507 lines
12 KiB
C
507 lines
12 KiB
C
/* $NetBSD: setmode.c,v 1.31 2005/10/01 20:08:01 christos Exp $ */
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/*
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* Copyright (c) 1989, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Dave Borman at Cray Research, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)setmode.c 8.2 (Berkeley) 3/25/94";
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#else
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__RCSID("$NetBSD: setmode.c,v 1.31 2005/10/01 20:08:01 christos Exp $");
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#endif
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <assert.h>
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#include <ctype.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <unistd.h>
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#ifdef SETMODE_DEBUG
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#include <stdio.h>
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#endif
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#ifdef __weak_alias
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__weak_alias(getmode,_getmode)
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__weak_alias(setmode,_setmode)
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#endif
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#define SET_LEN 6 /* initial # of bitcmd struct to malloc */
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#define SET_LEN_INCR 4 /* # of bitcmd structs to add as needed */
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typedef struct bitcmd {
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char cmd;
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char cmd2;
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mode_t bits;
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} BITCMD;
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#define CMD2_CLR 0x01
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#define CMD2_SET 0x02
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#define CMD2_GBITS 0x04
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#define CMD2_OBITS 0x08
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#define CMD2_UBITS 0x10
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#define _DIAGASSERT assert
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static BITCMD *addcmd (BITCMD *, mode_t, mode_t, mode_t, mode_t);
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static void compress_mode (BITCMD *);
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#ifdef SETMODE_DEBUG
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static void dumpmode (BITCMD *);
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#endif
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/*
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* Given the old mode and an array of bitcmd structures, apply the operations
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* described in the bitcmd structures to the old mode, and return the new mode.
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* Note that there is no '=' command; a strict assignment is just a '-' (clear
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* bits) followed by a '+' (set bits).
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*/
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mode_t
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getmode(bbox, omode)
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const void *bbox;
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mode_t omode;
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{
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const BITCMD *set;
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mode_t clrval, newmode, value;
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_DIAGASSERT(bbox != NULL);
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set = (const BITCMD *)bbox;
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newmode = omode;
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for (value = 0;; set++)
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switch(set->cmd) {
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/*
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* When copying the user, group or other bits around, we "know"
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* where the bits are in the mode so that we can do shifts to
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* copy them around. If we don't use shifts, it gets real
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* grundgy with lots of single bit checks and bit sets.
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*/
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case 'u':
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value = (newmode & S_IRWXU) >> 6;
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goto common;
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case 'g':
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value = (newmode & S_IRWXG) >> 3;
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goto common;
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case 'o':
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value = newmode & S_IRWXO;
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common: if (set->cmd2 & CMD2_CLR) {
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clrval =
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(set->cmd2 & CMD2_SET) ? S_IRWXO : value;
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if (set->cmd2 & CMD2_UBITS)
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newmode &= ~((clrval<<6) & set->bits);
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if (set->cmd2 & CMD2_GBITS)
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newmode &= ~((clrval<<3) & set->bits);
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if (set->cmd2 & CMD2_OBITS)
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newmode &= ~(clrval & set->bits);
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}
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if (set->cmd2 & CMD2_SET) {
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if (set->cmd2 & CMD2_UBITS)
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newmode |= (value<<6) & set->bits;
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if (set->cmd2 & CMD2_GBITS)
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newmode |= (value<<3) & set->bits;
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if (set->cmd2 & CMD2_OBITS)
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newmode |= value & set->bits;
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}
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break;
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case '+':
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newmode |= set->bits;
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break;
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case '-':
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newmode &= ~set->bits;
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break;
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case 'X':
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if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
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newmode |= set->bits;
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break;
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case '\0':
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default:
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#ifdef SETMODE_DEBUG
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(void)printf("getmode:%04o -> %04o\n", omode, newmode);
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#endif
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return (newmode);
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}
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}
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#define ADDCMD(a, b, c, d) do { \
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if (set >= endset) { \
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BITCMD *newset; \
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setlen += SET_LEN_INCR; \
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newset = realloc(saveset, sizeof(BITCMD) * setlen); \
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if (newset == NULL) \
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goto out; \
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set = newset + (set - saveset); \
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saveset = newset; \
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endset = newset + (setlen - 2); \
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} \
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set = addcmd(set, (mode_t)(a), (mode_t)(b), (mode_t)(c), (d)); \
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} while (/*CONSTCOND*/0)
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#define STANDARD_BITS (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
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void *
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setmode(p)
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const char *p;
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{
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int serrno;
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char op, *ep;
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BITCMD *set, *saveset, *endset;
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sigset_t signset, sigoset;
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mode_t mask, perm, permXbits, who;
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long lval;
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int equalopdone = 0; /* pacify gcc */
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int setlen;
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if (!*p) {
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errno = EINVAL;
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return NULL;
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}
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/*
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* Get a copy of the mask for the permissions that are mask relative.
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* Flip the bits, we want what's not set. Since it's possible that
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* the caller is opening files inside a signal handler, protect them
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* as best we can.
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*/
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sigfillset(&signset);
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(void)sigprocmask(SIG_BLOCK, &signset, &sigoset);
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(void)umask(mask = umask(0));
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mask = ~mask;
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(void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
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setlen = SET_LEN + 2;
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if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
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return (NULL);
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saveset = set;
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endset = set + (setlen - 2);
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/*
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* If an absolute number, get it and return; disallow non-octal digits
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* or illegal bits.
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*/
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if (isdigit((unsigned char)*p)) {
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errno = 0;
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lval = strtol(p, &ep, 8);
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if (*ep) {
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errno = EINVAL;
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goto out;
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}
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if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
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goto out;
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if (lval & ~(STANDARD_BITS
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#ifdef S_ISTXT
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|S_ISTXT
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#endif
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)) {
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errno = EINVAL;
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goto out;
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}
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perm = (mode_t)lval;
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ADDCMD('=', (STANDARD_BITS
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#ifdef S_ISTXT
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|S_ISTXT
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#endif
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), perm, mask);
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set->cmd = 0;
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return (saveset);
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}
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/*
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* Build list of structures to set/clear/copy bits as described by
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* each clause of the symbolic mode.
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*/
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for (;;) {
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/* First, find out which bits might be modified. */
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for (who = 0;; ++p) {
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switch (*p) {
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case 'a':
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who |= STANDARD_BITS;
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break;
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case 'u':
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who |= S_ISUID|S_IRWXU;
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break;
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case 'g':
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who |= S_ISGID|S_IRWXG;
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break;
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case 'o':
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who |= S_IRWXO;
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break;
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default:
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goto getop;
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}
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}
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getop:
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op = *p;
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p++;
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if (op != '+' && op != '-' && op != '=') {
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errno = EINVAL;
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goto out;
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}
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if (op == '=')
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equalopdone = 0;
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#ifdef S_ISTXT
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who &= ~S_ISTXT;
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#endif
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for (perm = 0, permXbits = 0;; ++p) {
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switch (*p) {
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case 'r':
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perm |= S_IRUSR|S_IRGRP|S_IROTH;
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break;
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case 's':
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/*
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* If specific bits where requested and
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* only "other" bits ignore set-id.
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*/
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if (who == 0 || (who & ~S_IRWXO))
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perm |= S_ISUID|S_ISGID;
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break;
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#ifdef S_ISTXT
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case 't':
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/*
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* If specific bits where requested and
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* only "other" bits ignore set-id.
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*/
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if (who == 0 || (who & ~S_IRWXO)) {
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who |= S_ISTXT;
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perm |= S_ISTXT;
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}
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#endif
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break;
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case 'w':
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perm |= S_IWUSR|S_IWGRP|S_IWOTH;
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break;
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case 'X':
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permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
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break;
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case 'x':
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perm |= S_IXUSR|S_IXGRP|S_IXOTH;
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break;
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case 'u':
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case 'g':
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case 'o':
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/*
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* When ever we hit 'u', 'g', or 'o', we have
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* to flush out any partial mode that we have,
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* and then do the copying of the mode bits.
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*/
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if (perm) {
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ADDCMD(op, who, perm, mask);
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perm = 0;
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}
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if (op == '=')
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equalopdone = 1;
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if (op == '+' && permXbits) {
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ADDCMD('X', who, permXbits, mask);
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permXbits = 0;
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}
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ADDCMD(*p, who, op, mask);
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break;
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default:
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/*
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* Add any permissions that we haven't already
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* done.
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*/
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if (perm || (op == '=' && !equalopdone)) {
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if (op == '=')
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equalopdone = 1;
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ADDCMD(op, who, perm, mask);
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perm = 0;
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}
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if (permXbits) {
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ADDCMD('X', who, permXbits, mask);
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permXbits = 0;
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}
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goto apply;
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}
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}
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apply: if (!*p)
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break;
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if (*p != ',')
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goto getop;
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++p;
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}
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set->cmd = 0;
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#ifdef SETMODE_DEBUG
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(void)printf("Before compress_mode()\n");
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dumpmode(saveset);
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#endif
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compress_mode(saveset);
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#ifdef SETMODE_DEBUG
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(void)printf("After compress_mode()\n");
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dumpmode(saveset);
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#endif
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return (saveset);
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out:
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serrno = errno;
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free(saveset);
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errno = serrno;
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return NULL;
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}
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static BITCMD *
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addcmd(BITCMD *set, mode_t op, mode_t who, mode_t oparg, mode_t mask)
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{
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_DIAGASSERT(set != NULL);
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switch (op) {
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case '=':
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set->cmd = '-';
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set->bits = who ? who : STANDARD_BITS;
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set++;
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op = '+';
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/* FALLTHROUGH */
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case '+':
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case '-':
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case 'X':
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set->cmd = op;
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set->bits = (who ? who : mask) & oparg;
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break;
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case 'u':
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case 'g':
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case 'o':
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set->cmd = op;
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if (who) {
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set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
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((who & S_IRGRP) ? CMD2_GBITS : 0) |
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((who & S_IROTH) ? CMD2_OBITS : 0);
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set->bits = (mode_t)~0;
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} else {
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set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
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set->bits = mask;
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}
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if (oparg == '+')
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set->cmd2 |= CMD2_SET;
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else if (oparg == '-')
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set->cmd2 |= CMD2_CLR;
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else if (oparg == '=')
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set->cmd2 |= CMD2_SET|CMD2_CLR;
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break;
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}
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return (set + 1);
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}
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#ifdef SETMODE_DEBUG
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static void
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dumpmode(set)
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BITCMD *set;
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{
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_DIAGASSERT(set != NULL);
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for (; set->cmd; ++set)
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(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
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set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
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set->cmd2 & CMD2_CLR ? " CLR" : "",
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set->cmd2 & CMD2_SET ? " SET" : "",
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set->cmd2 & CMD2_UBITS ? " UBITS" : "",
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set->cmd2 & CMD2_GBITS ? " GBITS" : "",
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set->cmd2 & CMD2_OBITS ? " OBITS" : "");
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}
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#endif
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/*
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* Given an array of bitcmd structures, compress by compacting consecutive
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* '+', '-' and 'X' commands into at most 3 commands, one of each. The 'u',
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* 'g' and 'o' commands continue to be separate. They could probably be
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* compacted, but it's not worth the effort.
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*/
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static void
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compress_mode(set)
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BITCMD *set;
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{
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BITCMD *nset;
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int setbits, clrbits, Xbits, op;
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_DIAGASSERT(set != NULL);
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for (nset = set;;) {
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/* Copy over any 'u', 'g' and 'o' commands. */
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while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
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*set++ = *nset++;
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if (!op)
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return;
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}
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for (setbits = clrbits = Xbits = 0;; nset++) {
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if ((op = nset->cmd) == '-') {
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clrbits |= nset->bits;
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setbits &= ~nset->bits;
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Xbits &= ~nset->bits;
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} else if (op == '+') {
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setbits |= nset->bits;
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clrbits &= ~nset->bits;
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Xbits &= ~nset->bits;
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} else if (op == 'X')
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Xbits |= nset->bits & ~setbits;
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else
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break;
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}
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if (clrbits) {
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set->cmd = '-';
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set->cmd2 = 0;
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set->bits = clrbits;
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set++;
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}
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if (setbits) {
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set->cmd = '+';
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set->cmd2 = 0;
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set->bits = setbits;
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set++;
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}
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if (Xbits) {
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set->cmd = 'X';
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set->cmd2 = 0;
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set->bits = Xbits;
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set++;
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}
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}
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}
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