the one true diff.

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

src/cmd/diff/diffdir.c

@@ -0,0 +1,108 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include "diff.h"
+
+static int
+itemcmp(void *v1, void *v2)
+{
+	char **d1 = v1, **d2 = v2;
+
+	return strcmp(*d1, *d2);
+}
+
+static char **
+scandir(char *name)
+{
+	char **cp;
+	Dir *db;
+	int nitems;
+	int fd, n;
+
+	if ((fd = open(name, OREAD)) < 0)
+		panic(2, "can't open %s\n", name);
+	cp = 0;
+	nitems = 0;
+	if((n = dirreadall(fd, &db)) > 0){
+		while (n--) {
+			cp = REALLOC(cp, char *, (nitems+1));
+			cp[nitems] = MALLOC(char, strlen((db+n)->name)+1);
+			strcpy(cp[nitems], (db+n)->name);
+			nitems++;
+		}
+		free(db);
+	}
+	cp = REALLOC(cp, char*, (nitems+1));
+	cp[nitems] = 0;
+	close(fd);
+	qsort((char *)cp, nitems, sizeof(char*), itemcmp);
+	return cp;
+}
+
+static int
+isdotordotdot(char *p)
+{
+	if (*p == '.') {
+		if (!p[1])
+			return 1;
+		if (p[1] == '.' && !p[2])
+			return 1;
+	}
+	return 0;
+}
+
+void
+diffdir(char *f, char *t, int level)
+{
+	char  **df, **dt, **dirf, **dirt;
+	char *from, *to;
+	int res;
+	char fb[MAXPATHLEN+1], tb[MAXPATHLEN+1];
+
+	df = scandir(f);
+	dt = scandir(t);
+	dirf = df;
+	dirt = dt;
+	while (*df || *dt) {
+		from = *df;
+		to = *dt;
+		if (from && isdotordotdot(from)) {
+			df++;
+			continue;
+		}
+		if (to && isdotordotdot(to)) {
+			dt++;
+			continue;
+		}
+		if (!from)
+			res = 1;
+		else if (!to)
+			res = -1;
+		else
+			res = strcmp(from, to);
+		if (res < 0) {
+			if (mode == 0 || mode == 'n')
+				Bprint(&stdout, "Only in %s: %s\n", f, from);
+			df++;
+			continue;
+		}
+		if (res > 0) {
+			if (mode == 0 || mode == 'n')
+				Bprint(&stdout, "Only in %s: %s\n", t, to);
+			dt++;
+			continue;
+		}
+		if (mkpathname(fb, f, from))
+			continue;
+		if (mkpathname(tb, t, to))
+			continue;
+		diff(fb, tb, level+1);
+		df++; dt++;
+	}
+	for (df = dirf; *df; df++)
+		FREE(*df);
+	for (dt = dirt; *dt; dt++)
+		FREE(*dt);
+	FREE(dirf);
+	FREE(dirt);
+}