diff options
| -rw-r--r-- | src/corelib/io/qresource.cpp | 120 |
1 files changed, 117 insertions, 3 deletions
diff --git a/src/corelib/io/qresource.cpp b/src/corelib/io/qresource.cpp index df57d12efc..acb6b786c1 100644 --- a/src/corelib/io/qresource.cpp +++ b/src/corelib/io/qresource.cpp @@ -36,6 +36,10 @@ #if defined(Q_OS_UNIX) && !defined(Q_OS_INTEGRITY) # define QT_USE_MMAP # include <sys/mman.h> +# ifdef Q_OS_LINUX +// since 5.7, so define in case we're being compiled with older kernel headers +# define MREMAP_DONTUNMAP 4 +# endif #endif #ifdef Q_OS_WIN # include <qt_windows.h> @@ -286,6 +290,8 @@ public: bool load(const QString &file); void clear(); + static bool mayRemapData(const QResource &resource); + QLocale locale; QString fileName, absoluteFilePath; QList<QResourceRoot *> related; @@ -1127,13 +1133,14 @@ public: : QDynamicBufferResourceRoot(_root), unmapPointer(nullptr), unmapLength(0) { } ~QDynamicFileResourceRoot() { - if (unmapPointer) + if (wasMemoryMapped()) unmap_sys(unmapPointer, unmapLength); else delete[] mappingBuffer(); } QString mappingFile() const { return fileName; } ResourceRootType type() const override { return Resource_File; } + bool wasMemoryMapped() const { return unmapPointer; } bool registerSelf(const QString &f); }; @@ -1377,11 +1384,21 @@ private: bool unmap(uchar *ptr); void uncompress() const; void mapUncompressed(); - qint64 offset; + bool mapUncompressed_sys(); + void unmapUncompressed_sys(); + qint64 offset = 0; QResource resource; mutable QByteArray uncompressed; + bool mustUnmap = false; + + // minimum size for which we'll try to re-open ourselves in mapUncompressed() + static constexpr qsizetype RemapCompressedThreshold = 16384; protected: - QResourceFileEnginePrivate() : offset(0) { } + ~QResourceFileEnginePrivate() + { + if (mustUnmap) + unmapUncompressed_sys(); + } }; bool QResourceFileEngine::caseSensitive() const @@ -1639,10 +1656,107 @@ void QResourceFileEnginePrivate::mapUncompressed() Q_ASSERT(resource.compressionAlgorithm() == QResource::NoCompression); if (!uncompressed.isNull()) return; // nothing to do + + if (resource.uncompressedSize() >= RemapCompressedThreshold) { + if (mapUncompressed_sys()) + return; + } + uncompressed = resource.uncompressedData(); uncompressed.detach(); } +#if defined(MREMAP_MAYMOVE) && defined(MREMAP_DONTUNMAP) +inline bool QResourcePrivate::mayRemapData(const QResource &resource) +{ + auto d = resource.d_func(); + + // assumptions from load(): + // - d->related is not empty + // - the first item in d->related is the one with our data + // by current construction, it's also the only item + const QResourceRoot *root = d->related.at(0); + + switch (root->type()) { + case QResourceRoot::Resource_Builtin: + return true; // always acceptable, memory is read-only + case QResourceRoot::Resource_Buffer: + return false; // never acceptable, memory is heap + case QResourceRoot::Resource_File: + break; + } + + auto df = static_cast<const QDynamicFileResourceRoot *>(root); + return df->wasMemoryMapped(); +} +#endif + +// Returns the page boundaries of where \a location is located in memory. +static auto mappingBoundaries(const void *location, qsizetype size) +{ +#ifdef Q_OS_WIN + auto getpagesize = [] { + SYSTEM_INFO sysinfo; + ::GetSystemInfo(&sysinfo); + return sysinfo.dwAllocationGranularity; + }; +#endif + struct R { + void *begin; + qsizetype size; + qptrdiff offset; + } r; + + const quintptr pageMask = getpagesize() - 1; + quintptr data = quintptr(location); + quintptr begin = data & ~pageMask; + quintptr end = (data + size + pageMask) & ~pageMask; + r.begin = reinterpret_cast<void *>(begin); + r.size = end - begin; + r.offset = data & pageMask; + return r; +} + +bool QResourceFileEnginePrivate::mapUncompressed_sys() +{ + auto r = mappingBoundaries(resource.data(), resource.uncompressedSize()); + void *ptr = nullptr; + +#if defined(MREMAP_MAYMOVE) && defined(MREMAP_DONTUNMAP) + // Use MREMAP_MAYMOVE to tell the kernel to give us a new address and use + // MREMAP_DONTUNMAP (supported since kernel 5.7) to request that it create + // a new mapping of the same pages, instead of moving. We can only do that + // for pages that are read-only, otherwise the kernel replaces the source + // with pages full of nulls. + if (!QResourcePrivate::mayRemapData(resource)) + return false; + + ptr = mremap(r.begin, r.size, r.size, MREMAP_MAYMOVE | MREMAP_DONTUNMAP); + if (ptr == MAP_FAILED) + return false; + + // Allow writing, which the documentation says we allow. This is safe + // because MREMAP_DONTUNMAP only works for private mappings. + if (mprotect(ptr, r.size, PROT_READ | PROT_WRITE) != 0) { + munmap(ptr, r.size); + return false; + } +#endif + + if (!ptr) + return false; + const char *newdata = static_cast<char *>(ptr) + r.offset; + uncompressed = QByteArray::fromRawData(newdata, resource.uncompressedSize()); + mustUnmap = true; + return true; +} + +void QResourceFileEnginePrivate::unmapUncompressed_sys() +{ + auto r = mappingBoundaries(uncompressed.constBegin(), uncompressed.size()); + QDynamicFileResourceRoot::unmap_sys(r.begin, r.size); +} + #endif // !defined(QT_BOOTSTRAPPED) QT_END_NAMESPACE |