Initial revision
diff --git a/Python/errors.c b/Python/errors.c
new file mode 100644
index 0000000..ac34742
--- /dev/null
+++ b/Python/errors.c
@@ -0,0 +1,111 @@
+/* Error handling -- see also run.c */
+
+/* New error handling interface.
+
+ The following problem exists (existed): methods of built-in modules
+ are called with 'self' and 'args' arguments, but without a context
+ argument, so they have no way to raise a specific exception.
+ The same is true for the object implementations: no context argument.
+ The old convention was to set 'errno' and to return NULL.
+ The caller (usually call_function() in eval.c) detects the NULL
+ return value and then calls puterrno(ctx) to turn the errno value
+ into a true exception. Problems with this approach are:
+ - it used standard errno values to indicate Python-specific errors,
+ but this means that when such an error code is reported by UNIX the
+ user gets a confusing message
+ - errno is a global variable, which makes extensions to a multi-
+ threading environment difficult; e.g., in IRIX, multi-threaded
+ programs must use the function getoserror() (sp.?) instead of
+ looking in errno
+ - there is no portable way to add new error numbers for specic
+ situations -- the value space for errno is reserved to the OS, yet
+ the way to turn module-specific errors into a module-specific
+ exception requires module-specific values for errno
+ - there is no way to add a more situation-specific message to an
+ error.
+
+ The new interface solves all these problems. To return an error, a
+ built-in function calls err_set(exception), err_set(valexception,
+ value) or err_setstr(exception, string), and returns NULL. These
+ functions save the value for later use by puterrno(). To adapt this
+ scheme to a multi-threaded environment, only the implementation of
+ err_setval() has to be changed.
+*/
+
+#include <stdio.h>
+
+#include "PROTO.h"
+#include "object.h"
+#include "stringobject.h"
+#include "errors.h"
+
+/* Last exception stored by err_setval() */
+
+static object *last_exception;
+static object *last_exc_val;
+
+void
+err_setval(exception, value)
+ object *exception;
+ object *value;
+{
+ if (last_exception != NULL)
+ DECREF(last_exception);
+ if (exception != NULL)
+ INCREF(exception);
+ last_exception = exception;
+
+ if (last_exc_val != NULL)
+ DECREF(last_exc_val);
+ if (value != NULL)
+ INCREF(value);
+ last_exc_val = value;
+}
+
+void
+err_set(exception)
+ object *exception;
+{
+ err_setval(exception, (object *)NULL);
+}
+
+void
+err_setstr(exception, string)
+ object *exception;
+ char *string;
+{
+ object *value = newstringobject(string);
+ err_setval(exception, value);
+ if (value != NULL)
+ DECREF(value);
+}
+
+int
+err_occurred()
+{
+ return last_exception != NULL;
+}
+
+void
+err_get(p_exc, p_val)
+ object **p_exc;
+ object **p_val;
+{
+ *p_exc = last_exception;
+ last_exception = NULL;
+ *p_val = last_exc_val;
+ last_exc_val = NULL;
+}
+
+void
+err_clear()
+{
+ if (last_exception != NULL) {
+ DECREF(last_exception);
+ last_exception = NULL;
+ }
+ if (last_exc_val != NULL) {
+ DECREF(last_exc_val);
+ last_exc_val = NULL;
+ }
+}