diff options
Diffstat (limited to 'src/corelib/kernel/qsystemsemaphore_unix.cpp')
| -rw-r--r-- | src/corelib/kernel/qsystemsemaphore_unix.cpp | 176 |
1 files changed, 150 insertions, 26 deletions
diff --git a/src/corelib/kernel/qsystemsemaphore_unix.cpp b/src/corelib/kernel/qsystemsemaphore_unix.cpp index 5e533e7..e060eb2 100644 --- a/src/corelib/kernel/qsystemsemaphore_unix.cpp +++ b/src/corelib/kernel/qsystemsemaphore_unix.cpp @@ -42,15 +42,17 @@ #include "qsystemsemaphore.h" #include "qsystemsemaphore_p.h" +#include <qcoreapplication.h> #include <qdebug.h> #include <qfile.h> -#include <qcoreapplication.h> #ifndef QT_NO_SYSTEMSEMAPHORE #include <sys/types.h> #include <sys/ipc.h> +#ifndef QT_POSIX_IPC #include <sys/sem.h> +#endif #include <fcntl.h> #include <errno.h> @@ -62,11 +64,17 @@ #define EIDRM EINVAL #endif +//#define QSYSTEMSEMAPHORE_DEBUG + QT_BEGIN_NAMESPACE QSystemSemaphorePrivate::QSystemSemaphorePrivate() : - semaphore(-1), createdFile(false), - createdSemaphore(false), unix_key(-1), error(QSystemSemaphore::NoError) +#ifndef QT_POSIX_IPC + unix_key(-1), semaphore(-1), createdFile(false), +#else + semaphore(SEM_FAILED), +#endif + createdSemaphore(false), error(QSystemSemaphore::NoError) { } @@ -88,40 +96,49 @@ void QSystemSemaphorePrivate::setErrorString(const QString &function) error = QSystemSemaphore::NotFound; break; case ERANGE: + case ENOMEM: case ENOSPC: + case EMFILE: + case ENFILE: + case EOVERFLOW: errorString = QCoreApplication::translate("QSystemSemaphore", "%1: out of resources").arg(function); error = QSystemSemaphore::OutOfResources; break; + case ENAMETOOLONG: + errorString = QCoreApplication::translate("QSystemSemaphore", "%1: name error").arg(function); + error = QSystemSemaphore::KeyError; + break; default: errorString = QCoreApplication::translate("QSystemSemaphore", "%1: unknown error %2").arg(function).arg(errno); error = QSystemSemaphore::UnknownError; -#if defined QSYSTEMSEMAPHORE_DEBUG +#ifdef QSYSTEMSEMAPHORE_DEBUG qDebug() << errorString << "key" << key << "errno" << errno << EINVAL; #endif + break; } } /*! \internal - Setup unix_key - */ + Initialise the semaphore +*/ +#ifndef QT_POSIX_IPC key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode) { - if (key.isEmpty()){ - errorString = QCoreApplication::tr("%1: key is empty", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:")); + if (-1 != unix_key) + return unix_key; + + if (key.isEmpty()) { + errorString = QCoreApplication::tr("%1: key is empty", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle")); error = QSystemSemaphore::KeyError; return -1; } // ftok requires that an actual file exists somewhere - if (-1 != unix_key) - return unix_key; - - // Create the file needed for ftok int built = QSharedMemoryPrivate::createUnixKeyFile(fileName); if (-1 == built) { - errorString = QCoreApplication::tr("%1: unable to make key", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:")); + errorString = QCoreApplication::tr("%1: unable to make key", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle")); error = QSystemSemaphore::KeyError; return -1; } @@ -130,7 +147,7 @@ key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode) // Get the unix key for the created file unix_key = ftok(QFile::encodeName(fileName).constData(), 'Q'); if (-1 == unix_key) { - errorString = QCoreApplication::tr("%1: ftok failed", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle:")); + errorString = QCoreApplication::tr("%1: ftok failed", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle")); error = QSystemSemaphore::KeyError; return -1; } @@ -145,17 +162,16 @@ key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode) cleanHandle(); return -1; } + if (mode == QSystemSemaphore::Create) { + createdSemaphore = true; + createdFile = true; + } } else { createdSemaphore = true; // Force cleanup of file, it is possible that it can be left over from a crash createdFile = true; } - if (mode == QSystemSemaphore::Create) { - createdSemaphore = true; - createdFile = true; - } - // Created semaphore so initialize its value. if (createdSemaphore && initialValue >= 0) { qt_semun init_op; @@ -169,14 +185,63 @@ key_t QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode) return unix_key; } +#else +bool QSystemSemaphorePrivate::handle(QSystemSemaphore::AccessMode mode) +{ + if (semaphore != SEM_FAILED) + return true; // we already have a semaphore + + if (fileName.isEmpty()) { + errorString = QCoreApplication::tr("%1: key is empty", "QSystemSemaphore").arg(QLatin1String("QSystemSemaphore::handle")); + error = QSystemSemaphore::KeyError; + return false; + } + + QByteArray semName = QFile::encodeName(fileName); + + // Always try with O_EXCL so we know whether we created the semaphore. + int oflag = O_CREAT | O_EXCL; + for (int tryNum = 0, maxTries = 1; tryNum < maxTries; ++tryNum) { + do { + semaphore = sem_open(semName.constData(), oflag, 0666, initialValue); + } while (semaphore == SEM_FAILED && errno == EINTR); + if (semaphore == SEM_FAILED && errno == EEXIST) { + if (mode == QSystemSemaphore::Create) { + if (sem_unlink(semName.constData()) == -1 && errno != ENOENT) { + setErrorString(QLatin1String("QSystemSemaphore::handle (sem_unlink)")); + return false; + } + // Race condition: the semaphore might be recreated before + // we call sem_open again, so we'll retry several times. + maxTries = 3; + } else { + // Race condition: if it no longer exists at the next sem_open + // call, we won't realize we created it, so we'll leak it later. + oflag &= ~O_EXCL; + maxTries = 2; + } + } else { + break; + } + } + if (semaphore == SEM_FAILED) { + setErrorString(QLatin1String("QSystemSemaphore::handle")); + return false; + } + + createdSemaphore = (oflag & O_EXCL) != 0; + return true; +} +#endif // QT_POSIX_IPC /*! \internal - Cleanup the unix_key - */ + Clean up the semaphore +*/ void QSystemSemaphorePrivate::cleanHandle() { +#ifndef QT_POSIX_IPC unix_key = -1; // remove the file if we made it @@ -189,21 +254,43 @@ void QSystemSemaphorePrivate::cleanHandle() if (-1 != semaphore) { if (-1 == semctl(semaphore, 0, IPC_RMID, 0)) { setErrorString(QLatin1String("QSystemSemaphore::cleanHandle")); -#if defined QSYSTEMSEMAPHORE_DEBUG - qDebug() << QLatin1String("QSystemSemaphore::cleanHandle semctl failed."); +#ifdef QSYSTEMSEMAPHORE_DEBUG + qDebug("QSystemSemaphore::cleanHandle semctl failed."); #endif } semaphore = -1; } createdSemaphore = false; } +#else + if (semaphore != SEM_FAILED) { + if (sem_close(semaphore) == -1) { + setErrorString(QLatin1String("QSystemSemaphore::cleanHandle (sem_close)")); +#ifdef QSYSTEMSEMAPHORE_DEBUG + qDebug() << QLatin1String("QSystemSemaphore::cleanHandle sem_close failed."); +#endif + } + semaphore = SEM_FAILED; + } + + if (createdSemaphore) { + if (sem_unlink(QFile::encodeName(fileName).constData()) == -1 && errno != ENOENT) { + setErrorString(QLatin1String("QSystemSemaphore::cleanHandle (sem_unlink)")); +#ifdef QSYSTEMSEMAPHORE_DEBUG + qDebug() << QLatin1String("QSystemSemaphore::cleanHandle sem_unlink failed."); +#endif + } + createdSemaphore = false; + } +#endif // QT_POSIX_IPC } /*! \internal - */ +*/ bool QSystemSemaphorePrivate::modifySemaphore(int count) { +#ifndef QT_POSIX_IPC if (-1 == handle()) return false; @@ -223,16 +310,53 @@ bool QSystemSemaphorePrivate::modifySemaphore(int count) return modifySemaphore(count); } setErrorString(QLatin1String("QSystemSemaphore::modifySemaphore")); -#if defined QSYSTEMSEMAPHORE_DEBUG +#ifdef QSYSTEMSEMAPHORE_DEBUG qDebug() << QLatin1String("QSystemSemaphore::modify failed") << count << semctl(semaphore, 0, GETVAL) << errno << EIDRM << EINVAL; #endif return false; } +#else + if (!handle()) + return false; + + if (count > 0) { + int cnt = count; + do { + if (sem_post(semaphore) == -1) { + setErrorString(QLatin1String("QSystemSemaphore::modifySemaphore (sem_post)")); +#ifdef QSYSTEMSEMAPHORE_DEBUG + qDebug() << QLatin1String("QSystemSemaphore::modify sem_post failed") << count << errno; +#endif + // rollback changes to preserve the SysV semaphore behavior + for ( ; cnt < count; ++cnt) { + register int res; + EINTR_LOOP(res, sem_wait(semaphore)); + } + return false; + } + --cnt; + } while (cnt > 0); + } else { + register int res; + EINTR_LOOP(res, sem_wait(semaphore)); + if (res == -1) { + // If the semaphore was removed be nice and create it and then modifySemaphore again + if (errno == EINVAL || errno == EIDRM) { + semaphore = SEM_FAILED; + return modifySemaphore(count); + } + setErrorString(QLatin1String("QSystemSemaphore::modifySemaphore (sem_wait)")); +#ifdef QSYSTEMSEMAPHORE_DEBUG + qDebug() << QLatin1String("QSystemSemaphore::modify sem_wait failed") << count << errno; +#endif + return false; + } + } +#endif // QT_POSIX_IPC return true; } - QT_END_NAMESPACE #endif // QT_NO_SYSTEMSEMAPHORE |