Fix resolution of relative symlinks from relative path on unix

Consider the following:
/root/target - a file
/root/path/link -> ../target
/root/path/other/exe - executable

Running from /root/path/other.

exe is:

#include <QDebug>
#include <QFileInfo>

int main()
{
    qDebug() << QFileInfo("../link").symLinkTarget()
    return 0;
}

The link references /root/target, but the current output is
/root/path/target.

The link doesn't depend on the PWD. It depends on its own directory.

Change-Id: I61e95018154a75e0e0d795ee801068e18870a5df
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

2 files changed, 12 insertions, 7 deletions

diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index ac0c43d055..7600c9a613 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -187,13 +187,11 @@ QFileSystemEntry QFileSystemEngine::getLinkTarget(const QFileSystemEntry &link,
 #endif
 
         if (!ret.startsWith(QLatin1Char('/'))) {
-            const QString linkFilePath = link.filePath();
-            if (linkFilePath.startsWith(QLatin1Char('/'))) {
-                ret.prepend(linkFilePath.leftRef(linkFilePath.lastIndexOf(QLatin1Char('/')))
-                            + QLatin1Char('/'));
-            } else {
-                ret.prepend(QDir::currentPath() + QLatin1Char('/'));
-            }
+            const QString linkPath = link.path();
+            if (linkPath.startsWith(QLatin1Char('/')))
+                ret.prepend(linkPath + QLatin1Char('/'));
+            else
+                ret.prepend(QDir::currentPath() + QLatin1Char('/') + linkPath + QLatin1Char('/'));
         }
         ret = QDir::cleanPath(ret);
         if (ret.size() > 1 && ret.endsWith(QLatin1Char('/')))
diff --git a/tests/auto/corelib/io/qfileinfo/tst_qfileinfo.cpp b/tests/auto/corelib/io/qfileinfo/tst_qfileinfo.cpp
index 87b579bb2b..17f41cba2b 100644
--- a/tests/auto/corelib/io/qfileinfo/tst_qfileinfo.cpp
+++ b/tests/auto/corelib/io/qfileinfo/tst_qfileinfo.cpp
@@ -1261,6 +1261,7 @@ void tst_QFileInfo::isSymLink_data()
     QFile::remove("link.lnk");
     QFile::remove("brokenlink.lnk");
     QFile::remove("dummyfile");
+    QFile::remove("relative/link.lnk");
 
     QFile file1(m_sourceFile);
     QVERIFY(file1.link("link.lnk"));
@@ -1277,6 +1278,12 @@ void tst_QFileInfo::isSymLink_data()
     QTest::newRow("existent file") << m_sourceFile << false << "";
     QTest::newRow("link") << "link.lnk" << true << QFileInfo(m_sourceFile).absoluteFilePath();
     QTest::newRow("broken link") << "brokenlink.lnk" << true << QFileInfo("dummyfile").absoluteFilePath();
+
+#ifndef Q_OS_WIN
+    QDir::current().mkdir("relative");
+    QFile::link("../dummyfile", "relative/link.lnk");
+    QTest::newRow("relative link") << "relative/link.lnk" << true << QFileInfo("dummyfile").absoluteFilePath();
+#endif
 #endif
 }