/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

/*
 * Copyright 2022 OmniOS Community Edition (OmniOSce) Association.
 */

/*
 *      diff - differential file comparison
 *
 *      Uses an algorithm  which finds
 *      a pair of longest identical subsequences in the two
 *      files.
 *
 *      The major goal is to generate the match vector J.
 *      J[i] is the index of the line in file1 corresponding
 *      to line i file0. J[i] = 0 if there is no
 *      such line in file1.
 *
 *      Lines are hashed so as to work in core. All potential
 *      matches are located by sorting the lines of each file
 *      on the hash (called value). In particular, this
 *      collects the equivalence classes in file1 together.
 *      Subroutine equiv  replaces the value of each line in
 *      file0 by the index of the first element of its
 *      matching equivalence in (the reordered) file1.
 *      To save space equiv squeezes file1 into a single
 *      array member in which the equivalence classes
 *      are simply concatenated, except that their first
 *      members are flagged by changing sign.
 *
 *      Next the indices that point into member are unsorted into
 *      array class according to the original order of file0.
 *
 *      The cleverness lies in routine stone. This marches
 *      through the lines of file0, developing a vector klist
 *      of "k-candidates". At step i a k-candidate is a matched
 *      pair of lines x,y (x in file0 y in file1) such that
 *      there is a common subsequence of lenght k
 *      between the first i lines of file0 and the first y
 *      lines of file1, but there is no such subsequence for
 *      any smaller y. x is the earliest possible mate to y
 *      that occurs in such a subsequence.
 *
 *      Whenever any of the members of the equivalence class of
 *      lines in file1 matable to a line in file0 has serial number
 *      less than the y of some k-candidate, that k-candidate
 *      with the smallest such y is replaced. The new
 *      k-candidate is chained (via pred) to the current
 *      k-1 candidate so that the actual subsequence can
 *      be recovered. When a member has serial number greater
 *      that the y of all k-candidates, the klist is extended.
 *      At the end, the longest subsequence is pulled out
 *      and placed in the array J by unravel.
 *
 *      With J in hand, the matches there recorded are
 *      checked against reality to assure that no spurious
 *      matches have crept in due to hashing. If they have,
 *      they are broken, and "jackpot " is recorded--a harmless
 *      matter except that a true match for a spuriously
 *      mated line may now be unnecessarily reported as a change.
 *
 *      Much of the complexity of the program comes simply
 *      from trying to minimize core utilization and
 *      maximize the range of doable problems by dynamically
 *      allocating what is needed and reusing what is not.
 *      The core requirements for problems larger than somewhat
 *      are (in words) 2*length(file0) + length(file1) +
 *      3*(number of k-candidates installed),  typically about
 *      6n words for files of length n.
 */
#include <stdio.h>
#include <wchar.h>
#include <ctype.h>
#include <stdlib.h>
#include <limits.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <dirent.h>
#include <locale.h>
#include <stdarg.h>
#include <errno.h>
#include <string.h>
#include "diff.h"

#define CHRTRAN(x)      (iflag ? (iswupper(x) ? towlower(x) : (x)) : (x))
#define NCCHRTRAN(x)    (iswupper(x) ? towlower(x) : (x))
#define max(a, b)       ((a) < (b) ? (b) : (a))
#define min(a, b)       ((a) > (b) ? (b) : (a))

int pref, suff;         /* length of prefix and suffix */
int *class;             /* will be overlaid on file[0] */
int *member;            /* will be overlaid on file[1] */
int *klist;             /* will be overlaid on file[0] after class */
struct cand *clist;     /* merely a free storage pot for candidates */
int clen = 0;
int *J;                 /* will be overlaid on class */
long *ixold;            /* will be overlaid on klist */
long *ixnew;            /* will be overlaid on file[1] */

static int      mbcurmax;

static void error(const char *);
static void unravel(int);
static void     check(void);
static void     output(void);
static void     change(int, int, int, int);
static void     range(int, int, char *);
static void     fetch(long *, int, int, int, char *, int);
static void     dump_context_vec(void);
static void     diffdir(char **);
static void     setfile(char **, char **, char *);
static void     scanpr(struct dir *, int, char *, char *,
        char *, char *, char *);
static void     only(struct dir *, int);
static void     sort(struct line *, int);
static void     unsort(struct line *, int, int *);
static void     filename(char **, char **, struct stat *, char **);
static void     prepare(int, char *);
static void     prune(void);
static void     equiv(struct line *, int, struct line *, int, int *);
static void     done(void);
static void     noroom(void);
static void     usage(void);
static void     initbuf(FILE *, int, long);
static void     resetbuf(int);

static int      stone(int *, int, int *, int *);
static int      newcand(int, int, int);
static int      search(int *, int, int);
static int      skipline(int);
static int      readhash(FILE *, int, char *);
static int      entcmp(struct dir *, struct dir *);
static int      compare(struct dir *);
static int      calldiff(char *);
static int      binary(int);
static int      filebinary(FILE *);
static int      isbinary(char *, int);
static int      useless(char *);
static char     *copytemp(char *);
static char *pfiletype(mode_t);
static struct dir *setupdir(char *);
static wint_t   getbufwchar(int, int *);
static wint_t   wcput(wint_t);
static long     ftellbuf(int);


/*
 * error message string constants
 */
#define BAD_MB_ERR      "invalid multibyte character encountered"
#define NO_PROCS_ERR    "no more processes"
#define NO_MEM_ERR      "out of memory"

static void *
talloc(size_t n)
{
        void *p;
        p = malloc(n);
        if (p == NULL)
                noroom();
        return (p);
}

static void *
ralloc(void *p, size_t n)       /* compacting reallocation */
{
        void    *q;
#if 0
        free(p);
#endif
        q = realloc(p, n);
        if (q == NULL)
                noroom();
        return (q);
}


int
main(int argc, char **argv)
{
        int k;
        char *argp;
        int flag;                       /* option flag read by getopt() */
        int i, j;
        char buf1[BUFSIZ], buf2[BUFSIZ];


        (void) setlocale(LC_ALL, "");
#if !defined(TEXT_DOMAIN)               /* Should be defined by cc -D */
#define TEXT_DOMAIN     "SYS_TEST"      /* Use this only if it weren't */
#endif
        (void) textdomain(TEXT_DOMAIN);

        mbcurmax = MB_CUR_MAX;

        diffargv = argv;
        whichtemp = 0;
        while ((flag = getopt(argc, argv, "bitwcuefhnlqrsC:D:S:U:")) != EOF) {
                switch (flag) {
                case 'D':
                        opt = D_IFDEF;
                        wantelses = 1;
                        ifdef1 = "";
                        ifdef2 = optarg;
                        break;

                case 'b':
                        bflag = 1;
                        break;

                case 'C':
                case 'U':
                        opt = D_CONTEXT;
                        argp = optarg;
                        context = 0;
                        while (*argp >= '0' && *argp <= '9')
                                context *= 10, context += *argp++ - '0';
                        if (*argp)
                                error(gettext("use [ -C num | -U num ]"));
                        if (flag == 'U')
                                uflag++;
                        else
                                uflag = 0;
                        break;

                case 'c':
                case 'u':
                        opt = D_CONTEXT;
                        context = 3;
                        if (flag == 'u')
                                uflag++;
                        else
                                uflag = 0;
                        break;

                case 'e':
                        opt = D_EDIT;
                        break;

                case 'f':
                        opt = D_REVERSE;
                        break;

                case 'h':
                        hflag++;
                        break;

                case 'i':
                        iflag = 1;
                        break;

                case 'l':
                        lflag = 1;
                        break;

                case 'n':
                        opt = D_NREVERSE;
                        break;

                case 'q':
                        qflag = 1;
                        break;

                case 'r':
                        rflag = 1;
                        break;

                case 'S':
                        (void) strcpy(start, optarg);
                        break;

                case 's':
                        sflag = 1;
                        break;

                case 't':
                        tflag = 1;
                        break;

                case 'w':
                        wflag = 1;
                        break;

                case '?':
                        usage();
                        break;

                default:
                        /* Not sure how it would get here, but just in case */
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr,
                            gettext("invalid option -%c\n"), flag);
                        usage();
                }
        }

        argc -= optind;
        argv = &argv[optind];

        if (opt != D_CONTEXT && uflag)
                uflag = 0;

        if (argc != 2)
                error(gettext("two filename arguments required"));

        file1 = argv[0];
        file2 = argv[1];

        if (hflag) {
                if (opt) {
                        error(gettext(
                            "-h doesn't support -e, -f, -n, -c, or -I"));
                } else {
                        diffargv[0] = "diffh";
                        (void) execv(diffh, diffargv);
                        (void) fprintf(stderr, "diffh: ");
                        perror(diffh);
                        status = 2;
                        done();
                }

        }

        if (strcmp(file1, "-") == 0) {
                if (fstat(fileno(stdin), &stb1) == 0)
                        stb1.st_mode = S_IFREG;
                else {
                        (void) fprintf(stderr, "diff: ");
                        perror("stdin");
                        done();
                }
        } else if (stat(file1, &stb1) < 0) {
                (void) fprintf(stderr, "diff: ");
                perror(file1);
                done();
        }

        if (strcmp(file2, "-") == 0) {
                if (strcmp(file1, "-") == 0)
                        error(gettext("cannot specify - -"));
                else {
                        if (fstat(fileno(stdin), &stb2) == 0)
                                stb2.st_mode = S_IFREG;
                        else {
                                (void) fprintf(stderr, "diff: ");
                                perror("stdin");
                                done();
                        }
                }
        } else if (stat(file2, &stb2) < 0) {
                (void) fprintf(stderr, "diff: ");
                perror(file2);
                done();
        }

        if ((stb1.st_mode & S_IFMT) == S_IFDIR &&
            (stb2.st_mode & S_IFMT) == S_IFDIR) {
                diffdir(argv);
                done();
        }

        filename(&file1, &file2, &stb1, &input_file1);
        filename(&file2, &file1, &stb2, &input_file2);
        if ((input[0] = fopen(file1, "r")) == NULL) {
                (void) fprintf(stderr, "diff: ");
                perror(file1);
                status = 2;
                done();
        }
        initbuf(input[0], 0, 0);

        if ((input[1] = fopen(file2, "r")) == NULL) {
                (void) fprintf(stderr, "diff: ");
                perror(file2);
                status = 2;
                done();
        }
        initbuf(input[1], 1, 0);

        if (stb1.st_size != stb2.st_size)
                goto notsame;

        for (;;) {
                i = fread(buf1, 1, BUFSIZ, input[0]);
                j = fread(buf2, 1, BUFSIZ, input[1]);
                if (ferror(input[0]) || ferror(input[1])) {
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr, gettext("Error reading "));
                        perror(ferror(input[0])? file1:file2);
                        (void) fclose(input[0]);
                        (void) fclose(input[1]);
                        status = 2;
                        done();
                }
                if (i != j)
                        goto notsame;
                if (i == 0 && j == 0) {
                        /* files are the same; diff -D needs to print one */
                        if (opt == D_IFDEF) {
                                rewind(input[0]);
                                while (i = fread(buf1, 1, BUFSIZ, input[0]))
                                        (void) fwrite(buf1, 1, i, stdout);
                        }
                        (void) fclose(input[0]);
                        (void) fclose(input[1]);
                        status = 0;
                        goto same;              /* files don't differ */
                }
                for (j = 0; j < i; j++)
                        if (buf1[j] != buf2[j])
                                goto notsame;
        }

notsame:
        status = 1;
        if (filebinary(input[0]) || filebinary(input[1])) {
                if (ferror(input[0]) || ferror(input[1])) {
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr, gettext("Error reading "));
                        perror(ferror(input[0])? file1:file2);
                        (void) fclose(input[0]);
                        (void) fclose(input[1]);
                        status = 2;
                        done();
                }
                (void) printf(gettext("Binary files %s and %s differ\n"),
                    file1, file2);
                (void) fclose(input[0]);
                (void) fclose(input[1]);
                done();
        }
        if (qflag) {
                (void) printf(gettext("Files %s and %s differ\n"),
                    file1, file2);
                (void) fclose(input[0]);
                (void) fclose(input[1]);
                done();
        }
        prepare(0, file1);
        prepare(1, file2);
        prune();
        sort(sfile[0], slen[0]);
        sort(sfile[1], slen[1]);

        member = (int *)file[1];
        equiv(sfile[0], slen[0], sfile[1], slen[1], member);
        member = (int *)ralloc((void *)member, (slen[1] + 2) * sizeof (int));

        class = (int *)file[0];
        unsort(sfile[0], slen[0], class);
        class = (int *)ralloc((void *)class, (slen[0] + 2) * sizeof (int));

        klist = (int *)talloc((slen[0] + 2) * sizeof (int));
        clist = (struct cand *)talloc(sizeof (cand));
        k = stone(class, slen[0], member, klist);
        free((void *)member);
        free((void *)class);

        J = (int *)talloc((len[0] + 2) * sizeof (int));
        unravel(klist[k]);
        free((char *)clist);
        free((char *)klist);

        ixold = (long *)talloc((len[0] + 2) * sizeof (long));
        ixnew = (long *)talloc((len[1] + 2) * sizeof (long));
        check();
        output();
        status = anychange;

same:
        if (opt == D_CONTEXT && anychange == 0)
                (void) printf(gettext("No differences encountered\n"));
        done();
        /*NOTREACHED*/
        return (0);
}

static int
stone(int *a, int n, int *b, int *c)
{
        int i, k, y;
        int j, l;
        int oldc, tc;
        int oldl;

        k = 0;
        c[0] = newcand(0, 0, 0);
        for (i = 1; i <= n; i++) {
                j = a[i];
                if (j == 0)
                        continue;
                y = -b[j];
                oldl = 0;
                oldc = c[0];
                do {
                        if (y <= clist[oldc].y)
                                continue;
                        l = search(c, k, y);
                        if (l != oldl+1)
                                oldc = c[l-1];
                        if (l <= k) {
                                if (clist[c[l]].y <= y)
                                        continue;
                                tc = c[l];
                                c[l] = newcand(i, y, oldc);
                                oldc = tc;
                                oldl = l;
                        } else {
                                c[l] = newcand(i, y, oldc);
                                k++;
                                break;
                        }
                } while ((y = b[++j]) > 0);
        }
        return (k);
}

static int
newcand(int x, int y, int pred)
{
        struct cand *q;

        clist = (struct cand *)ralloc((void *)clist, ++clen * sizeof (cand));
        q = clist + clen -1;
        q->x = x;
        q->y = y;
        q->pred = pred;
        return (clen - 1);
}

static int
search(int *c, int k, int y)
{
        int i, j, l;
        int t;

        if (clist[c[k]].y < y)  /* quick look for typical case */
                return (k + 1);
        i = 0;
        j = k+1;
        while ((l = (i + j) / 2) > i) {
                t = clist[c[l]].y;
                if (t > y)
                        j = l;
                else if (t < y)
                        i = l;
                else
                        return (l);
        }
        return (l + 1);
}

static void
unravel(int p)
{
        int i;
        struct cand *q;

        for (i = 0; i <= len[0]; i++)
                J[i] = i <= pref ? i :
                    i > len[0] - suff ? i + len[1] - len[0]: 0;
        for (q = clist + p; q->y != 0; q = clist + q->pred)
                J[q->x + pref] = q->y + pref;
}

/*
 * check does double duty:
 * 1. ferret out any fortuitous correspondences due to confounding by
 * hashing (which result in "jackpot")
 * 2. collect random access indexes to the two files
 */

static void
check(void)
{
        wint_t  c, d;
        int i, j;
        /* int jackpot; */
        int     mlen;
        long ctold, ctnew;

        resetbuf(0);
        resetbuf(1);

        j = 1;
        ixold[0] = ixnew[0] = 0;
        /* jackpot = 0; */

        /*
         * ctold and ctnew are byte positions within the file (suitable for
         * lseek()).  After we get a character with getwc(), instead of
         * just incrementing the byte position by 1, we have to determine
         * how many bytes the character actually is.  This is the reason for
         * the wctomb() calls here and in skipline().
         */
        ctold = ctnew = 0;
        for (i = 1; i <= len[0]; i++) {
                if (J[i] == 0) {
                        ixold[i] = ctold += skipline(0);
                        continue;
                }
                while (j < J[i]) {
                        ixnew[j] = ctnew += skipline(1);
                        j++;
                }
                if (bflag || wflag || iflag) {
                        for (;;) {
                                c = getbufwchar(0, &mlen);
                                ctold += mlen;
                                d = getbufwchar(1, &mlen);
                                ctnew += mlen;

                                if (bflag && iswspace(c) && iswspace(d)) {
                                        while (iswspace(c)) {
                                                if (c == '\n' || c == WEOF)
                                                        break;

                                                c = getbufwchar(0, &mlen);
                                                ctold += mlen;
                                        }
                                        while (iswspace(d)) {
                                                if (d == '\n' || d == WEOF)
                                                        break;

                                                d = getbufwchar(1, &mlen);
                                                ctnew += mlen;
                                        }
                                } else if (wflag) {
                                        while (iswspace(c) && c != '\n') {
                                                c = getbufwchar(0, &mlen);
                                                ctold += mlen;
                                        }
                                        while (iswspace(d) && d != '\n') {
                                                d = getbufwchar(1, &mlen);
                                                ctnew += mlen;
                                        }
                                }
                                if (c == WEOF || d == WEOF) {
                                        if (c != d) {
                                                /* jackpot++; */
                                                J[i] = 0;
                                                if (c != '\n' && c != WEOF)
                                                        ctold += skipline(0);
                                                if (d != '\n' && d != WEOF)
                                                        ctnew += skipline(1);
                                                break;
                                        }
                                        break;
                                } else {
                                        if (CHRTRAN(c) != CHRTRAN(d)) {
                                                /* jackpot++; */
                                                J[i] = 0;
                                                if (c != '\n')
                                                        ctold += skipline(0);
                                                if (d != '\n')
                                                        ctnew += skipline(1);
                                                break;
                                        }
                                        if (c == '\n')
                                                break;
                                }
                        }
                } else {
                        for (;;) {
                                c = getbufwchar(0, &mlen);
                                ctold += mlen;
                                d = getbufwchar(1, &mlen);
                                ctnew += mlen;
                                if (c != d) {
                                        /* jackpot++; */
                                        J[i] = 0;
                                        if (c != '\n' && c != WEOF)
                                                ctold += skipline(0);
                                        if (d != '\n' && d != WEOF)
                                                ctnew += skipline(1);
                                        break;
                                }
                                if (c == '\n' || c == WEOF)
                                        break;
                        }
                }
                ixold[i] = ctold;
                ixnew[j] = ctnew;
                j++;
        }
        for (; j <= len[1]; j++) {
                ixnew[j] = ctnew += skipline(1);
        }

/*      if(jackpot)                     */
/*              fprintf(stderr, "diff: jackpot\n");     */
}

static int
skipline(int f)
{
        int i;
        wint_t c;
        int     mlen;

        for (i = 1; c = getbufwchar(f, &mlen); ) {
                if (c == '\n' || c == WEOF)
                        return (i);
                i += mlen;
        }
        return (i);
}

static void
output(void)
{
        int m;
        wint_t  wc;
        int i0, i1, j1;
        int j0;
        int     mlen;

        resetbuf(0);
        resetbuf(1);

        m = len[0];
        J[0] = 0;
        J[m + 1] = len[1] + 1;
        if (opt != D_EDIT)
                for (i0 = 1; i0 <= m; i0 = i1+1) {
                        while (i0 <= m && J[i0] == J[i0 - 1] + 1)
                                i0++;
                        j0 = J[i0 - 1] + 1;
                        i1 = i0 - 1;
                        while (i1 < m && J[i1 + 1] == 0)
                                i1++;
                        j1 = J[i1 + 1] - 1;
                        J[i1] = j1;
                        change(i0, i1, j0, j1);
                } else for (i0 = m; i0 >= 1; i0 = i1 - 1) {
                        while (i0 >= 1 && J[i0] == J[i0 + 1] - 1 && J[i0] != 0)
                                i0--;
                        j0 = J[i0 + 1] - 1;
                        i1 = i0 + 1;
                        while (i1 > 1 && J[i1 - 1] == 0)
                                i1--;
                        j1 = J[i1 - 1] + 1;
                        J[i1] = j1;
                        change(i1, i0, j1, j0);
                }
        if (m == 0)
                change(1, 0, 1, len[1]);
        if (opt == D_IFDEF) {
                for (;;) {
                        wc = getbufwchar(0, &mlen);
                        if (wc == WEOF)
                                return;
                        (void) wcput(wc);
                }
        }
        if (anychange && opt == D_CONTEXT)
                dump_context_vec();
}


/*
 * indicate that there is a difference between lines a and b of the from file
 * to get to lines c to d of the to file.
 * If a is greater then b then there are no lines in the from file involved
 * and this means that there were lines appended (beginning at b).
 * If c is greater than d then there are lines missing from the to file.
 */
static void
change(int a, int b, int c, int d)
{
        char    time_buf[BUFSIZ];
        char    *dcmsg;

        if (opt != D_IFDEF && a > b && c > d)
                return;
        if (anychange == 0) {
                anychange = 1;
                if (opt == D_CONTEXT) {
                        /*
                         * TRANSLATION_NOTE_FOR_DC
                         * This message is the format of file
                         * timestamps written with the -C and
                         * -c options.
                         * %a -- locale's abbreviated weekday name
                         * %b -- locale's abbreviated month name
                         * %e -- day of month [1,31]
                         * %T -- Time as %H:%M:%S
                         * %Y -- Year, including the century
                         */
                        dcmsg = dcgettext(NULL, "%a %b %e %T %Y", LC_TIME);
                        (void) cftime(time_buf, dcmsg, &stb1.st_mtime);
                        if (uflag)
                                (void) printf("--- %s   %s\n", input_file1,
                                    time_buf);
                        else
                                (void) printf("*** %s   %s\n", input_file1,
                                    time_buf);
                        (void) cftime(time_buf, dcmsg, &stb2.st_mtime);
                        if (uflag)
                                (void) printf("+++ %s   %s\n", input_file2,
                                    time_buf);
                        else
                                (void) printf("--- %s   %s\n", input_file2,
                                    time_buf);

                        context_vec_start = malloc(MAX_CONTEXT *
                            sizeof (struct context_vec));
                        if (context_vec_start == NULL)
                                error(gettext(NO_MEM_ERR));

                        context_vec_end = context_vec_start + (MAX_CONTEXT - 1);
                        context_vec_ptr = context_vec_start - 1;
                }
        }

        if (opt == D_CONTEXT) {
                /*
                 * if this new change is within 'context' lines of
                 * the previous change, just add it to the change
                 * record.  If the record is full or if this
                 * change is more than 'context' lines from the previous
                 * change, dump the record, reset it & add the new change.
                 */
                if (context_vec_ptr >= context_vec_end ||
                    (context_vec_ptr >= context_vec_start &&
                    a > (context_vec_ptr->b + 2 * context) &&
                    c > (context_vec_ptr->d + 2 * context)))
                        dump_context_vec();

                context_vec_ptr++;
                context_vec_ptr->a = a;
                context_vec_ptr->b = b;
                context_vec_ptr->c = c;
                context_vec_ptr->d = d;
                return;
        }

        switch (opt) {
        case D_NORMAL:
        case D_EDIT:
                range(a, b, ",");
                (void) putchar(a > b ? 'a' : c > d ? 'd' : 'c');
                if (opt == D_NORMAL) range(c, d, ",");
                (void) printf("\n");
                break;
        case D_REVERSE:
                (void) putchar(a > b ? 'a' : c > d ? 'd' : 'c');
                range(a, b, " ");
                (void) printf("\n");
                break;
        case D_NREVERSE:
                if (a > b)
                        (void) printf("a%d %d\n", b, d - c + 1);
                else {
                        (void) printf("d%d %d\n", a, b - a + 1);
                        if (!(c > d))
                                /* add changed lines */
                                (void) printf("a%d %d\n", b, d - c + 1);
                }
                break;
        }
        if (opt == D_NORMAL || opt == D_IFDEF) {
                fetch(ixold, a, b, 0, "< ", 1);
                if (a <= b && c <= d && opt == D_NORMAL)
                        (void) prints("---\n");
        }
        fetch(ixnew, c, d, 1, opt == D_NORMAL?"> ":empty, 0);
        if ((opt == D_EDIT || opt == D_REVERSE) && c <= d)
                (void) prints(".\n");
        if (inifdef) {
                (void) fprintf(stdout, "#endif /* %s */\n", endifname);
                inifdef = 0;
        }
}

static void
range(int a, int b, char *separator)
{
        (void) printf("%d", a > b ? b : a);
        if (a < b) {
                (void) printf("%s%d", separator, b);
        }
}

static void
fetch(long *f, int a, int b, int filen, char *s, int oldfile)
{
        int i;
        int col;
        int nc;
        int mlen = 0;
        wint_t  ch;
        FILE    *lb;

        lb = input[filen];
        /*
         * When doing #ifdef's, copy down to current line
         * if this is the first file, so that stuff makes it to output.
         */
        if (opt == D_IFDEF && oldfile) {
                long curpos = ftellbuf(filen);
                /* print through if append (a>b), else to (nb: 0 vs 1 orig) */
                nc = f[(a > b) ? b : (a - 1) ] - curpos;
                for (i = 0; i < nc; i += mlen) {
                        ch = getbufwchar(filen, &mlen);
                        if (ch == WEOF) {
                                (void) putchar('\n');
                                break;
                        } else {
                                (void) wcput(ch);
                        }
                }
        }
        if (a > b)
                return;
        if (opt == D_IFDEF) {
                int oneflag = (*ifdef1 != '\0') != (*ifdef2 != '\0');
                if (inifdef)
                        (void) fprintf(stdout, "#else /* %s%s */\n",
                            oneflag && oldfile == 1 ? "!" : "", ifdef2);
                else {
                        if (oneflag) {
                                /* There was only one ifdef given */
                                endifname = ifdef2;
                                if (oldfile)
                                        (void) fprintf(stdout,
                                            "#ifndef %s\n", endifname);
                                else
                                        (void) fprintf(stdout,
                                            "#ifdef %s\n", endifname);
                        } else {
                                endifname = oldfile ? ifdef1 : ifdef2;
                                (void) fprintf(stdout,
                                    "#ifdef %s\n", endifname);
                        }
                }
                inifdef = 1 + oldfile;
        }

        for (i = a; i <= b; i++) {
                (void) fseek(lb, f[i - 1], SEEK_SET);
                initbuf(lb, filen, f[i - 1]);
                if (opt != D_IFDEF)
                        (void) prints(s);
                col = 0;
                while (ch = getbufwchar(filen, &mlen)) {
                        if (ch != '\n' && ch != WEOF) {
                                if (ch == '\t' && tflag)
                                        do {
                                                (void) putchar(' ');
                                        } while (++col & 7);
                                else {
                                        (void) wcput(ch);
                                        col++;
                                }
                        } else
                                break;
                }
                (void) putchar('\n');
        }
}

/*
 * hashing has the effect of
 * arranging line in 7-bit bytes and then
 * summing 1-s complement in 16-bit hunks
 */

static int
readhash(FILE *f, int filen, char *str)
{
        long sum;
        unsigned int    shift;
        int space;
        int t;
        wint_t  wt;
        int     mlen;

        sum = 1;
        space = 0;
        if (!bflag && !wflag) {
                if (iflag)
                        if (mbcurmax == 1) {
                                /* In this case, diff doesn't have to take */
                                /* care of multibyte characters. */
                                for (shift = 0; (t = getc(f)) != '\n';
                                    shift += 7) {
                                        if (t == EOF) {
                                                if (shift) {
                                                        (void) fprintf(stderr,
        gettext("Warning: missing newline at end of file %s\n"), str);
                                                        break;
                                                } else
                                                        return (0);
                                        }
                                        sum += (isupper(t) ? tolower(t) : t) <<
                                            (shift &= HALFMASK);
                                }
                        } else {
                                /* In this case, diff needs to take care of */
                                /* multibyte characters. */
                                for (shift = 0;
                                    (wt = getbufwchar(filen, &mlen)) != '\n';
                                    shift += 7) {
                                        if (wt == WEOF) {
                                                if (shift) {
                                                        (void) fprintf(stderr,
        gettext("Warning: missing newline at end of file %s\n"), str);
                                                        break;
                                                } else
                                                        return (0);
                                        }
                                        sum += NCCHRTRAN(wt) <<
                                            (shift &= HALFMASK);
                                }
                        }
                else
                        /* In this case, diff doesn't have to take care of */
                        /* multibyte characters. */
                        for (shift = 0; (t = getc(f)) != '\n'; shift += 7) {
                                if (t == EOF) {
                                        if (shift) {
                                                (void) fprintf(stderr,
        gettext("Warning: missing newline at end of file %s\n"), str);
                                                break;
                                        } else
                                                return (0);
                                }
                                sum += (long)t << (shift &= HALFMASK);
                        }
        } else {
                /* In this case, diff needs to take care of */
                /* multibyte characters. */
                for (shift = 0; ; ) {
                        wt = getbufwchar(filen, &mlen);

                        if (wt != '\n' && iswspace(wt)) {
                                space++;
                                continue;
                        } else {
                                switch (wt) {
                                case WEOF:
                                        if (shift) {
                                                (void) fprintf(stderr,
        gettext("Warning: missing newline at end of file %s\n"), str);
                                                break;
                                        } else
                                                return (0);
                                default:
                                        if (space && !wflag) {
                                                shift += 7;
                                                space = 0;
                                        }
                                        sum += CHRTRAN(wt) <<
                                            (shift &= HALFMASK);
                                        shift += 7;
                                        continue;
                                case L'\n':
                                        break;
                                }
                        }
                        break;
                }
        }
        return (sum);
}


/* dump accumulated "context" diff changes */
static void
dump_context_vec(void)
{
        int     a, b = 0, c, d = 0;
        char    ch;
        struct  context_vec *cvp = context_vec_start;
        int     lowa, upb, lowc, upd;
        int     do_output;

        if (cvp > context_vec_ptr)
                return;

        lowa = max(1, cvp->a - context);
        upb  = min(len[0], context_vec_ptr->b + context);
        lowc = max(1, cvp->c - context);
        upd  = min(len[1], context_vec_ptr->d + context);

        if (uflag) {
                (void) printf("@@ -%d,%d +%d,%d @@\n",
                    lowa, upb - lowa + 1,
                    lowc, upd - lowc + 1);
        } else {
                (void) printf("***************\n*** ");
                range(lowa, upb, ",");
                (void) printf(" ****\n");
        }

        /*
         * output changes to the "old" file.  The first loop suppresses
         * output if there were no changes to the "old" file (we'll see
         * the "old" lines as context in the "new" list).
         */
        if (uflag)
                do_output = 1;
        else
                for (do_output = 0; cvp <= context_vec_ptr; cvp++)
                        if (cvp->a <= cvp->b) {
                                cvp = context_vec_start;
                                do_output++;
                                break;
                        }

        if (do_output) {
                while (cvp <= context_vec_ptr) {
                        a = cvp->a; b = cvp->b; c = cvp->c; d = cvp->d;

                        if (a <= b && c <= d)
                                ch = 'c';
                        else
                                ch = (a <= b) ? 'd' : 'a';

                        if (ch == 'a') {
                                /* The last argument should not affect */
                                /* the behavior of fetch() */
                                fetch(ixold, lowa, b, 0, uflag ? " " : "  ", 1);
                                if (uflag)
                                        fetch(ixnew, c, d, 1, "+", 0);
                        } else if (ch == 'd') {
                                fetch(ixold, lowa, a - 1, 0, uflag ? " " :
                                    "  ", 1);
                                fetch(ixold, a, b, 0, uflag ? "-" : "- ", 1);
                        } else {
                                /* The last argument should not affect */
                                /* the behavior of fetch() */
                                fetch(ixold, lowa, a-1, 0, uflag ? " " : "  ",
                                    1);
                                if (uflag) {
                                        fetch(ixold, a, b, 0, "-", 1);
                                        fetch(ixnew, c, d, 1, "+", 0);
                                } else
                                        fetch(ixold, a, b, 0, "! ", 1);
                        }
                        lowa = b + 1;
                        cvp++;
                }
                /* The last argument should not affect the behavior */
                /* of fetch() */
                fetch(ixold, b+1, upb, 0, uflag ? " " : "  ", 1);
        }

        if (uflag) {
                context_vec_ptr = context_vec_start - 1;
                return;
        }

        /* output changes to the "new" file */
        (void) printf("--- ");
        range(lowc, upd, ",");
        (void) printf(" ----\n");

        do_output = 0;
        for (cvp = context_vec_start; cvp <= context_vec_ptr; cvp++)
                if (cvp->c <= cvp->d) {
                        cvp = context_vec_start;
                        do_output++;
                        break;
                }

        if (do_output) {
                while (cvp <= context_vec_ptr) {
                        a = cvp->a; b = cvp->b; c = cvp->c; d = cvp->d;

                        if (a <= b && c <= d)
                                ch = 'c';
                        else
                                ch = (a <= b) ? 'd' : 'a';

                        if (ch == 'd')
                                /* The last argument should not affect */
                                /* the behavior of fetch() */
                                fetch(ixnew, lowc, d, 1, "  ", 0);
                        else {
                                /* The last argument should not affect */
                                /* the behavior of fetch() */
                                fetch(ixnew, lowc, c - 1, 1, "  ", 0);
                                fetch(ixnew, c, d, 1,
                                    ch == 'c' ? "! " : "+ ", 0);
                        }
                        lowc = d + 1;
                        cvp++;
                }
                /* The last argument should not affect the behavior */
                /* of fetch() */
                fetch(ixnew, d + 1, upd, 1, "  ", 0);
        }
        context_vec_ptr = context_vec_start - 1;
}



/*
 * diff - directory comparison
 */

struct  dir *setupdir();
int     header;
char    title[2 * BUFSIZ], *etitle;

static void
diffdir(char **argv)
{
        struct dir *d1, *d2;
        struct dir *dir1, *dir2;
        int i;
        int cmp;
        int result, dirstatus;

        if (opt == D_IFDEF)
                error(gettext("cannot specify -D with directories"));

        if (opt == D_EDIT && (sflag || lflag)) {
                (void) fprintf(stderr, "diff: ");
                (void) fprintf(stderr, gettext(
                    "warning: should not give -s or -l with -e\n"));
        }
        dirstatus = 0;
        title[0] = 0;
        (void) strcpy(title, "diff ");
        for (i = 1; diffargv[i + 2]; i++) {
                if (strcmp(diffargv[i], "-") == 0) {
                        continue;       /* Skip -S and its argument */
                }
                (void) strcat(title, diffargv[i]);
                (void) strcat(title, " ");
        }
        for (etitle = title; *etitle; etitle++)
                ;
        setfile(&file1, &efile1, file1);
        setfile(&file2, &efile2, file2);
        argv[0] = file1;
        argv[1] = file2;
        dir1 = setupdir(file1);
        dir2 = setupdir(file2);
        d1 = dir1; d2 = dir2;
        while (d1->d_entry != 0 || d2->d_entry != 0) {
                if (d1->d_entry && useless(d1->d_entry)) {
                        d1++;
                        continue;
                }
                if (d2->d_entry && useless(d2->d_entry)) {
                        d2++;
                        continue;
                }
                if (d1->d_entry == 0)
                        cmp = 1;
                else if (d2->d_entry == 0)
                        cmp = -1;
                else
                        cmp = strcmp(d1->d_entry, d2->d_entry);
                if (cmp < 0) {
                        if (lflag)
                                d1->d_flags |= ONLY;
                        else if (opt == 0 || opt == 2)
                                only(d1, 1);
                        d1++;
                        if (dirstatus == 0)
                                dirstatus = 1;
                } else if (cmp == 0) {
                        result = compare(d1);
                        if (result > dirstatus)
                                dirstatus = result;
                        d1++;
                        d2++;
                } else {
                        if (lflag)
                                d2->d_flags |= ONLY;
                        else if (opt == 0 || opt == 2)
                                only(d2, 2);
                        d2++;
                        if (dirstatus == 0)
                                dirstatus = 1;
                }
        }
        if (lflag) {
                scanpr(dir1, ONLY,
                    gettext("Only in %.*s"), file1, efile1, 0, 0);
                scanpr(dir2, ONLY,
                    gettext("Only in %.*s"), file2, efile2, 0, 0);
                scanpr(dir1, SAME,
                    gettext("Common identical files in %.*s and %.*s"),
                    file1, efile1, file2, efile2);
                scanpr(dir1, DIFFER,
                    gettext("Binary files which differ in %.*s and %.*s"),
                    file1, efile1, file2, efile2);
                scanpr(dir1, DIRECT,
                    gettext("Common subdirectories of %.*s and %.*s"),
                    file1, efile1, file2, efile2);
        }
        if (rflag) {
                if (header && lflag)
                        (void) printf("\f");
                for (d1 = dir1; d1->d_entry; d1++)  {
                        if ((d1->d_flags & DIRECT) == 0)
                                continue;
                        (void) strcpy(efile1, d1->d_entry);
                        (void) strcpy(efile2, d1->d_entry);
                        result = calldiff((char *)0);
                        if (result > dirstatus)
                                dirstatus = result;
                }
        }
        status = dirstatus;
}

static void
setfile(char **fpp, char **epp, char *file)
{
        char *cp;

        *fpp = (char *)malloc(BUFSIZ);
        if (*fpp == 0) {
                (void) fprintf(stderr, "diff: ");
                (void) fprintf(stderr, gettext("out of memory\n"));
                exit(1);
        }
        (void) strcpy(*fpp, file);
        for (cp = *fpp; *cp; cp++)
                continue;
        *cp++ = '/';
        *cp = 0;
        *epp = cp;
}

static void
scanpr(struct dir *dp, int test, char *title, char *file1, char *efile1,
    char *file2, char *efile2)
{
        int titled = 0;

        for (; dp->d_entry; dp++) {
                if ((dp->d_flags & test) == 0)
                        continue;
                if (titled == 0) {
                        if (header == 0)
                                header = 1;
                        else
                                (void) printf("\n");
                        (void) printf(title,
                            efile1 - file1 - 1, file1,
                            efile2 - file2 - 1, file2);
                        (void) printf(":\n");
                        titled = 1;
                }
                (void) printf("\t%s\n", dp->d_entry);
        }
}

static void
only(struct dir *dp, int which)
{
        char *file = which == 1 ? file1 : file2;
        char *efile = which == 1 ? efile1 : efile2;

        (void) printf(gettext("Only in %.*s: %s\n"), efile - file - 1, file,
            dp->d_entry);
}

int     entcmp();

static struct dir *
setupdir(char *cp)
{
        struct dir *dp = 0, *ep;
        struct dirent64 *rp;
        int nitems;
        int size;
        DIR *dirp;

        dirp = opendir(cp);
        if (dirp == NULL) {
                (void) fprintf(stderr, "diff: ");
                perror(cp);
                done();
        }
        nitems = 0;
        dp = (struct dir *)malloc(sizeof (struct dir));
        if (dp == 0)
                error(gettext(NO_MEM_ERR));

        while (rp = readdir64(dirp)) {
                ep = &dp[nitems++];
                ep->d_reclen = rp->d_reclen;
                ep->d_entry = 0;
                ep->d_flags = 0;
                size = strlen(rp->d_name);
                if (size > 0) {
                        ep->d_entry = (char *)malloc(size + 1);
                        if (ep->d_entry == 0)
                                error(gettext(NO_MEM_ERR));

                        (void) strcpy(ep->d_entry, rp->d_name);
                }
                dp = (struct dir *)realloc((char *)dp,
                    (nitems + 1) * sizeof (struct dir));
                if (dp == 0)
                        error(gettext(NO_MEM_ERR));
        }
        dp[nitems].d_entry = 0;         /* delimiter */
        (void) closedir(dirp);
        qsort(dp, nitems, sizeof (struct dir),
            (int (*)(const void *, const void *))entcmp);
        return (dp);
}

static int
entcmp(struct dir *d1, struct dir *d2)
{
        return (strcmp(d1->d_entry, d2->d_entry));
}

static int
compare(struct dir *dp)
{
        int i, j;
        int f1 = -1, f2 = -1;
        mode_t fmt1, fmt2;
        struct stat stb1, stb2;
        char buf1[BUFSIZ], buf2[BUFSIZ];
        int result;

        (void) strcpy(efile1, dp->d_entry);
        (void) strcpy(efile2, dp->d_entry);

        if (stat(file1, &stb1) == -1) {
                (void) fprintf(stderr, "diff: ");
                perror(file1);
                return (2);
        }
        if (stat(file2, &stb2) == -1) {
                (void) fprintf(stderr, "diff: ");
                perror(file2);
                return (2);
        }

        fmt1 = stb1.st_mode & S_IFMT;
        fmt2 = stb2.st_mode & S_IFMT;

        if (fmt1 == S_IFREG) {
                f1 = open(file1, O_RDONLY);
                if (f1 < 0) {
                        (void) fprintf(stderr, "diff: ");
                        perror(file1);
                        return (2);
                }
        }

        if (fmt2 == S_IFREG) {
                f2 = open(file2, O_RDONLY);
                if (f2 < 0) {
                        (void) fprintf(stderr, "diff: ");
                        perror(file2);
                        (void) close(f1);
                        return (2);
                }
        }

        if (fmt1 != S_IFREG || fmt2 != S_IFREG) {
                if (fmt1 == fmt2) {
                        switch (fmt1) {

                        case S_IFDIR:
                                dp->d_flags = DIRECT;
                                if (lflag || opt == D_EDIT)
                                        goto closem;
                                (void) printf(gettext(
                                    "Common subdirectories: %s and %s\n"),
                                    file1, file2);
                                goto closem;

                        case S_IFCHR:
                        case S_IFBLK:
                                if (stb1.st_rdev == stb2.st_rdev)
                                        goto same;
                                (void) printf(gettext(
                                    "Special files %s and %s differ\n"),
                                    file1, file2);
                                break;

                        case S_IFLNK:
                                if ((i = readlink(file1, buf1, BUFSIZ)) == -1) {
                                        (void) fprintf(stderr, gettext(
                                            "diff: cannot read link\n"));
                                        return (2);
                                }

                                if ((j = readlink(file2, buf2, BUFSIZ)) == -1) {
                                        (void) fprintf(stderr, gettext(
                                            "diff: cannot read link\n"));
                                        return (2);
                                }

                                if (i == j) {
                                        if (strncmp(buf1, buf2, i) == 0)
                                                goto same;
                                }

                                (void) printf(gettext(
                                    "Symbolic links %s and %s differ\n"),
                                    file1, file2);
                                break;

                        case S_IFIFO:
                                if (stb1.st_ino == stb2.st_ino)
                                        goto same;
                                (void) printf(gettext(
                                    "Named pipes %s and %s differ\n"),
                                    file1, file2);
                                break;
                        }
                } else {
                        if (lflag)
                                dp->d_flags |= DIFFER;
                        else if (opt == D_NORMAL || opt == D_CONTEXT) {
/*
 * TRANSLATION_NOTE
 * The second and fourth parameters will take the gettext'ed string
 * of one of the following:
 * a directory
 * a character special file
 * a block special file
 * a plain file
 * a named pipe
 * a socket
 * a door
 * an event port
 * an unknown type
 */
                                (void) printf(gettext(
                                    "File %s is %s while file %s is %s\n"),
                                    file1, pfiletype(fmt1),
                                    file2, pfiletype(fmt2));
                        }
                }
                (void) close(f1); (void) close(f2);
                return (1);
        }
        if (stb1.st_size != stb2.st_size)
                goto notsame;
        for (;;) {
                i = read(f1, buf1, BUFSIZ);
                j = read(f2, buf2, BUFSIZ);
                if (i < 0 || j < 0) {
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr, gettext("Error reading "));
                        perror(i < 0 ? file1: file2);
                        (void) close(f1); (void) close(f2);
                        return (2);
                }
                if (i != j)
                        goto notsame;
                if (i == 0 && j == 0)
                        goto same;
                for (j = 0; j < i; j++)
                        if (buf1[j] != buf2[j])
                                goto notsame;
        }
same:
        if (sflag == 0)
                goto closem;
        if (lflag)
                dp->d_flags = SAME;
        else
                (void) printf(gettext("Files %s and %s are identical\n"),
                    file1, file2);

closem:
        (void) close(f1); (void) close(f2);
        return (0);

notsame:
        if (binary(f1) || binary(f2)) {
                if (lflag)
                        dp->d_flags |= DIFFER;
                else if (opt == D_NORMAL || opt == D_CONTEXT)
                        (void) printf(
                            gettext("Binary files %s and %s differ\n"),
                            file1, file2);
                (void) close(f1); (void) close(f2);
                return (1);
        }
        (void) close(f1); (void) close(f2);
        anychange = 1;
        if (lflag) {
                result = calldiff(title);
        } else {
                if (opt == D_EDIT)
                        (void) printf("ed - %s << '-*-END-*-'\n", dp->d_entry);
                else
                        (void) printf("%s%s %s\n", title, file1, file2);
                result = calldiff((char *)0);
                if (opt == D_EDIT)
                        (void) printf("w\nq\n-*-END-*-\n");
        }
        return (result);
}

char    *prargs[] = { "pr", "-h", 0, 0, 0 };

static int
calldiff(char *wantpr)
{
        pid_t pid;
        int diffstatus, pv[2];

        prargs[2] = wantpr;
        (void) fflush(stdout);
        if (wantpr) {
                (void) sprintf(etitle, "%s %s", file1, file2);
                (void) pipe(pv);
                pid = fork();
                if (pid == (pid_t)-1)
                        error(gettext(NO_PROCS_ERR));

                if (pid == 0) {
                        (void) close(0);
                        (void) dup(pv[0]);
                        (void) close(pv[0]);
                        (void) close(pv[1]);
                        (void) execv(pr+5, prargs);
                        (void) execv(pr, prargs);
                        perror(pr);
                        done();
                }
        }
        pid = fork();
        if (pid == (pid_t)-1)
                error(gettext(NO_PROCS_ERR));

        if (pid == 0) {
                if (wantpr) {
                        (void) close(1);
                        (void) dup(pv[1]);
                        (void) close(pv[0]);
                        (void) close(pv[1]);
                }
                (void) execv(diff+5, diffargv);
                (void) execv(diff, diffargv);
                perror(diff);
                done();
        }
        if (wantpr)     {
                (void) close(pv[0]);
                (void) close(pv[1]);
        }
        while (wait(&diffstatus) != pid)
                continue;
        while (wait((int *)0) != (pid_t)-1)
                continue;
        if ((diffstatus&0177) != 0)
                return (2);
        else
                return ((diffstatus>>8) & 0377);
}

static char *
pfiletype(mode_t fmt)
{
/*
 * TRANSLATION_NOTE
 * The following 9 messages will be used in the second and
 * the fourth parameters of the message
 * "File %s is %s while file %s is %s\n"
 */
        switch (fmt) {

        case S_IFDIR:
                return (gettext("a directory"));
                break;

        case S_IFCHR:
                return (gettext("a character special file"));
                break;

        case S_IFBLK:
                return (gettext("a block special file"));
                break;

        case S_IFREG:
                return (gettext("a plain file"));
                break;

        case S_IFIFO:
                return (gettext("a named pipe"));
                break;

        case S_IFSOCK:
                return (gettext("a socket"));
                break;

        case S_IFDOOR:
                return (gettext("a door"));
                break;

        case S_IFPORT:
                return (gettext("an event port"));
                break;

        default:
                return (gettext("an unknown type"));
                break;
        }
}

static int
binary(int f)
{
        char buf[BUFSIZ];
        int cnt;

        (void) lseek(f, (long)0, SEEK_SET);
        cnt = read(f, buf, BUFSIZ);
        if (cnt < 0)
                return (1);
        return (isbinary(buf, cnt));
}

static int
filebinary(FILE *f)
{
        char buf[BUFSIZ];
        int cnt;

        (void) fseek(f, (long)0, SEEK_SET);
        cnt = fread(buf, 1, BUFSIZ, f);
        if (ferror(f))
                return (1);
        return (isbinary(buf, cnt));
}


/*
 * We consider a "binary" file to be one that:
 * contains a null character ("diff" doesn't handle them correctly, and
 *    neither do many other UNIX text-processing commands).
 * Characters with their 8th bit set do NOT make a file binary; they may be
 * legitimate text characters, or parts of same.
 */
static int
isbinary(char *buf, int cnt)
{
        char *cp;

        cp = buf;
        while (--cnt >= 0)
                if (*cp++ == '\0')
                        return (1);
        return (0);
}


/*
 * THIS IS CRUDE.
 */
static int
useless(char *cp)
{

        if (cp[0] == '.') {
                if (cp[1] == '\0')
                        return (1);     /* directory "." */
                if (cp[1] == '.' && cp[2] == '\0')
                        return (1);     /* directory ".." */
        }
        if (strcmp(start, cp) > 0)
                return (1);
        return (0);
}


void
sort(struct line *a, int n)     /* shellsort CACM #201 */
{
        struct line w;
        int j, m;
        struct line *ai;
        struct line *aim;
        int k;

        for (j = 1, m = 0; j <= n; j *= 2)
                m = 2 * j - 1;
        for (m /= 2; m != 0; m /= 2) {
                k = n - m;
                for (j = 1; j <= k; j++) {
                        for (ai = &a[j]; ai > a; ai -= m) {
                                aim = &ai[m];
                                if (aim < ai)
                                        break;  /* wraparound */
                                if (aim->value > ai[0].value ||
                                    aim->value == ai[0].value &&
                                    aim->serial > ai[0].serial)
                                        break;
                                w.value = ai[0].value;
                                ai[0].value = aim->value;
                                aim->value = w.value;
                                w.serial = ai[0].serial;
                                ai[0].serial = aim->serial;
                                aim->serial = w.serial;
                        }
                }
        }
}

static void
unsort(struct line *f, int l, int *b)
{
        int *a;
        int i;

        a = (int *)talloc((l + 1) * sizeof (int));
        for (i = 1; i <= l; i++)
                a[f[i].serial] = f[i].value;
        for (i = 1; i <= l; i++)
                b[i] = a[i];
        free((char *)a);
}

static void
filename(char **pa1, char **pa2, struct stat *st, char **ifile)
{
        char *a1, *b1, *a2;

        a1 = *pa1;
        a2 = *pa2;

        if (strcmp(*pa1, "-") == 0)
                *ifile = strdup("-");
        else
                *ifile = strdup(*pa1);

        if (*ifile == (char *)NULL) {
                (void) fprintf(stderr, gettext(
                    "no more memory - try again later\n"));
                status = 2;
                done();
        }

        if ((st->st_mode & S_IFMT) == S_IFDIR) {
                b1 = *pa1 = (char *)malloc(PATH_MAX);
                while (*b1++ = *a1++)
                        ;
                b1[-1] = '/';
                a1 = b1;
                while (*a1++ = *a2++)
                        if (*a2 && *a2 != '/' && a2[-1] == '/')
                                a1 = b1;
                *ifile = strdup(*pa1);

                if (*ifile == (char *)NULL) {
                        (void) fprintf(stderr, gettext(
                            "no more memory - try again later\n"));
                        status = 2;
                        done();
                }

                if (stat(*pa1, st) < 0) {
                        (void) fprintf(stderr, "diff: ");
                        perror(*pa1);
                        done();
                }
        } else if ((st->st_mode & S_IFMT) == S_IFCHR)
                *pa1 = copytemp(a1);
        else if (a1[0] == '-' && a1[1] == 0) {
                *pa1 = copytemp(a1);    /* hack! */
                if (stat(*pa1, st) < 0) {
                        (void) fprintf(stderr, "diff: ");
                        perror(*pa1);
                        done();
                }
        }
}

static char *
copytemp(char *fn)
{
        int ifd, ofd;   /* input and output file descriptors */
        int i;
        char template[13];      /* template for temp file name */
        char buf[BUFSIZ];

        /*
         * a "-" file is interpreted as fd 0 for pre-/dev/fd systems
         * ... let's hope this goes away soon!
         */
        if ((ifd = (strcmp(fn, "-") ? open(fn, 0) : 0)) < 0) {
                (void) fprintf(stderr, "diff: ");
                (void) fprintf(stderr, gettext("cannot open %s\n"), fn);
                done();
        }
        (void) signal(SIGHUP, (void (*)(int))done);
        (void) signal(SIGINT, (void (*)(int))done);
        (void) signal(SIGPIPE, (void (*)(int))done);
        (void) signal(SIGTERM, (void (*)(int))done);
        (void) strcpy(template, "/tmp/dXXXXXX");
        if ((ofd = mkstemp(template)) < 0) {
                (void) fprintf(stderr, "diff: ");
                (void) fprintf(stderr, gettext("cannot create %s\n"), template);
                done();
        }
        (void) strcpy(tempfile[whichtemp++], template);
        while ((i = read(ifd, buf, BUFSIZ)) > 0)
                if (write(ofd, buf, i) != i) {
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr,
                            gettext("write failed %s\n"), template);
                        done();
                }
        (void) close(ifd); (void) close(ofd);
        return (tempfile[whichtemp-1]);
}

static void
prepare(int i, char *arg)
{
        struct line *p;
        int j, h;

        (void) fseek(input[i], (long)0, SEEK_SET);
        p = (struct line *)talloc(3 * sizeof (line));
        for (j = 0; h = readhash(input[i], i, arg); ) {
                p = (struct line *)ralloc((void *)p, (++j + 3) * sizeof (line));
                p[j].value = h;
        }
        len[i] = j;
        file[i] = p;
}

static void
prune(void)
{
        int i, j;

        for (pref = 0; pref < len[0] && pref < len[1] &&
            file[0][pref + 1].value == file[1][pref + 1].value;
            pref++)
                ;
        for (suff = 0; (suff < len[0] - pref) &&
            (suff < len[1] - pref) &&
            (file[0][len[0] - suff].value == file[1][len[1] - suff].value);
            suff++)
                ;

        /* decremnt suff by 2 iff suff >= 2, ensure that suff is never < 0 */
        if (suff >= 2)
                suff -= 2;

        for (j = 0; j < 2; j++) {
                sfile[j] = file[j] + pref;
                slen[j] = len[j] - pref - suff;
                for (i = 0; i <= slen[j]; i++)
                        sfile[j][i].serial = i;
        }
}

static void
equiv(struct line *a, int n, struct line *b, int m, int *c)
{
        int i, j;
        i = j = 1;
        while (i <= n && j <= m) {
                if (a[i].value < b[j].value)
                        a[i++].value = 0;
                else if (a[i].value == b[j].value)
                        a[i++].value = j;
                else
                        j++;
        }
        while (i <= n)
                a[i++].value = 0;
        b[m+1].value = 0;       j = 0;
        while (++j <= m) {
                c[j] = -b[j].serial;
                while (b[j + 1].value == b[j].value) {
                        j++;
                        c[j] = b[j].serial;
                }
        }
        c[j] = -1;
}

static void
done(void)
{
        if (whichtemp) (void) unlink(tempfile[0]);
        if (whichtemp == 2) (void) unlink(tempfile[1]);
        exit(status);
}

static void
noroom(void)
{
        (void) fprintf(stderr, "diff: ");
        (void) fprintf(stderr, gettext("files too big, try -h\n"));
        done();
}

static void
error(const char *s)
{
        (void) fprintf(stderr, "diff: ");
        (void) fprintf(stderr, s);
        (void) fprintf(stderr, "\n");
        done();
}

static void
usage(void)
{
        (void) fprintf(stderr, gettext(
            "usage: diff [-biqtw] [-c | -e | -f | -h | -n | -u] file1 "
            "file2\n"
            "       diff [-biqtw] [-C number | -U number] file1 file2\n"
            "       diff [-biqtw] [-D string] file1 file2\n"
            "       diff [-biqtw] [-c | -e | -f | -h | -n | -u] [-l] [-r] "
            "[-s] [-S name] directory1 directory2\n"));
        status = 2;
        done();
}

#define NW      1024
struct buff     {
        FILE    *iop;   /* I/O stream */
        char    buf[NW + MB_LEN_MAX];   /* buffer */
        char    *ptr;   /* current pointer in the buffer */
        int     buffered;       /* if non-zero, buffer has data */
        long    offset; /* offset in the file */
};

static struct buff bufwchar[2];

/*
 *      Initializes the buff structure for specified
 *      I/O stream.  Also sets the specified offset
 */
static void
initbuf(FILE *iop, int filen, long offset)
{
        bufwchar[filen].iop = iop;
        bufwchar[filen].ptr = NULL;
        bufwchar[filen].buffered = 0;
        bufwchar[filen].offset = offset;
}

/*
 *      Reset a buff structure, and rewind the associated file.
 */
static void
resetbuf(int filen)
{
        bufwchar[filen].ptr = NULL;
        bufwchar[filen].buffered = bufwchar[filen].offset = 0;
        rewind(bufwchar[filen].iop);
}


/*
 *      Returns the current offset in the file
 */
static long
ftellbuf(int filen)
{
        return (bufwchar[filen].offset);
}

static wint_t
wcput(wint_t wc)
{
        char    mbs[MB_LEN_MAX];
        unsigned char   *p;
        int     n;

        n = wctomb(mbs, (wchar_t)wc);
        if (n > 0) {
                p = (unsigned char *)mbs;
                while (n--) {
                        (void) putc((*p++), stdout);
                }
                return (wc);
        } else if (n < 0) {
                (void) putc((int)(wc & 0xff), stdout);
                return (wc & 0xff);
        } else {
                /* this should not happen */
                return (WEOF);
        }
}

/*
 *      Reads one wide-character from the file associated with filen.
 *      If multibyte locales, the input is buffered.
 *
 *      Input:  filen   the file number (0 or 1)
 *      Output: *len    number of bytes to make wide-character
 *      Return:                 wide-character
 */
static wint_t
getbufwchar(int filen, int *len)
{

        int     i, num, clen;
        wchar_t wc;
        size_t  mxlen;

        if (mbcurmax == 1) {
                /* If sigle byte locale, use getc() */
                int     ch;

                ch = getc(bufwchar[filen].iop);
                bufwchar[filen].offset++;
                *len = 1;

                if (isascii(ch) || (ch == EOF)) {
                        return ((wint_t)ch);
                } else {
                        wchar_t wc;
                        char    str[2] = {0, 0};

                        str[0] = (char)ch;
                        if (mbtowc(&wc, str, 1) > 0) {
                                return ((wint_t)wc);
                        } else {
                                return ((wint_t)ch);
                        }
                }
        } else {
                mxlen = mbcurmax;
        }

        if (bufwchar[filen].buffered == 0) {
                /* Not buffered */
                bufwchar[filen].ptr = &(bufwchar[filen].buf[MB_LEN_MAX]);
                num = fread((void *)bufwchar[filen].ptr,
                    sizeof (char), NW, bufwchar[filen].iop);
                if (ferror(bufwchar[filen].iop)) {
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr, gettext("Error reading "));
                        perror((filen == 0) ? file1 : file2);
                        status = 2;
                        done();
                }
                if (num == 0)
                        return (WEOF);
                bufwchar[filen].buffered = num;
        }

        if (bufwchar[filen].buffered < mbcurmax) {
                for (i = 0; i < bufwchar[filen].buffered; i++) {
                        bufwchar[filen].buf[MB_LEN_MAX -
                            (bufwchar[filen].buffered - i)] =
                            *(bufwchar[filen].ptr + i);
                }
                bufwchar[filen].ptr = &(bufwchar[filen].buf[MB_LEN_MAX]);
                num = fread((void *)bufwchar[filen].ptr,
                    sizeof (char), NW, bufwchar[filen].iop);
                if (ferror(bufwchar[filen].iop)) {
                        (void) fprintf(stderr, "diff: ");
                        (void) fprintf(stderr, gettext("Error reading "));
                        perror((filen == 0) ? file1 : file2);
                        status = 2;
                        done();
                }
                bufwchar[filen].ptr = &(bufwchar[filen].buf[MB_LEN_MAX -
                    bufwchar[filen].buffered]);
                bufwchar[filen].buffered += num;
                if (bufwchar[filen].buffered < mbcurmax) {
                        mxlen = bufwchar[filen].buffered;
                }
        }

        clen = mbtowc(&wc, bufwchar[filen].ptr, mxlen);
        if (clen <= 0) {
                (bufwchar[filen].buffered)--;
                *len = 1;
                (bufwchar[filen].offset)++;
                wc = (wchar_t)((unsigned char)*bufwchar[filen].ptr++);
                return ((wint_t)wc);
        } else {
                bufwchar[filen].buffered -= clen;
                bufwchar[filen].ptr += clen;
                bufwchar[filen].offset += clen;
                *len = clen;
                return ((wint_t)wc);
        }
}