MemoryRange(MAP_FAILED, 0);
michael@0:     }
michael@0:     int ret = inflate(&zStream, Z_SYNC_FLUSH);
michael@0:     if (ret < 0) {
michael@0:       LOG("inflate failed: %s", zStream.msg);
michael@0:       return MemoryRange(MAP_FAILED, 0);
michael@0:     }
michael@0:     if (ret == Z_NEED_DICT) {
michael@0:       LOG("zstream requires a dictionary. %s", zStream.msg);
michael@0:       return MemoryRange(MAP_FAILED, 0);
michael@0:     }
michael@0:     zStream.avail_out = avail_out - missing + zStream.avail_out;
michael@0:     if (ret == Z_STREAM_END) {
michael@0:       if (inflateEnd(&zStream) != Z_OK) {
michael@0:         LOG("inflateEnd failed: %s", zStream.msg);
michael@0:         return MemoryRange(MAP_FAILED, 0);
michael@0:       }
michael@0:       if (zStream.total_out != buffer->GetLength()) {
michael@0:         LOG("File not fully uncompressed! %ld / %d", zStream.total_out,
michael@0:             static_cast<unsigned int>(buffer->GetLength()));
michael@0:         return MemoryRange(MAP_FAILED, 0);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: #if defined(ANDROID) && defined(__arm__)
michael@0:   if (prot & PROT_EXEC) {
michael@0:     /* We just extracted data that may be executed in the future.
michael@0:      * We thus need to ensure Instruction and Data cache coherency. */
michael@0:     DEBUG_LOG("cacheflush(%p, %p)", *buffer + offset, *buffer + (offset + length));
michael@0:     cacheflush(reinterpret_cast<uintptr_t>(*buffer + offset),
michael@0:                reinterpret_cast<uintptr_t>(*buffer + (offset + length)), 0);
michael@0:   }
michael@0: #endif
michael@0: 
michael@0:   return MemoryRange(buffer->mmap(addr, length, prot, flags, offset), length);
michael@0: }
michael@0: 
michael@0: void
michael@0: MappableDeflate::finalize()
michael@0: {
michael@0:   /* Free zlib internal buffers */
michael@0:   inflateEnd(&zStream);
michael@0:   /* Free decompression buffer */
michael@0:   buffer = nullptr;
michael@0:   /* Remove reference to Zip archive */
michael@0:   zip = nullptr;
michael@0: }
michael@0: 
michael@0: size_t
michael@0: MappableDeflate::GetLength() const
michael@0: {
michael@0:   return buffer->GetLength();
michael@0: }
michael@0: 
michael@0: Mappable *
michael@0: MappableSeekableZStream::Create(const char *name, Zip *zip,
michael@0:                                 Zip::Stream *stream)
michael@0: {
michael@0:   MOZ_ASSERT(stream->GetType() == Zip::Stream::STORE);
michael@0:   mozilla::ScopedDeletePtr<MappableSeekableZStream> mappable;
michael@0:   mappable = new MappableSeekableZStream(zip);
michael@0: 
michael@0:   pthread_mutexattr_t recursiveAttr;
michael@0:   pthread_mutexattr_init(&recursiveAttr);
michael@0:   pthread_mutexattr_settype(&recursiveAttr, PTHREAD_MUTEX_RECURSIVE);
michael@0: 
michael@0:   if (pthread_mutex_init(&mappable->mutex, &recursiveAttr))
michael@0:     return nullptr;
michael@0: 
michael@0:   if (!mappable->zStream.Init(stream->GetBuffer(), stream->GetSize()))
michael@0:     return nullptr;
michael@0: 
michael@0:   mappable->buffer = _MappableBuffer::Create(name,
michael@0:                               mappable->zStream.GetUncompressedSize());
michael@0:   if (!mappable->buffer)
michael@0:     return nullptr;
michael@0: 
michael@0:   mappable->chunkAvail = new unsigned char[mappable->zStream.GetChunksNum()];
michael@0:   memset(mappable->chunkAvail, 0, mappable->zStream.GetChunksNum());
michael@0: 
michael@0:   return mappable.forget();
michael@0: }
michael@0: 
michael@0: MappableSeekableZStream::MappableSeekableZStream(Zip *zip)
michael@0: : zip(zip), chunkAvailNum(0) { }
michael@0: 
michael@0: MappableSeekableZStream::~MappableSeekableZStream()
michael@0: {
michael@0:   pthread_mutex_destroy(&mutex);
michael@0: }
michael@0: 
michael@0: MemoryRange
michael@0: MappableSeekableZStream::mmap(const void *addr, size_t length, int prot,
michael@0:                               int flags, off_t offset)
michael@0: {
michael@0:   /* Map with PROT_NONE so that accessing the mapping would segfault, and
michael@0:    * bring us to ensure() */
michael@0:   void *res = buffer->mmap(addr, length, PROT_NONE, flags, offset);
michael@0:   if (res == MAP_FAILED)
michael@0:     return MemoryRange(MAP_FAILED, 0);
michael@0: 
michael@0:   /* Store the mapping, ordered by offset and length */
michael@0:   std::vector<LazyMap>::reverse_iterator it;
michael@0:   for (it = lazyMaps.rbegin(); it < lazyMaps.rend(); ++it) {
michael@0:     if ((it->offset < offset) ||
michael@0:         ((it->offset == offset) && (it->length < length)))
michael@0:       break;
michael@0:   }
michael@0:   LazyMap map = { res, length, prot, offset };
michael@0:   lazyMaps.insert(it.base(), map);
michael@0:   return MemoryRange(res, length);
michael@0: }
michael@0: 
michael@0: void
michael@0: MappableSeekableZStream::munmap(void *addr, size_t length)
michael@0: {
michael@0:   std::vector<LazyMap>::iterator it;
michael@0:   for (it = lazyMaps.begin(); it < lazyMaps.end(); ++it)
michael@0:     if ((it->addr = addr) && (it->length == length)) {
michael@0:       lazyMaps.erase(it);
michael@0:       ::munmap(addr, length);
michael@0:       return;
michael@0:     }
michael@0:   MOZ_CRASH("munmap called with unknown mapping");
michael@0: }
michael@0: 
michael@0: void
michael@0: MappableSeekableZStream::finalize() { }
michael@0: 
michael@0: class AutoLock {
michael@0: public:
michael@0:   AutoLock(pthread_mutex_t *mutex): mutex(mutex)
michael@0:   {
michael@0:     if (pthread_mutex_lock(mutex))
michael@0:       MOZ_CRASH("pthread_mutex_lock failed");
michael@0:   }
michael@0:   ~AutoLock()
michael@0:   {
michael@0:     if (pthread_mutex_unlock(mutex))
michael@0:       MOZ_CRASH("pthread_mutex_unlock failed");
michael@0:   }
michael@0: private:
michael@0:   pthread_mutex_t *mutex;
michael@0: };
michael@0: 
michael@0: bool
michael@0: MappableSeekableZStream::ensure(const void *addr)
michael@0: {
michael@0:   DEBUG_LOG("ensure @%p", addr);
michael@0:   const void *addrPage = PageAlignedPtr(addr);
michael@0:   /* Find the mapping corresponding to the given page */
michael@0:   std::vector<LazyMap>::iterator map;
michael@0:   for (map = lazyMaps.begin(); map < lazyMaps.end(); ++map) {
michael@0:     if (map->Contains(addrPage))
michael@0:       break;
michael@0:   }
michael@0:   if (map == lazyMaps.end())
michael@0:     return false;
michael@0: 
michael@0:   /* Find corresponding chunk */
michael@0:   off_t mapOffset = map->offsetOf(addrPage);
michael@0:   off_t chunk = mapOffset / zStream.GetChunkSize();
michael@0: 
michael@0:   /* In the typical case, we just need to decompress the chunk entirely. But
michael@0:    * when the current mapping ends in the middle of the chunk, we want to
michael@0:    * stop at the end of the corresponding page.
michael@0:    * However, if another mapping needs the last part of the chunk, we still
michael@0:    * need to continue. As mappings are ordered by offset and length, we don't
michael@0:    * need to scan the entire list of mappings.
michael@0:    * It is safe to run through lazyMaps here because the linker is never
michael@0:    * going to call mmap (which adds lazyMaps) while this function is
michael@0:    * called. */
michael@0:   size_t length = zStream.GetChunkSize(chunk);
michael@0:   off_t chunkStart = chunk * zStream.GetChunkSize();
michael@0:   off_t chunkEnd = chunkStart + length;
michael@0:   std::vector<LazyMap>::iterator it;
michael@0:   for (it = map; it < lazyMaps.end(); ++it) {
michael@0:     if (chunkEnd <= it->endOffset())
michael@0:       break;
michael@0:   }
michael@0:   if ((it == lazyMaps.end()) || (chunkEnd > it->endOffset())) {
michael@0:     /* The mapping "it" points at now is past the interesting one */
michael@0:     --it;
michael@0:     length = it->endOffset() - chunkStart;
michael@0:   }
michael@0: 
michael@0:   length = PageAlignedSize(length);
michael@0: 
michael@0:   /* The following lock can be re-acquired by the thread holding it.
michael@0:    * If this happens, it means the following code is interrupted somehow by
michael@0:    * some signal, and ends up retriggering a chunk decompression for the
michael@0:    * same MappableSeekableZStream.
michael@0:    * If the chunk to decompress is different the second time, then everything
michael@0:    * is safe as the only common data touched below is chunkAvailNum, and it is
michael@0:    * atomically updated (leaving out any chance of an interruption while it is
michael@0:    * updated affecting the result). If the chunk to decompress is the same, the
michael@0:    * worst thing that can happen is chunkAvailNum being incremented one too
michael@0:    * many times, which doesn't affect functionality. The chances of it
michael@0:    * happening being pretty slim, and the effect being harmless, we can just
michael@0:    * ignore the issue. Other than that, we'd just be wasting time decompressing
michael@0:    * the same chunk twice. */
michael@0:   AutoLock lock(&mutex);
michael@0: 
michael@0:   /* The very first page is mapped and accessed separately of the rest, and
michael@0:    * as such, only the first page of the first chunk is decompressed this way.
michael@0:    * When we fault in the remaining pages of that chunk, we want to decompress
michael@0:    * the complete chunk again. Short of doing that, we would end up with
michael@0:    * no data between PageSize() and chunkSize, which would effectively corrupt
michael@0:    * symbol resolution in the underlying library. */
michael@0:   if (chunkAvail[chunk] < PageNumber(length)) {
michael@0:     if (!zStream.DecompressChunk(*buffer + chunkStart, chunk, length))
michael@0:       return false;
michael@0: 
michael@0: #if defined(ANDROID) && defined(__arm__)
michael@0:     if (map->prot & PROT_EXEC) {
michael@0:       /* We just extracted data that may be executed in the future.
michael@0:        * We thus need to ensure Instruction and Data cache coherency. */
michael@0:       DEBUG_LOG("cacheflush(%p, %p)", *buffer + chunkStart, *buffer + (chunkStart + length));
michael@0:       cacheflush(reinterpret_cast<uintptr_t>(*buffer + chunkStart),
michael@0:                  reinterpret_cast<uintptr_t>(*buffer + (chunkStart + length)), 0);
michael@0:     }
michael@0: #endif
michael@0:     /* Only count if we haven't already decompressed parts of the chunk */
michael@0:     if (chunkAvail[chunk] == 0)
michael@0:       chunkAvailNum++;
michael@0: 
michael@0:     chunkAvail[chunk] = PageNumber(length);
michael@0:   }
michael@0: 
michael@0:   /* Flip the chunk mapping protection to the recorded flags. We could
michael@0:    * also flip the protection for other mappings of the same chunk,
michael@0:    * but it's easier to skip that and let further segfaults call
michael@0:    * ensure again. */
michael@0:   const void *chunkAddr = reinterpret_cast<const void *>
michael@0:                           (reinterpret_cast<uintptr_t>(addrPage)
michael@0:                            - mapOffset % zStream.GetChunkSize());
michael@0:   const void *chunkEndAddr = reinterpret_cast<const void *>
michael@0:                              (reinterpret_cast<uintptr_t>(chunkAddr) + length);
michael@0:   
michael@0:   const void *start = std::max(map->addr, chunkAddr);
michael@0:   const void *end = std::min(map->end(), chunkEndAddr);
michael@0:   length = reinterpret_cast<uintptr_t>(end)
michael@0:            - reinterpret_cast<uintptr_t>(start);
michael@0: 
michael@0:   if (mprotect(const_cast<void *>(start), length, map->prot) == 0) {
michael@0:     DEBUG_LOG("mprotect @%p, 0x%" PRIxSize ", 0x%x", start, length, map->prot);
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   LOG("mprotect @%p, 0x%" PRIxSize ", 0x%x failed with errno %d",
michael@0:       start, length, map->prot, errno);
michael@0:   LOG("mprotect failed");
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: void
michael@0: MappableSeekableZStream::stats(const char *when, const char *name) const
michael@0: {
michael@0:   size_t nEntries = zStream.GetChunksNum();
michael@0:   DEBUG_LOG("%s: %s; %" PRIdSize "/%" PRIdSize " chunks decompressed",
michael@0:             name, when, static_cast<size_t>(chunkAvailNum), nEntries);
michael@0: 
michael@0:   size_t len = 64;
michael@0:   mozilla::ScopedDeleteArray<char> map;
michael@0:   map = new char[len + 3];
michael@0:   map[0] = '[';
michael@0: 
michael@0:   for (size_t i = 0, j = 1; i < nEntries; i++, j++) {
michael@0:     map[j] = chunkAvail[i] ? '*' : '_';
michael@0:     if ((j == len) || (i == nEntries - 1)) {
michael@0:       map[j + 1] = ']';
michael@0:       map[j + 2] = '\0';
michael@0:       DEBUG_LOG("%s", static_cast<char *>(map));
michael@0:       j = 0;
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: size_t
michael@0: MappableSeekableZStream::GetLength() const
michael@0: {
michael@0:   return buffer->GetLength();
michael@0: }