the one true diff.

at least it can handle "diff file1 file2 dir".

src/cmd/diff/diffio.c

@@ -0,0 +1,291 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <ctype.h>
+#include "diff.h"
+
+struct line {
+	int	serial;
+	int	value;
+};
+extern struct line *file[2];
+extern int len[2];
+extern long *ixold, *ixnew;
+extern int *J;
+
+static Biobuf *input[2];
+static char *file1, *file2;
+static int firstchange;
+
+#define MAXLINELEN	4096
+#define MIN(x, y)	((x) < (y) ? (x): (y))
+
+static int
+readline(Biobuf *bp, char *buf)
+{
+	int c;
+	char *p, *e;
+
+	p = buf;
+	e = p + MAXLINELEN-1;
+	do {
+		c = Bgetc(bp);
+		if (c < 0) {
+			if (p == buf)
+				return -1;
+			break;
+		}
+		if (c == '\n')
+			break;
+		*p++ = c;
+	} while (p < e);
+	*p = 0;
+	if (c != '\n' && c >= 0) {
+		do c = Bgetc(bp);
+		while (c >= 0 && c != '\n');
+	}
+	return p - buf;
+}
+
+#define HALFLONG 16
+#define low(x)	(x&((1L<<HALFLONG)-1))
+#define high(x)	(x>>HALFLONG)
+
+/*
+ * hashing has the effect of
+ * arranging line in 7-bit bytes and then
+ * summing 1-s complement in 16-bit hunks 
+ */
+static int
+readhash(Biobuf *bp, char *buf)
+{
+	long sum;
+	unsigned shift;
+	char *p;
+	int len, space;
+
+	sum = 1;
+	shift = 0;
+	if ((len = readline(bp, buf)) == -1)
+		return 0;
+	p = buf;
+	switch(bflag)	/* various types of white space handling */
+	{
+	case 0:
+		while (len--) {
+			sum += (long)*p++ << (shift &= (HALFLONG-1));
+			shift += 7;
+		}
+		break;
+	case 1:
+		/*
+		 * coalesce multiple white-space
+		 */
+		for (space = 0; len--; p++) {
+			if (isspace(*p)) {
+				space++;
+				continue;
+			}
+			if (space) {
+				shift += 7;
+				space = 0;
+			}
+			sum += (long)*p << (shift &= (HALFLONG-1));
+			shift += 7;
+		}
+		break;
+	default:
+		/*
+		 * strip all white-space
+		 */
+		while (len--) {
+			if (isspace(*p)) {
+				p++;
+				continue;
+			}
+			sum += (long)*p++ << (shift &= (HALFLONG-1));
+			shift += 7;
+		}
+		break;
+	}
+	sum = low(sum) + high(sum);
+	return ((short)low(sum) + (short)high(sum));
+}
+
+Biobuf *
+prepare(int i, char *arg)
+{
+	struct line *p;
+	int j, h;
+	Biobuf *bp;
+	char *cp, buf[MAXLINELEN];
+	int nbytes;
+	Rune r;
+
+	bp = Bopen(arg, OREAD);
+	if (!bp) {
+		panic(mflag ? 0: 2, "cannot open %s: %r\n", arg);
+		return 0;
+	}
+	if (binary)
+		return bp;
+	nbytes = Bread(bp, buf, MIN(1024, MAXLINELEN));
+	if (nbytes > 0) {
+		cp = buf;
+		while (cp < buf+nbytes-UTFmax) {
+			/*
+			 * heuristic for a binary file in the
+			 * brave new UNICODE world
+			 */
+			cp += chartorune(&r, cp);
+			if (r == 0 || (r > 0x7f && r <= 0xa0)) {
+				binary++;
+				return bp;
+			}
+		}
+		Bseek(bp, 0, 0);
+	}
+	p = MALLOC(struct line, 3);
+	for (j = 0; h = readhash(bp, buf); p[j].value = h)
+		p = REALLOC(p, struct line, (++j+3));
+	len[i] = j;
+	file[i] = p;
+	input[i] = bp;			/*fix*/
+	if (i == 0) {			/*fix*/
+		file1 = arg;
+		firstchange = 0;
+	}
+	else
+		file2 = arg;
+	return bp;
+}
+
+static int
+squishspace(char *buf)
+{
+	char *p, *q;
+	int space;
+
+	for (space = 0, q = p = buf; *q; q++) {
+		if (isspace(*q)) {
+			space++;
+			continue;
+		}
+		if (space && bflag == 1) {
+			*p++ = ' ';
+			space = 0;
+		}
+		*p++ = *q;
+	}
+	*p = 0;
+	return p - buf;
+}
+
+/*
+ * need to fix up for unexpected EOF's
+ */
+void
+check(Biobuf *bf, Biobuf *bt)
+{
+	int f, t, flen, tlen;
+	char fbuf[MAXLINELEN], tbuf[MAXLINELEN];
+
+	ixold[0] = ixnew[0] = 0;
+	for (f = t = 1; f < len[0]; f++) {
+		flen = readline(bf, fbuf);
+		ixold[f] = ixold[f-1] + flen + 1;		/* ftell(bf) */
+		if (J[f] == 0)
+			continue;
+		do {
+			tlen = readline(bt, tbuf);
+			ixnew[t] = ixnew[t-1] + tlen + 1;	/* ftell(bt) */
+		} while (t++ < J[f]);
+		if (bflag) {
+			flen = squishspace(fbuf);
+			tlen = squishspace(tbuf);
+		}
+		if (flen != tlen || strcmp(fbuf, tbuf))
+			J[f] = 0;
+	}
+	while (t < len[1]) {
+		tlen = readline(bt, tbuf);
+		ixnew[t] = ixnew[t-1] + tlen + 1;	/* fseek(bt) */
+		t++;
+	}
+}
+
+static void
+range(int a, int b, char *separator)
+{
+	Bprint(&stdout, "%d", a > b ? b: a);
+	if (a < b)
+		Bprint(&stdout, "%s%d", separator, b);
+}
+
+static void
+fetch(long *f, int a, int b, Biobuf *bp, char *s)
+{
+	char buf[MAXLINELEN];
+
+	Bseek(bp, f[a-1], 0);
+	while (a++ <= b) {
+		readline(bp, buf);
+		Bprint(&stdout, "%s%s\n", s, buf);
+	}
+}
+
+void
+change(int a, int b, int c, int d)
+{
+	char verb;
+	char buf[4];
+
+	if (a > b && c > d)
+		return;
+	anychange = 1;
+	if (mflag && firstchange == 0) {
+		if(mode) {
+			buf[0] = '-';
+			buf[1] = mode;
+			buf[2] = ' ';
+			buf[3] = '\0';
+		} else {
+			buf[0] = '\0';
+		}
+		Bprint(&stdout, "diff %s%s %s\n", buf, file1, file2);
+		firstchange = 1;
+	}
+	verb = a > b ? 'a': c > d ? 'd': 'c';
+	switch(mode) {
+	case 'e':
+		range(a, b, ",");
+		Bputc(&stdout, verb);
+		break;
+	case 0:
+		range(a, b, ",");
+		Bputc(&stdout, verb);
+		range(c, d, ",");
+		break;
+	case 'n':
+		Bprint(&stdout, "%s:", file1);
+		range(a, b, ",");
+		Bprint(&stdout, " %c ", verb);
+		Bprint(&stdout, "%s:", file2);
+		range(c, d, ",");
+		break;
+	case 'f':
+		Bputc(&stdout, verb);
+		range(a, b, " ");
+		break;
+	}
+	Bputc(&stdout, '\n');
+	if (mode == 0 || mode == 'n') {
+		fetch(ixold, a, b, input[0], "< ");
+		if (a <= b && c <= d)
+			Bprint(&stdout, "---\n");
+	}
+	fetch(ixnew, c, d, input[1], mode == 0 || mode == 'n' ? "> ": "");
+	if (mode != 0 && mode != 'n' && c <= d)
+		Bprint(&stdout, ".\n");
+}
+