usr/src/cmd/sh/stak.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  27 /*        All Rights Reserved   */
  28
  29 #pragma ident   "%Z%%M% %I%     %E% SMI"
  30 /*
  31  * UNIX shell
  32  */
  33
  34 #include        "defs.h"
  35
  36
  37 /* ========     storage allocation      ======== */
  38
  39 unsigned char *
  40 getstak(asize)                  /* allocate requested stack */
  41 int     asize;
  42 {
  43         unsigned char   *oldstak;
  44         int             size;
  45
  46         size = round(asize, BYTESPERWORD);
  47         oldstak = stakbot;
  48         staktop = stakbot += size;
  49         if (staktop >= brkend)
  50                 growstak(staktop);
  51         return(oldstak);
  52 }
  53
  54 /*
  55  * set up stack for local use
  56  * should be followed by `endstak'
  57  */
  58 unsigned char *
  59 locstak()
  60 {
  61         if (brkend - stakbot < BRKINCR)
  62         {
  63                 if (setbrk(brkincr) == -1)
  64                         error(nostack);
  65                 if (brkincr < BRKMAX)
  66                         brkincr += 256;
  67         }
  68         return(stakbot);
  69 }
  70
  71 void
  72 growstak(newtop)
  73 unsigned char   *newtop;
  74 {
  75         unsigned        incr;
  76
  77         incr = (unsigned)round(newtop - brkend + 1, BYTESPERWORD);
  78         if (brkincr > incr)
  79                 incr = brkincr;
  80         if (setbrk(incr) == -1)
  81                 error(nospace);
  82 }
  83
  84 unsigned char *
  85 savstak()
  86 {
  87         assert(staktop == stakbot);
  88         return(stakbot);
  89 }
  90
  91 unsigned char *
  92 endstak(unsigned char *argp)            /* tidy up after `locstak' */
  93 {
  94         unsigned char   *oldstak;
  95
  96         if (argp >= brkend)
  97                 growstak(argp);
  98         *argp++ = 0;
  99         oldstak = stakbot;
 100         stakbot = staktop = (unsigned char *)round(argp, BYTESPERWORD);
 101         if (staktop >= brkend)
 102                 growstak(staktop);
 103         return(oldstak);
 104 }
 105
 106 void
 107 tdystak(unsigned char   *x)             /* try to bring stack back to x */
 108 {
 109         struct blk *next;
 110
 111         while ((unsigned char *)stakbsy > x)
 112         {
 113                 next = stakbsy->word;
 114                 free(stakbsy);
 115                 stakbsy = next;
 116         }
 117         staktop = stakbot = max(x, stakbas);
 118         rmtemp(x);
 119 }
 120
 121 void
 122 stakchk(void)
 123 {
 124         if ((brkend - stakbas) > BRKINCR + BRKINCR)
 125                 setbrk(-BRKINCR);
 126 }
 127
 128 unsigned char *
 129 cpystak(x)
 130 unsigned char   *x;
 131 {
 132         return(endstak(movstrstak(x, locstak())));
 133 }
 134
 135 unsigned char *
 136 movstrstak(unsigned char *a, unsigned char *b)
 137 {
 138         do
 139         {
 140                 if (b >= brkend)
 141                         growstak(b);
 142         }
 143         while (*b++ = *a++);
 144         return(--b);
 145 }
 146
 147 /*
 148  * Copy s2 to s1, always copy n bytes.
 149  * Return s1
 150  */
 151 unsigned char *
 152 memcpystak(unsigned char *s1, unsigned char *s2, int n)
 153 {
 154         unsigned char *os1 = s1;
 155
 156         while (--n >= 0) {
 157                 if (s1 >= brkend)
 158                         growstak(s1);
 159                 *s1++ = *s2++;
 160         }
 161         return (os1);
 162 }