Fix VxWorks POSIX access() behavior

On VxWorks POSIX access() returns always false if it is called on file
which is not on POSIX file system, like DOSFS for example. Qt for
VxWorks 5.15 had similar patch omitting all access() calls and returning
true. This fix takes it a step further and checks if the file is on
POSIX filesystem or if it is DOSFS with read-only setting or not,
in case omitting access() call and returning true. Failure became
visible using QTranslator::load() method on DOSFS mmc card.

Task-number: QTBUG-134627
Pick-to: 6.8
Change-Id: I9c257d3cba1a2b976f2775ad129aae0e09f68ffd
Reviewed-by: Thiago Macieira <[email protected]>
(cherry picked from commit fd73b22)
Reviewed-by: Qt Cherry-pick Bot <[email protected]>

Author: kapinter

src/corelib/io/qfilesystemengine_unix.cpp

@@ -69,6 +69,13 @@
 #endif
 #endif
 
+#if defined(Q_OS_VXWORKS)
+# include <sys/statfs.h>
+# if __has_include(<dosFsLib.h>)
+#  include <dosFsLib.h>
+# endif
+#endif
+
 #if defined(Q_OS_ANDROID)
 // statx() is disabled on Android because quite a few systems
 // come with sandboxes that kill applications that make system calls outside a
@@ -331,8 +338,15 @@ flagsFromStMode(mode_t mode, [[maybe_unused]] quint64 attributes)
 #ifdef UF_HIDDEN
     if (attributes & UF_HIDDEN)
         entryFlags |= QFileSystemMetaData::HiddenAttribute;
+#elif defined(Q_OS_VXWORKS) && __has_include(<dosFsLib.h>)
+    if (attributes & DOS_ATTR_RDONLY) {
+        // on a DOS FS, stat() always returns 0777 bits set in st_mode
+        // when DOS FS is read only the write permissions are removed
+        entryFlags &= ~QFileSystemMetaData::OwnerWritePermission;
+        entryFlags &= ~QFileSystemMetaData::GroupWritePermission;
+        entryFlags &= ~QFileSystemMetaData::OtherWritePermission;
+    }
 #endif
-
     return entryFlags;
 }
 
@@ -476,8 +490,9 @@ void QFileSystemMetaData::fillFromStatBuf(const QT_STATBUF &statBuffer)
     quint64 attributes = 0;
 #if defined(UF_SETTABLE)        // BSDs (incl. Darwin)
     attributes = statBuffer.st_flags;
+#elif defined(Q_OS_VXWORKS) && __has_include(<dosFsLib.h>)
+    attributes = statBuffer.st_attrib;
 #endif
-
     // Permissions
     MetaDataFlags flags = flagsFromStMode(statBuffer.st_mode, attributes);
     entryFlags |= flags;
@@ -990,6 +1005,30 @@ bool QFileSystemEngine::fillMetaData(const QFileSystemEntry &entry, QFileSystemM
 
     // third, we try access(2)
     if (what & (QFileSystemMetaData::UserPermissions | QFileSystemMetaData::ExistsAttribute)) {
+#if defined(Q_OS_VXWORKS)
+        // on VxWorks if the filesystem is not POSIX, access() always returns false, despite the
+        // file is readable
+        struct statfs statBuf;
+        if (statfs(nativeFilePath, &statBuf) != 0) {
+            what &= ~QFileSystemMetaData::LinkType; // don't clear link: could be broken symlink
+            data.clearFlags(what);
+            return false;
+        }
+        if (statBuf.f_type != NFSV2_MAGIC && statBuf.f_type != NFSV3_MAGIC &&
+            statBuf.f_type != HRFS_MAGIC) {
+#if __has_include(<dosFsLib.h>)
+            if (data.entryFlags & QFileSystemMetaData::OwnerWritePermission) {
+                data.entryFlags |= QFileSystemMetaData::UserWritePermission;
+            }
+            if (data.entryFlags & QFileSystemMetaData::OwnerExecutePermission) {
+                data.entryFlags |= QFileSystemMetaData::UserExecutePermission;
+            }
+#endif
+            data.entryFlags |= QFileSystemMetaData::UserReadPermission |
+                    QFileSystemMetaData::ExistsAttribute;
+            return true;
+        }
+#endif
         // calculate user permissions
         auto checkAccess = [&](QFileSystemMetaData::MetaDataFlag flag, int mode) {
             if (entryErrno != 0 || (what & flag) == 0)
@@ -1001,7 +1040,6 @@ bool QFileSystemEngine::fillMetaData(const QFileSystemEntry &entry, QFileSystemM
                 entryErrno = errno;
             }
         };
-
         checkAccess(QFileSystemMetaData::UserReadPermission, R_OK);
         checkAccess(QFileSystemMetaData::UserWritePermission, W_OK);
         checkAccess(QFileSystemMetaData::UserExecutePermission, X_OK);