qlockfile_unix.cpp

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1 /**************************************************************************** -

2 ** -

3 ** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org> -

4 ** Copyright (C) 2016 Intel Corporation. -

5 ** Copyright (C) 2016 The Qt Company Ltd. -

6 ** Contact: https://www.qt.io/licensing/ -

7 ** -

8 ** This file is part of the QtCore module of the Qt Toolkit. -

9 ** -

10 ** $QT_BEGIN_LICENSE:LGPL$ -

11 ** Commercial License Usage -

12 ** Licensees holding valid commercial Qt licenses may use this file in -

13 ** accordance with the commercial license agreement provided with the -

14 ** Software or, alternatively, in accordance with the terms contained in -

15 ** a written agreement between you and The Qt Company. For licensing terms -

16 ** and conditions see https://www.qt.io/terms-conditions. For further -

17 ** information use the contact form at https://www.qt.io/contact-us. -

18 ** -

19 ** GNU Lesser General Public License Usage -

20 ** Alternatively, this file may be used under the terms of the GNU Lesser -

21 ** General Public License version 3 as published by the Free Software -

22 ** Foundation and appearing in the file LICENSE.LGPL3 included in the -

23 ** packaging of this file. Please review the following information to -

24 ** ensure the GNU Lesser General Public License version 3 requirements -

25 ** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. -

26 ** -

27 ** GNU General Public License Usage -

28 ** Alternatively, this file may be used under the terms of the GNU -

29 ** General Public License version 2.0 or (at your option) the GNU General -

30 ** Public license version 3 or any later version approved by the KDE Free -

31 ** Qt Foundation. The licenses are as published by the Free Software -

32 ** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 -

33 ** included in the packaging of this file. Please review the following -

34 ** information to ensure the GNU General Public License requirements will -

35 ** be met: https://www.gnu.org/licenses/gpl-2.0.html and -

36 ** https://www.gnu.org/licenses/gpl-3.0.html. -

37 ** -

38 ** $QT_END_LICENSE$ -

39 ** -

40 ****************************************************************************/ -

41 -

42 #include "private/qlockfile_p.h" -

43 -

44 #include "QtCore/qtemporaryfile.h" -

45 #include "QtCore/qcoreapplication.h" -

46 #include "QtCore/qfileinfo.h" -

47 #include "QtCore/qdebug.h" -

48 #include "QtCore/qdatetime.h" -

49 #include "QtCore/qfileinfo.h" -

50 #include "QtCore/qcache.h" -

51 #include "QtCore/qglobalstatic.h" -

52 #include "QtCore/qmutex.h" -

53 -

54 #include "private/qcore_unix_p.h" // qt_safe_open -

55 #include "private/qabstractfileengine_p.h" -

56 #include "private/qtemporaryfile_p.h" -

57 -

58 #if !defined(Q_OS_INTEGRITY) -

59 #include <sys/file.h> // flock -

60 #endif -

61 -

62 #include <sys/types.h> // kill -

63 #include <signal.h> // kill -

64 #include <unistd.h> // gethostname -

65 -

66 #if defined(Q_OS_OSX) -

67 # include <libproc.h> -

68 #elif defined(Q_OS_LINUX) -

69 # include <unistd.h> -

70 # include <cstdio> -

71 #elif defined(Q_OS_HAIKU) -

72 # include <kernel/OS.h> -

73 #elif defined(Q_OS_BSD4) && !defined(Q_OS_IOS) -

74 # include <sys/cdefs.h> -

75 # include <sys/param.h> -

76 # include <sys/sysctl.h> -

77 # if !defined(Q_OS_NETBSD) -

78 # include <sys/user.h> -

79 # endif -

80 #endif -

81 -

82 QT_BEGIN_NAMESPACE -

83 -

84 static QByteArray localHostName() // from QHostInfo::localHostName(), modified to return a QByteArray -

85 { -

86 QByteArray hostName(512, Qt::Uninitialized); -

87 if (gethostname(hostName.data(), hostName.size()) == -1) -

88 return QByteArray(); -

89 hostName.truncate(strlen(hostName.data())); -

90 return hostName; -

91 } -

92 -

93 // ### merge into qt_safe_write? -

94 static qint64 qt_write_loop(int fd, const char *data, qint64 len) -

95 { -

96 qint64 pos = 0; -

97 while (pos < len) { -

98 const qint64 ret = qt_safe_write(fd, data + pos, len - pos); -

99 if (ret == -1) // e.g. partition full -

100 return pos; -

101 pos += ret; -

102 } -

103 return pos; -

104 } -

105 -

106 int QLockFilePrivate::checkFcntlWorksAfterFlock(const QString &fn) -

107 { -

108 #ifndef QT_NO_TEMPORARYFILE -

109 QTemporaryFile file(fn); -

110 if (!file.open()) -

111 return 0; -

112 const int fd = file.d_func()->engine()->handle(); -

113 #if defined(LOCK_EX) && defined(LOCK_NB) -

114 if (flock(fd, LOCK_EX | LOCK_NB) == -1) // other threads, and other processes on a local fs -

115 return 0; -

116 #endif -

117 struct flock flockData; -

118 flockData.l_type = F_WRLCK; -

119 flockData.l_whence = SEEK_SET; -

120 flockData.l_start = 0; -

121 flockData.l_len = 0; // 0 = entire file -

122 flockData.l_pid = getpid(); -

123 if (fcntl(fd, F_SETLK, &flockData) == -1) // for networked filesystems -

124 return 0; -

125 return 1; -

126 #else -

127 return 0; -

128 #endif -

129 } -

130 -

131 // Cache the result of checkFcntlWorksAfterFlock for each directory a lock -

132 // file is created in because in some filesystems, like NFS, both locks -

133 // are the same. This does not take into account a filesystem changing. -

134 // QCache is set to hold a maximum of 10 entries, this is to avoid unbounded -

135 // growth, this is caching directories of files and it is assumed a low number -

136 // will be sufficient. -

137 typedef QCache<QString, bool> CacheType; -

138 Q_GLOBAL_STATIC_WITH_ARGS(CacheType, fcntlOK, (10)); -

139 static QBasicMutex fcntlLock; -

140 -

141 /*! -

142 \internal -

143 Checks that the OS isn't using POSIX locks to emulate flock(). -

144 \macos is one of those. -

145 */ -

146 static bool fcntlWorksAfterFlock(const QString &fn) -

147 { -

148 QMutexLocker lock(&fcntlLock); -

149 if (fcntlOK.isDestroyed()) -

150 return QLockFilePrivate::checkFcntlWorksAfterFlock(fn); -

151 bool *worksPtr = fcntlOK->object(fn); -

152 if (worksPtr) -

153 return *worksPtr; -

154 -

155 const bool val = QLockFilePrivate::checkFcntlWorksAfterFlock(fn); -

156 worksPtr = new bool(val); -

157 fcntlOK->insert(fn, worksPtr); -

158 -

159 return val; -

160 } -

161 -

162 static bool setNativeLocks(const QString &fileName, int fd) -

163 { -

164 #if defined(LOCK_EX) && defined(LOCK_NB) -

165 if (flock(fd, LOCK_EX | LOCK_NB) == -1) // other threads, and other processes on a local fs -

166 return false; -

167 #endif -

168 struct flock flockData; -

169 flockData.l_type = F_WRLCK; -

170 flockData.l_whence = SEEK_SET; -

171 flockData.l_start = 0; -

172 flockData.l_len = 0; // 0 = entire file -

173 flockData.l_pid = getpid(); -

174 if (fcntlWorksAfterFlock(QDir::cleanPath(QFileInfo(fileName).absolutePath()) + QString('/')) -

175 && fcntl(fd, F_SETLK, &flockData) == -1) { // for networked filesystems -

176 return false; -

177 } -

178 return true; -

179 } -

180 -

181 QLockFile::LockError QLockFilePrivate::tryLock_sys() -

182 { -

183 // Assemble data, to write in a single call to write -

184 // (otherwise we'd have to check every write call) -

185 // Use operator% from the fast builder to avoid multiple memory allocations. -

186 QByteArray fileData = QByteArray::number(QCoreApplication::applicationPid()) % '\n' -

187 % QCoreApplication::applicationName().toUtf8() % '\n' -

188 % localHostName() % '\n'; -

189 -

190 const QByteArray lockFileName = QFile::encodeName(fileName); -

191 const int fd = qt_safe_open(lockFileName.constData(), O_WRONLY | O_CREAT | O_EXCL, 0666); -

192 if (fd < 0) { -

193 switch (errno) { -

194 case EEXIST: -

195 return QLockFile::LockFailedError; -

196 case EACCES: -

197 case EROFS: -

198 return QLockFile::PermissionError; -

199 default: -

200 return QLockFile::UnknownError; -

201 } -

202 } -

203 // Ensure nobody else can delete the file while we have it -

204 if (!setNativeLocks(fileName, fd)) { -

205 const int errnoSaved = errno; -

206 qWarning() << "setNativeLocks failed:" << qt_error_string(errnoSaved); -

207 } -

208 -

209 if (qt_write_loop(fd, fileData.constData(), fileData.size()) < fileData.size()) { -

210 close(fd); -

211 if (!QFile::remove(fileName)) -

212 qWarning("QLockFile: Could not remove our own lock file %s.", qPrintable(fileName)); -

213 return QLockFile::UnknownError; // partition full -

214 } -

215 -

216 // We hold the lock, continue. -

217 fileHandle = fd; -

218 -

219 // Sync to disk if possible. Ignore errors (e.g. not supported). -

220 #if defined(_POSIX_SYNCHRONIZED_IO) && _POSIX_SYNCHRONIZED_IO > 0 -

221 fdatasync(fileHandle); -

222 #else -

223 fsync(fileHandle); -

224 #endif -

225 -

226 return QLockFile::NoError; -

227 } -

228 -

229 bool QLockFilePrivate::removeStaleLock() -

230 { -

231 const QByteArray lockFileName = QFile::encodeName(fileName); -

232 const int fd = qt_safe_open(lockFileName.constData(), O_WRONLY, 0666); -

233 if (fd < 0) // gone already? -

234 return false; -

235 bool success = setNativeLocks(fileName, fd) && (::unlink(lockFileName) == 0); -

236 close(fd); -

237 return success; -

238 } -

239 -

240 bool QLockFilePrivate::isApparentlyStale() const -

241 { -

242 qint64 pid; -

243 QString hostname, appname; -

244 if (getLockInfo(&pid, &hostname, &appname)) { -

245 if (hostname.isEmpty() || hostname == QString::fromLocal8Bit(localHostName())) { -

246 if (::kill(pid, 0) == -1 && errno == ESRCH) -

247 return true; // PID doesn't exist anymore -

248 const QString processName = processNameByPid(pid); -

249 if (!processName.isEmpty()) { -

250 QFileInfo fi(appname); -

251 if (fi.isSymLink()) -

252 fi.setFile(fi.symLinkTarget()); -

253 if (processName != fi.fileName()) -

254 return true; // PID got reused by a different application. -

255 } -

256 } -

257 } -

258 const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTime()); -

259 return staleLockTime > 0 && age > staleLockTime; -

260 } -

261 -

262 QString QLockFilePrivate::processNameByPid(qint64 pid) -

263 { -

264 #if defined(Q_OS_OSX) -

265 char name[1024]; -

266 proc_name(pid, name, sizeof(name) / sizeof(char)); -

267 return QFile::decodeName(name); -

268 #elif defined(Q_OS_LINUX) -

if (!QFile::exists(QStringLiteral("/proc/version")))

!QFile::exists...al_temp; }()))	Description
TRUE	never evaluated
FALSE	evaluated 12 times by 1 test Evaluated by: tst_QLockFile

0-12

return QString();

never executed: return QString();

0

271 char exePath[64]; -

272 char buf[PATH_MAX + 1]; -

273 sprintf(exePath, "/proc/%lld/exe", pid); -

274 size_t len = (size_t)readlink(exePath, buf, sizeof(buf)); -

if (len >= sizeof(buf)) {

len >= sizeof(buf)	Description
TRUE	never evaluated
FALSE	evaluated 12 times by 1 test Evaluated by: tst_QLockFile

0-12

276 // The pid is gone. Return some invalid process name to fail the test. -

return QStringLiteral("/ERROR/");

never executed:

return ([]() -> QString { enum { Size = sizeof(u"" "/ERROR/")/2 - 1 }; static const QStaticStringData<Size> qstring_literal = { { { { -1 } }, Size, 0, 0, sizeof(QStringData) }, u"" "/ERROR/" }; QStringDataPtr holder = { qstring_literal.data_ptr() }; const QString qstring_literal_temp(holder); return qstring_literal_temp; }());

never executed: return qstring_literal_temp;

0

278 } -

279 buf[len] = 0; -

return QFileInfo(QFile::decodeName(buf)).fileName();

executed 12 times by 1 test: return QFileInfo(QFile::decodeName(buf)).fileName();

Executed by:

tst_QLockFile

12

281 #elif defined(Q_OS_HAIKU) -

282 thread_info info; -

283 if (get_thread_info(pid, &info) != B_OK) -

284 return QString(); -

285 return QFile::decodeName(info.name); -

286 #elif defined(Q_OS_BSD4) && !defined(Q_OS_IOS) -

287 # if defined(Q_OS_NETBSD) -

288 struct kinfo_proc2 kp; -

289 int mib[6] = { CTL_KERN, KERN_PROC2, KERN_PROC_PID, (int)pid, sizeof(struct kinfo_proc2), 1 }; -

290 # elif defined(Q_OS_OPENBSD) -

291 struct kinfo_proc kp; -

292 int mib[6] = { CTL_KERN, KERN_PROC, KERN_PROC_PID, (int)pid, sizeof(struct kinfo_proc), 1 }; -

293 # else -

294 struct kinfo_proc kp; -

295 int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_PID, (int)pid }; -

296 # endif -

297 size_t len = sizeof(kp); -

298 u_int mib_len = sizeof(mib)/sizeof(u_int); -

299 -

300 if (sysctl(mib, mib_len, &kp, &len, NULL, 0) < 0) -

301 return QString(); -

302 -

303 # if defined(Q_OS_OPENBSD) || defined(Q_OS_NETBSD) -

304 if (kp.p_pid != pid) -

305 return QString(); -

306 QString name = QFile::decodeName(kp.p_comm); -

307 # else -

308 if (kp.ki_pid != pid) -

309 return QString(); -

310 QString name = QFile::decodeName(kp.ki_comm); -

311 # endif -

312 return name; -

313 -

314 #else -

315 Q_UNUSED(pid); -

316 return QString(); -

317 #endif -

318 } -

319 -

320 void QLockFile::unlock() -

321 { -

322 Q_D(QLockFile); -

323 if (!d->isLocked) -

324 return; -

325 close(d->fileHandle); -

326 d->fileHandle = -1; -

327 if (!QFile::remove(d->fileName)) { -

328 qWarning() << "Could not remove our own lock file" << d->fileName << "maybe permissions changed meanwhile?"; -

329 // This is bad because other users of this lock file will now have to wait for the stale-lock-timeout... -

330 } -

331 d->lockError = QLockFile::NoError; -

332 d->isLocked = false; -

333 } -

334 -

335 QT_END_NAMESPACE -

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