xref: /illumos-gate/usr/src/cmd/sh/stak.c (revision 948f2876ce2a3010558f4f6937e16086ebcd36f2)
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, Version 1.0 only
6   * (the "License").  You may not use this file except in compliance
7   * with the License.
8   *
9   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10   * or http://www.opensolaris.org/os/licensing.
11   * See the License for the specific language governing permissions
12   * and limitations under the License.
13   *
14   * When distributing Covered Code, include this CDDL HEADER in each
15   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16   * If applicable, add the following below this CDDL HEADER, with the
17   * fields enclosed by brackets "[]" replaced with your own identifying
18   * information: Portions Copyright [yyyy] [name of copyright owner]
19   *
20   * CDDL HEADER END
21   */
22  /*
23   * Copyright 1992 Sun Microsystems, Inc.  All rights reserved.
24   * Use is subject to license terms.
25   */
26  
27  /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
28  /*	  All Rights Reserved  	*/
29  
30  #pragma ident	"%Z%%M%	%I%	%E% SMI"
31  /*
32   * UNIX shell
33   */
34  
35  #include	"defs.h"
36  
37  
38  /* ========	storage allocation	======== */
39  
40  unsigned char *
41  getstak(asize)			/* allocate requested stack */
42  int	asize;
43  {
44  	unsigned char	*oldstak;
45  	int		size;
46  
47  	size = round(asize, BYTESPERWORD);
48  	oldstak = stakbot;
49  	staktop = stakbot += size;
50  	if (staktop >= brkend)
51  		growstak(staktop);
52  	return(oldstak);
53  }
54  
55  /*
56   * set up stack for local use
57   * should be followed by `endstak'
58   */
59  unsigned char *
60  locstak()
61  {
62  	if (brkend - stakbot < BRKINCR)
63  	{
64  		if (setbrk(brkincr) == -1)
65  			error(nostack);
66  		if (brkincr < BRKMAX)
67  			brkincr += 256;
68  	}
69  	return(stakbot);
70  }
71  
72  void
73  growstak(newtop)
74  unsigned char	*newtop;
75  {
76  	unsigned	incr;
77  
78  	incr = (unsigned)round(newtop - brkend + 1, BYTESPERWORD);
79  	if (brkincr > incr)
80  		incr = brkincr;
81  	if (setbrk(incr) == -1)
82  		error(nospace);
83  }
84  
85  unsigned char *
86  savstak()
87  {
88  	assert(staktop == stakbot);
89  	return(stakbot);
90  }
91  
92  unsigned char *
93  endstak(unsigned char *argp)		/* tidy up after `locstak' */
94  {
95  	unsigned char	*oldstak;
96  
97  	if (argp >= brkend)
98  		growstak(argp);
99  	*argp++ = 0;
100  	oldstak = stakbot;
101  	stakbot = staktop = (unsigned char *)round(argp, BYTESPERWORD);
102  	if (staktop >= brkend)
103  		growstak(staktop);
104  	return(oldstak);
105  }
106  
107  void
108  tdystak(unsigned char	*x)		/* try to bring stack back to x */
109  {
110  	while ((unsigned char *)stakbsy > x)
111  	{
112  		free(stakbsy);
113  		stakbsy = stakbsy->word;
114  	}
115  	staktop = stakbot = max(x, stakbas);
116  	rmtemp(x);
117  }
118  
119  void
120  stakchk(void)
121  {
122  	if ((brkend - stakbas) > BRKINCR + BRKINCR)
123  		setbrk(-BRKINCR);
124  }
125  
126  unsigned char *
127  cpystak(x)
128  unsigned char	*x;
129  {
130  	return(endstak(movstrstak(x, locstak())));
131  }
132  
133  unsigned char *
134  movstrstak(unsigned char *a, unsigned char *b)
135  {
136  	do
137  	{
138  		if (b >= brkend)
139  			growstak(b);
140  	}
141  	while (*b++ = *a++);
142  	return(--b);
143  }
144  
145  /*
146   * Copy s2 to s1, always copy n bytes.
147   * Return s1
148   */
149  unsigned char *
150  memcpystak(unsigned char *s1, unsigned char *s2, int n)
151  {
152  	unsigned char *os1 = s1;
153  
154  	while (--n >= 0) {
155  		if (s1 >= brkend)
156  			growstak(s1);
157  		*s1++ = *s2++;
158  	}
159  	return (os1);
160  }
161