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/*  $NetBSD: setmode.c,v 1.28 2000/01/25 15:43:43 enami Exp $   */

/*

 * Copyright (c) 1989, 1993, 1994

 *  The Regents of the University of California.  All rights reserved.

 *

 * This code is derived from software contributed to Berkeley by

 * Dave Borman at Cray Research, Inc.

 *

 * 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. All advertising materials mentioning features or use of this software

 *    must display the following acknowledgement:

 *  This product includes software developed by the University of

 *  California, Berkeley and its contributors.

 * 4. 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>

#if defined(LIBC_SCCS) && !defined(lint)

#if 0

static char sccsid[] = "@(#)setmode.c   8.2 (Berkeley) 3/25/94";

#else

__RCSID("$NetBSD: setmode.c,v 1.28 2000/01/25 15:43:43 enami Exp $");

#endif

#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>

#include <sys/stat.h>

#include <assert.h>

#include <ctype.h>

#include <errno.h>

#include <signal.h>

#include <stdlib.h>

#include <unistd.h>

#ifdef SETMODE_DEBUG

#include <stdio.h>

#endif

#ifdef __weak_alias

__weak_alias(getmode,_getmode)

__weak_alias(setmode,_setmode)

#endif

#ifdef __GLIBC__

#define S_ISTXT __S_ISVTX

#endif

#define SET_LEN 6       /* initial # of bitcmd struct to malloc */

#define SET_LEN_INCR 4      /* # of bitcmd structs to add as needed */

typedef struct bitcmd {

    char    cmd;

    char    cmd2;

    mode_t  bits;

} BITCMD;

#define CMD2_CLR    0x01

#define CMD2_SET    0x02

#define CMD2_GBITS  0x04

#define CMD2_OBITS  0x08

#define CMD2_UBITS  0x10

static BITCMD   *addcmd (BITCMD *, int, int, int, u_int);

static void  compress_mode (BITCMD *);

#ifdef SETMODE_DEBUG

static void  dumpmode (BITCMD *);

#endif

/*

 * Given the old mode and an array of bitcmd structures, apply the operations

 * described in the bitcmd structures to the old mode, and return the new mode.

 * Note that there is no '=' command; a strict assignment is just a '-' (clear

 * bits) followed by a '+' (set bits).

 */

mode_t

getmode(bbox, omode)

    const void *bbox;

    mode_t omode;

{

    const BITCMD *set;

    mode_t clrval, newmode, value;

    _DIAGASSERT(bbox != NULL);

    set = (const BITCMD *)bbox;

    newmode = omode;

    for (value = 0;; set++)

        switch(set->cmd) {

        /*

         * When copying the user, group or other bits around, we "know"

         * where the bits are in the mode so that we can do shifts to

         * copy them around.  If we don't use shifts, it gets real

         * grundgy with lots of single bit checks and bit sets.

         */

        case 'u':

            value = (newmode & S_IRWXU) >> 6;

            goto common;

        case 'g':

            value = (newmode & S_IRWXG) >> 3;

            goto common;

        case 'o':

            value = newmode & S_IRWXO;

common:         if (set->cmd2 & CMD2_CLR) {

                clrval =

                    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;

                if (set->cmd2 & CMD2_UBITS)

                    newmode &= ~((clrval<<6) & set->bits);

                if (set->cmd2 & CMD2_GBITS)

                    newmode &= ~((clrval<<3) & set->bits);

                if (set->cmd2 & CMD2_OBITS)

                    newmode &= ~(clrval & set->bits);

            }

            if (set->cmd2 & CMD2_SET) {

                if (set->cmd2 & CMD2_UBITS)

                    newmode |= (value<<6) & set->bits;

                if (set->cmd2 & CMD2_GBITS)

                    newmode |= (value<<3) & set->bits;

                if (set->cmd2 & CMD2_OBITS)

                    newmode |= value & set->bits;

            }

            break;

        case '+':

            newmode |= set->bits;

            break;

        case '-':

            newmode &= ~set->bits;

            break;

        case 'X':

            if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))

                newmode |= set->bits;

            break;

        case '\0':

        default:

#ifdef SETMODE_DEBUG

            (void)printf("getmode:%04o -> %04o\n", omode, newmode);

#endif

            return (newmode);

        }

}

#define ADDCMD(a, b, c, d) do {                     \

    if (set >= endset) {                        \

        BITCMD *newset;                     \

        setlen += SET_LEN_INCR;                 \

        newset = realloc(saveset, sizeof(BITCMD) * setlen); \

        if (newset == NULL) {                   \

            free(saveset);                  \

            return (NULL);                  \

        }                           \

        set = newset + (set - saveset);             \

        saveset = newset;                   \

        endset = newset + (setlen - 2);             \

    }                               \

    set = addcmd(set, (a), (b), (c), (d));              \

} while (/*CONSTCOND*/0)

#define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)

void *

setmode(p)

    const char *p;

{

    int perm, who;

    char op, *ep;

    BITCMD *set, *saveset, *endset;

    sigset_t sigset, sigoset;

    mode_t mask;

    int equalopdone = 0;    /* pacify gcc */

    int permXbits, setlen;

    if (!*p)

        return (NULL);

    /*

     * Get a copy of the mask for the permissions that are mask relative.

     * Flip the bits, we want what's not set.  Since it's possible that

     * the caller is opening files inside a signal handler, protect them

     * as best we can.

     */

    sigfillset(&sigset);

    (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);

    (void)umask(mask = umask(0));

    mask = ~mask;

    (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);

    setlen = SET_LEN + 2;

    if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)

        return (NULL);

    saveset = set;

    endset = set + (setlen - 2);

    /*

     * If an absolute number, get it and return; disallow non-octal digits

     * or illegal bits.

     */

    if (isdigit((unsigned char)*p)) {

        perm = (mode_t)strtol(p, &ep, 8);

        if (*ep || perm & ~(STANDARD_BITS|S_ISTXT)) {

            free(saveset);

            return (NULL);

        }

        ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);

        set->cmd = 0;

        return (saveset);

    }

    /*

     * Build list of structures to set/clear/copy bits as described by

     * each clause of the symbolic mode.

     */

    for (;;) {

        /* First, find out which bits might be modified. */

        for (who = 0;; ++p) {

            switch (*p) {

            case 'a':

                who |= STANDARD_BITS;

                break;

            case 'u':

                who |= S_ISUID|S_IRWXU;

                break;

            case 'g':

                who |= S_ISGID|S_IRWXG;

                break;

            case 'o':

                who |= S_IRWXO;

                break;

            default:

                goto getop;

            }

        }

getop:      if ((op = *p++) != '+' && op != '-' && op != '=') {

            free(saveset);

            return (NULL);

        }

        if (op == '=')

            equalopdone = 0;

        who &= ~S_ISTXT;

        for (perm = 0, permXbits = 0;; ++p) {

            switch (*p) {

            case 'r':

                perm |= S_IRUSR|S_IRGRP|S_IROTH;

                break;

            case 's':

                /*

                 * If specific bits where requested and

                 * only "other" bits ignore set-id.

                 */

                if (who == 0 || (who & ~S_IRWXO))

                    perm |= S_ISUID|S_ISGID;

                break;

            case 't':

                /*

                 * If specific bits where requested and

                 * only "other" bits ignore set-id.

                 */

                if (who == 0 || (who & ~S_IRWXO)) {

                    who |= S_ISTXT;

                    perm |= S_ISTXT;

                }

                break;

            case 'w':

                perm |= S_IWUSR|S_IWGRP|S_IWOTH;

                break;

            case 'X':

                permXbits = S_IXUSR|S_IXGRP|S_IXOTH;

                break;

            case 'x':

                perm |= S_IXUSR|S_IXGRP|S_IXOTH;

                break;

            case 'u':

            case 'g':

            case 'o':

                /*

                 * When ever we hit 'u', 'g', or 'o', we have

                 * to flush out any partial mode that we have,

                 * and then do the copying of the mode bits.

                 */

                if (perm) {

                    ADDCMD(op, who, perm, mask);

                    perm = 0;

                }

                if (op == '=')

                    equalopdone = 1;

                if (op == '+' && permXbits) {

                    ADDCMD('X', who, permXbits, mask);

                    permXbits = 0;

                }

                ADDCMD(*p, who, op, mask);

                break;

            default:

                /*

                 * Add any permissions that we haven't already

                 * done.

                 */

                if (perm || (op == '=' && !equalopdone)) {

                    if (op == '=')

                        equalopdone = 1;

                    ADDCMD(op, who, perm, mask);

                    perm = 0;

                }

                if (permXbits) {

                    ADDCMD('X', who, permXbits, mask);

                    permXbits = 0;

                }

                goto apply;

            }

        }

apply:      if (!*p)

            break;

        if (*p != ',')

            goto getop;

        ++p;

    }

    set->cmd = 0;

#ifdef SETMODE_DEBUG

    (void)printf("Before compress_mode()\n");

    dumpmode(saveset);

#endif

    compress_mode(saveset);

#ifdef SETMODE_DEBUG

    (void)printf("After compress_mode()\n");

    dumpmode(saveset);

#endif

    return (saveset);

}

static BITCMD *

addcmd(set, op, who, oparg, mask)

    BITCMD *set;

    int oparg, who;

    int op;

    u_int mask;

{

    _DIAGASSERT(set != NULL);

    switch (op) {

    case '=':

        set->cmd = '-';

        set->bits = who ? who : STANDARD_BITS;

        set++;

        op = '+';

        /* FALLTHROUGH */

    case '+':

    case '-':

    case 'X':

        set->cmd = op;

        set->bits = (who ? who : mask) & oparg;

        break;

    case 'u':

    case 'g':

    case 'o':

        set->cmd = op;

        if (who) {

            set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |

                    ((who & S_IRGRP) ? CMD2_GBITS : 0) |

                    ((who & S_IROTH) ? CMD2_OBITS : 0);

            set->bits = (mode_t)~0;

        } else {

            set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;

            set->bits = mask;

        }

        if (oparg == '+')

            set->cmd2 |= CMD2_SET;

        else if (oparg == '-')

            set->cmd2 |= CMD2_CLR;

        else if (oparg == '=')

            set->cmd2 |= CMD2_SET|CMD2_CLR;

        break;

    }

    return (set + 1);

}

#ifdef SETMODE_DEBUG

static void

dumpmode(set)

    BITCMD *set;

{

    _DIAGASSERT(set != NULL);

    for (; set->cmd; ++set)

        (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",

            set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",

            set->cmd2 & CMD2_CLR ? " CLR" : "",

            set->cmd2 & CMD2_SET ? " SET" : "",

            set->cmd2 & CMD2_UBITS ? " UBITS" : "",

            set->cmd2 & CMD2_GBITS ? " GBITS" : "",

            set->cmd2 & CMD2_OBITS ? " OBITS" : "");

}

#endif

/*

 * Given an array of bitcmd structures, compress by compacting consecutive

 * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',

 * 'g' and 'o' commands continue to be separate.  They could probably be

 * compacted, but it's not worth the effort.

 */

static void

compress_mode(set)

    BITCMD *set;

{

    BITCMD *nset;

    int setbits, clrbits, Xbits, op;

    _DIAGASSERT(set != NULL);

    for (nset = set;;) {

        /* Copy over any 'u', 'g' and 'o' commands. */

        while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {

            *set++ = *nset++;

            if (!op)

                return;

        }

        for (setbits = clrbits = Xbits = 0;; nset++) {

            if ((op = nset->cmd) == '-') {

                clrbits |= nset->bits;

                setbits &= ~nset->bits;

                Xbits &= ~nset->bits;

            } else if (op == '+') {

                setbits |= nset->bits;

                clrbits &= ~nset->bits;

                Xbits &= ~nset->bits;

            } else if (op == 'X')

                Xbits |= nset->bits & ~setbits;

            else

                break;

        }

        if (clrbits) {

            set->cmd = '-';

            set->cmd2 = 0;

            set->bits = clrbits;

            set++;

        }

        if (setbits) {

            set->cmd = '+';

            set->cmd2 = 0;

            set->bits = setbits;

            set++;

        }

        if (Xbits) {

            set->cmd = 'X';

            set->cmd2 = 0;

            set->bits = Xbits;

            set++;

        }

    }

}