cmd/diff3/diff3prog.c

	diff3prog.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * 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 (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */


/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <limits.h>
#include <sys/param.h>
#include <errno.h>
#

/*
 * diff3 - 3-way differential file comparison
 */

/*
 * diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
 *
 * d13 = diff report on f1 vs f3
 * d23 = diff report on f2 vs f3
 * f1, f2, f3 the 3 files
 * if changes in f1 overlap with changes in f3, m1 and m3 are used
 * to mark the overlaps; otherwise, the file names f1 and f3 are used
 * (only for options E and X).
 */

struct  range {int from, to; };
    /*
     * from is first in range of changed lines
     * to is last+1
     * from = to = line after point of insertion
     * for added lines
     */
struct diff {struct range old, new; };

#define NC 4096
/*
 * de is used to gather editing scripts,
 * that are later spewed out in reverse order.
 * its first element must be all zero
 * the "new" component of de contains line positions
 * or byte positions depending on when you look(!?)
 */
static struct diff d13[NC];
static struct diff d23[NC];

/*
 * array overlap indicates which sections in de correspond to
 * lines that are different in all three files.
 */

static struct diff de[NC];
static char overlap[NC];
static int  overlapcnt = 0;

static char line[LINE_MAX+1];
static FILE *fp[3];
/*
 *  the number of the last-read line in each file
 *  is kept in cline[0-2]
 */
static int cline[3];
/*
 *  the latest known correspondence between line
 *  numbers of the 3 files is stored in last[1-3]
 */
static int last[4];
static int eflag;
static int oflag;   /* indicates whether to mark overlaps (-E or -X) */
static int debug  = 0;
/* markers for -E and -X: */
static char f1mark[8+MAXPATHLEN], f3mark[8+MAXPATHLEN];
        /* Need space for "<<<<<<< " or ">>>>>>> " plus filename   */
static int save_err;    /* saves errno */

static int readin(char *name, struct diff *dd);
static int number(char **lc);
static int digit(int c);
static int getchange(FILE *b);
static int getline(FILE *b);
static void merge(int m1, int m2);
static void separate(char *s);
static void change(int i, struct range *rold, int dup);
static void prange(struct range *rold);
static void keep(int i, struct range *rnew);
static int skip(int i, int from, char *pr);
static int duplicate(struct range *r1, struct range *r2);
static void repos(int nchar);
static void trouble();
static int edit(struct diff *diff, int dup, int j);
static void edscript(int n);

int
main(int argc, char **argv)
{
    int i, m, n;
    eflag  = 0;
    oflag  = 0;
    if (*argv[1] == '-') {
        switch (argv[1][1]) {
        default:
            eflag = 3;
            break;
        case '3':
            eflag = 2;
            break;
        case 'x':
            eflag = 1;
            break;
        case 'E':
            eflag = 3;
            oflag = 1;
            break;
        case 'X':
            oflag = eflag = 1;
            break;
        }
        argv++;
        argc--;
    }
    if (argc < 6) {
        (void) fprintf(stderr, "diff3: arg count\n");
        exit(1);
    }

    if (oflag) {
        (void) snprintf(f1mark, sizeof (f1mark), "<<<<<<< %s",
                        argc >= 7 ? argv[6] : argv[3]);
        (void) snprintf(f3mark, sizeof (f3mark), ">>>>>>> %s",
                        argc >= 8 ? argv[7] : argv[5]);
    }

    m = readin(argv[1], d13);
    n = readin(argv[2], d23);
    for (i = 0; i <= 2; i++)
        if ((fp[i] = fopen(argv[i+3], "r")) == NULL) {
            save_err = errno;
            (void) fprintf(stderr, "diff3: can't open %s: ",
                argv[i+3]);
            errno = save_err;
            perror("");
            exit(1);
        }
    merge(m, n);
    return (0);
}

/*
 * pick up the line numbers of all changes from
 * one change file
 * (this puts the numbers in a vector, which is not
 * strictly necessary, since the vector is processed
 * in one sequential pass. The vector could be optimized
 * out of existence)
 */

static int
readin(char *name, struct diff *dd)
{
    int i;
    int a, b, c, d;
    char kind;
    char *p;
    if ((fp[0] = fopen(name, "r")) == NULL) {
        save_err = errno;
        (void) fprintf(stderr, "diff3: can't open %s: ", name);
        errno = save_err;
        perror("");
        exit(1);
    }
    for (i = 0; getchange(fp[0]); i++) {
        if (i >= NC) {
            (void) fprintf(stderr, "diff3: too many changes\n");
            exit(0);
        }
        p = line;
        a = b = number(&p);
        if (*p == ',') {
            p++;
            b = number(&p);
        }
        kind = *p++;
        c = d = number(&p);
        if (*p == ',') {
            p++;
            d = number(&p);
        }
        if (kind == 'a')
            a++;
        if (kind == 'd')
            c++;
        b++;
        d++;
        dd[i].old.from = a;
        dd[i].old.to = b;
        dd[i].new.from = c;
        dd[i].new.to = d;
    }
    dd[i].old.from = dd[i-1].old.to;
    dd[i].new.from = dd[i-1].new.to;
    (void) fclose(fp[0]);
    return (i);
}

static int
number(char **lc)
{
    int nn;
    nn = 0;
    while (digit(**lc))
        nn = nn*10 + *(*lc)++ - '0';
    return (nn);
}

static int
digit(int c)
{
    return (c >= '0' && c <= '9');
}

static int
getchange(FILE *b)
{
    while (getline(b))
        if (digit(line[0]))
            return (1);
    return (0);
}

static int
getline(FILE *b)
{
    int i, c;
    for (i = 0; i < sizeof (line)-1; i++) {
        c = getc(b);
        if (c == EOF) {
            line[i] = 0;
            return (i);
        }
        line[i] = c;
        if (c == '\n') {
            line[++i] = 0;
            return (i);
        }
    }
    return (0);
}

static void
merge(int m1, int m2)
{
    struct diff *d1, *d2, *d3;
    int dup;
    int j;
    int t1, t2;
    d1 = d13;
    d2 = d23;
    j = 0;
    for (; (t1 = d1 < d13+m1) | (t2 = d2 < d23+m2); ) {
        if (debug) {
            (void) printf("%d,%d=%d,%d %d,%d=%d,%d\n",
            d1->old.from, d1->old.to,
            d1->new.from, d1->new.to,
            d2->old.from, d2->old.to,
            d2->new.from, d2->new.to);
        }

        /* first file is different from others */
        if (!t2 || t1 && d1->new.to < d2->new.from) {
            /* stuff peculiar to 1st file */
            if (eflag == 0) {
                separate("1");
                change(1, &d1->old, 0);
                keep(2, &d1->new);
                change(3, &d1->new, 0);
            }
            d1++;
            continue;
        }

        /* second file is different from others */
        if (!t1 || t2 && d2->new.to < d1->new.from) {
            if (eflag == 0) {
                separate("2");
                keep(1, &d2->new);
                change(2, &d2->old, 0);
                change(3, &d2->new, 0);
            }
            d2++;
            continue;
        }
        /*
         * merge overlapping changes in first file
         * this happens after extension see below
         */
        if (d1+1 < d13+m1 && d1->new.to >= d1[1].new.from) {
            d1[1].old.from = d1->old.from;
            d1[1].new.from = d1->new.from;
            d1++;
            continue;
        }

        /* merge overlapping changes in second */
        if (d2+1 < d23+m2 && d2->new.to >= d2[1].new.from) {
            d2[1].old.from = d2->old.from;
            d2[1].new.from = d2->new.from;
            d2++;
            continue;
        }

        /* stuff peculiar to third file or different in all */
        if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
            dup = duplicate(&d1->old, &d2->old);
            /*
             * dup = 0 means all files differ
             * dup = 1 meands files 1&2 identical
             */
            if (eflag == 0) {
                separate(dup?"3":"");
                change(1, &d1->old, dup);
                change(2, &d2->old, 0);
                d3 = d1->old.to > d1->old.from ? d1 : d2;
                change(3, &d3->new, 0);
            } else
                j = edit(d1, dup, j);
            d1++;
            d2++;
            continue;
        }
        /*
         * overlapping changes from file1 & 2
         * extend changes appropriately to
         * make them coincide
         */
        if (d1->new.from < d2->new.from) {
            d2->old.from -= d2->new.from-d1->new.from;
            d2->new.from = d1->new.from;
        } else if (d2->new.from < d1->new.from) {
            d1->old.from -= d1->new.from-d2->new.from;
            d1->new.from = d2->new.from;
        }

        if (d1->new.to > d2->new.to) {
            d2->old.to += d1->new.to - d2->new.to;
            d2->new.to = d1->new.to;
        } else if (d2->new.to > d1->new.to) {
            d1->old.to += d2->new.to - d1->new.to;
            d1->new.to = d2->new.to;
        }
    }
    if (eflag) {
        edscript(j);
        if (j)
            (void) printf("w\nq\n");
    }
}

static void
separate(char *s)
{
    (void) printf("====%s\n", s);
}

/*
 * the range of ines rold.from thru rold.to in file i
 * is to be changed. it is to be printed only if
 * it does not duplicate something to be printed later
 */
static void
change(int i, struct range *rold, int dup)
{
    (void) printf("%d:", i);
    last[i] = rold->to;
    prange(rold);
    if (dup)
        return;
    if (debug)
        return;
    i--;
    (void) skip(i, rold->from, (char *)0);
    (void) skip(i, rold->to, "  ");
}

/*
 * print the range of line numbers, rold.from  thru rold.to
 * as n1, n2 or n1
 */
static void
prange(struct range *rold)
{
    if (rold->to <= rold->from)
        (void) printf("%da\n", rold->from-1);
    else {
        (void) printf("%d", rold->from);
        if (rold->to > rold->from+1)
            (void) printf(",%d", rold->to-1);
        (void) printf("c\n");
    }
}

/*
 * no difference was reported by diff between file 1(or 2)
 * and file 3, and an artificial dummy difference (trange)
 * must be ginned up to correspond to the change reported
 * in the other file
 */
static void
keep(int i, struct range *rnew)
{
    int delta;
    struct range trange;
    delta = last[3] - last[i];
    trange.from = rnew->from - delta;
    trange.to = rnew->to - delta;
    change(i, &trange, 1);
}

/*
 * skip to just befor line number from in file i
 * if "pr" is nonzero, print all skipped stuff
 * with string pr as a prefix
 */
static int
skip(int i, int from, char *pr)
{
    int j, n;
    for (n = 0; cline[i] < from-1; n += j) {
        if ((j = getline(fp[i])) == 0)
            trouble();
        if (pr)
            (void) printf("%s%s", pr, line);
        cline[i]++;
    }
    return (n);
}

/*
 * return 1 or 0 according as the old range
 * (in file 1) contains exactly the same data
 * as the new range (in file 2)
 */
static int
duplicate(struct range *r1, struct range *r2)
{
    int c, d;
    int nchar;
    int nline;
    if (r1->to-r1->from != r2->to-r2->from)
        return (0);
    (void) skip(0, r1->from, (char *)0);
    (void) skip(1, r2->from, (char *)0);
    nchar = 0;
    for (nline = 0; nline < r1->to-r1->from; nline++) {
        do {
            c = getc(fp[0]);
            d = getc(fp[1]);
            if (c == -1 || d == -1)
                trouble();
            nchar++;
            if (c != d) {
                repos(nchar);
                return (0);
            }
        } while (c != '\n');
    }
    repos(nchar);
    return (1);
}

static void
repos(int nchar)
{
    int i;
    for (i = 0; i < 2; i++)
        (void) fseek(fp[i], (long)-nchar, 1);
}

static void
trouble()
{
    (void) fprintf(stderr, "diff3: logic error\n");
    abort();
}

/*
 * collect an editing script for later regurgitation
 */
static int
edit(struct diff *diff, int dup, int j)
{
    if (((dup+1)&eflag) == 0)
        return (j);
    j++;
    overlap[j] = !dup;
    if (!dup) overlapcnt++;
    de[j].old.from = diff->old.from;
    de[j].old.to = diff->old.to;
    de[j].new.from = de[j-1].new.to + skip(2, diff->new.from, (char *)0);
    de[j].new.to = de[j].new.from + skip(2, diff->new.to, (char *)0);
    return (j);
}

/*      regurgitate */
static void
edscript(int n)
{
    int j, k;
    char     block[BUFSIZ];

    for (n = n; n > 0; n--) {
        if (!oflag || !overlap[n])
            prange(&de[n].old);
        else
            (void) printf("%da\n=======\n", de[n].old.to -1);
        (void) fseek(fp[2], (long)de[n].new.from, 0);
        for (k = de[n].new.to-de[n].new.from; k > 0; k -= j) {
            j = k > BUFSIZ?BUFSIZ:k;
            if (fread(block, 1, j, fp[2]) != j)
                trouble();
            (void) fwrite(block, 1, j, stdout);
        }
        if (!oflag || !overlap[n])
            (void) printf(".\n");
        else {
            (void) printf("%s\n.\n", f3mark);
            (void) printf("%da\n%s\n.\n", de[n].old.from-1, f1mark);
        }
    }
}