/*      $OpenBSD: split.c,v 1.23 2021/11/28 19:28:42 deraadt Exp $      */
/*      $NetBSD: split.c,v 1.5 1995/08/31 22:22:05 jtc 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/types.h>

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

#define _MAXBSIZE (64 * 1024)

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

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

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

int
main(int argc, char *argv[])
{
        int ch, scale;
        char *ep, *p;
        const char *errstr;

        if (pledge("stdio rpath wpath cpath", NULL) == -1)
                err(1, "pledge");

        while ((ch = getopt(argc, argv, "0123456789a:b:l: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(1, "%s: illegal line count",
                                            optarg);
                        }
                        break;
                case '-':               /* Undocumented: historic stdin flag. */
                        if (ifd != -1)
                                usage();
                        ifd = 0;
                        break;
                case 'a':               /* suffix length. */
                        sufflen = strtonum(optarg, 1, NAME_MAX, &errstr);
                        if (errstr)
                                errx(1, "%s: %s", optarg, errstr);
                        break;
                case 'b':               /* Byte count. */
                        if ((bytecnt = strtol(optarg, &ep, 10)) <= 0 ||
                            (*ep != '\0' && *ep != 'k' && *ep != 'm'))
                                errx(1, "%s: illegal byte count", optarg);
                        if (*ep == 'k')
                                scale = 1024;
                        else if (*ep == 'm')
                                scale = 1048576;
                        else
                                scale = 1;
                        if (bytecnt > SSIZE_MAX / scale)
                                errx(1, "%s: byte count too large", optarg);
                        bytecnt *= scale;
                        break;
                case 'p' :      /* pattern matching. */
                        if (regcomp(&rgx, optarg, REG_EXTENDED|REG_NOSUB) != 0)
                                errx(1, "%s: illegal regexp", optarg);
                        pflag = 1;
                        break;
                case 'l':               /* Line count. */
                        if (numlines != 0)
                                usage();
                        if ((numlines = strtol(optarg, &ep, 10)) <= 0 || *ep)
                                errx(1, "%s: illegal line count", optarg);
                        break;
                default:
                        usage();
                }
        argv += optind;
        argc -= optind;

        if (*argv != NULL)
                if (ifd == -1) {                /* Input file. */
                        if ((ifd = open(*argv, O_RDONLY)) < 0)
                                err(1, "%s", *argv);
                        ++argv;
                }
        if (*argv != NULL)                      /* File name prefix. */
                (void)strlcpy(fname, *argv++, sizeof(fname));
        if (*argv != NULL)
                usage();

        if (strlen(fname) + sufflen >= sizeof(fname))
                errx(1, "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.
 */
void
split1(void)
{
        ssize_t bcnt, dist, len;
        char *C;

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

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

        /* Stick a stream on top of input file descriptor */
        if ((infp = fdopen(ifd, "r")) == NULL)
                err(1, "fdopen");

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

                if (len == 0)
                        continue;

                /* If line is too long to deal with, just write it out */
                if (bfr[len - 1] != '\n')
                        goto writeit;

                /* 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;
                }

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

                /* Write out line */
                if (write(ofd, bfr, len) != len)
                        err(1, "write");
        }

        /* EOF or error? */
        if (ferror(infp))
                err(1, "read");
        else
                exit(0);
}

/*
 * newfile --
 *      Open a new output file.
 */
void
newfile(void)
{
        static char *suffix, *sufftail;
        char *sptr;

        if (ofd == -1) {
                ofd = fileno(stdout);
                if (*fname == '\0') {
                        *fname = 'x';   /* no name specified, use 'x' */
                        memset(fname + 1, 'a', sufflen);
                        suffix = fname;
                        sufflen++;      /* treat 'x' as part of suffix */
                } else {
                        suffix = fname + strlen(fname);
                        memset(suffix, 'a', sufflen);
                }
                suffix[sufflen] = '\0';
                sufftail = suffix + sufflen - 1;
        } else {
                for (sptr = sufftail; sptr >= suffix; sptr--) {
                        if (*sptr != 'z') {
                                (*sptr)++;
                                break;
                        } else
                                *sptr = 'a';
                }
                if (sptr < suffix)
                        errx(1, "too many files");
        }

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

__dead void
usage(void)
{
        extern char *__progname;

        (void)fprintf(stderr, "usage: %s [-a suffix_length]\n"
            "             [-b byte_count[k|m] | -l line_count | -p pattern] "
            "[file [name]]\n", __progname);
        exit(1);
}