Fix malloc errors from legacy realpath on Mac OSX.

Avoid using realpath(X,0) on Mac OSX at all, since
even on versions of OSX where realpath(X,0) is supported,
we still get the legacy version due to our compiler flags.
If we were to change the -mmacosx-version-min to 10.5 or
higher then this patch would be safe but unnecessary.

Task-number: QTBUG-28282
Change-Id: Iee21003f3e9616482483a05ceee706b476091914
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>

1 files changed, 9 insertions, 2 deletions

diff --git a/src/corelib/io/qfilesystemengine_unix.cpp b/src/corelib/io/qfilesystemengine_unix.cpp
index 5870cdf7de..f8cb130997 100644
--- a/src/corelib/io/qfilesystemengine_unix.cpp
+++ b/src/corelib/io/qfilesystemengine_unix.cpp
@@ -174,9 +174,16 @@ QFileSystemEntry QFileSystemEngine::canonicalName(const QFileSystemEntry &entry,
 #else
     char *ret = 0;
 # if defined(Q_OS_MAC) && !defined(Q_OS_IOS)
-    // Mac OS X 10.5.x doesn't support the realpath(X,0) extension we use here.
+    // When using -mmacosx-version-min=10.4, we get the legacy realpath implementation,
+    // which does not work properly with the realpath(X,0) form. See QTBUG-28282.
     if (QSysInfo::MacintoshVersion >= QSysInfo::MV_10_6) {
-        ret = realpath(entry.nativeFilePath().constData(), (char*)0);
+        ret = (char*)malloc(PATH_MAX + 1);
+        if (ret && realpath(entry.nativeFilePath().constData(), (char*)ret) == 0) {
+            const int savedErrno = errno; // errno is checked below, and free() might change it
+            free(ret);
+            errno = savedErrno;
+            ret = 0;
+        }
     } else {
         // on 10.5 we can use FSRef to resolve the file path.
         QString path = QDir::cleanPath(entry.filePath());