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mirror of https://git.FreeBSD.org/src.git synced 2024-12-28 11:57:28 +00:00
freebsd/bin/sh/alias.c
Jilles Tjoelker 026dfd4aef sh: Fix use after free when resetting an in-use alias.
The special case of modifying an existing alias does not work correctly if
the alias is currently in use. Instead, handle this case by unaliasing the
old alias (if any) and then creating a new alias.
2017-04-16 22:10:02 +00:00

257 lines
5.3 KiB
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.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#)alias.c 8.3 (Berkeley) 5/4/95";
#endif
#endif /* not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#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 struct alias **hashalias(const char *);
static
void
setalias(const char *name, const char *val)
{
struct alias *ap, **app;
unalias(name);
app = 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 = 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 = *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 ((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 struct alias **
hashalias(const char *p)
{
unsigned int hashval;
hashval = (unsigned char)*p << 4;
while (*p)
hashval+= *p++;
return &atab[hashval % ATABSIZE];
}