python#3773: Check for errors around the use of PyTokenizer_FindEncod…

…ing().

reviewed by Brett Cannon.

Misc/NEWS

@@ -12,6 +12,9 @@ What's New in Python 3.0 release candidate 1
 Core and Builtins
 -----------------
 
+- Issue 3774: Added a few more checks in PyTokenizer_FindEncoding to handle
+  error conditions.
+
 - Issue 3594: Fix Parser/tokenizer.c:fp_setreadl() to open the file being
   tokenized by either a file path or file pointer for the benefit of
   PyTokenizer_FindEncoding().

Parser/tokenizer.c

@@ -1610,7 +1610,10 @@ PyTokenizer_FindEncoding(int fd)
 	fclose(fp);
 	if (tok->encoding) {
             encoding = (char *)PyMem_MALLOC(strlen(tok->encoding) + 1);
-            strcpy(encoding, tok->encoding);
+            if (encoding)
+                strcpy(encoding, tok->encoding);
+            else
+                PyErr_NoMemory();
         }
 	PyTokenizer_Free(tok);
 	return encoding;

Python/import.c

@@ -2830,6 +2830,8 @@ call_find_module(char *name, PyObject *path)
 			   memory. */
 			found_encoding = PyTokenizer_FindEncoding(fd);
 			lseek(fd, 0, 0); /* Reset position */
+			if (found_encoding == NULL && PyErr_Occurred())
+				return NULL;
 			encoding = (found_encoding != NULL) ? found_encoding :
 				   (char*)PyUnicode_GetDefaultEncoding();
 		}