| 1 | /* |
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| 2 | This file is part of the KDE project. |
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| 3 | |
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| 4 | SPDX-FileCopyrightText: 2010 Michael Pyne <mpyne@kde.org> |
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| 5 | |
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| 6 | SPDX-License-Identifier: LGPL-2.0-only |
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| 7 | */ |
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| 8 | |
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| 9 | #ifndef KSHAREDDATACACHE_P_H |
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| 10 | #define KSHAREDDATACACHE_P_H |
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| 11 | |
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| 12 | #include "kcoreaddons_debug.h" |
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| 13 | |
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| 14 | #include <cerrno> |
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| 15 | #include <fcntl.h> |
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| 16 | #include <unistd.h> // for _POSIX_ADVISORY_INFO |
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| 17 | |
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| 18 | // posix_fallocate is used to ensure that the file used for the cache is |
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| 19 | // actually fully committed to disk before attempting to use the file. |
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| 20 | #if defined(_POSIX_ADVISORY_INFO) && ((_POSIX_ADVISORY_INFO == 0) || (_POSIX_ADVISORY_INFO >= 200112L)) |
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| 21 | #define KSDC_POSIX_FALLOCATE_SUPPORTED 1 |
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| 22 | #endif |
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| 23 | #ifdef Q_OS_OSX |
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| 24 | #include "posix_fallocate_mac.h" |
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| 25 | #define KSDC_POSIX_FALLOCATE_SUPPORTED 1 |
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| 26 | #endif |
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| 27 | |
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| 28 | static bool ensureFileAllocated(int fd, size_t fileSize) |
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| 29 | { |
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| 30 | #ifdef KSDC_POSIX_FALLOCATE_SUPPORTED |
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| 31 | int result; |
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| 32 | while ((result = ::posix_fallocate(fd: fd, offset: 0, len: fileSize)) == EINTR) { |
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| 33 | ; |
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| 34 | } |
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| 35 | |
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| 36 | if (result != 0) { |
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| 37 | if (result == ENOSPC) { |
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| 38 | qCCritical(KCOREADDONS_DEBUG) << "No space left on device. Check filesystem free space at your XDG_CACHE_HOME!" ; |
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| 39 | } |
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| 40 | qCCritical(KCOREADDONS_DEBUG) << "The operating system is unable to promise" << fileSize |
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| 41 | << "bytes for mapped cache, " |
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| 42 | "abandoning the cache for crash-safety." ; |
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| 43 | return false; |
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| 44 | } |
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| 45 | |
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| 46 | return true; |
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| 47 | #else |
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| 48 | |
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| 49 | #ifdef __GNUC__ |
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| 50 | #warning \ |
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| 51 | "This system does not seem to support posix_fallocate, which is needed to ensure KSharedDataCache's underlying files are fully committed to disk to avoid crashes with low disk space." |
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| 52 | #endif |
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| 53 | qCWarning(KCOREADDONS_DEBUG) << "This system misses support for posix_fallocate()" |
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| 54 | " -- ensure this partition has room for at least" |
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| 55 | << fileSize << "bytes." ; |
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| 56 | |
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| 57 | // TODO: It's possible to emulate the functionality, but doing so |
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| 58 | // overwrites the data in the file so we don't do this. If you were to add |
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| 59 | // this emulation, you must ensure it only happens on initial creation of a |
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| 60 | // new file and not just mapping an existing cache. |
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| 61 | |
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| 62 | return true; |
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| 63 | #endif // KSDC_POSIX_FALLOCATE_SUPPORTED |
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| 64 | } |
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| 65 | |
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| 66 | #endif /* KSHAREDDATACACHE_P_H */ |
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| 67 | |
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