QResource: quick refactor of registerSelf for files to support LFS

This commit adds sufficient support for large files in resources, but
not completely because the rest Qt is not ready for it (and not
tested). We've had the QT_MMAP macro in qplatformdefs.h for a while, so
let's use it and use qsizetype where we can.

This also the check that the file existed before opening it (you can
only open it if it exists), plus a few nullptr updates.

Change-Id: I42a48bd64ccc41aebf84fffd15653ffdabb0e66b
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 28 insertions, 39 deletions

diff --git a/src/corelib/io/qresource.cpp b/src/corelib/io/qresource.cpp
index 4638de6520..52a20191a9 100644
--- a/src/corelib/io/qresource.cpp
+++ b/src/corelib/io/qresource.cpp
@@ -68,6 +68,11 @@
 # include "private/qcore_unix_p.h"
 #endif
 
+#if defined(Q_OS_UNIX) && !defined(Q_OS_NACL) && !defined(Q_OS_INTEGRITY)
+#  define QT_USE_MMAP
+#  include <sys/mman.h>
+#endif
+
 //#define DEBUG_RESOURCE_MATCH
 
 QT_BEGIN_NAMESPACE
@@ -969,7 +974,7 @@ public:
     ResourceRootType type() const override { return Resource_Buffer; }
 
     // size == -1 means "unknown"
-    bool registerSelf(const uchar *b, int size)
+    bool registerSelf(const uchar *b, qsizetype size)
     {
         // 5 int "pointers"
         if (size >= 0 && size < 20)
@@ -1010,28 +1015,12 @@ public:
     }
 };
 
-#if defined(Q_OS_UNIX) && !defined (Q_OS_NACL) && !defined(Q_OS_INTEGRITY)
-#define QT_USE_MMAP
-#endif
-
-// most of the headers below are already included in qplatformdefs.h
-// also this lacks Large File support but that's probably irrelevant
-#if defined(QT_USE_MMAP)
-// for mmap
-QT_BEGIN_INCLUDE_NAMESPACE
-#include <sys/mman.h>
-#include <errno.h>
-QT_END_INCLUDE_NAMESPACE
-#endif
-
-
-
 class QDynamicFileResourceRoot: public QDynamicBufferResourceRoot
 {
     QString fileName;
     // for mmap'ed files, this is what needs to be unmapped.
     uchar *unmapPointer;
-    unsigned int unmapLength;
+    qsizetype unmapLength;
 
 public:
     inline QDynamicFileResourceRoot(const QString &_root) : QDynamicBufferResourceRoot(_root), unmapPointer(0), unmapLength(0) { }
@@ -1057,14 +1046,14 @@ public:
 #  define MAP_FILE 0
 #endif
 #ifndef MAP_FAILED
-#  define MAP_FAILED -1
+#  define MAP_FAILED reinterpret_cast<void *>(-1)
 #endif
 
 bool QDynamicFileResourceRoot::registerSelf(const QString &f)
 {
     bool fromMM = false;
-    uchar *data = 0;
-    unsigned int data_len = 0;
+    uchar *data = nullptr;
+    qsizetype data_len = 0;
 
 #ifdef QT_USE_MMAP
     int fd = QT_OPEN(QFile::encodeName(f), O_RDONLY,
@@ -1076,35 +1065,35 @@ bool QDynamicFileResourceRoot::registerSelf(const QString &f)
                      );
     if (fd >= 0) {
         QT_STATBUF st;
-        if (!QT_FSTAT(fd, &st)) {
-            uchar *ptr;
-            ptr = reinterpret_cast<uchar *>(
-                        mmap(0, st.st_size,             // any address, whole file
-                             PROT_READ,                 // read-only memory
-                             MAP_FILE | MAP_PRIVATE,    // swap-backed map from file
-                             fd, 0));                   // from offset 0 of fd
-            if (ptr && ptr != reinterpret_cast<uchar *>(MAP_FAILED)) {
-                data = ptr;
+        if (!QT_FSTAT(fd, &st) && st.st_size <= std::numeric_limits<qsizetype>::max()) {
+            int protection = PROT_READ;                 // read-only memory
+            int flags = MAP_FILE | MAP_PRIVATE;         // swap-backed map from file
+            void *ptr = QT_MMAP(nullptr, st.st_size,    // any address, whole file
+                                protection, flags,
+                                fd, 0);                 // from offset 0 of fd
+            if (ptr != MAP_FAILED) {
+                data = static_cast<uchar *>(ptr);
                 data_len = st.st_size;
                 fromMM = true;
             }
         }
-        ::close(fd);
+        QT_CLOSE(fd);
     }
 #endif // QT_USE_MMAP
     if (!data) {
         QFile file(f);
-        if (!file.exists())
-            return false;
-        data_len = file.size();
-        data = new uchar[data_len];
-
         bool ok = false;
-        if (file.open(QIODevice::ReadOnly))
-            ok = (data_len == (uint)file.read((char*)data, data_len));
+        if (file.open(QIODevice::ReadOnly)) {
+            qint64 fsize = file.size();
+            if (fsize <= std::numeric_limits<qsizetype>::max()) {
+                data_len = file.size();
+                data = new uchar[data_len];
+                ok = (data_len == file.read((char*)data, data_len));
+            }
+        }
         if (!ok) {
             delete [] data;
-            data = 0;
+            data = nullptr;
             data_len = 0;
             return false;
         }