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/*
* revoutput.c --- Provide an output wrapper that reverses lines.
*
* Arnold Robbins
* arnold@skeeve.com
* Written 8/2012
*/
/*
* Copyright (C) 2012, 2013 the Free Software Foundation, Inc.
*
* This file is part of GAWK, the GNU implementation of the
* AWK Programming Language.
*
* GAWK is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* GAWK is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "gawkapi.h"
#include "gettext.h"
#define _(msgid) gettext(msgid)
#define N_(msgid) msgid
static const gawk_api_t *api; /* for convenience macros to work */
static awk_ext_id_t *ext_id;
static const char *ext_version = "revoutput extension: version 1.0";
static awk_bool_t init_revoutput(void);
static awk_bool_t (*init_func)(void) = init_revoutput;
int plugin_is_GPL_compatible;
/* rev_fwrite --- write out characters in reverse order */
static size_t
rev_fwrite(const void *buf, size_t size, size_t count, FILE *fp, void *opaque)
{
const char *cp = buf;
int nbytes = size * count;
(void) opaque;
for (; nbytes >= 1; nbytes--)
putc(cp[nbytes-1], fp);
return (size * count);
}
/* revoutput_can_take_file --- return true if we want the file */
static awk_bool_t
revoutput_can_take_file(const awk_output_buf_t *outbuf)
{
awk_value_t value;
if (outbuf == NULL)
return awk_false;
if (! sym_lookup("REVOUT", AWK_NUMBER, & value))
return awk_false;
return (value.num_value != 0);
}
/*
* revoutput_take_control_of --- set up output wrapper.
* We can assume that revoutput_can_take_file just returned true,
* and no state has changed since then.
*/
static awk_bool_t
revoutput_take_control_of(awk_output_buf_t *outbuf)
{
if (outbuf == NULL)
return awk_false;
outbuf->gawk_fwrite = rev_fwrite;
outbuf->redirected = awk_true;
return awk_true;
}
static awk_output_wrapper_t output_wrapper = {
"revoutput",
revoutput_can_take_file,
revoutput_take_control_of,
NULL
};
/* init_revoutput --- set things ups */
static awk_bool_t
init_revoutput()
{
awk_value_t value;
register_output_wrapper(& output_wrapper);
make_number(0.0, & value); /* init to false */
if (! sym_update("REVOUT", & value)) {
warning(ext_id, _("revoutput: could not initialize REVOUT variable"));
return awk_false;
}
return awk_true;
}
static awk_ext_func_t func_table[] = {
{ NULL, NULL, 0 }
};
/* define the dl_load function using the boilerplate macro */
dl_load_func(func_table, revoutput, "")
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