| 1 | /****************************************************************************
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| 2 | **
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| 3 | ** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
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| 4 | ** Contact: http://www.qt-project.org/legal
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| 5 | **
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| 6 | ** This file is part of the Qt Solutions component.
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| 7 | **
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| 8 | ** $QT_BEGIN_LICENSE:BSD$
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| 9 | ** You may use this file under the terms of the BSD license as follows:
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| 10 | **
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| 11 | ** "Redistribution and use in source and binary forms, with or without
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| 12 | ** modification, are permitted provided that the following conditions are
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| 13 | ** met:
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| 14 | ** * Redistributions of source code must retain the above copyright
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| 15 | ** notice, this list of conditions and the following disclaimer.
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| 16 | ** * Redistributions in binary form must reproduce the above copyright
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| 17 | ** notice, this list of conditions and the following disclaimer in
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| 18 | ** the documentation and/or other materials provided with the
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| 19 | ** distribution.
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| 20 | ** * Neither the name of Digia Plc and its Subsidiary(-ies) nor the names
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| 21 | ** of its contributors may be used to endorse or promote products derived
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| 22 | ** from this software without specific prior written permission.
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| 23 | **
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| 24 | **
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| 25 | ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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| 26 | ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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| 27 | ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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| 28 | ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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| 29 | ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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| 30 | ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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| 31 | ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 32 | ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 33 | ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 34 | ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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| 35 | ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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| 36 | **
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| 37 | ** $QT_END_LICENSE$
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| 38 | **
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| 39 | ****************************************************************************/
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| 40 |
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| 41 | #include <string.h>
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| 42 | #include <errno.h>
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| 43 | #include <unistd.h>
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| 44 | #include <fcntl.h>
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| 45 |
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| 46 | #include "qtlockedfile.h"
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| 47 |
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| 48 | bool QtLockedFile::lock(LockMode mode, bool block)
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| 49 | {
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| 50 | if (!isOpen()) {
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| 51 | qWarning("QtLockedFile::lock(): file is not opened");
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| 52 | return false;
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| 53 | }
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| 54 |
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| 55 | if (mode == NoLock)
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| 56 | return unlock();
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| 57 |
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| 58 | if (mode == m_lock_mode)
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| 59 | return true;
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| 60 |
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| 61 | if (m_lock_mode != NoLock)
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| 62 | unlock();
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| 63 |
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| 64 | struct flock fl;
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| 65 | fl.l_whence = SEEK_SET;
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| 66 | fl.l_start = 0;
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| 67 | fl.l_len = 0;
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| 68 | fl.l_type = (mode == ReadLock) ? F_RDLCK : F_WRLCK;
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| 69 | int cmd = block ? F_SETLKW : F_SETLK;
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| 70 | int ret = fcntl(handle(), cmd, &fl);
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| 71 |
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| 72 | if (ret == -1) {
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| 73 | if (errno != EINTR && errno != EAGAIN)
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| 74 | qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno));
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| 75 | return false;
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| 76 | }
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| 77 |
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| 78 |
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| 79 | m_lock_mode = mode;
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| 80 | return true;
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| 81 | }
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| 82 |
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| 83 |
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| 84 | bool QtLockedFile::unlock()
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| 85 | {
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| 86 | if (!isOpen()) {
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| 87 | qWarning("QtLockedFile::unlock(): file is not opened");
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| 88 | return false;
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| 89 | }
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| 90 |
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| 91 | if (!isLocked())
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| 92 | return true;
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| 93 |
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| 94 | struct flock fl;
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| 95 | fl.l_whence = SEEK_SET;
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| 96 | fl.l_start = 0;
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| 97 | fl.l_len = 0;
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| 98 | fl.l_type = F_UNLCK;
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| 99 | int ret = fcntl(handle(), F_SETLKW, &fl);
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| 100 |
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| 101 | if (ret == -1) {
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| 102 | qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno));
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| 103 | return false;
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| 104 | }
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| 105 |
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| 106 | m_lock_mode = NoLock;
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| 107 | return true;
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| 108 | }
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| 109 |
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| 110 | QtLockedFile::~QtLockedFile()
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| 111 | {
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| 112 | if (isOpen())
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| 113 | unlock();
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| 114 | }
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| 115 |
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