QLockFile: refactor local helper into static member functions

To prepare for the Windows backend doing extra work.
We want to open the file with FILE_SHARE_DELETE so that
we can eventually create the file with the DELETE permission,
enabling us to delete it without closing the handle first.

Since we can't do that through QFile directly we need to open
the file descriptor first and then pass that to QFile.

Change-Id: I0baf0ee3089b489f3bd1e0259cc06195e9256647
Reviewed-by: Thiago Macieira <[email protected]>

4 files changed, 34 insertions, 18 deletions

diff --git a/src/corelib/io/qlockfile.cpp b/src/corelib/io/qlockfile.cpp
index 908db7b9d38..47229c8e6a1 100644
--- a/src/corelib/io/qlockfile.cpp
+++ b/src/corelib/io/qlockfile.cpp
@@ -24,19 +24,6 @@ QT_BEGIN_NAMESPACE
 
 using namespace Qt::StringLiterals;
 
-namespace {
-struct LockFileInfo
-{
-    qint64 pid;
-    QString appname;
-    QString hostname;
-    QByteArray hostid;
-    QByteArray bootid;
-};
-}
-
-static bool getLockInfo_helper(const QString &fileName, LockFileInfo *info);
-
 static QString machineName()
 {
 #ifdef Q_OS_WIN
@@ -364,8 +351,8 @@ bool QLockFile::tryLock(std::chrono::milliseconds timeout)
 bool QLockFile::getLockInfo(qint64 *pid, QString *hostname, QString *appname) const
 {
     Q_D(const QLockFile);
-    LockFileInfo info;
-    if (!getLockInfo_helper(d->fileName, &info))
+    QLockFilePrivate::LockFileInfo info;
+    if (!QLockFilePrivate::getLockInfo_helper(d->fileName, &info))
         return false;
     if (pid)
         *pid = info.pid;
@@ -399,11 +386,16 @@ QByteArray QLockFilePrivate::lockFileContents() const
             % QSysInfo::bootUniqueId() % '\n';
 }
 
-static bool getLockInfo_helper(const QString &fileName, LockFileInfo *info)
+bool QLockFilePrivate::getLockInfo_helper(const QString &fileName, LockFileInfo *info)
 {
-    QFile reader(fileName);
-    if (!reader.open(QIODevice::ReadOnly | QIODevice::Text))
+    int fd = openNewFileDescriptor(fileName);
+    if (fd < 0)
+        return false;
+    QFile reader;
+    if (!reader.open(fd, QFile::ReadOnly | QFile::Text, QFile::AutoCloseHandle)) {
+        QT_CLOSE(fd);
         return false;
+    }
 
     QByteArray pidLine = reader.readLine();
     pidLine.chop(1);
diff --git a/src/corelib/io/qlockfile_p.h b/src/corelib/io/qlockfile_p.h
index 2a7ebe1926d..ea9b29e9f57 100644
--- a/src/corelib/io/qlockfile_p.h
+++ b/src/corelib/io/qlockfile_p.h
@@ -25,6 +25,15 @@ QT_BEGIN_NAMESPACE
 class QLockFilePrivate
 {
 public:
+    struct LockFileInfo
+    {
+        qint64 pid;
+        QString appname;
+        QString hostname;
+        QByteArray hostid;
+        QByteArray bootid;
+    };
+
     explicit QLockFilePrivate(const QString &fn);
     ~QLockFilePrivate();
 
@@ -41,6 +50,9 @@ public:
 
     QString fileName;
 
+    static bool getLockInfo_helper(const QString &fileName, LockFileInfo *info);
+    static int openNewFileDescriptor(const QString &fileName);
+
 #ifdef Q_OS_WIN
     Qt::HANDLE fileHandle;
 #else
diff --git a/src/corelib/io/qlockfile_unix.cpp b/src/corelib/io/qlockfile_unix.cpp
index 87faac8b33d..34276373a1f 100644
--- a/src/corelib/io/qlockfile_unix.cpp
+++ b/src/corelib/io/qlockfile_unix.cpp
@@ -285,6 +285,11 @@ QString QLockFilePrivate::processNameByPid(qint64 pid)
 #endif
 }
 
+int QLockFilePrivate::openNewFileDescriptor(const QString &fileName)
+{
+    return QT_OPEN(fileName.toLocal8Bit().constData(), QT_OPEN_RDONLY);
+}
+
 void QLockFile::unlock()
 {
     Q_D(QLockFile);
diff --git a/src/corelib/io/qlockfile_win.cpp b/src/corelib/io/qlockfile_win.cpp
index 12a668def0f..611f90679d5 100644
--- a/src/corelib/io/qlockfile_win.cpp
+++ b/src/corelib/io/qlockfile_win.cpp
@@ -16,6 +16,8 @@
 
 #include <qt_windows.h>
 #include <psapi.h>
+#include <io.h>
+#include <fcntl.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -142,6 +144,11 @@ QString QLockFilePrivate::processNameByPid(qint64 pid)
     return name;
 }
 
+int QLockFilePrivate::openNewFileDescriptor(const QString &fileName)
+{
+    return _open(fileName.toLocal8Bit().constData(), _O_RDONLY);
+}
+
 void QLockFile::unlock()
 {
     Q_D(QLockFile);