2 files changed, 38 insertions, 1 deletions
diff --git a/src/corelib/tools/qcryptographichash.cpp b/src/corelib/tools/qcryptographichash.cpp
index 8baec8ecc8b..3807e32a723 100644
--- a/src/corelib/tools/qcryptographichash.cpp
+++ b/src/corelib/tools/qcryptographichash.cpp
@@ -1153,13 +1153,42 @@ void QCryptographicHashPrivate::State::finalizeUnchecked(QCryptographicHash::Alg
 
   \note In Qt versions prior to 6.3, this function took QByteArray,
   not QByteArrayView.
+
+  \sa hashInto()
 */
 QByteArray QCryptographicHash::hash(QByteArrayView data, Algorithm method)
 {
+    QByteArray ba(hashLengthInternal(method), Qt::Uninitialized);
+    [[maybe_unused]] const auto r = hashInto(ba, data, method);
+    Q_ASSERT(r.size() == ba.size());
+    return ba;
+}
+
+/*!
+    \since 6.8
+    \fn QCryptographicHash::hashInto(QSpan<char> buffer, QByteArrayView data, Algorithm method);
+    \fn QCryptographicHash::hashInto(QSpan<uchar> buffer, QByteArrayView data, Algorithm method);
+    \fn QCryptographicHash::hashInto(QSpan<std::byte> buffer, QByteArrayView data, Algorithm method);
+
+    Returns the hash of \a data using \a method, using \a buffer to store the result.
+
+    The return value will be a sub-span of \a buffer, unless \a buffer is of
+    insufficient size, in which case a null QByteArrayView is returned.
+
+    \sa hash()
+*/
+QByteArrayView QCryptographicHash::hashInto(QSpan<std::byte> buffer, QByteArrayView data,
+                                            Algorithm method) noexcept
+{
     QCryptographicHashPrivate hash(method);
     hash.addData(data);
     hash.finalizeUnchecked(); // no mutex needed: no-one but us has access to 'hash'
-    return hash.resultView().toByteArray();
+    auto result = hash.resultView();
+    if (buffer.size() < result.size())
+        return {}; // buffer too small
+    // ### optimize: have the method directly write into `buffer`
+    memcpy(buffer.data(), result.data(), result.size());
+    return buffer.first(result.size());
 }
 
 /*!
diff --git a/src/corelib/tools/qcryptographichash.h b/src/corelib/tools/qcryptographichash.h
index 294453adceb..3d91c1f917c 100644
--- a/src/corelib/tools/qcryptographichash.h
+++ b/src/corelib/tools/qcryptographichash.h
@@ -8,6 +8,7 @@
 
 #include <QtCore/qbytearray.h>
 #include <QtCore/qobjectdefs.h>
+#include <QtCore/qspan.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -91,6 +92,13 @@ public:
     static QByteArray hash(const QByteArray &data, Algorithm method);
 #endif
     static QByteArray hash(QByteArrayView data, Algorithm method);
+
+    static QByteArrayView hashInto(QSpan<char> buffer, QByteArrayView data, Algorithm method) noexcept
+    { return hashInto(as_writable_bytes(buffer), data, method); }
+    static QByteArrayView hashInto(QSpan<uchar> buffer, QByteArrayView data, Algorithm method) noexcept
+    { return hashInto(as_writable_bytes(buffer), data, method); }
+    static QByteArrayView hashInto(QSpan<std::byte> buffer, QByteArrayView data, Algorithm method) noexcept;
+
     static int hashLength(Algorithm method);
     static bool supportsAlgorithm(Algorithm method);
 private: