From f0c42af362c1ebbd5fe8b162224ed2d84962802c Mon Sep 17 00:00:00 2001
From: Ivailo Monev <xakepa10@laimg.moc>
Date: Fri, 13 Dec 2019 12:58:56 +0000
Subject: [PATCH] implement file copying for Linux

Signed-off-by: Ivailo Monev <xakepa10@laimg.moc>
---
 src/core/global/qplatformdefs.h        |  2 +
 src/core/io/qfilesystemengine_unix.cpp | 53 ++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/src/core/global/qplatformdefs.h b/src/core/global/qplatformdefs.h
index 6681923a1..99441ac0a 100644
--- a/src/core/global/qplatformdefs.h
+++ b/src/core/global/qplatformdefs.h
@@ -93,6 +93,7 @@
 #define QT_LSEEK                ::lseek64
 #define QT_FSTAT                ::fstat64
 #define QT_FTRUNCATE            ::ftruncate64
+#define QT_CREAT                ::creat64
 
 // Standard C89
 #define QT_FOPEN                ::fopen64
@@ -125,6 +126,7 @@
 #define QT_LSEEK                ::lseek
 #define QT_FSTAT                ::fstat
 #define QT_FTRUNCATE            ::ftruncate
+#define QT_CREAT                ::creat
 
 // Posix extensions to C89
 #if !defined(QT_NO_USE_FSEEKO)
diff --git a/src/core/io/qfilesystemengine_unix.cpp b/src/core/io/qfilesystemengine_unix.cpp
index c8b331280..8f3b6a4e5 100644
--- a/src/core/io/qfilesystemengine_unix.cpp
+++ b/src/core/io/qfilesystemengine_unix.cpp
@@ -44,6 +44,10 @@
 #include <pwd.h>
 #include <grp.h>
 
+#ifdef Q_OS_LINUX
+#  include <sys/sendfile.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 bool QFileSystemEngine::isCaseSensitive()
@@ -370,9 +374,58 @@ bool QFileSystemEngine::createLink(const QFileSystemEntry &source, const QFileSy
 //static
 bool QFileSystemEngine::copyFile(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error)
 {
+#ifdef Q_OS_LINUX
+
+// not in qplatformdefs.h since it is Linux specific
+#if defined(QT_USE_XOPEN_LFS_EXTENSIONS) && defined(QT_LARGEFILE_SUPPORT)
+#  define QT_SENDFILE ::sendfile64
+#else
+#  define QT_SENDFILE ::sendfile
+#endif
+
+    QT_STATBUF st;
+    if (QT_STAT(source.nativeFilePath().constData(), &st) != -1) {
+        if (!S_ISREG(st.st_mode))
+            return false;
+    }
+
+    const int sourcefd = QT_OPEN(source.nativeFilePath().constData(), O_RDONLY);
+    if (sourcefd == -1) {
+        error = QSystemError(errno, QSystemError::StandardLibraryError);
+        return false;
+    }
+
+    const int targetfd = QT_CREAT(target.nativeFilePath().constData(), st.st_mode);
+    if (targetfd == -1) {
+        ::close(sourcefd);
+        error = QSystemError(errno, QSystemError::StandardLibraryError);
+        return false;
+    }
+
+    QT_OFF_T tosend = st.st_size;
+    ssize_t sendresult = QT_SENDFILE(targetfd, sourcefd, Q_NULLPTR, tosend);
+    while (sendresult != tosend) {
+        if (sendresult == -1) {
+            error = QSystemError(errno, QSystemError::StandardLibraryError);
+            ::close(sourcefd);
+            ::close(targetfd);
+            return false;
+        }
+        tosend -= sendresult;
+        sendresult = QT_SENDFILE(targetfd, sourcefd, &tosend, tosend);
+    }
+
+    ::close(sourcefd);
+    ::close(targetfd);
+    return true;
+
+#undef QT_SENDFILE
+
+#else
     Q_UNUSED(source);
     Q_UNUSED(target);
     error = QSystemError(ENOSYS, QSystemError::StandardLibraryError); //Function not implemented
+#endif // Q_OS_LINUX
     return false;
 }