Ticket #5520: libbe_storagekit_file-isreadable_iswritable-checkmode.patch

src/kits/storage/File.cpp

@@ -295 +295 @@
 /*! \brief Returns whether the file is readable.
     \return
     - \c true, if the BFile has been initialized properly and the file has
-      been been opened for reading,
+      been been opened for reading, and has read permissions.
     - \c false, otherwise.
 */
 bool
 BFile::IsReadable() const
 {
-    return InitCheck() == B_OK
-        && ((fMode & O_RWMASK) == O_RDONLY || (fMode & O_RWMASK) == O_RDWR);
+    if (InitCheck() != B_OK)
+        return false;
+
+    struct stat st;
+    if (!fstat(get_fd(), &st)) {
+        return false;
+    }
+
+    unsigned int fUid = getuid();                                                                                                                                           
+    unsigned int fGid = getgid();                                                                                                                                           
+
+    bool fReadable = !((fUid == st.st_uid && (S_IRUSR & st.st_mode))                                                                                                        
+            || (fGid == st.st_gid && (S_IRGRP & st.st_mode))                                                                                                        
+            || (S_IROTH & st.st_mode));
+
+    if (false==fReadable)
+        return false;
+
+    return (fMode & O_RWMASK) == O_RDONLY || (fMode & O_RWMASK) == O_RDWR;
 }
 
 
 /*! \brief Returns whether the file is writable.
     \return
     - \c true, if the BFile has been initialized properly and the file has
-      been opened for writing,
+      been opened for writing, and has write permissions.
     - \c false, otherwise.
 */
 bool
 BFile::IsWritable() const
 {
-    return InitCheck() == B_OK
-        && ((fMode & O_RWMASK) == O_WRONLY || (fMode & O_RWMASK) == O_RDWR);
+    if (InitCheck() != B_OK)
+        return false;
+
+    struct stat st;
+    if (!fstat(get_fd(), &st)) {
+        return false;
+    }
+
+    unsigned int fUid = getuid();                                                                                                                                           
+    unsigned int fGid = getgid();                                                                                                                                           
+
+    bool fReadOnly = !((fUid == st.st_uid && (S_IWUSR & st.st_mode))                                                                                                        
+            || (fGid == st.st_gid && (S_IWGRP & st.st_mode))                                                                                                        
+            || (S_IWOTH & st.st_mode));
+
+    if (true==fReadOnly)
+        return false;
+
+    return (fMode & O_RWMASK) == O_WRONLY || (fMode & O_RWMASK) == O_RDWR;
 }