source: trunk/ash/alias.c@ 3211

/*      $NetBSD: alias.c,v 1.12 2003/08/07 09:05:29 agc Exp $   */

/*-
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)alias.c     8.3 (Berkeley) 5/4/95";
#else
__RCSID("$NetBSD: alias.c,v 1.12 2003/08/07 09:05:29 agc Exp $");
#endif
#endif /* not lint */

#include <stdlib.h>
#include "shell.h"
#include "input.h"
#include "output.h"
#include "error.h"
#include "memalloc.h"
#include "mystring.h"
#include "alias.h"
#include "options.h"    /* XXX for argptr (should remove?) */
#include "var.h"

#define ATABSIZE 39

struct alias *atab[ATABSIZE];

STATIC void setalias(char *, char *);
STATIC int unalias(char *);
STATIC struct alias **hashalias(char *);

STATIC
void
setalias(char *name, char *val)
{
        struct alias *ap, **app;

        app = hashalias(name);
        for (ap = *app; ap; ap = ap->next) {
                if (equal(name, ap->name)) {
                        INTOFF;
                        ckfree(ap->val);
                        ap->val = savestr(val);
                        INTON;
                        return;
                }
        }
        /* not found */
        INTOFF;
        ap = ckmalloc(sizeof (struct alias));
        ap->name = savestr(name);
        /*
         * XXX - HACK: in order that the parser will not finish reading the
         * alias value off the input before processing the next alias, we
         * dummy up an extra space at the end of the alias.  This is a crock
         * and should be re-thought.  The idea (if you feel inclined to help)
         * is to avoid alias recursions.  The mechanism used is: when
         * expanding an alias, the value of the alias is pushed back on the
         * input as a string and a pointer to the alias is stored with the
         * string.  The alias is marked as being in use.  When the input
         * routine finishes reading the string, it markes the alias not
         * in use.  The problem is synchronization with the parser.  Since
         * it reads ahead, the alias is marked not in use before the
         * resulting token(s) is next checked for further alias sub.  The
         * H A C K is that we add a little fluff after the alias value
         * so that the string will not be exhausted.  This is a good
         * idea ------- ***NOT***
         */
#ifdef notyet
        ap->val = savestr(val);
#else /* hack */
        {
        int len = strlen(val);
        ap->val = ckmalloc(len + 2);
        memcpy(ap->val, val, len);
        ap->val[len] = ' ';     /* fluff */
        ap->val[len+1] = '\0';
        }
#endif
        ap->next = *app;
        *app = ap;
        INTON;
}

STATIC int
unalias(char *name)
{
        struct alias *ap, **app;

        app = hashalias(name);

        for (ap = *app; ap; app = &(ap->next), ap = ap->next) {
                if (equal(name, ap->name)) {
                        /*
                         * if the alias is currently in use (i.e. its
                         * buffer is being used by the input routine) we
                         * just null out the name instead of freeing it.
                         * We could clear it out later, but this situation
                         * is so rare that it hardly seems worth it.
                         */
                        if (ap->flag & ALIASINUSE)
                                *ap->name = '\0';
                        else {
                                INTOFF;
                                *app = ap->next;
                                ckfree(ap->name);
                                ckfree(ap->val);
                                ckfree(ap);
                                INTON;
                        }
                        return (0);
                }
        }

        return (1);
}

#ifdef mkinit
MKINIT void rmaliases(void);

SHELLPROC {
        rmaliases();
}
#endif

void
rmaliases(void)
{
        struct alias *ap, *tmp;
        int i;

        INTOFF;
        for (i = 0; i < ATABSIZE; i++) {
                ap = atab[i];
                atab[i] = NULL;
                while (ap) {
                        ckfree(ap->name);
                        ckfree(ap->val);
                        tmp = ap;
                        ap = ap->next;
                        ckfree(tmp);
                }
        }
        INTON;
}

struct alias *
lookupalias(char *name, int check)
{
        struct alias *ap = *hashalias(name);

        for (; ap; ap = ap->next) {
                if (equal(name, ap->name)) {
                        if (check && (ap->flag & ALIASINUSE))
                                return (NULL);
                        return (ap);
                }
        }

        return (NULL);
}

char *
get_alias_text(char *name)
{
        struct alias *ap;

        ap = lookupalias(name, 0);
        if (ap == NULL)
                return NULL;
        return ap->val;
}

/*
 * TODO - sort output
 */
int
aliascmd(int argc, char **argv)
{
        char *n, *v;
        int ret = 0;
        struct alias *ap;

        if (argc == 1) {
                int i;

                for (i = 0; i < ATABSIZE; i++)
                        for (ap = atab[i]; ap; ap = ap->next) {
                                if (*ap->name != '\0') {
                                        out1fmt("alias %s=", ap->name);
                                        print_quoted(ap->val);
                                        out1c('\n');
                                }
                        }
                return (0);
        }
        while ((n = *++argv) != NULL) {
                if ((v = strchr(n+1, '=')) == NULL) { /* n+1: funny ksh stuff */
                        if ((ap = lookupalias(n, 0)) == NULL) {
                                outfmt(out2, "alias: %s not found\n", n);
                                ret = 1;
                        } else {
                                out1fmt("alias %s=", n);
                                print_quoted(ap->val);
                                out1c('\n');
                        }
                } else {
                        *v++ = '\0';
                        setalias(n, v);
                }
        }

        return (ret);
}

int
unaliascmd(int argc, char **argv)
{
        int i;

        while ((i = nextopt("a")) != '\0') {
                if (i == 'a') {
                        rmaliases();
                        return (0);
                }
        }
        for (i = 0; *argptr; argptr++)
                i = unalias(*argptr);

        return (i);
}

STATIC struct alias **
hashalias(char *p)
{
        unsigned int hashval;

        hashval = *p << 4;
        while (*p)
                hashval+= *p++;
        return &atab[hashval % ATABSIZE];
}