QFileSystemEngine: add rmpath()

removeDirectory() acts in two mode, rmdir (one entry) and rmpath (the
entry and all empty parent directories). This is irregular behavior, and
API with a very specific use-case (in unittests, where you create a dir
tree and want to cleanup after the test finishes).

So, split the code into rmdir() and rmpath(), which matches
QDir::rmdir() and QDir::rmpath().

On Unix, a further optimization pointed out by Thiago in review, remove
the stat() call, ::rmdir() will fail with ENOTDIR if we try to remove
anything that isn't a dir.

Change-Id: I1bbb6e6c1ce49ba6d73d3c510b449223498612fb
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qdir.cpp

@@ -1552,7 +1552,7 @@ bool QDir::rmdir(const QString &dirName) const
 
     QString fn = filePath(dirName);
     if (!d->fileEngine)
-        return QFileSystemEngine::removeDirectory(QFileSystemEntry(fn), false);
+        return QFileSystemEngine::rmdir(QFileSystemEntry(fn));
 
     return d->fileEngine->rmdir(fn, false);
 }
@@ -1606,7 +1606,7 @@ bool QDir::rmpath(const QString &dirPath) const
 
     QString fn = filePath(dirPath);
     if (!d->fileEngine)
-        return QFileSystemEngine::removeDirectory(QFileSystemEntry(fn), true);
+        return QFileSystemEngine::rmpath(QFileSystemEntry(fn));
     return d->fileEngine->rmdir(fn, true);
 }
 

src/corelib/io/qfilesystemengine_p.h

@@ -117,7 +117,15 @@ public:
 
     static bool createDirectory(const QFileSystemEntry &entry, bool createParents,
                                 std::optional<QFile::Permissions> permissions = std::nullopt);
-    static bool removeDirectory(const QFileSystemEntry &entry, bool removeEmptyParents);
+    static bool removeDirectory(const QFileSystemEntry &entry, bool removeEmptyParents)
+    {
+        if (removeEmptyParents)
+            return rmpath(entry);
+        return rmdir(entry);
+    }
+
+    static bool rmdir(const QFileSystemEntry &entry);
+    static bool rmpath(const QFileSystemEntry &entry);
 
     static bool createLink(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error);
 

src/corelib/io/qfilesystemengine_unix.cpp

@@ -1189,30 +1189,28 @@ bool QFileSystemEngine::createDirectory(const QFileSystemEntry &entry, bool crea
     return createDirectoryWithParents(dirName, mode, false);
 }
 
-//static
-bool QFileSystemEngine::removeDirectory(const QFileSystemEntry &entry, bool removeEmptyParents)
+bool QFileSystemEngine::rmdir(const QFileSystemEntry &entry)
 {
-    Q_CHECK_FILE_NAME(entry, false);
+    const QByteArray path = entry.nativeFilePath();
+    Q_CHECK_FILE_NAME(path, false);
+    return ::rmdir(path.constData()) == 0;
+}
 
-    if (removeEmptyParents) {
-        QString dirName = QDir::cleanPath(entry.filePath());
-        for (qsizetype oldslash = 0, slash=dirName.size(); slash > 0; oldslash = slash) {
-            const QByteArray chunk = QFile::encodeName(dirName.left(slash));
-            QT_STATBUF st;
-            if (QT_STAT(chunk.constData(), &st) != -1) {
-                if ((st.st_mode & S_IFMT) != S_IFDIR)
-                    return false;
+bool QFileSystemEngine::rmpath(const QFileSystemEntry &entry)
+{
+    const QString path = QDir::cleanPath(entry.filePath());
+    Q_CHECK_FILE_NAME(path, false);
+
+    for (qsizetype oldslash = 0, slash = path.size(); slash > 0; oldslash = slash) {
+        const QByteArray chunk = QFile::encodeName(path.left(slash));
         if (::rmdir(chunk.constData()) != 0)
             return oldslash != 0;
-            } else {
-                return false;
-            }
-            slash = dirName.lastIndexOf(QDir::separator(), oldslash-1);
+
+        slash = path.lastIndexOf(QDir::separator(), oldslash - 1);
     }
+
     return true;
 }
-    return rmdir(QFile::encodeName(entry.filePath()).constData()) == 0;
-}
 
 //static
 bool QFileSystemEngine::createLink(const QFileSystemEntry &source, const QFileSystemEntry &target, QSystemError &error)

src/corelib/io/qfilesystemengine_win.cpp

@@ -1554,31 +1554,36 @@ bool QFileSystemEngine::createDirectory(const QFileSystemEntry &entry, bool crea
     return createDirectoryWithParents(dirName, securityAttributes, false);
 }
 
-//static
-bool QFileSystemEngine::removeDirectory(const QFileSystemEntry &entry, bool removeEmptyParents)
+bool QFileSystemEngine::rmdir(const QFileSystemEntry &entry)
 {
     QString dirName = entry.filePath();
     Q_CHECK_FILE_NAME(dirName, false);
 
-    if (removeEmptyParents) {
-        dirName = QDir::toNativeSeparators(QDir::cleanPath(dirName));
-        for (int oldslash = 0, slash=dirName.length(); slash > 0; oldslash = slash) {
+    return rmDir(dirName);
+}
+
+bool QFileSystemEngine::rmpath(const QFileSystemEntry &entry)
+{
+    const QString dirName = QDir::toNativeSeparators(QDir::cleanPath(entry.filePath()));
+    Q_CHECK_FILE_NAME(dirName, false);
+
+    for (int oldslash = 0, slash = dirName.size(); slash > 0; oldslash = slash) {
         const auto chunkRef = QStringView{dirName}.left(slash);
         if (chunkRef.length() == 2 && chunkRef.at(0).isLetter()
             && chunkRef.at(1) == u':') {
             break;
         }
         const QString chunk = chunkRef.toString();
+        // TODO: get isDirPath() and rmDir() to accept QStringView
         if (!isDirPath(chunk, nullptr))
             return false;
         if (!rmDir(chunk))
             return oldslash != 0;
         slash = dirName.lastIndexOf(QDir::separator(), oldslash - 1);
     }
+
     return true;
 }
-    return rmDir(entry.filePath());
-}
 
 //static
 QString QFileSystemEngine::rootPath()