/*      $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);
}