68 lines
2.6 KiB
C
68 lines
2.6 KiB
C
/*
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* This file is part of ltrace.
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* Copyright (C) 2011,2012,2013 Petr Machata, Red Hat Inc.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA
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*/
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#ifndef _CALLBACK_H_
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#define _CALLBACK_H_
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/* Notes on the iteration interface used across ltrace. Typically the
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* iteration function looks something like this:
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*
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* foo *each_foo(foo *start_after,
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* enum callback_status (*cb)(foo *f, void *data),
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* void *data);
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*
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* The iteration starts after the element designated by START_AFTER,
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* or at the first element if START_AFTER is NULL. CB is then called
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* for each element of the collection. DATA is passed verbatim to CB.
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* If CB returns CBS_STOP, the iteration stops and the current element
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* is returned. That element can then be passed as START_AFTER to
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* restart the iteration. NULL is returned when iteration ends.
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*
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* CBS_FAIL is not currently handled, and essentially means the same
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* thing as CBS_STOP. There's no provision for returning error
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* states. Errors need to be signaled to the caller via DATA,
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* together with any other data that the callback needs.
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*
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* A richer iteration interface looks like this:
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*
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* struct each_foo_t {
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* foo *restart;
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* int status;
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* } each_foo(foo *start_after,
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* enum callback_status (*cb)(foo *f, void *data),
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* void *data);
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*
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* These provide error handling. The two-part structure encodes both
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* the restart cookie and status. Status of 0 means success, negative
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* values signify failures. Status of -1 is dedicated to failures in
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* user callback (such that the callback returns CBS_FAIL). Other
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* negative values signal failures in the iteration mechanism itself.
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*/
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enum callback_status {
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CBS_STOP, /* The iteration should stop. */
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CBS_CONT, /* The iteration should continue. */
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CBS_FAIL, /* There was an error. The iteration should stop
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* and return error. */
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};
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#define CBS_STOP_IF(X) ((X) ? CBS_STOP : CBS_CONT)
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#define CBS_CONT_IF(X) ((X) ? CBS_CONT : CBS_STOP)
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#endif /* _CALLBACK_H_ */
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