printlib.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
/* @(#)printlib.c	4.1      ULTRIX 7/2/90 */
#endif

/**********************************************************************
 *   Copyright (c) Digital Equipment Corporation 1984, 1985, 1986.    *
 *   All Rights Reserved. 					      *
 **********************************************************************/

#include 	<stdio.h>	/* DEBUG	*/
#ifndef BUFSIZ
#define	BUFSIZ	1024
#endif

#define MAXHOP	32	/* max number of tc= indirections */

#include	<ctype.h>

/*
 * termcap - routines for dealing with the terminal capability data base
 *
 * TODO:	Should use a "last" pointer in tbuf, so that searching
 *		for capabilities alphabetically would not be a n**2/2
 *		process when large numbers of capabilities are given.
 * Note:	If we add a last pointer now we will screw up the
 *		tc capability. We really should compile termcap.
 *
 * Essentially all the work here is scanning and decoding escapes
 * in string capabilities.  We don't use stdio because the editor
 * doesn't, and because living w/o it is not hard.
 */

/**********
* Testing
#define LOCAL
**********/

#define	PRINTCAP

#ifdef	PRINTCAP
#define	tgetent		pgetent
#define	tskip		pskip
#define	tgetstr		pgetstr
#define	tdecode		pdecode
#define	tgetnum		pgetnum
#define	tgetflag	pgetflag
#define	tnchktc		pnchktc
#define	tnamatch	pnamatch
#undef	E_TERMCAP
#endif  PRINTCAP

#ifdef LOCAL
#define E_TERMCAP       "printcap"
#else
#define E_TERMCAP       "/etc/printcap"
#endif 

static	char *tbuf;
static	int hopcount = 0;	/* detect infinite loops in termcap */
char	*tskip();
char	*tgetstr();
char	*tdecode();
char	*getenv();

/*
 * Get an entry for terminal name in buffer bp,
 * from the termcap file.  Parse is very rudimentary;
 * we just notice escaped newlines.
 */
tgetent(bp, name)
	char *bp, *name;
{
	register char *cp;
	register int c;
	register int i = 0, cnt = 0;
	char ibuf[BUFSIZ];
	char *cp2;
	int tf;

	tbuf = bp;
	tf = 0;
	tf = open(E_TERMCAP, 0);
	if (tf < 0)
		return (-1);
	for (;;) {
		cp = bp;
		for (;;) {
			if (i == cnt) {
				cnt = read(tf, ibuf, BUFSIZ);
				if (cnt <= 0) {
					close(tf);
					return (0);
				}
				i = 0;
			}
			c = ibuf[i++];
			if (c == '\n') {
				if (cp > bp && cp[-1] == '\\'){
					cp--;
					continue;
				}
				break;
			}
#ifndef	UNM
			if (cp >= bp+BUFSIZ) {
#else	UNM
			if (cp == bp+BUFSIZ) {
#endif	UNM
				write(2,"printcap entry too long\n", 24);
				break;
			} else
				*cp++ = c;
		}
		*cp = 0;

		/*
		 * The real work for the match.
		 */
		if (tnamatch(name)) {
			close(tf);
			return(tnchktc());
		}
	}
}

/*
 * tnchktc: check the last entry, see if it's tc=xxx. If so,
 * recursively find xxx and append that entry (minus the names)
 * to take the place of the tc=xxx entry. This allows termcap
 * entries to say "like an HP2621 but doesn't turn on the labels".
 * Note that this works because of the left to right scan.
 */
tnchktc()
{
	register char *p, *q;
	char tcname[16];	/* name of similar terminal */
	char tcbuf[BUFSIZ];
	char *holdtbuf = tbuf;
	int l;

	p = tbuf + strlen(tbuf) - 2;	/* before the last colon */
	while (*--p != ':')
		if (p<tbuf) {
			write(2, "Bad printcap entry\n", 19);
			return (0);
		}
	p++;
	/* p now points to beginning of last field */
	if (p[0] != 't' || p[1] != 'c')
		return(1);
	strcpy(tcname,p+3);
	q = tcname;
	while (q && *q != ':')
		q++;
	*q = 0;
	if (++hopcount > MAXHOP) {
		write(2, "Infinite tc= loop\n", 18);
		return (0);
	}
	if (tgetent(tcbuf, tcname) != 1)
		return(0);
	for (q=tcbuf; *q != ':'; q++)
		;
	l = p - holdtbuf + strlen(q);
	if (l > BUFSIZ) {
		write(2, "printcap entry too long\n", 24);
		q[BUFSIZ - (p-tbuf)] = 0;
	}
	strcpy(p, q+1);
	tbuf = holdtbuf;
	return(1);
}

/*
 * Tnamatch deals with name matching.  The first field of the termcap
 * entry is a sequence of names separated by |'s, so we compare
 * against each such name.  The normal : terminator after the last
 * name (before the first field) stops us.
 */
tnamatch(np)
	char *np;
{
	register char *Np, *Bp;

	Bp = tbuf;
	if (*Bp == '#')
		return(0);
	for (;;) {
		for (Np = np; *Np && *Bp == *Np; Bp++, Np++)
			continue;
		if (*Np == 0 && (*Bp == '|' || *Bp == ':' || *Bp == 0))
			return (1);
		while (*Bp && *Bp != ':' && *Bp != '|')
			Bp++;
		if (*Bp == 0 || *Bp == ':')
			return (0);
		Bp++;
	}
}

/*
 * Skip to the next field.  Notice that this is very dumb, not
 * knowing about \: escapes or any such.  If necessary, :'s can be put
 * into the termcap file in octal.
 */
static char *
tskip(bp)
	register char *bp;
{

	while (*bp && *bp != ':')
		bp++;
	if (*bp == ':')
		bp++;
	return (bp);
}

/*
 * Return the (numeric) option id.
 * Numeric options look like
 *	li#80
 * i.e. the option string is separated from the numeric value by
 * a # character.  If the option is not found we return -1.
 * Note that we handle octal numbers beginning with 0.
 */
tgetnum(id)
	char *id;
{
	register int i, base;
	register char *bp = tbuf;

	for (;;) {
		bp = tskip(bp);
		if (*bp == 0)
			return (-1);
		if (*bp++ != id[0] || *bp == 0 || *bp++ != id[1])
			continue;
		if (*bp == '@')
			return(-1);
		if (*bp != '#')
			continue;
		bp++;
		base = 10;
		if (*bp == '0')
			base = 8;
		i = 0;
		while (isdigit(*bp))
			i *= base, i += *bp++ - '0';
		return (i);
	}
}

/*
 * Handle a flag option.
 * Flag options are given "naked", i.e. followed by a : or the end
 * of the buffer.  Return 1 if we find the option, or 0 if it is
 * not given.
 */
tgetflag(id)
	char *id;
{
	register char *bp = tbuf;

	for (;;) {
		bp = tskip(bp);
		if (!*bp)
			return (0);
		if (*bp++ == id[0] && *bp != 0 && *bp++ == id[1]) {
			if (!*bp || *bp == ':')
				return (1);
			else if (*bp == '@')
				return(0);
		}
	}
}

/*
 * Get a string valued option.
 * These are given as
 *	cl=^Z
 * Much decoding is done on the strings, and the strings are
 * placed in area, which is a ref parameter which is updated.
 * No checking on area overflow.
 */
char *
tgetstr(id, area)
	char *id, **area;	/* deBUG: was **area */
{
	register char *bp = tbuf;

	for (;;) {
		bp = tskip(bp);
		if (!*bp)
			return (0);
		if (*bp++ != id[0] || *bp == 0 || *bp++ != id[1])
			continue;
		if (*bp == '@')
			return(0);
		if (*bp != '=')
			continue;
		bp++;

	return(tdecode(bp,area));
	}
}

/*
 * Tdecode does the grunge work to decode the
 * string capability escapes.
 */
static char *
tdecode(str, area)
	register char *str;
	char **area;		
{
	register char *cp;
	register int c;
	register char *dp;
	int i;

	cp = *area;
	while ((c = *str++) && c != ':') {

	/* Leave out this section for lprsetup program since
	 * we want the string exactly as it is from /etc/printcap.
	 *
	 *
		switch (c) {

		case '^':
			c = *str++ & 037;
			break;

		case '\\':
			dp = "E\033^^\\\\::n\nr\rt\tb\bf\f";
			c = *str++;
nextc:
			if (*dp++ == c) {
				c = *dp++;
				break;
			}
			dp++;
			if (*dp)
				goto nextc;
			if (isdigit(c)) {
				c -= '0', i = 2;
				do
					c <<= 3, c |= *str++ - '0';
				while (--i && isdigit(*str));
			}
			break;
		}
	 *
	 *
	 * ...end of omitted section.
	 */

		*cp++ = c;
	}

	*cp++ = 0;
	str = *area;
	*area = cp;

	return (str);
}