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39 | |
40 | #include "qv4compilationunitmapper_p.h" |
41 | |
42 | #include <sys/mman.h> |
43 | #include <functional> |
44 | #include <private/qcore_unix_p.h> |
45 | #include <QScopeGuard> |
46 | #include <QDateTime> |
47 | |
48 | #include "qv4executablecompilationunit_p.h" |
49 | |
50 | QT_BEGIN_NAMESPACE |
51 | |
52 | using namespace QV4; |
53 | |
54 | CompiledData::Unit *CompilationUnitMapper::open(const QString &cacheFileName, const QDateTime &sourceTimeStamp, QString *errorString) |
55 | { |
56 | close(); |
57 | |
58 | int fd = qt_safe_open(pathname: QFile::encodeName(fileName: cacheFileName).constData(), O_RDONLY); |
59 | if (fd == -1) { |
60 | *errorString = qt_error_string(errno); |
61 | return nullptr; |
62 | } |
63 | |
64 | auto cleanup = qScopeGuard(f: [fd]{ |
65 | qt_safe_close(fd) ; |
66 | }); |
67 | |
68 | CompiledData::Unit ; |
69 | qint64 bytesRead = qt_safe_read(fd, data: reinterpret_cast<char *>(&header), maxlen: sizeof(header)); |
70 | |
71 | if (bytesRead != sizeof(header)) { |
72 | *errorString = QStringLiteral("File too small for the header fields" ); |
73 | return nullptr; |
74 | } |
75 | |
76 | if (!ExecutableCompilationUnit::verifyHeader(unit: &header, expectedSourceTimeStamp: sourceTimeStamp, errorString)) |
77 | return nullptr; |
78 | |
79 | // Data structure and qt version matched, so now we can access the rest of the file safely. |
80 | |
81 | length = static_cast<size_t>(lseek(fd: fd, offset: 0, SEEK_END)); |
82 | |
83 | void *ptr = mmap(addr: nullptr, len: length, PROT_READ, MAP_SHARED, fd: fd, /*offset*/0); |
84 | if (ptr == MAP_FAILED) { |
85 | *errorString = qt_error_string(errno); |
86 | return nullptr; |
87 | } |
88 | dataPtr = ptr; |
89 | |
90 | return reinterpret_cast<CompiledData::Unit*>(dataPtr); |
91 | } |
92 | |
93 | void CompilationUnitMapper::close() |
94 | { |
95 | // Do not unmap the data here. |
96 | if (dataPtr != nullptr) { |
97 | // Do not unmap cache files that are built with the StaticData flag. That's the majority of |
98 | // them and it's necessary to benefit from the QString literal optimization. There might |
99 | // still be QString instances around that point into that memory area. The memory is backed |
100 | // on the disk, so the kernel is free to release the pages and all that remains is the |
101 | // address space allocation. |
102 | if (!(reinterpret_cast<CompiledData::Unit*>(dataPtr)->flags & CompiledData::Unit::StaticData)) |
103 | munmap(addr: dataPtr, len: length); |
104 | } |
105 | dataPtr = nullptr; |
106 | } |
107 | |
108 | QT_END_NAMESPACE |
109 | |