Add md5sum

No support for -c at the moment.

md5sum.c

@@ -0,0 +1,67 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include "util.h"
+#include "md5.h"
+
+static void md5sum(int fd, const char *f);
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [file...]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int fd;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc == 0) {
+		md5sum(STDIN_FILENO, "<stdin>");
+	} else {
+		for (; argc > 0; argc--) {
+			if ((fd = open(*argv, O_RDONLY)) < 0)
+				eprintf("open %s:", *argv);
+			md5sum(fd, *argv);
+			close(fd);
+			argv++;
+		}
+	}
+
+	return 0;
+}
+
+static void
+md5sum(int fd, const char *f)
+{
+	unsigned char buf[BUFSIZ];
+	unsigned char digest[MD5_DIGEST_LENGTH];
+	struct md5 s;
+	ssize_t n;
+	int i;
+
+	md5_init(&s);
+	while ((n = read(fd, buf, sizeof buf)) > 0)
+		md5_update(&s, buf, n);
+	if (n < 0) {
+		eprintf("%s: read error:", f);
+		return;
+	}
+
+	md5_sum(&s, digest);
+
+	for (i = 0; i < sizeof(digest); i++)
+		printf("%02x", digest[i]);
+	printf("  %s\n", f);
+}