Move growth computation to re-allocation function

Callers of QByteArray/QString::realloc() are still responsible for the
heuristics and decide whether to provide the "grow" hint, but
computation is centralized there.

With this change we also ensure growth takes into account the
terminating null. Previously, calls to qAllocMore took into account
header and string size, for left out the null, meaning we ended up
allocating ("nice-size" + Null).

Change-Id: Iad1536e7706cd2d446daee96859db9b01c5f9680
Reviewed-by: Marius Storm-Olsen <marius.storm-olsen@nokia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 8 insertions, 10 deletions

diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index c5c43673bc..123d332bad 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -799,11 +799,6 @@ const QString::Null QString::null = { };
 const QStaticStringData<1> QString::shared_null = { Q_STATIC_STRING_DATA_HEADER_INITIALIZER(0), { 0 } };
 const QStaticStringData<1> QString::shared_empty = { Q_STATIC_STRING_DATA_HEADER_INITIALIZER(0), { 0 } };
 
-int QString::grow(int size)
-{
-    return qAllocMore(size * sizeof(QChar), sizeof(Data)) / sizeof(QChar);
-}
-
 /*! \typedef QString::ConstIterator
 
     Qt-style synonym for QString::const_iterator.
@@ -1247,7 +1242,7 @@ void QString::resize(int size)
     } else {
         if (d->ref.isShared() || size > int(d->alloc) ||
             (!d->capacityReserved && size < d->size && size < int(d->alloc) >> 1))
-            realloc(grow(size));
+            realloc(size, true);
         if (int(d->alloc) >= size) {
             d->size = size;
             d->data()[size] = '\0';
@@ -1306,8 +1301,11 @@ void QString::resize(int size)
 */
 
 // ### Qt 5: rename reallocData() to avoid confusion. 197625
-void QString::realloc(int alloc)
+void QString::realloc(int alloc, bool grow)
 {
+    if (grow)
+        alloc = qAllocMore((alloc+1) * sizeof(QChar), sizeof(Data)) / sizeof(QChar) - 1;
+
     if (d->ref.isShared() || IS_RAW_DATA(d)) {
         Data *x = static_cast<Data *>(::malloc(sizeof(Data) + (alloc+1) * sizeof(QChar)));
         Q_CHECK_PTR(x);
@@ -1534,7 +1532,7 @@ QString &QString::append(const QString &str)
             operator=(str);
         } else {
             if (d->ref.isShared() || d->size + str.d->size > int(d->alloc))
-                realloc(grow(d->size + str.d->size));
+                realloc(d->size + str.d->size, true);
             memcpy(d->data() + d->size, str.d->data(), str.d->size * sizeof(QChar));
             d->size += str.d->size;
             d->data()[d->size] = '\0';
@@ -1554,7 +1552,7 @@ QString &QString::append(const QLatin1String &str)
     if (s) {
         int len = str.size();
         if (d->ref.isShared() || d->size + len > int(d->alloc))
-            realloc(grow(d->size + len));
+            realloc(d->size + len, true);
         ushort *i = d->data() + d->size;
         while ((*i++ = *s++))
             ;
@@ -1597,7 +1595,7 @@ QString &QString::append(const QLatin1String &str)
 QString &QString::append(QChar ch)
 {
     if (d->ref.isShared() || d->size + 1 > int(d->alloc))
-        realloc(grow(d->size + 1));
+        realloc(d->size + 1, true);
     d->data()[d->size++] = ch.unicode();
     d->data()[d->size] = '\0';
     return *this;