/*
 * pg  - A clone of the System V CRT paging utility.
 *
 *	Copyright (c) 2000-2001 Gunnar Ritter. All rights reserved.
 *
 * 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. [deleted]
 * 4. Neither the name of Gunnar Ritter nor the names of his contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY GUNNAR RITTER 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 GUNNAR RITTER 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.
 */

/* Sccsid @(#)pg.c 1.44 (gritter) 2/8/02 - modified for util-linux */

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#ifndef	TIOCGWINSZ
# include <sys/ioctl.h>
#endif
#include <sys/termios.h>
#include <fcntl.h>
#include <regex.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <ctype.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <setjmp.h>
#include <libgen.h>

#ifdef HAVE_NCURSES_H
# include <ncurses.h>
#elif defined(HAVE_NCURSES_NCURSES_H)
# include <ncurses/ncurses.h>
#endif

#include <term.h>

#include "nls.h"
#include "xalloc.h"
#include "widechar.h"
#include "all-io.h"
#include "closestream.h"
#include "strutils.h"

#define	READBUF		LINE_MAX	/* size of input buffer */
#define CMDBUF		255		/* size of command buffer */
#define	TABSIZE		8		/* spaces consumed by tab character */

#define	cuc(c)		((c) & 0377)

enum { FORWARD = 1, BACKWARD = 2 };	/* search direction */
enum { TOP, MIDDLE, BOTTOM };		/* position of matching line */

/* States for syntax-aware command line editor. */
enum {
	COUNT,
	SIGN,
	CMD_FIN,
	SEARCH,
	SEARCH_FIN,
	ADDON_FIN,
	STRING,
	INVALID
};

/* Current command */
struct {
	char cmdline[CMDBUF];
	size_t cmdlen;
	int count;
	int key;
	char pattern[CMDBUF];
	char addon;
} cmd;

/* Position of file arguments on argv[] to main() */
struct {
	int first;
	int current;
	int last;
} files;

void (*oldint) (int);		/* old SIGINT handler */
void (*oldquit) (int);		/* old SIGQUIT handler */
void (*oldterm) (int);		/* old SIGTERM handler */
char *tty;			/* result of ttyname(1) */
unsigned ontty;			/* whether running on tty device */
unsigned exitstatus;		/* exit status */
int pagelen = 23;		/* lines on a single screen page */
int ttycols = 79;		/* screen columns (starting at 0) */
struct termios otio;		/* old termios settings */
int tinfostat = -1;		/* terminfo routines initialized */
int searchdisplay = TOP;	/* matching line position */
regex_t re;			/* regular expression to search for */
int remembered;			/* have a remembered search string */
int cflag;			/* clear screen before each page */
int eflag;			/* suppress (EOF) */
int fflag;			/* do not split lines */
int nflag;			/* no newline for commands required */
int rflag;			/* "restricted" pg */
int sflag;			/* use standout mode */
const char *pstring = ":";	/* prompt string */
char *searchfor;		/* search pattern from argv[] */
int havepagelen;		/* page length is manually defined */
long startline;			/* start line from argv[] */
int nextfile = 1;		/* files to advance */
jmp_buf jmpenv;			/* jump from signal handlers */
int canjump;			/* jmpenv is valid */
wchar_t wbuf[READBUF];		/* used in several widechar routines */

char *copyright;
const char *helpscreen = N_("\
-------------------------------------------------------\n\
  h                       this screen\n\
  q or Q                  quit program\n\
  <newline>               next page\n\
  f                       skip a page forward\n\
  d or ^D                 next halfpage\n\
  l                       next line\n\
  $                       last page\n\
  /regex/                 search forward for regex\n\
  ?regex? or ^regex^      search backward for regex\n\
  . or ^L                 redraw screen\n\
  w or z                  set page size and go to next page\n\
  s filename              save current file to filename\n\
  !command                shell escape\n\
  p                       go to previous file\n\
  n                       go to next file\n\
\n\
Many commands accept preceding numbers, for example:\n\
+1<newline> (next page); -1<newline> (previous page); 1<newline> (first page).\n\
\n\
See pg(1) for more information.\n\
-------------------------------------------------------\n");

#ifndef HAVE_FSEEKO
static int fseeko(FILE *f, off_t off, int whence)
{
	return fseek(f, (long)off, whence);
}

static off_t ftello(FILE *f)
{
	return (off_t) ftell(f);
}
#endif

#ifdef USE_SIGSET	/* never defined */
/* sigset and sigrelse are obsolete - use when POSIX stuff is unavailable */
# define my_sigset	sigset
# define my_sigrelse	sigrelse
#else
static int my_sigrelse(int sig)
{
	sigset_t sigs;

	if (sigemptyset(&sigs) || sigaddset(&sigs, sig))
		return -1;
	return sigprocmask(SIG_UNBLOCK, &sigs, NULL);
}

typedef void (*my_sighandler_t) (int);
static my_sighandler_t my_sigset(int sig, my_sighandler_t disp)
{
	struct sigaction act, oact;

	act.sa_handler = disp;
	if (sigemptyset(&act.sa_mask))
		return SIG_ERR;
	act.sa_flags = 0;
	if (sigaction(sig, &act, &oact))
		return SIG_ERR;
	if (my_sigrelse(sig))
		return SIG_ERR;
	return oact.sa_handler;
}
#endif	/* USE_SIGSET */

/* Quit pg. */
static void __attribute__((__noreturn__)) quit(int status)
{
	exit(status < 0100 ? status : 077);
}

/* Usage message and similar routines. */
static void __attribute__((__noreturn__)) usage(FILE *out)
{
	fputs(USAGE_HEADER, out);
	fprintf(out,
		_(" %s [options] [+line] [+/pattern/] [files]\n"),
		program_invocation_short_name);
	fputs(USAGE_OPTIONS, out);
	fputs(_(" -number      lines per page\n"), out);
	fputs(_(" -c           clear screen before displaying\n"), out);
	fputs(_(" -e           do not pause at end of a file\n"), out);
	fputs(_(" -f           do not split long lines\n"), out);
	fputs(_(" -n           terminate command with new line\n"), out);
	fputs(_(" -p <prompt>  specify prompt\n"), out);
	fputs(_(" -r           disallow shell escape\n"), out);
	fputs(_(" -s           print messages to stdout\n"), out);
	fputs(_(" +number      start at the given line\n"), out);
	fputs(_(" +/pattern/   start at the line containing pattern\n"), out);

	fputs(USAGE_SEPARATOR, out);
	fputs(USAGE_HELP, out);
	fputs(USAGE_VERSION, out);

	fprintf(out, USAGE_MAN_TAIL("pg(1)"));
	quit(out == stderr ? 2 : 0);
}

static void __attribute__((__noreturn__)) needarg(const char *s)
{
	warnx(_("option requires an argument -- %s"), s);
	usage(stderr);
}

static void __attribute__((__noreturn__)) invopt(const char *s)
{
	warnx(_("illegal option -- %s"), s);
	usage(stderr);
}

#ifdef HAVE_WIDECHAR
/* A mbstowcs()-alike function that transparently handles invalid
 * sequences. */
static size_t xmbstowcs(wchar_t * pwcs, const char *s, size_t nwcs)
{
	size_t n = nwcs;
	int c;

	ignore_result(mbtowc(pwcs, NULL, MB_CUR_MAX));	/* reset shift state */
	while (*s && n) {
		if ((c = mbtowc(pwcs, s, MB_CUR_MAX)) < 0) {
			s++;
			*pwcs = L'?';
		} else
			s += c;
		pwcs++;
		n--;
	}
	if (n)
		*pwcs = L'\0';
	ignore_result(mbtowc(pwcs, NULL, MB_CUR_MAX));
	return nwcs - n;
}
#endif

/* Helper function for tputs(). */
static int outcap(int i)
{
	char c = i;
	return write_all(STDOUT_FILENO, &c, 1) == 0 ? 1 : -1;
}

/* Write messages to terminal. */
static void mesg(const char *message)
{
	if (ontty == 0)
		return;
	if (*message != '\n' && sflag)
		vidputs(A_STANDOUT, outcap);
	write_all(STDOUT_FILENO, message, strlen(message));
	if (*message != '\n' && sflag)
		vidputs(A_NORMAL, outcap);
}

/* Get the window size. */
static void getwinsize(void)
{
	static int initialized, envlines, envcols, deflines, defcols;
#ifdef	TIOCGWINSZ
	struct winsize winsz;
	int badioctl;
#endif
	char *p;

	if (initialized == 0) {
		if ((p = getenv("LINES")) != NULL && *p != '\0')
			if ((envlines = atoi(p)) < 0)
				envlines = 0;
		if ((p = getenv("COLUMNS")) != NULL && *p != '\0')
			if ((envcols = atoi(p)) < 0)
				envcols = 0;
		/* terminfo values. */
		if (tinfostat != 1 || columns == 0)
			defcols = 24;
		else
			defcols = columns;
		if (tinfostat != 1 || lines == 0)
			deflines = 80;
		else
			deflines = lines;
		initialized = 1;
	}
#ifdef	TIOCGWINSZ
	badioctl = ioctl(STDOUT_FILENO, TIOCGWINSZ, &winsz);
#endif
	if (envcols)
		ttycols = envcols - 1;
#ifdef	TIOCGWINSZ
	else if (!badioctl)
		ttycols = winsz.ws_col - 1;
#endif
	else
		ttycols = defcols - 1;
	if (havepagelen == 0) {
		if (envlines)
			pagelen = envlines - 1;
#ifdef	TIOCGWINSZ
		else if (!badioctl)
			pagelen = winsz.ws_row - 1;
#endif
		else
			pagelen = deflines - 1;
	}
}

/* Message if skipping parts of files. */
static void skip(int direction)
{
	if (direction > 0)
		mesg(_("...skipping forward\n"));
	else
		mesg(_("...skipping backward\n"));
}

/* Signal handler while reading from input file. */
static void sighandler(int signum)
{
	if (canjump && (signum == SIGINT || signum == SIGQUIT))
		longjmp(jmpenv, signum);
	tcsetattr(STDOUT_FILENO, TCSADRAIN, &otio);
	quit(exitstatus);
}

/* Check whether the requested file was specified on the command line. */
static int checkf(void)
{
	if (files.current + nextfile >= files.last) {
		mesg(_("No next file"));
		return 1;
	}
	if (files.current + nextfile < files.first) {
		mesg(_("No previous file"));
		return 1;
	}
	return 0;
}

#ifdef HAVE_WIDECHAR
/* Return the last character that will fit on the line at col columns in
 * case MB_CUR_MAX > 1. */
static char *endline_for_mb(unsigned col, char *s)
{
	size_t pos = 0;
	wchar_t *p = wbuf;
	wchar_t *end;
	size_t wl;
	char *t = s;

	if ((wl = xmbstowcs(wbuf, t, sizeof wbuf - 1)) == (size_t)-1)
		return s + 1;
	wbuf[wl] = L'\0';
	while (*p != L'\0') {
		switch (*p) {
			/* Cursor left. */
		case L'\b':
			if (pos > 0)
				pos--;
			break;
			/* No cursor movement. */
		case L'\a':
			break;
			/* Special. */
		case L'\r':
			pos = 0;
			break;
		case L'\n':
			end = p + 1;
			goto ended;
			/* Cursor right. */
		case L'\t':
			pos += TABSIZE - (pos % TABSIZE);
			break;
		default:
			if (iswprint(*p))
				pos += wcwidth(*p);
			else
				pos += wcwidth(L'?');
		}
		if (pos > col) {
			if (*p == L'\t')
				p++;
			else if (pos > col + 1)
				/* wcwidth() found a character that has
				 * multiple columns.  What happens now?
				 * Assume the terminal will print the
				 * entire character onto the next row. */
				p--;
			if (*++p == L'\n')
				p++;
			end = p;
			goto ended;
		}
		p++;
	}
	end = p;
 ended:
	*end = L'\0';
	p = wbuf;
	if ((pos = wcstombs(NULL, p, READBUF)) == (size_t)-1)
		return s + 1;
	return s + pos;
}
#endif	/* HAVE_WIDECHAR */

/* Return the last character that will fit on the line at col columns. */
static char *endline(unsigned col, char *s)
{
	unsigned pos = 0;
	char *t = s;

#ifdef HAVE_WIDECHAR
	if (MB_CUR_MAX > 1)
		return endline_for_mb(col, s);
#endif

	while (*s != '\0') {
		switch (*s) {
			/* Cursor left. */
		case '\b':
			if (pos > 0)
				pos--;
			break;
			/* No cursor movement. */
		case '\a':
			break;
			/* Special. */
		case '\r':
			pos = 0;
			break;
		case '\n':
			t = s + 1;
			goto cend;
			/* Cursor right. */
		case '\t':
			pos += TABSIZE - (pos % TABSIZE);
			break;
		default:
			pos++;
		}
		if (pos > col) {
			if (*s == '\t')
				s++;
			if (*++s == '\n')
				s++;
			t = s;
			goto cend;
		}
		s++;
	}
	t = s;
 cend:
	return t;
}

/* Clear the current line on the terminal's screen. */
static void cline(void)
{
	char *buf = xmalloc(ttycols + 2);
	memset(buf, ' ', ttycols + 2);
	buf[0] = '\r';
	buf[ttycols + 1] = '\r';
	write_all(STDOUT_FILENO, buf, ttycols + 2);
	free(buf);
}

/* Evaluate a command character's semantics. */
static int getstate(int c)
{
	switch (c) {
	case '1':
	case '2':
	case '3':
	case '4':
	case '5':
	case '6':
	case '7':
	case '8':
	case '9':
	case '0':
	case '\0':
		return COUNT;
	case '-':
	case '+':
		return SIGN;
	case 'l':
	case 'd':
	case '\004':
	case 'f':
	case 'z':
	case '.':
	case '\014':
	case '$':
	case 'n':
	case 'p':
	case 'w':
	case 'h':
	case 'q':
	case 'Q':
		return CMD_FIN;
	case '/':
	case '?':
	case '^':
		return SEARCH;
	case 's':
	case '!':
		return STRING;
	case 'm':
	case 'b':
	case 't':
		return ADDON_FIN;
	default:
#ifdef PG_BELL
		if (bell)
			tputs(bell, STDOUT_FILENO, outcap);
#endif
		return INVALID;
	}
}

/* Get the count and ignore last character of string. */
static int getcount(char *cmdstr)
{
	char *buf;
	char *p;
	int i;

	if (*cmdstr == '\0')
		return 1;
	buf = xmalloc(strlen(cmdstr) + 1);
	strcpy(buf, cmdstr);
	if (cmd.key != '\0') {
		if (cmd.key == '/' || cmd.key == '?' || cmd.key == '^') {
			if ((p = strchr(buf, cmd.key)) != NULL)
				*p = '\0';
		} else
			*(buf + strlen(buf) - 1) = '\0';
	}
	if (*buf == '\0') {
		free(buf);
		return 1;
	}
	if (buf[0] == '-' && buf[1] == '\0') {
		i = -1;
	} else {
		if (*buf == '+')
			i = atoi(buf + 1);
		else
			i = atoi(buf);
	}
	free(buf);
	return i;
}

/* Read what the user writes at the prompt. This is tricky because we
 * check for valid input. */
static void prompt(long long pageno)
{
	struct termios tio;
	char key;
	int state = COUNT;
	int escape = 0;
	char b[LINE_MAX], *p;

	if (pageno != -1) {
		if ((p = strstr(pstring, "%d")) == NULL) {
			mesg(pstring);
		} else {
			strcpy(b, pstring);
			sprintf(b + (p - pstring), "%lld", pageno);
			strcat(b, p + 2);
			mesg(b);
		}
	}
	cmd.key = cmd.addon = cmd.cmdline[0] = '\0';
	cmd.cmdlen = 0;
	tcgetattr(STDOUT_FILENO, &tio);
	tio.c_lflag &= ~(ICANON | ECHO);
	tio.c_cc[VMIN] = 1;
	tio.c_cc[VTIME] = 0;
	tcsetattr(STDOUT_FILENO, TCSADRAIN, &tio);
	tcflush(STDOUT_FILENO, TCIFLUSH);
	for (;;) {
		switch (read(STDOUT_FILENO, &key, 1)) {
		case 0:
			quit(0);
			/* NOTREACHED */
		case -1:
			quit(1);
		}
		if (key == tio.c_cc[VERASE]) {
			if (cmd.cmdlen) {
				write_all(STDOUT_FILENO, "\b \b", 3);
				cmd.cmdline[--cmd.cmdlen] = '\0';
				switch (state) {
				case ADDON_FIN:
					state = SEARCH_FIN;
					cmd.addon = '\0';
					break;
				case CMD_FIN:
					cmd.key = '\0';
					state = COUNT;
					break;
				case SEARCH_FIN:
					state = SEARCH;
					/* FALLTHRU */
				case SEARCH:
					if (cmd.cmdline[cmd.cmdlen - 1] == '\\') {
						escape = 1;
						while (cmd.cmdline[cmd.cmdlen
								   - escape - 1]
						       == '\\')
							escape++;
						escape %= 2;
					} else {
						escape = 0;
						if (strchr(cmd.cmdline, cmd.key)
						    == NULL) {
							cmd.key = '\0';
							state = COUNT;
						}
					}
					break;
				}
			}
			if (cmd.cmdlen == 0) {
				state = COUNT;
				cmd.key = '\0';
			}
			continue;
		}
		if (key == tio.c_cc[VKILL]) {
			cline();
			cmd.cmdlen = 0;
			cmd.cmdline[0] = '\0';
			state = COUNT;
			cmd.key = '\0';
			continue;
		}
		if (key == '\n' || (nflag && state == COUNT && key == ' '))
			break;
		if (cmd.cmdlen >= CMDBUF - 1)
			continue;
		switch (state) {
		case STRING:
			break;
		case SEARCH:
			if (!escape) {
				if (key == cmd.key)
					state = SEARCH_FIN;
				if (key == '\\')
					escape = 1;
			} else
				escape = 0;
			break;
		case SEARCH_FIN:
			if (getstate(key) != ADDON_FIN)
				continue;
			state = ADDON_FIN;
			cmd.addon = key;
			switch (key) {
			case 't':
				searchdisplay = TOP;
				break;
			case 'm':
				searchdisplay = MIDDLE;
				break;
			case 'b':
				searchdisplay = BOTTOM;
				break;
			}
			break;
		case CMD_FIN:
		case ADDON_FIN:
			continue;
		default:
			state = getstate(key);
			switch (state) {
			case SIGN:
				if (cmd.cmdlen != 0) {
					state = INVALID;
					continue;
				}
				state = COUNT;
				/* FALLTHRU */
			case COUNT:
				break;
			case ADDON_FIN:
			case INVALID:
				continue;
			default:
				cmd.key = key;
			}
		}
		write_all(STDOUT_FILENO, &key, 1);
		cmd.cmdline[cmd.cmdlen++] = key;
		cmd.cmdline[cmd.cmdlen] = '\0';
		if (nflag && state == CMD_FIN)
			goto endprompt;
	}
 endprompt:
	tcsetattr(STDOUT_FILENO, TCSADRAIN, &otio);
	cline();
	cmd.count = getcount(cmd.cmdline);
}

#ifdef HAVE_WIDECHAR
/* Remove backspace formatting, for searches in case MB_CUR_MAX > 1. */
static char *colb_for_mb(char *s)
{
	char *p = s;
	wchar_t *wp, *wq;
	size_t l = strlen(s), wl;
	unsigned i;

	if ((wl = xmbstowcs(wbuf, p, sizeof wbuf)) == (size_t)-1)
		return s;
	for (wp = wbuf, wq = wbuf, i = 0; *wp != L'\0' && i < wl; wp++, wq++) {
		if (*wp == L'\b') {
			if (wq != wbuf)
				wq -= 2;
			else
				wq--;
		} else
			*wq = *wp;
	}
	*wq = L'\0';
	wp = wbuf;
	wcstombs(s, wp, l + 1);

	return s;
}
#endif

/* Remove backspace formatting, for searches. */
static char *colb(char *s)
{
	char *p = s, *q;

#ifdef HAVE_WIDECHAR
	if (MB_CUR_MAX > 1)
		return colb_for_mb(s);
#endif

	for (q = s; *p != '\0'; p++, q++) {
		if (*p == '\b') {
			if (q != s)
				q -= 2;
			else
				q--;
		} else
			*q = *p;
	}
	*q = '\0';

	return s;
}

#ifdef HAVE_WIDECHAR
/* Convert nonprintable characters to spaces in case MB_CUR_MAX > 1.  */
static void makeprint_for_mb(char *s, size_t l)
{
	char *t = s;
	wchar_t *wp = wbuf;
	size_t wl;

	if ((wl = xmbstowcs(wbuf, t, sizeof wbuf)) == (size_t)-1)
		return;
	while (wl--) {
		if (!iswprint(*wp) && *wp != L'\n' && *wp != L'\r'
		    && *wp != L'\b' && *wp != L'\t')
			*wp = L'?';
		wp++;
	}
	wp = wbuf;
	wcstombs(s, wp, l);
}
#endif

/* Convert nonprintable characters to spaces. */
static void makeprint(char *s, size_t l)
{
#ifdef HAVE_WIDECHAR
	if (MB_CUR_MAX > 1) {
		makeprint_for_mb(s, l);
		return;
	}
#endif

	while (l--) {
		if (!isprint(cuc(*s)) && *s != '\n' && *s != '\r'
		    && *s != '\b' && *s != '\t')
			*s = '?';
		s++;
	}
}

/* Strip backslash characters from the given string. */
static void striprs(char *s)
{
	char *p = s;

	do {
		if (*s == '\\') {
			s++;
		}
		*p++ = *s;
	} while (*s++ != '\0');
}

/* Extract the search pattern off the command line. */
static char *makepat(void)
{
	char *p;

	if (cmd.addon == '\0')
		p = cmd.cmdline + strlen(cmd.cmdline) - 1;
	else
		p = cmd.cmdline + strlen(cmd.cmdline) - 2;
	if (*p == cmd.key)
		*p = '\0';
	else
		*(p + 1) = '\0';
	if ((p = strchr(cmd.cmdline, cmd.key)) != NULL) {
		p++;
		striprs(p);
	}
	return p;
}

/* Process errors that occurred in temporary file operations. */
static void __attribute__((__noreturn__)) tmperr(FILE *f, const char *ftype)
{
	if (ferror(f))
		warn(_("Read error from %s file"), ftype);
	else if (feof(f))
		/* Most likely '\0' in input. */
		warnx(_("Unexpected EOF in %s file"), ftype);
	else
		warn(_("Unknown error in %s file"), ftype);
	quit(++exitstatus);
}

/* Read the file and respond to user input.  Beware: long and ugly. */
static void pgfile(FILE *f, const char *name)
{
	off_t pos, oldpos, fpos;
	/* These are the line counters:
	 *   line	the line desired to display
	 *   fline	the current line of the input file
	 *   bline	the current line of the file buffer
	 *   oldline	the line before a search was started
	 *   eofline	the last line of the file if it is already reached
	 *   dline	the line on the display */
	off_t line = 0, fline = 0, bline = 0, oldline = 0, eofline = 0;
	int dline = 0;
	int search = 0;
	unsigned searchcount = 0;
	/* Advance to EOF immediately. */
	int seekeof = 0;
	/* EOF has been reached by `line'. */
	int eof = 0;
	/* f and fbuf refer to the same file. */
	int nobuf = 0;
	int sig;
	int rerror;
	size_t sz;
	char b[READBUF + 1];
	char *p;
	/*   fbuf	an exact copy of the input file as it gets read
	 *   find	index table for input, one entry per line
	 *   save	for the s command, to save to a file */
	FILE *fbuf, *find, *save;

	if (ontty == 0) {
		/* Just copy stdin to stdout. */
		while ((sz = fread(b, sizeof *b, READBUF, f)) != 0)
			write_all(STDOUT_FILENO, b, sz);
		if (ferror(f)) {
			warn("%s", name);
			exitstatus++;
		}
		return;
	}
	if ((fpos = fseeko(f, (off_t)0, SEEK_SET)) == -1)
		fbuf = tmpfile();
	else {
		fbuf = f;
		nobuf = 1;
	}
	find = tmpfile();
	if (fbuf == NULL || find == NULL) {
		warn(_("Cannot create tempfile"));
		quit(++exitstatus);
	}
	if (searchfor) {
		search = FORWARD;
		oldline = 0;
		searchcount = 1;
		rerror = regcomp(&re, searchfor, REG_NOSUB | REG_NEWLINE);
		if (rerror != 0) {
			mesg(_("RE error: "));
			regerror(rerror, &re, b, READBUF);
			mesg(b);
			goto newcmd;
		}
		remembered = 1;
	}

	for (line = startline;;) {
		/* Get a line from input file or buffer. */
		if (line < bline) {
			fseeko(find, line * sizeof pos, SEEK_SET);
			if (fread(&pos, sizeof pos, 1, find) == 0)
				tmperr(find, "index");
			fseeko(find, (off_t)0, SEEK_END);
			fseeko(fbuf, pos, SEEK_SET);
			if (fgets(b, READBUF, fbuf) == NULL)
				tmperr(fbuf, "buffer");
		} else if (eofline == 0) {
			fseeko(find, (off_t)0, SEEK_END);
			do {
				if (!nobuf)
					fseeko(fbuf, (off_t)0, SEEK_END);
				pos = ftello(fbuf);
				if ((sig = setjmp(jmpenv)) != 0) {
					/* We got a signal. */
					canjump = 0;
					my_sigrelse(sig);
					fseeko(fbuf, pos, SEEK_SET);
					*b = '\0';
					dline = pagelen;
					break;
				} else {
					if (nobuf)
						fseeko(f, fpos, SEEK_SET);
					canjump = 1;
					p = fgets(b, READBUF, f);
					if (nobuf)
						if ((fpos = ftello(f)) == -1)
							warn("%s", name);
					canjump = 0;
				}
				if (p == NULL || *b == '\0') {
					if (ferror(f))
						warn("%s", name);
					eofline = fline;
					eof = 1;
					break;
				} else {
					if (!nobuf)
						fputs(b, fbuf);
					fwrite_all(&pos, sizeof pos, 1, find);
					if (!fflag) {
						oldpos = pos;
						p = b;
						while (*(p = endline(ttycols,
								     p))
						       != '\0') {
							pos = oldpos + (p - b);
							fwrite_all(&pos,
								   sizeof pos,
								   1, find);
							fline++;
							bline++;
						}
					}
					fline++;
				}
			} while (line > bline++);
		} else {
			/* eofline != 0 */
			eof = 1;
		}
		if (search == FORWARD && remembered == 1) {
			if (eof) {
				line = oldline;
				search = searchcount = 0;
				mesg(_("Pattern not found"));
				eof = 0;
				goto newcmd;
			}
			line++;
			colb(b);
			if (regexec(&re, b, 0, NULL, 0) == 0) {
				searchcount--;
			}
			if (searchcount == 0) {
				search = dline = 0;
				switch (searchdisplay) {
				case TOP:
					line -= 1;
					break;
				case MIDDLE:
					line -= pagelen / 2 + 1;
					break;
				case BOTTOM:
					line -= pagelen;
					break;
				}
				skip(1);
			}
			continue;
		} else if (eof) {
			/* We are not searching. */
			line = bline;
		} else if (*b != '\0') {
			if (cflag && clear_screen) {
				switch (dline) {
				case 0:
					tputs(clear_screen, STDOUT_FILENO,
					      outcap);
					dline = 0;
				}
			}
			line++;
			if (eofline && line == eofline)
				eof = 1;
			dline++;
			if ((sig = setjmp(jmpenv)) != 0) {
				/* We got a signal. */
				canjump = 0;
				my_sigrelse(sig);
				dline = pagelen;
			} else {
				p = endline(ttycols, b);
				sz = p - b;
				makeprint(b, sz);
				canjump = 1;
				write_all(STDOUT_FILENO, b, sz);
				canjump = 0;
			}
		}
		if (dline >= pagelen || eof) {
			/* Time for prompting! */
			if (eof && seekeof) {
				eof = seekeof = 0;
				if (line >= pagelen)
					line -= pagelen;
				else
					line = 0;
				dline = -1;
				continue;
			}
 newcmd:
			if (eof) {
				if (fline == 0 || eflag)
					break;
				mesg(_("(EOF)"));
			}
			prompt((line - 1) / pagelen + 1);
			switch (cmd.key) {
			case '/':
				/* Search forward. */
				search = FORWARD;
				oldline = line;
				searchcount = cmd.count;
				p = makepat();
				if (p != NULL && *p) {
					if (remembered == 1)
						regfree(&re);
					rerror = regcomp(&re, p,
							 REG_NOSUB |
							 REG_NEWLINE);
					if (rerror != 0) {
						mesg(_("RE error: "));
						sz = regerror(rerror, &re,
							      b, READBUF);
						mesg(b);
						goto newcmd;
					}
					remembered = 1;
				} else if (remembered == 0) {
					mesg(_("No remembered search string"));
					goto newcmd;
				}
				continue;
			case '?':
			case '^':
				/* Search backward. */
				search = BACKWARD;
				oldline = line;
				searchcount = cmd.count;
				p = makepat();
				if (p != NULL && *p) {
					if (remembered == 1)
						regfree(&re);
					rerror = regcomp(&re, p,
							 REG_NOSUB |
							 REG_NEWLINE);
					if (rerror != 0) {
						mesg(_("RE error: "));
						regerror(rerror, &re,
							 b, READBUF);
						mesg(b);
						goto newcmd;
					}
					remembered = 1;
				} else if (remembered == 0) {
					mesg(_("No remembered search string"));
					goto newcmd;
				}
				line -= pagelen;
				if (line <= 0)
					goto notfound_bw;
				while (line) {
					fseeko(find, --line * sizeof pos,
					       SEEK_SET);
					if (fread(&pos, sizeof pos, 1, find) ==
					    0)
						tmperr(find, "index");
					fseeko(find, (off_t)0, SEEK_END);
					fseeko(fbuf, pos, SEEK_SET);
					if (fgets(b, READBUF, fbuf) == NULL)
						tmperr(fbuf, "buffer");
					colb(b);
					if (regexec(&re, b, 0, NULL, 0) == 0)
						searchcount--;
					if (searchcount == 0)
						goto found_bw;
				}
 notfound_bw:
				line = oldline;
				search = searchcount = 0;
				mesg(_("Pattern not found"));
				goto newcmd;
 found_bw:
				eof = search = dline = 0;
				skip(-1);
				switch (searchdisplay) {
				case TOP:
					/* line -= 1; */
					break;
				case MIDDLE:
					line -= pagelen / 2;
					break;
				case BOTTOM:
					if (line != 0)
						dline = -1;
					line -= pagelen;
					break;
				}
				if (line < 0)
					line = 0;
				continue;
			case 's':
				/* Save to file. */
				p = cmd.cmdline;
				while (*++p == ' ') ;
				if (*p == '\0')
					goto newcmd;
				save = fopen(p, "wb");
				if (save == NULL) {
					cmd.count = errno;
					mesg(_("cannot open "));
					mesg(p);
					mesg(": ");
					mesg(strerror(cmd.count));
					goto newcmd;
				}
				/* Advance to EOF. */
				fseeko(find, (off_t)0, SEEK_END);
				for (;;) {
					if (!nobuf)
						fseeko(fbuf, (off_t)0,
						       SEEK_END);
					pos = ftello(fbuf);
					if (fgets(b, READBUF, f) == NULL) {
						eofline = fline;
						break;
					}
					if (!nobuf)
						fputs(b, fbuf);
					fwrite_all(&pos, sizeof pos, 1, find);
					if (!fflag) {
						oldpos = pos;
						p = b;
						while (*(p = endline(ttycols,
								     p))
						       != '\0') {
							pos = oldpos + (p - b);
							fwrite_all(&pos,
								   sizeof pos,
								   1, find);
							fline++;
							bline++;
						}
					}
					fline++;
					bline++;
				}
				fseeko(fbuf, (off_t)0, SEEK_SET);
				while ((sz = fread(b, sizeof *b, READBUF,
						   fbuf)) != 0) {
					/* No error check for compat. */
					fwrite_all(b, sizeof *b, sz, save);
				}
				if (close_stream(save) != 0) {
					cmd.count = errno;
					mesg(_("write failed"));
					mesg(": ");
					mesg(p);
					mesg(strerror(cmd.count));
					goto newcmd;
				}
				fseeko(fbuf, (off_t)0, SEEK_END);
				mesg(_("saved"));
				goto newcmd;
			case 'l':
				/* Next line. */
				if (*cmd.cmdline != 'l')
					eof = 0;
				if (cmd.count == 0)
					cmd.count = 1;	/* compat */
				if (isdigit(cuc(*cmd.cmdline))) {
					line = cmd.count - 2;
					dline = 0;
				} else {
					if (cmd.count != 1) {
						line += cmd.count - 1 - pagelen;
						dline = -1;
						skip(cmd.count);
					}
					/* Nothing to do if (count == 1) */
				}
				break;
			case 'd':
				/* Half screen forward. */
			case '\004':	/* ^D */
				if (*cmd.cmdline != cmd.key)
					eof = 0;
				if (cmd.count == 0)
					cmd.count = 1;	/* compat */
				line += (cmd.count * pagelen / 2)
				    - pagelen - 1;
				dline = -1;
				skip(cmd.count);
				break;
			case 'f':
				/* Skip forward. */
				if (cmd.count <= 0)
					cmd.count = 1;	/* compat */
				line += cmd.count * pagelen - 2;
				if (eof)
					line += 2;
				if (*cmd.cmdline != 'f')
					eof = 0;
				else if (eof)
					break;
				if (eofline && line >= eofline)
					line -= pagelen;
				dline = -1;
				skip(cmd.count);
				break;
			case '\0':
				/* Just a number, or '-', or <newline>. */
				if (cmd.count == 0)
					cmd.count = 1;	/* compat */
				if (isdigit(cuc(*cmd.cmdline)))
					line = (cmd.count - 1) * pagelen - 2;
				else
					line += (cmd.count - 1)
					    * (pagelen - 1) - 2;
				if (*cmd.cmdline != '\0')
					eof = 0;
				if (cmd.count != 1) {
					skip(cmd.count);
					dline = -1;
				} else {
					dline = 1;
					line += 2;
				}
				break;
			case '$':
				/* Advance to EOF. */
				if (!eof)
					skip(1);
				eof = 0;
				line = LONG_MAX;
				seekeof = 1;
				dline = -1;
				break;
			case '.':
			case '\014':	/* ^L */
				/* Repaint screen. */
				eof = 0;
				if (line >= pagelen)
					line -= pagelen;
				else
					line = 0;
				dline = 0;
				break;
			case '!':
				/* Shell escape. */
				if (rflag) {
					mesg(program_invocation_short_name);
					mesg(_(": !command not allowed in "
					       "rflag mode.\n"));
				} else {
					pid_t cpid;

					write_all(STDOUT_FILENO, cmd.cmdline,
						  strlen(cmd.cmdline));
					write_all(STDOUT_FILENO, "\n", 1);
					my_sigset(SIGINT, SIG_IGN);
					my_sigset(SIGQUIT, SIG_IGN);
					switch (cpid = fork()) {
					case 0:
					{
						const char *sh = getenv("SHELL");
						if (!sh)
							sh = "/bin/sh";
						if (!nobuf)
							fclose(fbuf);
						fclose(find);
						if (isatty(0) == 0) {
							close(0);
							open(tty, O_RDONLY);
						} else {
							fclose(f);
						}
						my_sigset(SIGINT, oldint);
						my_sigset(SIGQUIT, oldquit);
						my_sigset(SIGTERM, oldterm);
						execl(sh, sh, "-c",
						      cmd.cmdline + 1, NULL);
						warn(_("failed to execute %s"), sh);
						_exit(0177);
						/* NOTREACHED */
					}
					case -1:
						mesg(_("fork() failed, "
						       "try again later\n"));
						break;
					default:
						while (wait(NULL) != cpid) ;
					}
					my_sigset(SIGINT, sighandler);
					my_sigset(SIGQUIT, sighandler);
					mesg("!\n");
				}
				goto newcmd;
			case 'h':
				{
					/* Help! */
					const char *help = _(helpscreen);
					write_all(STDOUT_FILENO, copyright,
						  strlen(copyright));
					write_all(STDOUT_FILENO, help,
						  strlen(help));
					goto newcmd;
				}
			case 'n':
				/* Next file. */
				if (cmd.count == 0)
					cmd.count = 1;
				nextfile = cmd.count;
				if (checkf()) {
					nextfile = 1;
					goto newcmd;
				}
				eof = 1;
				break;
			case 'p':
				/* Previous file. */
				if (cmd.count == 0)
					cmd.count = 1;
				nextfile = 0 - cmd.count;
				if (checkf()) {
					nextfile = 1;
					goto newcmd;
				}
				eof = 1;
				break;
			case 'q':
			case 'Q':
				/* Exit pg. */
				quit(exitstatus);
				/* NOTREACHED */
			case 'w':
			case 'z':
				/* Set window size. */
				if (cmd.count < 0)
					cmd.count = 0;
				if (*cmd.cmdline != cmd.key)
					pagelen = ++cmd.count;
				dline = 1;
				break;
			}
			if (line <= 0) {
				line = 0;
				dline = 0;
			}
			if (cflag && dline == 1) {
				dline = 0;
				line--;
			}
		}
		if (eof)
			break;
	}
	fclose(find);
	if (!nobuf)
		fclose(fbuf);
}

static int parse_arguments(int arg, int argc, char **argv)
{
	FILE *input;

	files.first = arg;
	files.last = arg + argc - 1;
	for (; argv[arg]; arg += nextfile) {
		nextfile = 1;
		files.current = arg;
		if (argc > 2) {
			static int firsttime;
			firsttime++;
			if (firsttime > 1) {
				mesg(_("(Next file: "));
				mesg(argv[arg]);
				mesg(")");
 newfile:
				if (ontty) {
					prompt(-1);
					switch (cmd.key) {
					case 'n':
						/* Next file. */
						if (cmd.count == 0)
							cmd.count = 1;
						nextfile = cmd.count;
						if (checkf()) {
							nextfile = 1;
							mesg(":");
							goto newfile;
						}
						continue;
					case 'p':
						/* Previous file. */
						if (cmd.count == 0)
							cmd.count = 1;
						nextfile = 0 - cmd.count;
						if (checkf()) {
							nextfile = 1;
							mesg(":");
							goto newfile;
						}
						continue;
					case 'q':
					case 'Q':
						quit(exitstatus);
					}
				} else
					mesg("\n");
			}
		}
		if (strcmp(argv[arg], "-") == 0)
			input = stdin;
		else {
			input = fopen(argv[arg], "r");
			if (input == NULL) {
				warn("%s", argv[arg]);
				exitstatus++;
				continue;
			}
		}
		if (ontty == 0 && argc > 2) {
			/* Use the prefix as specified by SUSv2. */
			write_all(STDOUT_FILENO, "::::::::::::::\n", 15);
			write_all(STDOUT_FILENO, argv[arg], strlen(argv[arg]));
			write_all(STDOUT_FILENO, "\n::::::::::::::\n", 16);
		}
		pgfile(input, argv[arg]);
		if (input != stdin)
			fclose(input);
	}
	return exitstatus;
}

int main(int argc, char **argv)
{
	int arg, i;
	char *p;

	xasprintf(&copyright,
		  _("%s %s Copyright (c) 2000-2001 Gunnar Ritter. All rights reserved.\n"),
		  program_invocation_short_name, PACKAGE_VERSION);

	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);
	atexit(close_stdout);

	if (tcgetattr(STDOUT_FILENO, &otio) == 0) {
		ontty = 1;
		oldint = my_sigset(SIGINT, sighandler);
		oldquit = my_sigset(SIGQUIT, sighandler);
		oldterm = my_sigset(SIGTERM, sighandler);
		setlocale(LC_CTYPE, "");
		setlocale(LC_COLLATE, "");
		tty = ttyname(STDOUT_FILENO);
		setupterm(NULL, STDOUT_FILENO, &tinfostat);
		getwinsize();
		helpscreen = _(helpscreen);
	}
	for (arg = 1; argv[arg]; arg++) {
		if (*argv[arg] == '+')
			continue;
		if (*argv[arg] != '-' || argv[arg][1] == '\0')
			break;
		argc--;

		if (!strcmp(argv[arg], "--help")) {
		    usage(stdout);
		}

		if (!strcmp(argv[arg], "--version")) {
		    printf(UTIL_LINUX_VERSION);
		    return EXIT_SUCCESS;
		}

		for (i = 1; argv[arg][i]; i++) {
			switch (argv[arg][i]) {
			case '-':
				if (i != 1 || argv[arg][i + 1])
					invopt(&argv[arg][i]);
				goto endargs;
			case '1':
			case '2':
			case '3':
			case '4':
			case '5':
			case '6':
			case '7':
			case '8':
			case '9':
			case '0':
				pagelen = strtol_or_err(argv[arg] + 1,
						_("failed to parse number of lines per page"));
				havepagelen = 1;
				goto nextarg;
			case 'c':
				cflag = 1;
				break;
			case 'e':
				eflag = 1;
				break;
			case 'f':
				fflag = 1;
				break;
			case 'n':
				nflag = 1;
				break;
			case 'p':
				if (argv[arg][i + 1]) {
					pstring = &argv[arg][i + 1];
				} else if (argv[++arg]) {
					--argc;
					pstring = argv[arg];
				} else
					needarg("-p");
				goto nextarg;
			case 'r':
				rflag = 1;
				break;
			case 's':
				sflag = 1;
				break;
			case 'h':
				usage(stdout);
			case 'V':
				printf(UTIL_LINUX_VERSION);
				return EXIT_SUCCESS;
			default:
				invopt(&argv[arg][i]);
			}
		}
 nextarg:
		;
	}
 endargs:
	for (arg = 1; argv[arg]; arg++) {
		if (*argv[arg] == '-') {
			if (argv[arg][1] == '-') {
				arg++;
				break;
			}
			if (argv[arg][1] == '\0')
				break;
			if (argv[arg][1] == 'p' && argv[arg][2] == '\0')
				arg++;
			continue;
		}
		if (*argv[arg] != '+')
			break;
		argc--;
		switch (*(argv[arg] + 1)) {
		case '\0':
			needarg("+");
			/*NOTREACHED*/
		case '1':
		case '2':
		case '3':
		case '4':
		case '5':
		case '6':
		case '7':
		case '8':
		case '9':
		case '0':
			startline = strtol_or_err(argv[arg] + 1,
					_("failed to parse number of lines per page"));
			break;
		case '/':
			searchfor = argv[arg] + 2;
			if (*searchfor == '\0')
				needarg("+/");
			p = searchfor + strlen(searchfor) - 1;
			if (*p == '/')
				*p = '\0';
			if (*searchfor == '\0')
				needarg("+/");
			break;
		default:
			invopt(argv[arg]);
		}
	}
	if (argc == 1)
		pgfile(stdin, "stdin");
	else
		exitstatus = parse_arguments(arg, argc, argv);

	quit(exitstatus);
	/* NOTREACHED */
	return 0;
}
