/*
 * Copyright (c) 1987, 1993, 1994
 *      The Regents of the University of California.  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. 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.
 *
 * @(#) Copyright (c) 1987, 1993, 1994 The Regents of the University of California.  All rights reserved.
 * @(#)split.c  8.2 (Berkeley) 4/16/94
 * $FreeBSD: src/usr.bin/split/split.c,v 1.6.2.2 2002/07/25 12:46:36 tjr Exp $
 */

#include <sys/param.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libutil.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <regex.h>
#include <sysexits.h>

#define DEFLINE 1000                    /* Default num lines per file. */

static int64_t   bytecnt;               /* Byte count to split on. */
static long      numlines;              /* Line count to split on. */
static int       file_open;             /* If a file open. */
static int       ifd = -1, ofd = -1;    /* Input/output file descriptors. */
static char      *bfr;                  /* I/O buffer. */
static char      fname[MAXPATHLEN];     /* File name prefix. */
static regex_t   rgx;
static bool      dflag;
static int       pflag;
static long      sufflen = 2;           /* File name suffix length. */

static void newfile(void);
static void split1(void);
static void split2(void);
static void usage(void);

int
main(int argc, char **argv)
{
        int ch;
        char *ep, *p;
        int error;

        while ((ch = getopt(argc, argv, "0123456789a:b:dl:p:")) != -1)
                switch (ch) {
                case '0': case '1': case '2': case '3': case '4':
                case '5': case '6': case '7': case '8': case '9':
                        /*
                         * Undocumented kludge: split was originally designed
                         * to take a number after a dash.
                         */
                        if (numlines == 0) {
                                p = argv[optind - 1];
                                if (p[0] == '-' && p[1] == ch && !p[2])
                                        numlines = strtol(++p, &ep, 10);
                                else
                                        numlines =
                                            strtol(argv[optind] + 1, &ep, 10);
                                if (numlines <= 0 || *ep)
                                        errx(EX_USAGE,
                                            "%s: illegal line count", optarg);
                        }
                        break;
                case 'a':               /* Suffix length */
                        if ((sufflen = strtol(optarg, &ep, 10)) <= 0 || *ep)
                                errx(EX_USAGE,
                                    "%s: illegal suffix length", optarg);
                        break;
                case 'b':               /* Byte count. */
                        error = dehumanize_number(optarg, &bytecnt);
                        if (error != 0)
                                errx(EX_USAGE, "%s: illegal byte count",
                                    optarg);
                        break;
                case 'd':       /* Decimal suffix */
                        dflag = true;
                        break;
                case 'p' :      /* pattern matching. */
                        if (regcomp(&rgx, optarg, REG_EXTENDED|REG_NOSUB) != 0)
                                errx(EX_USAGE, "%s: illegal regexp", optarg);
                        pflag = 1;
                        break;
                case 'l':               /* Line count. */
                        if (numlines != 0)
                                usage();
                        if ((numlines = strtol(optarg, &ep, 10)) <= 0 || *ep)
                                errx(EX_USAGE,
                                    "%s: illegal line count", optarg);
                        break;
                default:
                        usage();
                }
        argv += optind;
        argc -= optind;

        if (*argv != NULL) {
                if (strcmp(*argv, "-") == 0)
                        ifd = STDIN_FILENO;
                else if ((ifd = open(*argv, O_RDONLY, 0)) < 0)
                        err(EX_NOINPUT, "%s", *argv);
                ++argv;
        }

        if (*argv != NULL)                      /* File name prefix. */
                if (strlcpy(fname, *argv++, sizeof(fname)) >= sizeof(fname))
                        errx(EX_USAGE, "file name prefix is too long");
        if (*argv != NULL)
                usage();

        if (strlen(fname) + (unsigned long)sufflen >= sizeof(fname))
                errx(EX_USAGE, "suffix is too long");
        if (pflag && (numlines != 0 || bytecnt != 0))
                usage();

        if (numlines == 0)
                numlines = DEFLINE;
        else if (bytecnt != 0)
                usage();

        if (ifd == -1)                          /* Stdin by default. */
                ifd = 0;

        if (bytecnt) {
                split1();
                exit (0);
        }
        split2();
        if (pflag)
                regfree(&rgx);
        exit(0);
}

/*
 * split1 --
 *      Split the input by bytes.
 */
static void
split1(void)
{
        off_t bcnt;
        char *C;
        ssize_t dist, len;

        if((bfr = (char *)malloc(bytecnt)) == NULL)
                err(EX_OSERR, "malloc");

        for (bcnt = 0;;)
                switch ((len = read(ifd, bfr, bytecnt))) {
                case 0:
                        free(bfr);
                        exit(0);
                case -1:
                        free(bfr);
                        err(EX_IOERR, "read");
                        /* NOTREACHED */
                default:
                        if (!file_open)
                                newfile();
                        if (bcnt + len >= bytecnt) {
                                dist = bytecnt - bcnt;
                                if (write(ofd, bfr, dist) != dist)
                                        err(EX_IOERR, "write");
                                len -= dist;
                                for (C = bfr + dist; len >= bytecnt;
                                    len -= bytecnt, C += bytecnt) {
                                        newfile();
                                        if (write(ofd,
                                            C, (int)bytecnt) != bytecnt) {
                                                free(bfr);
                                                err(EX_IOERR, "write");
                                        }
                                }
                                if (len != 0) {
                                        newfile();
                                        if (write(ofd, C, len) != len) {
                                                free(bfr);
                                                err(EX_IOERR, "write");
                                        }
                                } else
                                        file_open = 0;
                                bcnt = len;
                        } else {
                                bcnt += len;
                                if (write(ofd, bfr, len) != len) {
                                        free(bfr);
                                        err(EX_IOERR, "write");
                                }
                        }
                }
        free(bfr);
}

/*
 * split2 --
 *      Split the input by lines.
 */
static void
split2(void)
{
        int startofline = 1;
        long lcnt = 0;
        FILE *infp;

        /* Stick a stream on top of input file descriptor */
        if ((infp = fdopen(ifd, "r")) == NULL)
                err(EX_NOINPUT, "fdopen");

        if((bfr = (char *)malloc(MAXBSIZE)) == NULL)
                err(EX_OSERR, "malloc");

        /* Process input one line at a time */
        while (fgets(bfr, MAXBSIZE, infp) != NULL) {
                const int len = strlen(bfr);

                /* Consider starting a new file only when at beginning of a line */
                if (startofline) {
                        /* Check if we need to start a new file */
                        if (pflag) {
                                regmatch_t pmatch;

                                pmatch.rm_so = 0;
                                pmatch.rm_eo = len - 1;
                                if (regexec(&rgx, bfr, 0, &pmatch, REG_STARTEND) == 0)
                                        newfile();
                        } else if (lcnt++ == numlines) {
                                newfile();
                                lcnt = 1;
                        }
                }
                
                if (bfr[len - 1] != '\n')
                        startofline = 0;
                else
                        startofline = 1;

                /* Open output file if needed */
                if (!file_open)
                        newfile();

                /* Write out line */
                if (write(ofd, bfr, len) != len) {
                        free(bfr);
                        err(EX_IOERR, "write");
                }
        }

        free(bfr);

        /* EOF or error? */
        if (ferror(infp))
                err(EX_IOERR, "read");
        else
                exit(0);
}

/*
 * newfile --
 *      Open a new output file.
 */
static void
newfile(void)
{
        long i, maxfiles, tfnum;
        static long fnum;
        static char *fpnt;
        char beg, end;
        int pattlen;

        if (ofd == -1) {
                if (fname[0] == '\0') {
                        fname[0] = 'x';
                        fpnt = fname + 1;
                } else {
                        fpnt = fname + strlen(fname);
                }
                ofd = fileno(stdout);
        }

        if (dflag) {
                beg = '0';
                end = '9';
        }
        else {
                beg = 'a';
                end = 'z';
        }
        pattlen = end - beg + 1;

        /* maxfiles = pattlen^sufflen, but don't use libm. */
        for (maxfiles = 1, i = 0; i < sufflen; i++)
                if (LONG_MAX / pattlen < maxfiles)
                        errx(EX_USAGE, "suffix is too long (max %ld)", i);
                else
                        maxfiles *= pattlen;

        if (fnum == maxfiles)
                errx(EX_DATAERR, "too many files");

        /* Generate suffix of sufflen letters */
        tfnum = fnum;
        i = sufflen - 1;
        do {
                fpnt[i] = tfnum % pattlen + beg;
                tfnum /= pattlen;
        } while (i-- > 0);
        fpnt[sufflen] = '\0';

        ++fnum;
        if (!freopen(fname, "w", stdout))
                err(EX_IOERR, "%s", fname);
        file_open = 1;
}

static void
usage(void)
{
        (void)fprintf(stderr,
"usage: split [-a sufflen] [-b byte_count] [-l line_count] [-p pattern]\n");
        (void)fprintf(stderr,
"             [file [prefix]]\n");
        exit(EX_USAGE);
}