alias.c

/*-
 * 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 <stdlib.h>
#include "shell.h"
#include "output.h"
#include "error.h"
#include "memalloc.h"
#include "mystring.h"
#include "alias.h"
#include "options.h"
#include "builtins.h"

#define ATABSIZE 39

static struct alias *atab[ATABSIZE];
static int aliases;

static void setalias(const char *, const char *);
static int unalias(const char *);
static size_t hashalias(const char *);

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

	unalias(name);
	app = &atab[hashalias(name)];
	INTOFF;
	ap = ckmalloc(sizeof (struct alias));
	ap->name = savestr(name);
	ap->val = savestr(val);
	ap->flag = 0;
	ap->next = *app;
	*app = ap;
	aliases++;
	INTON;
}

static void
freealias(struct alias *ap)
{
	ckfree(ap->name);
	ckfree(ap->val);
	ckfree(ap);
}

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

	app = &atab[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;
				freealias(ap);
				INTON;
			}
			aliases--;
			return (0);
		}
	}

	return (1);
}

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

	INTOFF;
	for (i = 0; i < ATABSIZE; i++) {
		app = &atab[i];
		while (*app) {
			ap = *app;
			if (ap->flag & ALIASINUSE) {
				*ap->name = '\0';
				app = &(*app)->next;
			} else {
				*app = ap->next;
				freealias(ap);
			}
		}
	}
	aliases = 0;
	INTON;
}

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

	if (aliases == 0)
		return (NULL);
	for (ap = atab[hashalias(name)]; ap; ap = ap->next) {
		if (equal(name, ap->name)) {
			if (check && (ap->flag & ALIASINUSE))
				return (NULL);
			return (ap);
		}
	}

	return (NULL);
}

static int
comparealiases(const void *p1, const void *p2)
{
	const struct alias *const *a1 = p1;
	const struct alias *const *a2 = p2;

	return strcmp((*a1)->name, (*a2)->name);
}

static void
printalias(const struct alias *a)
{
	out1fmt("%s=", a->name);
	out1qstr(a->val);
	out1c('\n');
}

static void
printaliases(void)
{
	int i, j;
	struct alias **sorted, *ap;

	INTOFF;
	sorted = ckmalloc(aliases * sizeof(*sorted));
	j = 0;
	for (i = 0; i < ATABSIZE; i++)
		for (ap = atab[i]; ap; ap = ap->next)
			if (*ap->name != '\0')
				sorted[j++] = ap;
	qsort(sorted, aliases, sizeof(*sorted), comparealiases);
	for (i = 0; i < aliases; i++) {
		printalias(sorted[i]);
		if (int_pending())
			break;
	}
	ckfree(sorted);
	INTON;
}

int
aliascmd(int argc __unused, char **argv __unused)
{
	char *n, *v;
	int ret = 0;
	struct alias *ap;

	nextopt("");

	if (*argptr == NULL) {
		printaliases();
		return (0);
	}
	while ((n = *argptr++) != NULL) {
		if (n[0] == '\0') {
			warning("'': not found");
			ret = 1;
			continue;
		}
		if ((v = strchr(n+1, '=')) == NULL) /* n+1: funny ksh stuff */
			if ((ap = lookupalias(n, 0)) == NULL) {
				warning("%s: not found", n);
				ret = 1;
			} else
				printalias(ap);
		else {
			*v++ = '\0';
			setalias(n, v);
		}
	}

	return (ret);
}

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

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

	return (i);
}

static size_t
hashalias(const char *p)
{
	unsigned int hashval;

	hashval = (unsigned char)*p << 4;
	while (*p)
		hashval+= *p++;
	return (hashval % ATABSIZE);
}

const struct alias *
iteralias(const struct alias *index)
{
	size_t i = 0;

	if (index != NULL) {
		if (index->next != NULL)
			return (index->next);
		i = hashalias(index->name) + 1;
	}
	for (; i < ATABSIZE; i++)
		if (atab[i] != NULL)
			return (atab[i]);

	return (NULL);
}