| 1 | /**************************************************************************** |
| 2 | ** |
| 3 | ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). |
| 4 | ** All rights reserved. |
| 5 | ** |
| 6 | ** Contact: Nokia Corporation (qt-info@nokia.com) |
| 7 | ** |
| 8 | ** This file is part of a Qt Solutions component. |
| 9 | ** |
| 10 | ** You may use this file under the terms of the BSD license as follows: |
| 11 | ** |
| 12 | ** "Redistribution and use in source and binary forms, with or without |
| 13 | ** modification, are permitted provided that the following conditions are |
| 14 | ** met: |
| 15 | ** * Redistributions of source code must retain the above copyright |
| 16 | ** notice, this list of conditions and the following disclaimer. |
| 17 | ** * Redistributions in binary form must reproduce the above copyright |
| 18 | ** notice, this list of conditions and the following disclaimer in |
| 19 | ** the documentation and/or other materials provided with the |
| 20 | ** distribution. |
| 21 | ** * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor |
| 22 | ** the names of its contributors may be used to endorse or promote |
| 23 | ** products derived from this software without specific prior written |
| 24 | ** permission. |
| 25 | ** |
| 26 | ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 27 | ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 28 | ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 29 | ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 30 | ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 31 | ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 32 | ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 33 | ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 34 | ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 35 | ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 36 | ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." |
| 37 | ** |
| 38 | ****************************************************************************/ |
| 39 | |
| 40 | #include <string.h> |
| 41 | #include <errno.h> |
| 42 | #include <unistd.h> |
| 43 | #include <fcntl.h> |
| 44 | |
| 45 | #include "qtlockedfile.h" |
| 46 | |
| 47 | bool QtLockedFile::lock(LockMode mode, bool block) |
| 48 | { |
| 49 | if (!isOpen()) { |
| 50 | qWarning("QtLockedFile::lock(): file is not opened"); |
| 51 | return false; |
| 52 | } |
| 53 | |
| 54 | if (mode == NoLock) |
| 55 | return unlock(); |
| 56 | |
| 57 | if (mode == m_lock_mode) |
| 58 | return true; |
| 59 | |
| 60 | if (m_lock_mode != NoLock) |
| 61 | unlock(); |
| 62 | |
| 63 | struct flock fl; |
| 64 | fl.l_whence = SEEK_SET; |
| 65 | fl.l_start = 0; |
| 66 | fl.l_len = 0; |
| 67 | fl.l_type = (mode == ReadLock) ? F_RDLCK : F_WRLCK; |
| 68 | int cmd = block ? F_SETLKW : F_SETLK; |
| 69 | int ret = fcntl(handle(), cmd, &fl); |
| 70 | |
| 71 | if (ret == -1) { |
| 72 | if (errno != EINTR && errno != EAGAIN) |
| 73 | qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno)); |
| 74 | return false; |
| 75 | } |
| 76 | |
| 77 | |
| 78 | m_lock_mode = mode; |
| 79 | return true; |
| 80 | } |
| 81 | |
| 82 | |
| 83 | bool QtLockedFile::unlock() |
| 84 | { |
| 85 | if (!isOpen()) { |
| 86 | qWarning("QtLockedFile::unlock(): file is not opened"); |
| 87 | return false; |
| 88 | } |
| 89 | |
| 90 | if (!isLocked()) |
| 91 | return true; |
| 92 | |
| 93 | struct flock fl; |
| 94 | fl.l_whence = SEEK_SET; |
| 95 | fl.l_start = 0; |
| 96 | fl.l_len = 0; |
| 97 | fl.l_type = F_UNLCK; |
| 98 | int ret = fcntl(handle(), F_SETLKW, &fl); |
| 99 | |
| 100 | if (ret == -1) { |
| 101 | qWarning("QtLockedFile::lock(): fcntl: %s", strerror(errno)); |
| 102 | return false; |
| 103 | } |
| 104 | |
| 105 | m_lock_mode = NoLock; |
| 106 | return true; |
| 107 | } |
| 108 | |
| 109 | QtLockedFile::~QtLockedFile() |
| 110 | { |
| 111 | if (isOpen()) |
| 112 | unlock(); |
| 113 | } |
| 114 | |