Avoid generating corrupt pdf output for out of range coordinates

The local qreal to string conversion would fail and produce
unsyntactic output if the integer part exceeded the range of an
unsigned int. Introduce check for that, and fall back to just output a
0 value instead in such cases.

Testing indicates that there is no point in supporting values beyond
4G, as pdf readers do not seem to accept higher values anyway.

As a driveby, also extend the check to catch all non-finite real
values, not only nan.

As a second driveby, simplify the splitting of a qreal into integer
and fraction parts by just using the std library function for that.

Fixes: QTBUG-117740
Pick-to: 6.6 6.5
Change-Id: I247b0612bd565fb2e6f47a182e74f19b8bb0d683
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/gui/painting/qpdf.cpp b/src/gui/painting/qpdf.cpp
index 02fd2fdeea..d49249b1dd 100644
--- a/src/gui/painting/qpdf.cpp
+++ b/src/gui/painting/qpdf.cpp
@@ -99,7 +99,7 @@ static void removeTransparencyFromBrush(QBrush &brush)
 const char *qt_real_to_string(qreal val, char *buf) {
     const char *ret = buf;
 
-    if (qIsNaN(val)) {
+    if (!qIsFinite(val) || std::abs(val) > std::numeric_limits<quint32>::max()) {
         *(buf++) = '0';
         *(buf++) = ' ';
         *buf = 0;
@@ -110,8 +110,8 @@ const char *qt_real_to_string(qreal val, char *buf) {
         *(buf++) = '-';
         val = -val;
     }
-    unsigned int ival = (unsigned int) val;
-    qreal frac = val - (qreal)ival;
+    qreal frac = std::modf(val, &val);
+    quint32 ival(val);
 
     int ifrac = (int)(frac * 1000000000);
     if (ifrac == 1000000000) {