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  1. /*  $NetBSD: setmode.c,v 1.28 2000/01/25 15:43:43 enami Exp $   */
  2.  
  3. /*
  4.  * Copyright (c) 1989, 1993, 1994
  5.  *  The Regents of the University of California.  All rights reserved.
  6.  *
  7.  * This code is derived from software contributed to Berkeley by
  8.  * Dave Borman at Cray Research, Inc.
  9.  *
  10.  * Redistribution and use in source and binary forms, with or without
  11.  * modification, are permitted provided that the following conditions
  12.  * are met:
  13.  * 1. Redistributions of source code must retain the above copyright
  14.  *    notice, this list of conditions and the following disclaimer.
  15.  * 2. Redistributions in binary form must reproduce the above copyright
  16.  *    notice, this list of conditions and the following disclaimer in the
  17.  *    documentation and/or other materials provided with the distribution.
  18.  * 3. All advertising materials mentioning features or use of this software
  19.  *    must display the following acknowledgement:
  20.  *  This product includes software developed by the University of
  21.  *  California, Berkeley and its contributors.
  22.  * 4. Neither the name of the University nor the names of its contributors
  23.  *    may be used to endorse or promote products derived from this software
  24.  *    without specific prior written permission.
  25.  *
  26.  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27.  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28.  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29.  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30.  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31.  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32.  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33.  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34.  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35.  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36.  * SUCH DAMAGE.
  37.  */
  38.  
  39. #include <sys/cdefs.h>
  40. #if defined(LIBC_SCCS) && !defined(lint)
  41. #if 0
  42. static char sccsid[] = "@(#)setmode.c   8.2 (Berkeley) 3/25/94";
  43. #else
  44. __RCSID("$NetBSD: setmode.c,v 1.28 2000/01/25 15:43:43 enami Exp $");
  45. #endif
  46. #endif /* LIBC_SCCS and not lint */
  47.  
  48. #include <sys/types.h>
  49. #include <sys/stat.h>
  50.  
  51. #include <assert.h>
  52. #include <ctype.h>
  53. #include <errno.h>
  54. #include <signal.h>
  55. #include <stdlib.h>
  56. #include <unistd.h>
  57.  
  58. #ifdef SETMODE_DEBUG
  59. #include <stdio.h>
  60. #endif
  61.  
  62. #ifdef __weak_alias
  63. __weak_alias(getmode,_getmode)
  64. __weak_alias(setmode,_setmode)
  65. #endif
  66.  
  67. #ifdef __GLIBC__
  68. #define S_ISTXT __S_ISVTX
  69. #endif
  70.  
  71. #define SET_LEN 6       /* initial # of bitcmd struct to malloc */
  72. #define SET_LEN_INCR 4      /* # of bitcmd structs to add as needed */
  73.  
  74. typedef struct bitcmd {
  75.     char    cmd;
  76.     char    cmd2;
  77.     mode_t  bits;
  78. } BITCMD;
  79.  
  80. #define CMD2_CLR    0x01
  81. #define CMD2_SET    0x02
  82. #define CMD2_GBITS  0x04
  83. #define CMD2_OBITS  0x08
  84. #define CMD2_UBITS  0x10
  85.  
  86. static BITCMD   *addcmd (BITCMD *, int, int, int, u_int);
  87. static void  compress_mode (BITCMD *);
  88. #ifdef SETMODE_DEBUG
  89. static void  dumpmode (BITCMD *);
  90. #endif
  91.  
  92. /*
  93.  * Given the old mode and an array of bitcmd structures, apply the operations
  94.  * described in the bitcmd structures to the old mode, and return the new mode.
  95.  * Note that there is no '=' command; a strict assignment is just a '-' (clear
  96.  * bits) followed by a '+' (set bits).
  97.  */
  98. mode_t
  99. getmode(bbox, omode)
  100.     const void *bbox;
  101.     mode_t omode;
  102. {
  103.     const BITCMD *set;
  104.     mode_t clrval, newmode, value;
  105.  
  106.     _DIAGASSERT(bbox != NULL);
  107.  
  108.     set = (const BITCMD *)bbox;
  109.     newmode = omode;
  110.     for (value = 0;; set++)
  111.         switch(set->cmd) {
  112.         /*
  113.          * When copying the user, group or other bits around, we "know"
  114.          * where the bits are in the mode so that we can do shifts to
  115.          * copy them around.  If we don't use shifts, it gets real
  116.          * grundgy with lots of single bit checks and bit sets.
  117.          */
  118.         case 'u':
  119.             value = (newmode & S_IRWXU) >> 6;
  120.             goto common;
  121.  
  122.         case 'g':
  123.             value = (newmode & S_IRWXG) >> 3;
  124.             goto common;
  125.  
  126.         case 'o':
  127.             value = newmode & S_IRWXO;
  128. common:         if (set->cmd2 & CMD2_CLR) {
  129.                 clrval =
  130.                     (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
  131.                 if (set->cmd2 & CMD2_UBITS)
  132.                     newmode &= ~((clrval<<6) & set->bits);
  133.                 if (set->cmd2 & CMD2_GBITS)
  134.                     newmode &= ~((clrval<<3) & set->bits);
  135.                 if (set->cmd2 & CMD2_OBITS)
  136.                     newmode &= ~(clrval & set->bits);
  137.             }
  138.             if (set->cmd2 & CMD2_SET) {
  139.                 if (set->cmd2 & CMD2_UBITS)
  140.                     newmode |= (value<<6) & set->bits;
  141.                 if (set->cmd2 & CMD2_GBITS)
  142.                     newmode |= (value<<3) & set->bits;
  143.                 if (set->cmd2 & CMD2_OBITS)
  144.                     newmode |= value & set->bits;
  145.             }
  146.             break;
  147.  
  148.         case '+':
  149.             newmode |= set->bits;
  150.             break;
  151.  
  152.         case '-':
  153.             newmode &= ~set->bits;
  154.             break;
  155.  
  156.         case 'X':
  157.             if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
  158.                 newmode |= set->bits;
  159.             break;
  160.  
  161.         case '\0':
  162.         default:
  163. #ifdef SETMODE_DEBUG
  164.             (void)printf("getmode:%04o -> %04o\n", omode, newmode);
  165. #endif
  166.             return (newmode);
  167.         }
  168. }
  169.  
  170. #define ADDCMD(a, b, c, d) do {                     \
  171.     if (set >= endset) {                        \
  172.         BITCMD *newset;                     \
  173.         setlen += SET_LEN_INCR;                 \
  174.         newset = realloc(saveset, sizeof(BITCMD) * setlen); \
  175.         if (newset == NULL) {                   \
  176.             free(saveset);                  \
  177.             return (NULL);                  \
  178.         }                           \
  179.         set = newset + (set - saveset);             \
  180.         saveset = newset;                   \
  181.         endset = newset + (setlen - 2);             \
  182.     }                               \
  183.     set = addcmd(set, (a), (b), (c), (d));              \
  184. } while (/*CONSTCOND*/0)
  185.  
  186. #define STANDARD_BITS   (S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
  187.  
  188. void *
  189. setmode(p)
  190.     const char *p;
  191. {
  192.     int perm, who;
  193.     char op, *ep;
  194.     BITCMD *set, *saveset, *endset;
  195.     sigset_t sigset, sigoset;
  196.     mode_t mask;
  197.     int equalopdone = 0;    /* pacify gcc */
  198.     int permXbits, setlen;
  199.  
  200.     if (!*p)
  201.         return (NULL);
  202.  
  203.     /*
  204.      * Get a copy of the mask for the permissions that are mask relative.
  205.      * Flip the bits, we want what's not set.  Since it's possible that
  206.      * the caller is opening files inside a signal handler, protect them
  207.      * as best we can.
  208.      */
  209.     sigfillset(&sigset);
  210.     (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
  211.     (void)umask(mask = umask(0));
  212.     mask = ~mask;
  213.     (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
  214.  
  215.     setlen = SET_LEN + 2;
  216.    
  217.     if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
  218.         return (NULL);
  219.     saveset = set;
  220.     endset = set + (setlen - 2);
  221.  
  222.     /*
  223.      * If an absolute number, get it and return; disallow non-octal digits
  224.      * or illegal bits.
  225.      */
  226.     if (isdigit((unsigned char)*p)) {
  227.         perm = (mode_t)strtol(p, &ep, 8);
  228.         if (*ep || perm & ~(STANDARD_BITS|S_ISTXT)) {
  229.             free(saveset);
  230.             return (NULL);
  231.         }
  232.         ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
  233.         set->cmd = 0;
  234.         return (saveset);
  235.     }
  236.  
  237.     /*
  238.      * Build list of structures to set/clear/copy bits as described by
  239.      * each clause of the symbolic mode.
  240.      */
  241.     for (;;) {
  242.         /* First, find out which bits might be modified. */
  243.         for (who = 0;; ++p) {
  244.             switch (*p) {
  245.             case 'a':
  246.                 who |= STANDARD_BITS;
  247.                 break;
  248.             case 'u':
  249.                 who |= S_ISUID|S_IRWXU;
  250.                 break;
  251.             case 'g':
  252.                 who |= S_ISGID|S_IRWXG;
  253.                 break;
  254.             case 'o':
  255.                 who |= S_IRWXO;
  256.                 break;
  257.             default:
  258.                 goto getop;
  259.             }
  260.         }
  261.  
  262. getop:      if ((op = *p++) != '+' && op != '-' && op != '=') {
  263.             free(saveset);
  264.             return (NULL);
  265.         }
  266.         if (op == '=')
  267.             equalopdone = 0;
  268.  
  269.         who &= ~S_ISTXT;
  270.         for (perm = 0, permXbits = 0;; ++p) {
  271.             switch (*p) {
  272.             case 'r':
  273.                 perm |= S_IRUSR|S_IRGRP|S_IROTH;
  274.                 break;
  275.             case 's':
  276.                 /*
  277.                  * If specific bits where requested and
  278.                  * only "other" bits ignore set-id.
  279.                  */
  280.                 if (who == 0 || (who & ~S_IRWXO))
  281.                     perm |= S_ISUID|S_ISGID;
  282.                 break;
  283.             case 't':
  284.                 /*
  285.                  * If specific bits where requested and
  286.                  * only "other" bits ignore set-id.
  287.                  */
  288.                 if (who == 0 || (who & ~S_IRWXO)) {
  289.                     who |= S_ISTXT;
  290.                     perm |= S_ISTXT;
  291.                 }
  292.                 break;
  293.             case 'w':
  294.                 perm |= S_IWUSR|S_IWGRP|S_IWOTH;
  295.                 break;
  296.             case 'X':
  297.                 permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
  298.                 break;
  299.             case 'x':
  300.                 perm |= S_IXUSR|S_IXGRP|S_IXOTH;
  301.                 break;
  302.             case 'u':
  303.             case 'g':
  304.             case 'o':
  305.                 /*
  306.                  * When ever we hit 'u', 'g', or 'o', we have
  307.                  * to flush out any partial mode that we have,
  308.                  * and then do the copying of the mode bits.
  309.                  */
  310.                 if (perm) {
  311.                     ADDCMD(op, who, perm, mask);
  312.                     perm = 0;
  313.                 }
  314.                 if (op == '=')
  315.                     equalopdone = 1;
  316.                 if (op == '+' && permXbits) {
  317.                     ADDCMD('X', who, permXbits, mask);
  318.                     permXbits = 0;
  319.                 }
  320.                 ADDCMD(*p, who, op, mask);
  321.                 break;
  322.  
  323.             default:
  324.                 /*
  325.                  * Add any permissions that we haven't already
  326.                  * done.
  327.                  */
  328.                 if (perm || (op == '=' && !equalopdone)) {
  329.                     if (op == '=')
  330.                         equalopdone = 1;
  331.                     ADDCMD(op, who, perm, mask);
  332.                     perm = 0;
  333.                 }
  334.                 if (permXbits) {
  335.                     ADDCMD('X', who, permXbits, mask);
  336.                     permXbits = 0;
  337.                 }
  338.                 goto apply;
  339.             }
  340.         }
  341.  
  342. apply:      if (!*p)
  343.             break;
  344.         if (*p != ',')
  345.             goto getop;
  346.         ++p;
  347.     }
  348.     set->cmd = 0;
  349. #ifdef SETMODE_DEBUG
  350.     (void)printf("Before compress_mode()\n");
  351.     dumpmode(saveset);
  352. #endif
  353.     compress_mode(saveset);
  354. #ifdef SETMODE_DEBUG
  355.     (void)printf("After compress_mode()\n");
  356.     dumpmode(saveset);
  357. #endif
  358.     return (saveset);
  359. }
  360.  
  361. static BITCMD *
  362. addcmd(set, op, who, oparg, mask)
  363.     BITCMD *set;
  364.     int oparg, who;
  365.     int op;
  366.     u_int mask;
  367. {
  368.  
  369.     _DIAGASSERT(set != NULL);
  370.  
  371.     switch (op) {
  372.     case '=':
  373.         set->cmd = '-';
  374.         set->bits = who ? who : STANDARD_BITS;
  375.         set++;
  376.  
  377.         op = '+';
  378.         /* FALLTHROUGH */
  379.     case '+':
  380.     case '-':
  381.     case 'X':
  382.         set->cmd = op;
  383.         set->bits = (who ? who : mask) & oparg;
  384.         break;
  385.  
  386.     case 'u':
  387.     case 'g':
  388.     case 'o':
  389.         set->cmd = op;
  390.         if (who) {
  391.             set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
  392.                     ((who & S_IRGRP) ? CMD2_GBITS : 0) |
  393.                     ((who & S_IROTH) ? CMD2_OBITS : 0);
  394.             set->bits = (mode_t)~0;
  395.         } else {
  396.             set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
  397.             set->bits = mask;
  398.         }
  399.    
  400.         if (oparg == '+')
  401.             set->cmd2 |= CMD2_SET;
  402.         else if (oparg == '-')
  403.             set->cmd2 |= CMD2_CLR;
  404.         else if (oparg == '=')
  405.             set->cmd2 |= CMD2_SET|CMD2_CLR;
  406.         break;
  407.     }
  408.     return (set + 1);
  409. }
  410.  
  411. #ifdef SETMODE_DEBUG
  412. static void
  413. dumpmode(set)
  414.     BITCMD *set;
  415. {
  416.  
  417.     _DIAGASSERT(set != NULL);
  418.  
  419.     for (; set->cmd; ++set)
  420.         (void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
  421.             set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
  422.             set->cmd2 & CMD2_CLR ? " CLR" : "",
  423.             set->cmd2 & CMD2_SET ? " SET" : "",
  424.             set->cmd2 & CMD2_UBITS ? " UBITS" : "",
  425.             set->cmd2 & CMD2_GBITS ? " GBITS" : "",
  426.             set->cmd2 & CMD2_OBITS ? " OBITS" : "");
  427. }
  428. #endif
  429.  
  430. /*
  431.  * Given an array of bitcmd structures, compress by compacting consecutive
  432.  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
  433.  * 'g' and 'o' commands continue to be separate.  They could probably be
  434.  * compacted, but it's not worth the effort.
  435.  */
  436. static void
  437. compress_mode(set)
  438.     BITCMD *set;
  439. {
  440.     BITCMD *nset;
  441.     int setbits, clrbits, Xbits, op;
  442.  
  443.     _DIAGASSERT(set != NULL);
  444.  
  445.     for (nset = set;;) {
  446.         /* Copy over any 'u', 'g' and 'o' commands. */
  447.         while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
  448.             *set++ = *nset++;
  449.             if (!op)
  450.                 return;
  451.         }
  452.  
  453.         for (setbits = clrbits = Xbits = 0;; nset++) {
  454.             if ((op = nset->cmd) == '-') {
  455.                 clrbits |= nset->bits;
  456.                 setbits &= ~nset->bits;
  457.                 Xbits &= ~nset->bits;
  458.             } else if (op == '+') {
  459.                 setbits |= nset->bits;
  460.                 clrbits &= ~nset->bits;
  461.                 Xbits &= ~nset->bits;
  462.             } else if (op == 'X')
  463.                 Xbits |= nset->bits & ~setbits;
  464.             else
  465.                 break;
  466.         }
  467.         if (clrbits) {
  468.             set->cmd = '-';
  469.             set->cmd2 = 0;
  470.             set->bits = clrbits;
  471.             set++;
  472.         }
  473.         if (setbits) {
  474.             set->cmd = '+';
  475.             set->cmd2 = 0;
  476.             set->bits = setbits;
  477.             set++;
  478.         }
  479.         if (Xbits) {
  480.             set->cmd = 'X';
  481.             set->cmd2 = 0;
  482.             set->bits = Xbits;
  483.             set++;
  484.         }
  485.     }
  486. }
  487.