/*
 * $Copyright:	$
 * Copyright (c) 1984, 1985, 1986, 1987, 1988, 1989, 1990 
 * Sequent Computer Systems, Inc.   All rights reserved.
 *  
 * This software is furnished under a license and may be used
 * only in accordance with the terms of that license and with the
 * inclusion of the above copyright notice.   This software may not
 * be provided or otherwise made available to, or used by, any
 * other person.  No title to or ownership of the software is
 * hereby transferred.
 *
 */
/*	Copyright (c) 1984 AT&T	*/
/*	  All Rights Reserved  	*/

/*	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T	*/
/*	The copyright notice above does not evidence any   	*/
/*	actual or intended publication of such source code.	*/

/*
 * Copyright  (c) 1985 AT&T
 *	All Rights Reserved
 */
#ident	"$Header: expand.c 1.3 90/05/22 $@(#)vm.sys:src/sys/expand.c	1.3"

#include	<stdio.h>
#include	<string.h>
#include	<ctype.h>
#include	"wish.h"
#include	"moremacros.h"
#include	"terror.h"

/*
 * Globals to maintain dynamic expansion buffer
 * (destination buffer for "variable expanded" text)
 */
static char *Destbuf;
static int  Bufsize;
static int  Bufcnt;

/*
 * These macros check that the expansion buffer is BIG enough
 * before text is copies into it.
 */
#define CHKbuf(p, q)		if (++Bufcnt >= Bufsize) { \
					growbuf(q, BUFSIZ); \
					p = Destbuf + Bufcnt - 1; \
				}

#define CHKnbuf(p, q, num)	if ((Bufcnt += num) >= Bufsize) { \
					growbuf(q, num); \
					p = Destbuf + Bufcnt - num; \
				}

/*
 * GROWBUF will allocate/grow Destbuf by BUFSIZ
 */
static void 
growbuf(buf, num)
char *buf;
int num;
{
	void *malloc(), *realloc();

	Bufsize += num;
	if (Destbuf == NULL) {
		if ((Destbuf = malloc(Bufsize)) == NULL)
			fatal(NOMEM, nil);
		strcpy(Destbuf, buf);
	}
 	else if ((Destbuf = realloc(Destbuf, Bufsize)) == NULL)
		fatal(NOMEM, nil);
}

/*
 * EXPAND will "expand" all environment variables in the
 * string pointed to by "src" and return a pointer to
 * the expanded text.
 */ 
char *
expand(src)
char *src;
{
	char	buf[BUFSIZ];
	char	*ret;
	char	*pexpand();

	/*
	 * Use a static 1K buffer by default ....
	 * pexpand() will create a dynamic buffer
	 * if necessary and set "Destbuf" to it.
	 */ 
	Destbuf = NULL;
	Bufsize = BUFSIZ;
	Bufcnt = 0;

	(void) pexpand(buf, src, '\0');
	if (Destbuf)		
		ret = Destbuf;		/* return malloc'd buffer */
	else
		ret = strsave(buf);	/* strsave text from static buffer */
	return(ret);
}

static char *
pexpand(buf, name, eos)
char	*buf;
char	*name;
char	eos;
{
	register char	delim;
	register char	*src;
	register char	*dst;
	register char	*file;
	char	fbuf[PATHSIZ];
	char	*anyenv();
	char	*getepenv();
	char	*savebuf;
	int	savesize;
	int	savecnt;

	dst = buf;
	src = name;
	while (*src && *src != eos) {
		if (*src == '\\') {
			++src;
			CHKbuf(dst, buf);
			*dst++ = *src++;
		}
		else if (*src == '$') {
			register char	*start;

			if ((delim = (*++src == '{') ? '}' : '\0'))
				start = ++src;
			else
				start = src;
			file = NULL;
			if (*src == '(') {
				/*
				 * Save dynamic buffer before calling
				 * pexpand() recursively
				 */
				savebuf = Destbuf;
				savesize = Bufsize;
				savecnt = Bufcnt;

				/*
				 * Initialize globals
				 */
				Destbuf = NULL;
				Bufsize = PATHSIZ;
				Bufcnt = 0;

				src = pexpand(fbuf, ++src, ')');
				if (*src) {
					start = ++src;
					if (Destbuf)
						file = Destbuf;
					else
						file = fbuf;
				}

				/*
				 * Restore previous values for 
				 * dynamic buffer and continue
				 * as usual ....
				 */
				Destbuf = savebuf;
				Bufsize = savesize;
				Bufcnt = savecnt;
			}
			if (isalpha(*src)) {
				register char	*p;
				register char	savechar;

				while (isalpha(*src) || isdigit(*src) || *src == '_')
					src++;
				savechar = *src;
				*src = '\0';
				if ((p = (file ? anyenv(file, start) : getepenv(start))) == NULL) {
					if (delim) {
						if ((*src = savechar) == ':' && *++src == '-')
							while (*++src && *src != delim) {
								CHKbuf(dst, buf);
								*dst++ = *src;
							}
					}
					else
						*src = savechar;
				}
				else {
					*src = savechar;
					CHKnbuf(dst, buf, strlen(p));
					strcpy(dst, p);
					dst += strlen(p);
					free(p);
				}
				if (delim)
					while (*src && *src++ != delim)
						;
			}
		}
		else {
			CHKbuf(dst, buf);
			*dst++ = *src++;
		}
	}
	CHKbuf(dst, buf);
	*dst = '\0';
	return src;
}
