/*	$NetBSD: nl.c,v 1.15 2020/12/31 04:07:37 ginsbach Exp $	*/

/*-
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Klaus Klein.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1999\
 The NetBSD Foundation, Inc.  All rights reserved.");
__RCSID("$NetBSD: nl.c,v 1.15 2020/12/31 04:07:37 ginsbach Exp $");
#endif    

#include <errno.h>
#include <limits.h>
#include <locale.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <err.h>

typedef enum {
	number_all,		/* number all lines */
	number_nonempty,	/* number non-empty lines */
	number_none,		/* no line numbering */
	number_regex		/* number lines matching regular expression */
} numbering_type;

struct numbering_property {
	const char * const	name;		/* for diagnostics */
	numbering_type		type;		/* numbering type */
	regex_t			expr;		/* for type == number_regex */
};

/* line numbering formats */
#define FORMAT_LN	"%-*d"	/* left justified, leading zeros suppressed */
#define FORMAT_RN	"%*d"	/* right justified, leading zeros suppressed */
#define FORMAT_RZ	"%0*d"	/* right justified, leading zeros kept */

#define FOOTER		0
#define BODY		1
#define HEADER		2
#define NP_LAST		HEADER

static struct numbering_property numbering_properties[NP_LAST + 1] = {
	{ "footer",	number_none,	{ 0, 0, 0, 0 } },
	{ "body",	number_nonempty, { 0, 0, 0, 0 } },
	{ "header",	number_none,	{ 0, 0, 0, 0 } },
};

#define max(a, b)	((a) > (b) ? (a) : (b))

/*
 * Maximum number of characters required for a decimal representation of a
 * (signed) int; courtesy of tzcode.
 */
#define INT_STRLEN_MAXIMUM \
	((sizeof (int) * CHAR_BIT - 1) * 302 / 1000 + 2)

static void	filter(void);
static void	parse_numbering(const char *, int);
static void	usage(void) __attribute__((__noreturn__));

/*
 * Pointer to dynamically allocated input line buffer, and its size.
 */
static char *buffer;
static size_t buffersize;

/*
 * Dynamically allocated buffer suitable for string representation of ints.
 */
static char *intbuffer;
static size_t intbuffersize;

/*
 * Configurable parameters.
 */
/* delimiter characters that indicate the start of a logical page section */
static char delim[2] = { '\\', ':' };

/* line numbering format */
static const char *format = FORMAT_RN;

/* increment value used to number logical page lines */
static int incr = 1;

/* number of adjacent blank lines to be considered (and numbered) as one */
static unsigned int nblank = 1;

/* whether to restart numbering at logical page delimiters */
static int restart = 1;

/* characters used in separating the line number and the corrsp. text line */
static const char *sep = "\t";

/* initial value used to number logical page lines */
static int startnum = 1;

/* number of characters to be used for the line number */
/* should be unsigned but required signed by `*' precision conversion */
static int width = 6;


int
main(int argc, char *argv[])
{
	int c;
	long val;
	unsigned long uval;
	char *ep;

	(void)setlocale(LC_ALL, "");

	/*
	 * Note: this implementation strictly conforms to the XBD Utility
	 * Syntax Guidelines and does not permit the optional `file' operand
	 * to be intermingled with the options, which is defined in the
	 * XCU specification (Issue 5) but declared an obsolescent feature that
	 * will be removed from a future issue.  It shouldn't matter, though.
	 */
	while ((c = getopt(argc, argv, "pb:d:f:h:i:l:n:s:v:w:")) != -1) {
		switch (c) {
		case 'p':
			restart = 0;
			break;
		case 'b':
			parse_numbering(optarg, BODY);
			break;
		case 'd':
			if (optarg[0] != '\0')
				delim[0] = optarg[0];
			if (optarg[1] != '\0') {
				delim[1] = optarg[1];
				/* at most two delimiter characters */
				if (optarg[2] != '\0') {
					errx(EXIT_FAILURE,
					    "invalid delim argument -- %s",
					    optarg);
					/* NOTREACHED */
				}
			}
			break;
		case 'f':
			parse_numbering(optarg, FOOTER);
			break;
		case 'h':
			parse_numbering(optarg, HEADER);
			break;
		case 'i':
			errno = 0;
			val = strtol(optarg, &ep, 10);
			if ((ep != NULL && *ep != '\0') ||
			 ((val == LONG_MIN || val == LONG_MAX) && errno != 0))
				errx(EXIT_FAILURE,
				    "invalid incr argument -- %s", optarg);
			incr = (int)val;
			break;
		case 'l':
			errno = 0;
			uval = strtoul(optarg, &ep, 10);
			if ((ep != NULL && *ep != '\0') ||
			    (uval == ULONG_MAX && errno != 0))
				errx(EXIT_FAILURE,
				    "invalid num argument -- %s", optarg);
			nblank = (unsigned int)uval;
			break;
		case 'n':
			if (strcmp(optarg, "ln") == 0) {
				format = FORMAT_LN;
			} else if (strcmp(optarg, "rn") == 0) {
				format = FORMAT_RN;
			} else if (strcmp(optarg, "rz") == 0) {
				format = FORMAT_RZ;
			} else
				errx(EXIT_FAILURE,
				    "illegal format -- %s", optarg);
			break;
		case 's':
			sep = optarg;
			break;
		case 'v':
			errno = 0;
			val = strtol(optarg, &ep, 10);
			if ((ep != NULL && *ep != '\0') ||
			 ((val == LONG_MIN || val == LONG_MAX) && errno != 0))
				errx(EXIT_FAILURE,
				    "invalid startnum value -- %s", optarg);
			startnum = (int)val;
			break;
		case 'w':
			errno = 0;
			val = strtol(optarg, &ep, 10);
			if ((ep != NULL && *ep != '\0') ||
			 ((val == LONG_MIN || val == LONG_MAX) && errno != 0))
				errx(EXIT_FAILURE,
				    "invalid width value -- %s", optarg);
			width = (int)val;
			if (!(width > 0))
				errx(EXIT_FAILURE,
				    "width argument must be > 0 -- %d",
				    width);
			break;
		case '?':
		default:
			usage();
			/* NOTREACHED */
		}
	}
	argc -= optind;
	argv += optind;

	switch (argc) {
	case 0:
		break;
	case 1:
		if (strcmp(argv[0], "-") != 0 &&
		    freopen(argv[0], "r", stdin) == NULL)
			err(EXIT_FAILURE, "Cannot open `%s'", argv[0]);
		break;
	default:
		usage();
		/* NOTREACHED */
	}

	/* Determine the maximum input line length to operate on. */
	if ((val = sysconf(_SC_LINE_MAX)) == -1) /* ignore errno */
		val = LINE_MAX;
	/* Allocate sufficient buffer space (including the terminating NUL). */
	buffersize = (size_t)val + 1;
	if ((buffer = malloc(buffersize)) == NULL)
		err(EXIT_FAILURE, "Cannot allocate input line buffer");

	/* Allocate a buffer suitable for preformatting line number. */
	intbuffersize = max((int)INT_STRLEN_MAXIMUM, width) + 1; /* NUL */
	if ((intbuffer = malloc(intbuffersize)) == NULL)
		err(EXIT_FAILURE, "cannot allocate preformatting buffer");

	/* Do the work. */
	filter();

	return EXIT_SUCCESS;
	/* NOTREACHED */
}

static void
filter(void)
{
	int line;		/* logical line number */
	int section;		/* logical page section */
	unsigned int adjblank;	/* adjacent blank lines */
	int consumed;		/* intbuffer measurement */
	int donumber, idx;

	adjblank = 0;
	line = startnum;
	section = BODY;
#ifdef __GNUC__
	donumber = 0;	/* avoid bogus `uninitialized' warning */
#endif

	while (fgets(buffer, (int)buffersize, stdin) != NULL) {
		for (idx = FOOTER; idx <= NP_LAST; idx++) {
			/* Does it look like a delimiter? */
			if (buffer[2 * idx + 0] == delim[0] &&
			    buffer[2 * idx + 1] == delim[1]) {
				/* Was this the whole line? */
				if (buffer[2 * idx + 2] == '\n') {
					section = idx;
					adjblank = 0;
					if (restart)
						line = startnum;
					goto nextline;
				}
			} else {
				break;
			}
		}

		switch (numbering_properties[section].type) {
		case number_all:
			/*
			 * Doing this for number_all only is disputable, but
			 * the standard expresses an explicit dependency on
			 * `-b a' etc.
			 */
			if (buffer[0] == '\n' && ++adjblank < nblank)
				donumber = 0;
			else
				donumber = 1, adjblank = 0;
			break;
		case number_nonempty:
			donumber = (buffer[0] != '\n');
			break;
		case number_none:
			donumber = 0;
			break;
		case number_regex:
			donumber =
			    (regexec(&numbering_properties[section].expr,
			    buffer, 0, NULL, 0) == 0);
			break;
		}

		if (donumber) {
			consumed = snprintf(intbuffer, intbuffersize, format,
			    width, line);
			(void)printf("%s%s",
			    intbuffer + max(0, consumed - width), sep);
			line += incr;
		} else {
			(void)printf("%*s%*s", width, "", (int)strlen(sep), "");
		}
		(void)printf("%s", buffer);

		if (ferror(stdout))
			err(EXIT_FAILURE, "output error");
nextline:
		;
	}

	if (ferror(stdin))
		err(EXIT_FAILURE, "input error");
}

/*
 * Various support functions.
 */

static void
parse_numbering(const char *argstr, int section)
{
	int error;
	char errorbuf[NL_TEXTMAX];

	switch (argstr[0]) {
	case 'a':
		numbering_properties[section].type = number_all;
		break;
	case 'n':
		numbering_properties[section].type = number_none;
		break;
	case 't':
		numbering_properties[section].type = number_nonempty;
		break;
	case 'p':
		/* If there was a previous expression, throw it away. */
		if (numbering_properties[section].type == number_regex)
			regfree(&numbering_properties[section].expr);
		else
			numbering_properties[section].type = number_regex;

		/* Compile/validate the supplied regular expression. */
		if ((error = regcomp(&numbering_properties[section].expr,
		    &argstr[1], REG_NEWLINE|REG_NOSUB)) != 0) {
			(void)regerror(error,
			    &numbering_properties[section].expr,
			    errorbuf, sizeof (errorbuf));
			errx(EXIT_FAILURE,
			    "%s expr: %s -- %s",
			    numbering_properties[section].name, errorbuf,
			    &argstr[1]);
		}
		break;
	default:
		errx(EXIT_FAILURE,
		    "illegal %s line numbering type -- %s",
		    numbering_properties[section].name, argstr);
	}
}

static void
usage(void)
{
	(void)fprintf(stderr, "Usage: %s [-p] [-b type] [-d delim] [-f type] "
	    "[-h type] [-i incr] [-l num]\n\t[-n format] [-s sep] "
	    "[-v startnum] [-w width] [file]\n", getprogname());
	exit(EXIT_FAILURE);
}