source: vendor/gawk/3.1.5/ext.c@ 3513

/*
 * ext.c - Builtin function that links external gawk functions and related
 *         utilities.
 *
 * Christos Zoulas, Thu Jun 29 17:40:41 EDT 1995
 * Arnold Robbins, update for 3.1, Mon Nov 23 12:53:39 EST 1998
 */

/*
 * Copyright (C) 1995 - 2001, 2003-2005 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 2 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
 */

#include "awk.h"

#ifdef DYNAMIC

#include <dlfcn.h>

#ifdef __GNUC__
static unsigned long long dummy;        /* fake out gcc for dynamic loading? */
#endif

extern int errcount;

/* do_ext --- load an extension */

NODE *
do_ext(NODE *tree)
{
        NODE *obj;
        NODE *fun;
        NODE *(*func) P((NODE *, void *));
        void *dl;
        int flags = RTLD_LAZY;

#ifdef __GNUC__
        AWKNUM junk;

        junk = (AWKNUM) dummy;
#endif

        if (do_lint)
                lintwarn(_("`extension' is a gawk extension"));

        if (do_traditional || do_posix) {
                errcount++;
                error(_("`extension' is a gawk extension"));
        }

        obj = tree_eval(tree->lnode);
        force_string(obj);

#ifdef RTLD_GLOBAL
        flags |= RTLD_GLOBAL;
#endif
        if ((dl = dlopen(obj->stptr, flags)) == NULL)
                fatal(_("extension: cannot open `%s' (%s)\n"), obj->stptr,
                      dlerror());

        fun = tree_eval(tree->rnode->lnode);
        force_string(fun);

        func = (NODE *(*) P((NODE *, void *))) dlsym(dl, fun->stptr);
        if (func == NULL)
                fatal(_("extension: library `%s': cannot call function `%s' (%s)\n"),
                                obj->stptr, fun->stptr, dlerror());
        free_temp(obj);
        free_temp(fun);

        return (*func)(tree, dl);
}

/* make_builtin --- register name to be called as func with a builtin body */

void
make_builtin(char *name, NODE *(*func) P((NODE *)), int count)
{
        NODE *p, *b, *f;
        char **vnames, *parm_names, *sp;
        char c, buf[200];
        int space_needed, i;

        sp = name;
        if (sp == NULL || *sp == '\0')
                fatal(_("extension: missing function name")); 

        while ((c = *sp++) != '\0')
                if ((sp == &name[1] && c != '_' && ! ISALPHA(c))
                                || (sp > &name[1] && ! is_identchar(c)))
                        fatal(_("extension: illegal character `%c' in function name `%s'"), c, name);

        f = lookup(name);
        if (f != NULL) {
                if (f->type == Node_func) {
                        if (f->rnode->type != Node_builtin)                     /* user-defined function */
                                fatal(_("extension: can't redefine function `%s'"), name);
                        else {
                                /* multiple extension() calls etc. */ 
                                if (do_lint)
                                        lintwarn(_("extension: function `%s' already defined"), name);
                                return;
                        }
                } else {
                        if (check_special(name) >= 0)
                                fatal(_("extension: can't use gawk built-in `%s' as function name"), name); 
                        /* variable name etc. */ 
                        fatal(_("extension: function name `%s' previously defined"), name);
                }
        }

        /* count parameters, create artificial list of param names */
        space_needed = 0;
        for (i = 0; i < count; i++) {
                sprintf(buf, "p%d", i);
                space_needed += strlen(buf) + 1;
        }
        emalloc(parm_names, char *, space_needed, "make_builtin");
        emalloc(vnames, char **, count * sizeof(char  *), "make_builtin");
        sp = parm_names;
        for (i = 0; i < count; i++) {
                sprintf(sp, "p%d",i);
                vnames[i] = sp;
                sp += strlen(sp) + 1;
        }

        getnode(p);
        p->type = Node_param_list;
        p->flags |= FUNC;
        p->rnode = NULL;
        p->param = name;
        p->param_cnt = count;
#if 0
        /* setting these  blows away the param_cnt. dang unions! */
        p->source_line = __LINE__;
        p->source_file = __FILE__;
#endif

        getnode(b);
        b->type = Node_builtin;
        b->builtin = func;
        b->subnode = p;
        b->source_line = __LINE__;
        b->source_file = __FILE__;

        f = node(p, Node_func, b);
        f->parmlist = vnames;
        install(name, f);
}

/* get_argument --- Get the n'th argument of a dynamically linked function */

NODE *
get_argument(NODE *tree, int i)
{
        extern NODE **stack_ptr;
        int actual_args;

        actual_args = get_curfunc_arg_count();
        if (i < 0 || i >= tree->param_cnt || i >= actual_args)
                return NULL;

        tree = stack_ptr[i];
        if (tree->type == Node_array_ref)
                tree = tree->orig_array;
        if (tree->type == Node_var_new || tree->type == Node_var_array)
                return tree;

        return tree->lnode;
}

/* get_actual_argument --- get a scalar or array, allowed to be optional */

NODE *
get_actual_argument(NODE *tree, unsigned int i, int optional, int want_array)
{
        /* optional : if TRUE and i th argument not present return NULL, else fatal. */

        NODE *t;

        t = get_argument(tree, i);

        if (t == NULL) {
                if (i >= tree->param_cnt)               /* must be fatal */
                        fatal(_("function `%s' defined to take no more than %d argument(s)"),
                                        tree->param, tree->param_cnt);
                if (! optional)
                        fatal(_("function `%s': missing argument #%d"),
                                        tree->param, i + 1);
                return NULL;
        }

        if (t->type == Node_var_new)
                return (want_array ? get_array(t) : tree_eval(t));

        if (want_array) {
                if (t->type != Node_var_array)
                        fatal(_("function `%s': argument #%d: attempt to use scalar as an array"),
                                tree->param, i + 1);
        } else {
                if (t->type != Node_val)
                        fatal(_("function `%s': argument #%d: attempt to use array as a scalar"),
                                tree->param, i + 1);
        }
        return t;
}

/* set_value --- set the return value of a dynamically linked function */

void
set_value(NODE *tree)
{
        extern NODE *ret_node;

        if (tree)
                ret_node = tree;
        else
                ret_node = Nnull_string;
}
#else

/* do_ext --- dummy version if extensions not available */

NODE *
do_ext(NODE *tree)
{
        const char *emsg = _("Operation Not Supported");

        unref(ERRNO_node->var_value);
        ERRNO_node->var_value = make_string((char *) emsg, strlen(emsg));
        return tmp_number((AWKNUM) -1);
}
#endif