don't rewrite symlink on save, rewrite target instead

Merge-request: 399
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

Change-Id: If81446a8fd49e9de7611c2f09abd39af2c9c930d

src/libs/utils/fileutils.cpp

@@ -92,6 +92,18 @@ namespace Utils {
   \return Whether at least one file in \a filePath has a newer date than \a timeStamp.
 */
 
+/*!
+  \fn Utils::FileUtils::resolveSymlinks(const QString &filePath)
+
+  Recursively resolve possibly present symlinks in \a filePath.
+  Unlike QFileInfo::canonicalFilePath(), this function will still return the expected target file
+  even if the symlink is dangling.
+
+  \note Maximum recursion depth == 16.
+
+  return Symlink target file path.
+*/
+
 bool FileUtils::removeRecursively(const QString &filePath, QString *error)
 {
     QFileInfo fileInfo(filePath);
@@ -197,6 +209,16 @@ bool FileUtils::isFileNewerThan(const QString &filePath,
     return false;
 }
 
+QString FileUtils::resolveSymlinks(const QString &path)
+{
+    QFileInfo f(path);
+    int links = 16;
+    while (links-- && f.isSymLink())
+        f.setFile(f.symLinkTarget());
+    if (links <= 0)
+        return QString();
+    return f.filePath();
+}
 
 
 QByteArray FileReader::fetchQrc(const QString &fileName)

src/libs/utils/fileutils.h

@@ -57,6 +57,7 @@ public:
                          const QString &tgtFilePath, QString *error = 0);
     static bool isFileNewerThan(const QString &filePath,
                             const QDateTime &timeStamp);
+    static QString resolveSymlinks(const QString &path);
 };
 
 class QTCREATOR_UTILS_EXPORT FileReader

src/libs/utils/savefile.cpp

@@ -32,6 +32,7 @@
 
 #include "savefile.h"
 #include "qtcassert.h"
+#include "fileutils.h"
 
 namespace Utils {
 
@@ -84,11 +85,12 @@ bool SaveFile::commit()
         return false;
     }
 
-    QString bakname = m_finalFileName + QLatin1Char('~');
+    QString finalFileName = Utils::FileUtils::resolveSymlinks(m_finalFileName);
+    QString bakname = finalFileName + QLatin1Char('~');
     QFile::remove(bakname); // Kill old backup
-    QFile::rename(m_finalFileName, bakname); // Backup current file
-    if (!rename(m_finalFileName)) { // Replace current file
-        QFile::rename(bakname, m_finalFileName); // Rollback to current file
+    QFile::rename(finalFileName, bakname); // Backup current file
+    if (!rename(finalFileName)) { // Replace current file
+        QFile::rename(bakname, finalFileName); // Rollback to current file
         return false;
     }
     if (!m_backup)