cmd/diff/diff.c

/*
 * 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.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 *  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, "bitwcuefhnlrsC: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 '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();
    }
    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 = (struct context_vec *)
                        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, c, d;
    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 (start && 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 [-bitw] [-c | -e | -f | -h | -n | -u] file1 "
            "file2\n"
        "       diff [-bitw] [-C number | -U number] file1 file2\n"
        "       diff [-bitw] [-D string] file1 file2\n"
        "       diff [-bitw] [-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);
    }
}