git: plan9front

--- a/sys/src/cmd/diff/diff.h

+++ b/sys/src/cmd/diff/diff.h

@@ -57,6 +57,7 @@

 extern Biobuf	stdout;

 #define MAXPATHLEN	1024

+#define MAXLINELEN	4096

 #define	DIRECTORY(s)		((s)->qid.type&QTDIR)

 #define	REGULAR_FILE(s)		((s)->type == 'M' && !DIRECTORY(s))

@@ -76,3 +77,4 @@

 void freediff(Diff *);

 void flushchanges(Diff *);

 void fetch(Diff *d, long *f, int a, int b, Biobuf *bp, char *s);

+int readline(Biobuf*, char*, int);

--- a/sys/src/cmd/diff/diffio.c

+++ b/sys/src/cmd/diff/diffio.c

@@ -4,17 +4,16 @@

 #include <ctype.h>

 #include "diff.h"

-#define MAXLINELEN	4096

 #define MIN(x, y)	((x) < (y) ? (x): (y))

-static int

-readline(Biobuf *bp, char *buf)

+int

+readline(Biobuf *bp, char *buf, int nbuf)

 	int c;

 	char *p, *e;

 	p = buf;

-	e = p + MAXLINELEN-1;

+	e = p + nbuf-1;

 	do {

 		c = Bgetc(bp);

 		if (c < 0) {

@@ -44,7 +43,7 @@

  * summing 1-s complement in 16-bit hunks

*/

 static int

-readhash(Biobuf *bp, char *buf)

+readhash(Biobuf *bp, char *buf, int nbuf)

 	long sum;

 	unsigned shift;

@@ -53,7 +52,7 @@

 	sum = 1;

 	shift = 0;

-	if ((len = readline(bp, buf)) == -1)

+	if ((len = readline(bp, buf, nbuf)) == -1)

 		return 0;

 	p = buf;

 	switch(bflag)	/* various types of white space handling */

@@ -138,7 +137,7 @@

 		Bseek(bp, 0, 0);

 	p = emalloc(3*sizeof(Line));

-	for (j = 0; h = readhash(bp, buf); p[j].value = h)

+	for (j = 0; h = readhash(bp, buf, sizeof(buf)); p[j].value = h)

 		p = erealloc(p, (++j+3)*sizeof(Line));

 	d->len[i] = j;

 	d->file[i] = p;

@@ -179,12 +178,12 @@

 	d->ixold[0] = 0;

 	d->ixnew[0] = 0;

 	for (f = t = 1; f < d->len[0]; f++) {

-		flen = readline(bf, fbuf);

+		flen = readline(bf, fbuf, sizeof(fbuf));

 		d->ixold[f] = d->ixold[f-1] + flen;		/* ftell(bf) */

 		if (d->J[f] == 0)

 			continue;

 		do {

-			tlen = readline(bt, tbuf);

+			tlen = readline(bt, tbuf, sizeof(tbuf));

 			d->ixnew[t] = d->ixnew[t-1] + tlen;	/* ftell(bt) */

 		} while (t++ < d->J[f]);

 		if (bflag) {

@@ -195,7 +194,7 @@

 			d->J[f] = 0;

 	while (t < d->len[1]) {

-		tlen = readline(bt, tbuf);

+		tlen = readline(bt, tbuf, sizeof(tbuf));

 		d->ixnew[t] = d->ixnew[t-1] + tlen;	/* fseek(bt) */

 		t++;

@@ -227,7 +226,7 @@

 		return;

 	Bseek(bp, f[a-1], 0);

 	while (a++ <= b) {

-		len = readline(bp, buf);

+		len = readline(bp, buf, sizeof(buf));

 		if(len == 0 || buf[len-1] != '\n'){

 			Bprint(&stdout, "%s%s\n", s, buf);

 			Bprint(&stdout, "\\ No newline at end of file\n");

--- a/sys/src/cmd/diff/merge3.c

+++ b/sys/src/cmd/diff/merge3.c

@@ -58,6 +58,33 @@

 		return ry >= lx;

+static int

+same(Diff *l, Change *lc, Diff *r, Change *rc)

+{

+	char lbuf[MAXLINELEN], rbuf[MAXLINELEN];

+	int i, ll, rl, lx, ly, rx, ry;

+	lx = lc->newx;

+	ly = lc->newy;

+	rx = rc->newx;

+	ry = rc->newy;

+	if(ly - lx != ry - rx)

+		return 0;

+	assert(lx <= ly && ly < l->len[1]);

+	assert(rx <= ry && ry < r->len[1]);

+	Bseek(l->input[1], l->ixnew[lx-1], 0);

+	Bseek(r->input[1], r->ixnew[rx-1], 0);

+	for(i = 0; i <= (ly - lx); i++){

+		ll = readline(l->input[1], lbuf, sizeof(lbuf));

+		rl = readline(r->input[1], rbuf, sizeof(rbuf));

+		if(ll != rl)

+			return 0;

+		if(memcmp(lbuf, rbuf, ll) != 0)

+			return 0;

+	}

+	return 1;

+}

 char*

 merge(Diff *l, Diff *r)

@@ -116,14 +143,19 @@

 				lc->oldy += δ;

 				lc->newy += δ;

-			fetch(l, l->ixold, ln, x-1, l->input[0], "");

-			Bprint(&stdout, "<<<<<<<<<< %s\n", l->file2);

-			fetch(l, l->ixnew, lc->newx, lc->newy, l->input[1], "");

-			Bprint(&stdout, "========== original\n");

-			fetch(l, l->ixold, x, y, l->input[0], "");

-			Bprint(&stdout, "========== %s\n", r->file2);

-			fetch(r, r->ixnew, rc->newx, rc->newy, r->input[1], "");

-			Bprint(&stdout, ">>>>>>>>>>\n");

+			if(same(l, lc, r, rc)){

+				fetch(l, l->ixold, ln, x-1, l->input[0], "");

+				fetch(l, l->ixnew, lc->newx, lc->newy, l->input[1], "");

+			}else{

+				fetch(l, l->ixold, ln, x-1, l->input[0], "");

+				Bprint(&stdout, "<<<<<<<<<< %s\n", l->file2);

+				fetch(l, l->ixnew, lc->newx, lc->newy, l->input[1], "");

+				Bprint(&stdout, "========== original\n");

+				fetch(l, l->ixold, x, y, l->input[0], "");

+				Bprint(&stdout, "========== %s\n", r->file2);

+				fetch(r, r->ixnew, rc->newx, rc->newy, r->input[1], "");

+				Bprint(&stdout, ">>>>>>>>>>\n");

+			}

 			ln = y+1;

 			il++;

 			ir++;

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t10.c

@@ -1,0 +1,10 @@

+1

+2

+3

+4

+5

+6

+7

+8

+9

+10

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t10.expected

@@ -1,0 +1,10 @@

+1

+2

+3

+4

+y

+6

+7

+8

+9

+10

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t10.l

@@ -1,0 +1,10 @@

+1

+2

+3

+4

+y

+6

+7

+8

+9

+10

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t10.r

@@ -1,0 +1,10 @@

+1

+2

+3

+4

+y

+6

+7

+8

+9

+10

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t11.c

@@ -1,0 +1,10 @@

+1

+2

+3

+4

+5

+6

+7

+8

+9

+10

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t11.expected

@@ -1,0 +1,12 @@

+A

+1

+2

+3

+4

+y

+6

+7

+8

+9

+10

+Z

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t11.l

@@ -1,0 +1,12 @@

+A

+1

+2

+3

+4

+y

+6

+7

+8

+9

+10

+Z

--- /dev/null

+++ b/sys/src/cmd/diff/test/merge-t11.r

@@ -1,0 +1,10 @@

+1

+2

+3

+4

+y

+6

+7

+8

+9

+10

--- a/sys/src/cmd/diff/test/merge.rc

+++ b/sys/src/cmd/diff/test/merge.rc

@@ -1,6 +1,6 @@

 #!/bin/rc

-tests=`{seq 9}

+tests=`{seq 11}

 for(t in $tests){

 	echo ../$O.merge3 merge-t$t.l merge-t$t.c merge-t$t.r

 	../$O.merge3 merge-t$t.l merge-t$t.c merge-t$t.r > merge-t$t.out

code: plan9front