xref: /src/usr.bin/sed/process.c

/*	$NetBSD: process.c,v 1.47 2015/02/28 21:56:53 asau Exp $	*/

/*-
 * Copyright (c) 1992 Diomidis Spinellis.
 * Copyright (c) 1992, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Diomidis Spinellis of Imperial College, University of London.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
__RCSID("$NetBSD: process.c,v 1.47 2015/02/28 21:56:53 asau Exp $");
#ifdef __FBSDID
__FBSDID("$FreeBSD: head/usr.bin/sed/process.c 192732 2009-05-25 06:45:33Z brian $");
#endif

#if 0
static const char sccsid[] = "@(#)process.c	8.6 (Berkeley) 4/20/94";
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/uio.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>

#include "defs.h"
#include "extern.h"

static SPACE HS, PS, SS, YS;
#define	pd		PS.deleted
#define	ps		PS.space
#define	psl		PS.len
#define	hs		HS.space
#define	hsl		HS.len

static int mf_fgets(SPACE *, enum e_spflag);
static int lastline(void);

static __inline int	 applies(struct s_command *);
static void		 do_tr(struct s_tr *);
static void		 flush_appends(void);
static void		 lputs(char *, size_t);
static __inline int	 regexec_e(regex_t *, const char *, int, int, size_t);
static void		 regsub(SPACE *, char *, char *);
static int		 substitute(struct s_command *);

/*
 * Current file and line number; line numbers restart across compilation
 * units, but span across input files.  The latter is optional if editing
 * in place.
 */
static const char *fname;	/* File name. */
static const char *outfname;	/* Output file name */
static char oldfname[PATH_MAX];	/* Old file name (for in-place editing) */
static char tmpfname[PATH_MAX];	/* Temporary file name (for in-place editing) */
static const char *inplace;	/* Inplace edit file extension. */
static u_long linenum;

static int rval;		/* Exit status */

struct s_appends *appends;	/* Array of pointers to strings to append. */
static size_t appendx;		/* Index into appends array. */
size_t appendnum;			/* Size of appends array. */

static int lastaddr;		/* Set by applies if last address of a range. */
static int sdone;		/* If any substitutes since last line input. */
				/* Iov structure for 'w' commands. */
static regex_t *defpreg;
size_t maxnsub;
regmatch_t *match;

#define OUT() do {fwrite(ps, 1, psl, outfile); fputc('\n', outfile);} while (0)

int
process(void)
{
	struct s_command *cp;
	SPACE tspace;
	size_t oldpsl = 0;
	char *p;

	p = NULL;

	for (linenum = 0; mf_fgets(&PS, REPLACE);) {
		pd = 0;
top:
		cp = prog;
redirect:
		while (cp != NULL) {
			if (!applies(cp)) {
				cp = cp->next;
				continue;
			}
			switch (cp->code) {
			case '{':
				cp = cp->u.c;
				goto redirect;
			case 'a':
				if (appendx >= appendnum)
					appends = xrealloc(appends,
					    sizeof(struct s_appends) *
					    (appendnum *= 2));
				appends[appendx].type = AP_STRING;
				appends[appendx].s = cp->t;
				appends[appendx].len = strlen(cp->t);
				appendx++;
				break;
			case 'b':
				cp = cp->u.c;
				goto redirect;
			case 'c':
				pd = 1;
				psl = 0;
				if (cp->a2 == NULL || lastaddr || lastline())
					(void)fprintf(outfile, "%s", cp->t);
				goto new;
			case 'd':
				pd = 1;
				goto new;
			case 'D':
				if (pd)
					goto new;
				if (psl == 0 ||
				    (p = memchr(ps, '\n', psl - 1)) == NULL) {
					pd = 1;
					goto new;
				} else {
					psl -= (size_t)((p + 1) - ps);
					memmove(ps, p + 1, psl);
					goto top;
				}
			case 'g':
				cspace(&PS, hs, hsl, REPLACE);
				break;
			case 'G':
				cspace(&PS, "\n", 1, APPEND);
				cspace(&PS, hs, hsl, APPEND);
				break;
			case 'h':
				cspace(&HS, ps, psl, REPLACE);
				break;
			case 'H':
				cspace(&HS, "\n", 1, APPEND);
				cspace(&HS, ps, psl, APPEND);
				break;
			case 'i':
				(void)fprintf(outfile, "%s", cp->t);
				break;
			case 'l':
				lputs(ps, psl);
				break;
			case 'n':
				if (!nflag && !pd)
					OUT();
				flush_appends();
				if (!mf_fgets(&PS, REPLACE))
					exit(0);
				pd = 0;
				break;
			case 'N':
				flush_appends();
				cspace(&PS, "\n", 1, APPEND);
				if (!mf_fgets(&PS, APPEND))
					exit(0);
				break;
			case 'p':
				if (pd)
					break;
				OUT();
				break;
			case 'P':
				if (pd)
					break;
				if ((p = memchr(ps, '\n', psl - 1)) != NULL) {
					oldpsl = psl;
					psl = (size_t)(p - ps);
				}
				OUT();
				if (p != NULL)
					psl = oldpsl;
				break;
			case 'q':
				if (!nflag && !pd)
					OUT();
				flush_appends();
				exit(0);
			case 'r':
				if (appendx >= appendnum)
					appends = xrealloc(appends,
					    sizeof(struct s_appends) *
					    (appendnum *= 2));
				appends[appendx].type = AP_FILE;
				appends[appendx].s = cp->t;
				appends[appendx].len = strlen(cp->t);
				appendx++;
				break;
			case 's':
				sdone |= substitute(cp);
				break;
			case 't':
				if (sdone) {
					sdone = 0;
					cp = cp->u.c;
					goto redirect;
				}
				break;
			case 'w':
				if (pd)
					break;
				if (cp->u.fd == -1 && (cp->u.fd = open(cp->t,
				    O_WRONLY|O_APPEND|O_CREAT|O_TRUNC,
				    DEFFILEMODE)) == -1)
					err(1, "%s", cp->t);
				if (write(cp->u.fd, ps, psl) != (ssize_t)psl ||
				    write(cp->u.fd, "\n", 1) != 1)
					err(1, "%s", cp->t);
				break;
			case 'x':
				/*
				 * If the hold space is null, make it empty
				 * but not null.  Otherwise the pattern space
				 * will become null after the swap, which is
				 * an abnormal condition.
				 */
				if (hs == NULL)
					cspace(&HS, "", 0, REPLACE);
				tspace = PS;
				PS = HS;
				HS = tspace;
				break;
			case 'y':
				if (pd || psl == 0)
					break;
				do_tr(cp->u.y);
				break;
			case ':':
			case '}':
				break;
			case '=':
				(void)fprintf(outfile, "%lu\n", linenum);
			}
			cp = cp->next;
		} /* for all cp */

new:		if (!nflag && !pd)
			OUT();
		flush_appends();
	} /* for all lines */
	return rval;
}

/*
 * TRUE if the address passed matches the current program state
 * (lastline, linenumber, ps).
 */
#define	MATCH(a)							\
	((a)->type == AT_RE ? regexec_e((a)->u.r, ps, 0, 1, psl) :	\
	    (a)->type == AT_LINE ? linenum == (a)->u.l : lastline())

/*
 * Return TRUE if the command applies to the current line.  Sets the start
 * line for process ranges.  Interprets the non-select (``!'') flag.
 */
static __inline int
applies(struct s_command *cp)
{
	int r;

	lastaddr = 0;
	if (cp->a1 == NULL && cp->a2 == NULL)
		r = 1;
	else if (cp->a2)
		if (cp->startline > 0) {
			switch (cp->a2->type) {
			case AT_RELLINE:
				if (linenum - cp->startline <= cp->a2->u.l)
					r = 1;
				else {
					cp->startline = 0;
					r = 0;
				}
				break;
			default:
				if (MATCH(cp->a2)) {
					cp->startline = 0;
					lastaddr = 1;
					r = 1;
				} else if (cp->a2->type == AT_LINE &&
				    linenum > cp->a2->u.l) {
					/*
					 * We missed the 2nd address due to a
					 * branch, so just close the range and
					 * return false.
					 */
					cp->startline = 0;
					r = 0;
				} else
					r = 1;
			}
		} else if (cp->a1 && MATCH(cp->a1)) {
			/*
			 * If the second address is a number less than or
			 * equal to the line number first selected, only
			 * one line shall be selected.
			 *	-- POSIX 1003.2
			 * Likewise if the relative second line address is zero.
			 */
			if ((cp->a2->type == AT_LINE &&
			    linenum >= cp->a2->u.l) ||
			    (cp->a2->type == AT_RELLINE && cp->a2->u.l == 0))
				lastaddr = 1;
			else {
				cp->startline = linenum;
			}
			r = 1;
		} else
			r = 0;
	else
		r = MATCH(cp->a1);
	return (cp->nonsel ? ! r : r);
}

/*
 * Reset the sed processor to its initial state.
 */
void
resetstate(void)
{
	struct s_command *cp;

	/*
	 * Reset all in-range markers.
	 */
	for (cp = prog; cp; cp = cp->code == '{' ? cp->u.c : cp->next)
		if (cp->a2)
			cp->startline = 0;

	/*
	 * Clear out the hold space.
	 */
	cspace(&HS, "", 0, REPLACE);
}

/*
 * substitute --
 *	Do substitutions in the pattern space.  Currently, we build a
 *	copy of the new pattern space in the substitute space structure
 *	and then swap them.
 */
static int
substitute(struct s_command *cp)
{
	SPACE tspace;
	regex_t *re;
	regoff_t re_off, slen;
	int lastempty, n;
	char *s;

	s = ps;
	re = cp->u.s->re;
	if (re == NULL) {
		if (defpreg != NULL && cp->u.s->maxbref > defpreg->re_nsub) {
			linenum = cp->u.s->linenum;
			errx(1, "%lu: %s: \\%u not defined in the RE",
					linenum, fname, cp->u.s->maxbref);
		}
	}
	if (!regexec_e(re, s, 0, 0, psl))
		return (0);

	SS.len = 0;				/* Clean substitute space. */
	slen = (regoff_t)psl;
	n = cp->u.s->n;
	lastempty = 1;

	switch (n) {
	case 0:					/* Global */
		do {
			if (lastempty || match[0].rm_so != match[0].rm_eo) {
				/* Locate start of replaced string. */
				re_off = match[0].rm_so;
				/* Copy leading retained string. */
				cspace(&SS, s, (size_t)re_off, APPEND);
				/* Add in regular expression. */
				regsub(&SS, s, cp->u.s->new);
			}

			/* Move past this match. */
			if (match[0].rm_so != match[0].rm_eo) {
				s += match[0].rm_eo;
				slen -= match[0].rm_eo;
				lastempty = 0;
			} else {
				if (match[0].rm_so < slen)
					cspace(&SS, s + match[0].rm_so, 1,
					    APPEND);
				s += match[0].rm_so + 1;
				slen -= match[0].rm_so + 1;
				lastempty = 1;
			}
		} while (slen >= 0 && regexec_e(re, s, REG_NOTBOL, 0, (size_t)slen));
		/* Copy trailing retained string. */
		if (slen > 0)
			cspace(&SS, s, (size_t)slen, APPEND);
		break;
	default:				/* Nth occurrence */
		while (--n) {
			if (match[0].rm_eo == match[0].rm_so)
				match[0].rm_eo = match[0].rm_so + 1;
			s += match[0].rm_eo;
			slen -= match[0].rm_eo;
			if (slen < 0)
				return (0);
			if (!regexec_e(re, s, REG_NOTBOL, 0, (size_t)slen))
				return (0);
		}
		/* FALLTHROUGH */
	case 1:					/* 1st occurrence */
		/* Locate start of replaced string. */
		re_off = match[0].rm_so + (s - ps);
		/* Copy leading retained string. */
		cspace(&SS, ps, (size_t)re_off, APPEND);
		/* Add in regular expression. */
		regsub(&SS, s, cp->u.s->new);
		/* Copy trailing retained string. */
		s += match[0].rm_eo;
		slen -= match[0].rm_eo;
		cspace(&SS, s, (size_t)slen, APPEND);
		break;
	}

	/*
	 * Swap the substitute space and the pattern space, and make sure
	 * that any leftover pointers into stdio memory get lost.
	 */
	tspace = PS;
	PS = SS;
	SS = tspace;
	SS.space = SS.back;

	/* Handle the 'p' flag. */
	if (cp->u.s->p)
		OUT();

	/* Handle the 'w' flag. */
	if (cp->u.s->wfile && !pd) {
		if (cp->u.s->wfd == -1 && (cp->u.s->wfd = open(cp->u.s->wfile,
		    O_WRONLY|O_APPEND|O_CREAT|O_TRUNC, DEFFILEMODE)) == -1)
			err(1, "%s", cp->u.s->wfile);
		if (write(cp->u.s->wfd, ps, psl) != (ssize_t)psl ||
		    write(cp->u.s->wfd, "\n", 1) != 1)
			err(1, "%s", cp->u.s->wfile);
	}
	return (1);
}

/*
 * do_tr --
 *	Perform translation ('y' command) in the pattern space.
 */
static void
do_tr(struct s_tr *y)
{
	SPACE tmp;
	char c, *p;
	size_t clen, left;
	size_t i;

	if (MB_CUR_MAX == 1) {
		/*
		 * Single-byte encoding: perform in-place translation
		 * of the pattern space.
		 */
		for (p = ps; p < &ps[psl]; p++)
			*p = (char)y->bytetab[(u_char)*p];
	} else {
		/*
		 * Multi-byte encoding: perform translation into the
		 * translation space, then swap the translation and
		 * pattern spaces.
		 */
		/* Clean translation space. */
		YS.len = 0;
		for (p = ps, left = psl; left > 0; p += clen, left -= clen) {
			if ((c = (char)y->bytetab[(u_char)*p]) != '\0') {
				cspace(&YS, &c, 1, APPEND);
				clen = 1;
				continue;
			}
			for (i = 0; i < y->nmultis; i++)
				if (left >= y->multis[i].fromlen &&
				    memcmp(p, y->multis[i].from,
				    y->multis[i].fromlen) == 0)
					break;
			if (i < y->nmultis) {
				cspace(&YS, y->multis[i].to,
				    y->multis[i].tolen, APPEND);
				clen = y->multis[i].fromlen;
			} else {
				cspace(&YS, p, 1, APPEND);
				clen = 1;
			}
		}
		/* Swap the translation space and the pattern space. */
		tmp = PS;
		PS = YS;
		YS = tmp;
		YS.space = YS.back;
	}
}

/*
 * Flush append requests.  Always called before reading a line,
 * therefore it also resets the substitution done (sdone) flag.
 */
static void
flush_appends(void)
{
	FILE *f;
	size_t count, i;
	char buf[8 * 1024];

	for (i = 0; i < appendx; i++)
		switch (appends[i].type) {
		case AP_STRING:
			fwrite(appends[i].s, sizeof(char), appends[i].len,
			    outfile);
			break;
		case AP_FILE:
			/*
			 * Read files probably shouldn't be cached.  Since
			 * it's not an error to read a non-existent file,
			 * it's possible that another program is interacting
			 * with the sed script through the filesystem.  It
			 * would be truly bizarre, but possible.  It's probably
			 * not that big a performance win, anyhow.
			 */
			if ((f = fopen(appends[i].s, "r")) == NULL)
				break;
			while ((count = fread(buf, sizeof(char), sizeof(buf), f)))
				(void)fwrite(buf, sizeof(char), count, outfile);
			(void)fclose(f);
			break;
		}
	if (ferror(outfile))
		errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
	appendx = 0;
	sdone = 0;
}

static void
lputs(char *s, size_t len)
{
	static const char escapes[] = "\\\a\b\f\r\t\v";
	int c;
	size_t col, width;
	const char *p;
#ifdef TIOCGWINSZ
	struct winsize win;
#endif
	static size_t termwidth = (size_t)-1;
	size_t clen, i;
	wchar_t wc;
	mbstate_t mbs;

	if (outfile != stdout)
		termwidth = 60;
	if (termwidth == (size_t)-1) {
		if ((p = getenv("COLUMNS")) && *p != '\0')
			termwidth = (size_t)atoi(p);
#ifdef TIOCGWINSZ
		else if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) == 0 &&
		    win.ws_col > 0)
			termwidth = win.ws_col;
#endif
		else
			termwidth = 60;
	}
	if (termwidth == 0)
		termwidth = 1;

	memset(&mbs, 0, sizeof(mbs));
	col = 0;
	while (len != 0) {
		clen = mbrtowc(&wc, s, len, &mbs);
		if (clen == 0)
			clen = 1;
		if (clen == (size_t)-1 || clen == (size_t)-2) {
			wc = (unsigned char)*s;
			clen = 1;
			memset(&mbs, 0, sizeof(mbs));
		}
		if (wc == '\n') {
			if (col + 1 >= termwidth)
				fprintf(outfile, "\\\n");
			fputc('$', outfile);
			fputc('\n', outfile);
			col = 0;
		} else if (iswprint(wc)) {
			width = (size_t)wcwidth(wc);
			if (col + width >= termwidth) {
				fprintf(outfile, "\\\n");
				col = 0;
			}
			fwrite(s, 1, clen, outfile);
			col += width;
		} else if (wc != L'\0' && (c = wctob(wc)) != EOF &&
		    (p = strchr(escapes, c)) != NULL) {
			if (col + 2 >= termwidth) {
				fprintf(outfile, "\\\n");
				col = 0;
			}
			fprintf(outfile, "\\%c", "\\abfrtv"[p - escapes]);
			col += 2;
		} else {
			if (col + 4 * clen >= termwidth) {
				fprintf(outfile, "\\\n");
				col = 0;
			}
			for (i = 0; i < clen; i++)
				fprintf(outfile, "\\%03o",
				    (int)(unsigned char)s[i]);
			col += 4 * clen;
		}
		s += clen;
		len -= clen;
	}
	if (col + 1 >= termwidth)
		fprintf(outfile, "\\\n");
	(void)fputc('$', outfile);
	(void)fputc('\n', outfile);
	if (ferror(outfile))
		errx(1, "%s: %s", outfname, strerror(errno ? errno : EIO));
}

static __inline int
regexec_e(regex_t *preg, const char *string, int eflags, int nomatch,
	size_t slen)
{
	int eval;
#ifndef REG_STARTEND
	char *buf;
#endif

	if (preg == NULL) {
		if (defpreg == NULL)
			errx(1, "first RE may not be empty");
	} else
		defpreg = preg;

	/* Set anchors */
#ifndef REG_STARTEND
	buf = xmalloc(slen + 1);
	(void)memcpy(buf, string, slen);
	buf[slen] = '\0';
	eval = regexec(defpreg, buf,
	    nomatch ? 0 : maxnsub + 1, match, eflags);
	free(buf);
#else
	match[0].rm_so = 0;
	match[0].rm_eo = (regoff_t)slen;
	eval = regexec(defpreg, string,
	    nomatch ? 0 : maxnsub + 1, match, eflags | REG_STARTEND);
#endif
	switch(eval) {
	case 0:
		return (1);
	case REG_NOMATCH:
		return (0);
	}
	errx(1, "RE error: %s", strregerror(eval, defpreg));
	/* NOTREACHED */
}

/*
 * regsub - perform substitutions after a regexp match
 * Based on a routine by Henry Spencer
 */
static void
regsub(SPACE *sp, char *string, char *src)
{
	size_t len;
	int no;
	char c, *dst;

#define	NEEDSP(reqlen)							\
	/* XXX What is the +1 for? */					\
	if (sp->len + (reqlen) + 1 >= sp->blen) {			\
		sp->blen += (reqlen) + 1024;				\
		sp->space = sp->back = xrealloc(sp->back, sp->blen);	\
		dst = sp->space + sp->len;				\
	}

	dst = sp->space + sp->len;
	while ((c = *src++) != '\0') {
		if (c == '&')
			no = 0;
		else if (c == '\\' && isdigit((unsigned char)*src))
			no = *src++ - '0';
		else
			no = -1;
		if (no < 0) {		/* Ordinary character. */
			if (c == '\\' && (*src == '\\' || *src == '&'))
				c = *src++;
			NEEDSP(1);
			*dst++ = c;
			++sp->len;
		} else if (match[no].rm_so != -1 && match[no].rm_eo != -1) {
			len = (size_t)(match[no].rm_eo - match[no].rm_so);
			NEEDSP(len);
			memmove(dst, string + match[no].rm_so, len);
			dst += len;
			sp->len += len;
		}
	}
	NEEDSP(1);
	*dst = '\0';
}

/*
 * cspace --
 *	Concatenate space: append the source space to the destination space,
 *	allocating new space as necessary.
 */
void
cspace(SPACE *sp, const char *p, size_t len, enum e_spflag spflag)
{
	size_t tlen;

	/* Make sure SPACE has enough memory and ramp up quickly. */
	tlen = sp->len + len + 1;
	if (tlen > sp->blen) {
		sp->blen = tlen + 1024;
		sp->space = sp->back = xrealloc(sp->back, sp->blen);
	}

	if (spflag == REPLACE)
		sp->len = 0;

	memmove(sp->space + sp->len, p, len);

	sp->space[sp->len += len] = '\0';
}

/*
 * Close all cached opened files and report any errors
 */
void
cfclose(struct s_command *cp, struct s_command *end)
{

	for (; cp != end; cp = cp->next)
		switch(cp->code) {
		case 's':
			if (cp->u.s->wfd != -1 && close(cp->u.s->wfd))
				err(1, "%s", cp->u.s->wfile);
			cp->u.s->wfd = -1;
			break;
		case 'w':
			if (cp->u.fd != -1 && close(cp->u.fd))
				err(1, "%s", cp->t);
			cp->u.fd = -1;
			break;
		case '{':
			cfclose(cp->u.c, cp->next);
			break;
		}
}

/*
 * Like fgets, but go through the list of files chaining them together.
 * Set len to the length of the line.
 */
int
mf_fgets(SPACE *sp, enum e_spflag spflag)
{
	struct stat sb;
	size_t len;
	static char *p = NULL;
	static size_t plen = 0;
	int c;
	static int firstfile;

	if (infile == NULL) {
		/* stdin? */
		if (files->fname == NULL) {
			if (inplace != NULL)
				errx(1, "-I or -i may not be used with stdin");
			infile = stdin;
			fname = "stdin";
			outfile = stdout;
			outfname = "stdout";
		}
		firstfile = 1;
	}

	for (;;) {
		if (infile != NULL && (c = getc(infile)) != EOF) {
			(void)ungetc(c, infile);
			break;
		}
		/* If we are here then either eof or no files are open yet */
		if (infile == stdin) {
			sp->len = 0;
			return (0);
		}
		if (infile != NULL) {
			fclose(infile);
			if (*oldfname != '\0') {
				/* if there was a backup file, remove it */
				unlink(oldfname);
				/*
				 * Backup the original.  Note that hard links
				 * are not supported on all filesystems.
				 */
				if ((link(fname, oldfname) != 0) &&
				   (rename(fname, oldfname) != 0)) {
					warn("rename()");
					if (*tmpfname)
						unlink(tmpfname);
					exit(1);
				}
				*oldfname = '\0';
			}
			if (*tmpfname != '\0') {
				if (outfile != NULL && outfile != stdout)
					if (fclose(outfile) != 0) {
						warn("fclose()");
						unlink(tmpfname);
						exit(1);
					}
				outfile = NULL;
				if (rename(tmpfname, fname) != 0) {
					/* this should not happen really! */
					warn("rename()");
					unlink(tmpfname);
					exit(1);
				}
				*tmpfname = '\0';
			}
			outfname = NULL;
		}
		if (firstfile == 0)
			files = files->next;
		else
			firstfile = 0;
		if (files == NULL) {
			sp->len = 0;
			return (0);
		}
		fname = files->fname;
		if (inplace != NULL) {
			if (lstat(fname, &sb) != 0)
				err(1, "%s", fname);
			if (!(sb.st_mode & S_IFREG))
				errx(1, "%s: %s %s", fname,
				    "in-place editing only",
				    "works for regular files");
			if (*inplace != '\0') {
				strlcpy(oldfname, fname,
				    sizeof(oldfname));
				len = strlcat(oldfname, inplace,
				    sizeof(oldfname));
				if (len > sizeof(oldfname))
					errx(1, "%s: name too long", fname);
			}
			char d_name[PATH_MAX], f_name[PATH_MAX];
			(void)strlcpy(d_name, fname, sizeof(d_name));
			(void)strlcpy(f_name, fname, sizeof(f_name));
			len = (size_t)snprintf(tmpfname, sizeof(tmpfname),
			    "%s/.!%ld!%s", dirname(d_name), (long)getpid(),
			    basename(f_name));
			if (len >= sizeof(tmpfname))
				errx(1, "%s: name too long", fname);
			unlink(tmpfname);
			if (outfile != NULL && outfile != stdout)
				fclose(outfile);
			if ((outfile = fopen(tmpfname, "w")) == NULL)
				err(1, "%s", fname);
			fchown(fileno(outfile), sb.st_uid, sb.st_gid);
			fchmod(fileno(outfile), sb.st_mode & ALLPERMS);
			outfname = tmpfname;
			if (!ispan) {
				linenum = 0;
				resetstate();
			}
		} else {
			outfile = stdout;
			outfname = "stdout";
		}
		if ((infile = fopen(fname, "r")) == NULL) {
			warn("%s", fname);
			rval = 1;
			continue;
		}
	}
	/*
	 * We are here only when infile is open and we still have something
	 * to read from it.
	 *
	 * Use getline() so that we can handle essentially infinite input
	 * data.  The p and plen are static so each invocation gives
	 * getline() the same buffer which is expanded as needed.
	 */
	ssize_t slen = getline(&p, &plen, infile);
	if (slen == -1)
		err(1, "%s", fname);
	if (slen != 0 && p[slen - 1] == '\n')
		slen--;
	cspace(sp, p, (size_t)slen, spflag);

	linenum++;

	return (1);
}

static int
lastline(void)
{
	int ch;

	if (files->next != NULL && (inplace == NULL || ispan))
		return (0);
	if ((ch = getc(infile)) == EOF)
		return (1);
	ungetc(ch, infile);
	return (0);
}