/*      $NetBSD: split.c,v 1.33 2024/02/09 22:08:38 andvar Exp $        */

/*
 * 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.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1987, 1993, 1994\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)split.c     8.3 (Berkeley) 4/25/94";
#endif
__RCSID("$NetBSD: split.c,v 1.33 2024/02/09 22:08:38 andvar Exp $");
#endif /* not lint */

#include <sys/param.h>
#include <sys/stat.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

static int file_open;           /* If a file is open. */
static int ifd = STDIN_FILENO, ofd = -1; /* Input/output file descriptors. */
static char *fname;             /* File name prefix. */
static size_t sfxlen = 2;       /* Suffix length. */
static int autosfx = 1;         /* Whether to auto-extend the suffix length. */

static void newfile(void);
static void split1(off_t, int) __dead;
static void split2(off_t) __dead;
static void split3(off_t) __dead;
static void usage(void) __dead;
static size_t bigwrite(int, void const *, size_t);

int
main(int argc, char *argv[])
{
        int ch;
        char *ep, *p;
        char const *base;
        off_t bytecnt = 0;      /* Byte count to split on. */
        off_t numlines = 0;     /* Line count to split on. */
        off_t chunks = 0;       /* Number of chunks to split into. */

        while ((ch = getopt(argc, argv, "0123456789a:b:l:n:")) != -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])
                                        p++;
                                else
                                        p = argv[optind] + 1;
                                numlines = strtoull(p, &ep, 10);
                                if (numlines == 0 || *ep != '\0')
                                        errx(EXIT_FAILURE, "%s: illegal line count.", p);
                        }
                        break;
                case 'a':               /* Suffix length. */
                        if (!isdigit((unsigned char)optarg[0]) ||
                            (sfxlen = (size_t)strtoul(optarg, &ep, 10)) == 0 ||
                            *ep != '\0')
                                errx(EXIT_FAILURE, "%s: illegal suffix length.", optarg);
                        autosfx = 0;
                        break;
                case 'b':               /* Byte count. */
                        if (!isdigit((unsigned char)optarg[0]) ||
                            (bytecnt = strtoull(optarg, &ep, 10)) == 0 ||
                            (*ep != '\0' && *ep != 'k' && *ep != 'm'))
                                errx(EXIT_FAILURE, "%s: illegal byte count.", optarg);
                        if (*ep == 'k')
                                bytecnt *= 1024;
                        else if (*ep == 'm')
                                bytecnt *= 1024 * 1024;
                        break;
                case 'l':               /* Line count. */
                        if (numlines != 0)
                                usage();
                        if (!isdigit((unsigned char)optarg[0]) ||
                            (numlines = strtoull(optarg, &ep, 10)) == 0 ||
                            *ep != '\0')
                                errx(EXIT_FAILURE, "%s: illegal line count.", optarg);
                        break;
                case 'n':               /* Chunks. */
                        if (!isdigit((unsigned char)optarg[0]) ||
                            (chunks = (size_t)strtoul(optarg, &ep, 10)) == 0 ||
                            *ep != '\0')
                                errx(EXIT_FAILURE, "%s: illegal number of chunks.", optarg);
                        break;
                default:
                        usage();
                }
        argv += optind;
        argc -= optind;

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


        base = (*argv != NULL) ? *argv++ : "x";
        if ((fname = malloc(strlen(base) + sfxlen + 1)) == NULL)
                err(EXIT_FAILURE, NULL);
        (void)strcpy(fname, base);              /* File name prefix. */

        if (*argv != NULL)
                usage();

        if (numlines == 0)
                numlines = DEFLINE;
        else if (bytecnt || chunks)
                usage();

        if (bytecnt && chunks)
                usage();

        if (bytecnt)
                split1(bytecnt, 0);
        else if (chunks)
                split3(chunks);
        else 
                split2(numlines);

        return 0;
}

/*
 * split1 --
 *      Split the input by bytes.
 */
static void
split1(off_t bytecnt, int maxcnt)
{
        off_t bcnt;
        ssize_t dist, len;
        char *C;
        char bfr[MAXBSIZE];
        int nfiles;

        nfiles = 0;

        for (bcnt = 0;;)
                switch (len = read(ifd, bfr, MAXBSIZE)) {
                case 0:
                        exit(EXIT_SUCCESS);
                        /* NOTREACHED */
                case -1:
                        err(EXIT_FAILURE, "read");
                        /* NOTREACHED */
                default:
                        if (!file_open) {
                                if (!maxcnt || (nfiles < maxcnt)) {
                                        newfile();
                                        nfiles++;
                                        file_open = 1;
                                }
                        }
                        if (bcnt + len >= bytecnt) {
                                /* LINTED: bytecnt - bcnt <= len */
                                dist = bytecnt - bcnt;
                                if (bigwrite(ofd, bfr, dist) != (size_t)dist)
                                        err(EXIT_FAILURE, "write");
                                len -= dist;
                                for (C = bfr + dist; len >= bytecnt;
                                    /* LINTED: bytecnt <= len */
                                    len -= bytecnt, C += bytecnt) {
                                        if (!maxcnt || (nfiles < maxcnt)) {
                                                newfile();
                                                nfiles++;
                                        }
                                        /* LINTED: as above */
                                        if (bigwrite(ofd,
                                            C, bytecnt) != (size_t)bytecnt)
                                                err(EXIT_FAILURE, "write");
                                }
                                if (len) {
                                        if (!maxcnt || (nfiles < maxcnt)) {
                                                newfile();
                                                nfiles++;
                                        }
                                        /* LINTED: len >= 0 */
                                        if (bigwrite(ofd, C, len) != (size_t)len)
                                                err(EXIT_FAILURE, "write");
                                } else
                                        file_open = 0;
                                bcnt = len;
                        } else {
                                bcnt += len;
                                /* LINTED: len >= 0 */
                                if (bigwrite(ofd, bfr, len) != (size_t)len)
                                        err(EXIT_FAILURE, "write");
                        }
                }
}

/*
 * split2 --
 *      Split the input by lines.
 */
static void
split2(off_t numlines)
{
        off_t lcnt;
        size_t bcnt;
        ssize_t len;
        char *Ce, *Cs;
        char bfr[MAXBSIZE];

        for (lcnt = 0;;)
                switch (len = read(ifd, bfr, MAXBSIZE)) {
                case 0:
                        exit(EXIT_SUCCESS);
                        /* NOTREACHED */
                case -1:
                        err(EXIT_FAILURE, "read");
                        /* NOTREACHED */
                default:
                        if (!file_open) {
                                newfile();
                                file_open = 1;
                        }
                        for (Cs = Ce = bfr; len--; Ce++)
                                if (*Ce == '\n' && ++lcnt == numlines) {
                                        bcnt = Ce - Cs + 1;
                                        if (bigwrite(ofd, Cs, bcnt) != (size_t)bcnt)
                                                err(EXIT_FAILURE, "write");
                                        lcnt = 0;
                                        Cs = Ce + 1;
                                        if (len)
                                                newfile();
                                        else
                                                file_open = 0;
                                }
                        if (Cs < Ce) {
                                bcnt = Ce - Cs;
                                if (bigwrite(ofd, Cs, bcnt) != (size_t)bcnt)
                                        err(EXIT_FAILURE, "write");
                        }
                }
}

/*
 * split3 --
 *      Split the input into specified number of chunks
 */
static void
split3(off_t chunks)
{
        struct stat sb;

        if (fstat(ifd, &sb) == -1) {
                err(EXIT_FAILURE, "stat");
                /* NOTREACHED */
        }

        if (chunks > sb.st_size) {
                errx(EXIT_FAILURE, "can't split into more than %d files",
                                (int)sb.st_size);
                /* NOTREACHED */
        }

        split1(sb.st_size/chunks, chunks);
}

/*
 * newfile --
 *      Open a new output file.
 */
static void
newfile(void)
{
        static int fnum;
        static char *fpnt;
        int quot, i;

        if (ofd == -1) {
                fpnt = fname + strlen(fname);
                fpnt[sfxlen] = '\0';
        } else if (close(ofd) != 0)
                err(EXIT_FAILURE, "%s", fname);

        quot = fnum;

        /* If '-a' is not specified, then we automatically expand the
         * suffix length to accommodate splitting all input.  We do this
         * by moving the suffix pointer (fpnt) forward and incrementing
         * sfxlen by one, thereby yielding an additional two characters
         * and allowing all output files to sort such that 'cat *' yields
         * the input in order.  I.e., the order is '... xyy xyz xzaaa
         * xzaab ... xzyzy, xzyzz, xzzaaaa, xzzaaab' and so on. */
        if (autosfx && (fpnt[0] == 'y') && (strspn(fpnt+1, "z") == strlen(fpnt+1))) {
                if ((fname = realloc(fname, strlen(fname) + sfxlen + 2 + 1)) == NULL)
                        err(EXIT_FAILURE, NULL);
                        /* NOTREACHED */

                fpnt = fname + strlen(fname) - sfxlen;
                fpnt[sfxlen + 2] = '\0';

                fpnt[0] = 'z';
                fpnt[1] = 'a';

                /*  Basename | Suffix
                 *  before:
                 *  x        | yz
                 *  after:
                 *  xz       | a.. */
                fpnt++;
                sfxlen++;

                /* Reset so we start back at all 'a's in our extended suffix. */
                quot = 0;
                fnum = 0;
        }

        for (i = sfxlen - 1; i >= 0; i--) {
                fpnt[i] = quot % 26 + 'a';
                quot = quot / 26;
        }
        if (quot > 0)
                errx(EXIT_FAILURE, "too many files.");
        ++fnum;
        if ((ofd = open(fname, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE)) < 0)
                err(EXIT_FAILURE, "%s", fname);
}

static size_t
bigwrite(int fd, const void *buf, size_t len)
{
        const char *ptr = buf;
        size_t sofar = 0;
        ssize_t w;

        while (len != 0) {
                if  ((w = write(fd, ptr, len)) == -1)
                        return sofar;
                len -= w;
                ptr += w;
                sofar += w;
        }
        return sofar;
}


static void
usage(void)
{
        (void)fprintf(stderr,
"usage: %s [-b byte_count] [-l line_count] [-n chunk_count] [-a suffix_length] "
"[file [prefix]]\n", getprogname());
        exit(EXIT_FAILURE);
}