mirror of https://github.com/python/cpython.git
169 lines
4.5 KiB
C
169 lines
4.5 KiB
C
/***********************************************************
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Copyright 1991, 1992, 1993, 1994 by Stichting Mathematisch Centrum,
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Amsterdam, The Netherlands.
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and its
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documentation for any purpose and without fee is hereby granted,
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provided that the above copyright notice appear in all copies and that
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both that copyright notice and this permission notice appear in
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supporting documentation, and that the names of Stichting Mathematisch
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Centrum or CWI not be used in advertising or publicity pertaining to
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distribution of the software without specific, written prior permission.
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STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
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THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
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FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
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FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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******************************************************************/
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/* Error handling -- see also run.c */
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/* New error handling interface.
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The following problem exists (existed): methods of built-in modules
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are called with 'self' and 'args' arguments, but without a context
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argument, so they have no way to raise a specific exception.
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The same is true for the object implementations: no context argument.
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The old convention was to set 'errno' and to return NULL.
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The caller (usually call_function() in eval.c) detects the NULL
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return value and then calls puterrno(ctx) to turn the errno value
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into a true exception. Problems with this approach are:
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- it used standard errno values to indicate Python-specific errors,
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but this means that when such an error code is reported by a system
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call (e.g., in module posix), the user gets a confusing message
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- errno is a global variable, which makes extensions to a multi-
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threading environment difficult; e.g., in IRIX, multi-threaded
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programs must use the function oserror() instead of looking in errno
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- there is no portable way to add new error numbers for specic
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situations -- the value space for errno is reserved to the OS, yet
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the way to turn module-specific errors into a module-specific
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exception requires module-specific values for errno
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- there is no way to add a more situation-specific message to an
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error.
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The new interface solves all these problems. To return an error, a
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built-in function calls err_set(exception), err_setval(exception,
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value) or err_setstr(exception, string), and returns NULL. These
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functions save the value for later use by puterrno(). To adapt this
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scheme to a multi-threaded environment, only the implementation of
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err_setval() has to be changed.
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*/
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#include "allobjects.h"
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#include "traceback.h"
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#include <errno.h>
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extern char *strerror PROTO((int));
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/* Last exception stored by err_setval() */
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static object *last_exception;
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static object *last_exc_val;
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void
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err_setval(exception, value)
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object *exception;
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object *value;
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{
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err_clear();
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XINCREF(exception);
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last_exception = exception;
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XINCREF(value);
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last_exc_val = value;
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}
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void
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err_set(exception)
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object *exception;
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{
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err_setval(exception, (object *)NULL);
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}
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void
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err_setstr(exception, string)
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object *exception;
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char *string;
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{
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object *value = newstringobject(string);
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err_setval(exception, value);
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XDECREF(value);
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}
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object *
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err_occurred()
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{
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return last_exception;
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}
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void
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err_get(p_exc, p_val)
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object **p_exc;
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object **p_val;
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{
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*p_exc = last_exception;
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last_exception = NULL;
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*p_val = last_exc_val;
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last_exc_val = NULL;
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}
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void
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err_clear()
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{
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object *tb;
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XDECREF(last_exception);
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last_exception = NULL;
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XDECREF(last_exc_val);
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last_exc_val = NULL;
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/* Also clear interpreter stack trace */
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tb = tb_fetch();
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XDECREF(tb);
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}
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/* Convenience functions to set a type error exception and return 0 */
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int
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err_badarg()
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{
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err_setstr(TypeError, "illegal argument type for built-in operation");
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return 0;
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}
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object *
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err_nomem()
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{
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err_set(MemoryError);
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return NULL;
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}
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object *
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err_errno(exc)
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object *exc;
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{
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object *v;
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int i = errno;
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if (i == EINTR && sigcheck())
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return NULL;
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v = mkvalue("(is)", i, strerror(i));
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if (v != NULL) {
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err_setval(exc, v);
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DECREF(v);
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}
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return NULL;
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}
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void
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err_badcall()
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{
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err_setstr(SystemError, "bad argument to internal function");
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}
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