Add qcore_unix_p.h containing mostly safe versions of Unix functions.

Most of these functions are from unistd.h and need to have a loop
around the actual call because the calls can be interrupted by a
signal delivery.

Some special calls (open, dup2, pipe) require an extra flag to support
thread-safe execution: the file descriptor must be created from the
operating system with the FD_CLOEXEC flag already set.

The O_CLOEXEC flag is specified in POSIX.1-2008, but the rest is
Linux-specific.

Reviewed-By: João Abecasis

2 files changed, 247 insertions, 0 deletions

diff --git a/src/corelib/kernel/kernel.pri b/src/corelib/kernel/kernel.pri
index ecef555..6f28029 100644
--- a/src/corelib/kernel/kernel.pri
+++ b/src/corelib/kernel/kernel.pri
@@ -92,6 +92,7 @@ unix {
                 kernel/qsharedmemory_unix.cpp \
                 kernel/qsystemsemaphore_unix.cpp
 	HEADERS += \
+                kernel/qcore_unix_p.h \
 		kernel/qcrashhandler_p.h
 
         contains(QT_CONFIG, glib) {
diff --git a/src/corelib/kernel/qcore_unix_p.h b/src/corelib/kernel/qcore_unix_p.h
new file mode 100644
index 0000000..4e3158a
--- /dev/null
+++ b/src/corelib/kernel/qcore_unix_p.h
@@ -0,0 +1,246 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QCORE_UNIX_P_H
+#define QCORE_UNIX_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of Qt code on Unix. This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qplatformdefs.h"
+
+#ifndef Q_OS_UNIX
+# error "qcore_unix_p.h included on a non-Unix system"
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <sys/wait.h>
+#include <errno.h>
+#include <fcntl.h>
+
+QT_BEGIN_NAMESPACE
+
+#if defined(Q_OS_LINUX) && defined(__GLIBC__) && (__GLIBC__ * 0x100 + __GLIBC_MINOR__) >= 0x0209
+# define QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC 1
+#else
+# define QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC 0
+#endif
+
+#define EINTR_LOOP(var, cmd)                    \
+    do {                                        \
+        var = cmd;                              \
+    } while (var == -1 && errno == EINTR)
+
+
+// don't call QT_OPEN or ::open
+// call qt_safe_open
+static inline int qt_safe_open(const char *pathname, int flags, mode_t mode = 0777)
+{
+#ifdef O_CLOEXEC
+    flags |= O_CLOEXEC;
+#endif
+    register int fd;
+    EINTR_LOOP(fd, QT_OPEN(pathname, flags, mode));
+
+    // unknown flags are ignored, so we have no way of verifying if
+    // O_CLOEXEC was accepted
+    if (fd != -1)
+        ::fcntl(fd, F_SETFD, FD_CLOEXEC);
+    return fd;
+}
+#undef QT_OPEN
+#define QT_OPEN         qt_safe_open
+
+// don't call ::pipe
+// call qt_safe_pipe
+static inline int qt_safe_pipe(int pipefd[2], int flags = 0)
+{
+#ifdef O_CLOEXEC
+    Q_ASSERT((flags & ~(O_CLOEXEC | O_NONBLOCK)) == 0);
+#else
+    Q_ASSERT((flags & ~O_NONBLOCK) == 0);
+#endif
+
+    register int ret;
+#if QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC
+    // use pipe2
+    flags |= O_CLOEXEC;
+    ret = ::pipe2(pipefd, flags); // pipe2 is Linux-specific and is documented not to return EINTR
+    if (ret == 0 || errno != ENOSYS)
+        return ret;
+#endif
+
+    ret = ::pipe(pipefd);
+    if (ret == -1)
+        return -1;
+
+    ::fcntl(pipefd[0], F_SETFD, FD_CLOEXEC);
+    ::fcntl(pipefd[1], F_SETFD, FD_CLOEXEC);
+
+    // set non-block too?
+    if (flags & O_NONBLOCK) {
+        ::fcntl(pipefd[0], F_SETFL, ::fcntl(pipefd[0], F_GETFL) | O_NONBLOCK);
+        ::fcntl(pipefd[1], F_SETFL, ::fcntl(pipefd[1], F_GETFL) | O_NONBLOCK);
+    }
+
+    return 0;
+}
+
+// don't call dup or fcntl(F_DUPFD)
+static inline int qt_safe_dup(int oldfd, int atleast = 0, int flags = FD_CLOEXEC)
+{
+    Q_ASSERT(flags == FD_CLOEXEC || flags == 0);
+
+    register int ret;
+#ifdef F_DUPFD_CLOEXEC
+    // use this fcntl
+    if (flags & FD_CLOEXEC) {
+        ret = ::fcntl(oldfd, F_DUPFD_CLOEXEC, atleast);
+        if (ret != -1 || errno != EINVAL)
+            return ret;
+    }
+#endif
+
+    // use F_DUPFD
+    ret = ::fcntl(oldfd, F_DUPFD, atleast);
+
+    if (flags && ret != -1)
+        ::fcntl(ret, F_SETFD, flags);
+    return ret;
+}
+
+// don't call dup2
+// call qt_safe_dup2
+static inline int qt_safe_dup2(int oldfd, int newfd, int flags = FD_CLOEXEC)
+{
+    Q_ASSERT(flags == FD_CLOEXEC || flags == 0);
+
+    register int ret;
+#if QT_UNIX_SUPPORTS_THREADSAFE_CLOEXEC
+    // use dup3
+    if (flags & FD_CLOEXEC) {
+        EINTR_LOOP(ret, ::dup3(oldfd, newfd, O_CLOEXEC));
+        if (ret == 0 || errno != ENOSYS)
+            return ret;
+    }
+#endif
+    EINTR_LOOP(ret, ::dup2(oldfd, newfd));
+    if (ret == -1)
+        return -1;
+
+    if (flags)
+        ::fcntl(newfd, F_SETFD, flags);
+    return 0;
+}
+
+static inline qint64 qt_safe_read(int fd, char *data, qint64 maxlen)
+{
+    qint64 ret = 0;
+    EINTR_LOOP(ret, QT_READ(fd, data, maxlen));
+    return ret;
+}
+#undef QT_READ
+#define QT_READ qt_safe_read
+
+static inline qint64 qt_safe_write(int fd, const char *data, qint64 len)
+{
+    qint64 ret = 0;
+    EINTR_LOOP(ret, QT_WRITE(fd, data, len));
+    return ret;
+}
+#undef QT_WRITE
+#define QT_WRITE qt_safe_write
+
+static inline int qt_safe_close(int fd)
+{
+    register int ret;
+    EINTR_LOOP(ret, QT_CLOSE(fd));
+    return ret;
+}
+#undef QT_CLOSE
+#define QT_CLOSE qt_safe_close
+
+static inline int qt_safe_execve(const char *filename, char *const argv[],
+                                 char *const envp[])
+{
+    register int ret;
+    EINTR_LOOP(ret, ::execve(filename, argv, envp));
+    return ret;
+}
+
+static inline int qt_safe_execv(const char *path, char *const argv[])
+{
+    register int ret;
+    EINTR_LOOP(ret, ::execv(path, argv));
+    return ret;
+}
+
+static inline int qt_safe_execvp(const char *file, char *const argv[])
+{
+    register int ret;
+    EINTR_LOOP(ret, ::execvp(file, argv));
+    return ret;
+}
+
+static inline pid_t qt_safe_waitpid(pid_t pid, int *status, int options)
+{
+    register int ret;
+    EINTR_LOOP(ret, ::waitpid(pid, status, options));
+    return ret;
+}
+
+Q_CORE_EXPORT int qt_safe_select(int nfds, fd_set *fdread, fd_set *fdwrite, fd_set *fdexcept,
+                                 const struct timeval *tv);
+
+QT_END_NAMESPACE
+
+#endif