From 433c030b1e1921e0253f6b9896a827aac5728cdc Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Sat, 27 Dec 2008 05:37:47 -0600
Subject: [PATCH] Add cksum.

---
 toys/cksum.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 toys/cksum.c

diff --git a/toys/cksum.c b/toys/cksum.c
new file mode 100644
index 0000000..a3e53de
--- /dev/null
+++ b/toys/cksum.c
@@ -0,0 +1,71 @@
+/* vi: set sw=4 ts=4:
+ *
+ * cksum.c - produce crc32 checksum value for each input
+ *
+ * Copyright 2008 Rob Landley <rob@landley.net>
+ *
+ * See http://www.opengroup.org/onlinepubs/009695399/utilities/cksum.html
+
+USE_CKSUM(NEWTOY(cksum, NULL, TOYFLAG_BIN))
+
+config CKSUM
+	bool "cksum"
+	default y
+	help
+	  usage: cksum [file...]
+	  For each file, output crc32 checksum value, length and name of file.
+	  If no files listed, copy from stdin.  Filename "-" is a synonym for stdin.
+*/
+
+#include "toys.h"
+
+DEFINE_GLOBALS(
+	unsigned crc_table[256];
+)
+
+#define TT this.cksum
+
+static unsigned cksum(unsigned crc, unsigned char c)
+{
+	return (crc<<8)^TT.crc_table[(crc>>24)^c];
+}
+
+static void do_cksum(int fd, char *name)
+{
+	unsigned crc = 0;
+	uint64_t llen = 0, llen2;
+
+	// CRC the data
+
+	for (;;) {
+		int len, i;
+
+		len = read(fd, toybuf, sizeof(toybuf));
+		if (len<0) {
+			perror_msg("%s",name);
+			toys.exitval = EXIT_FAILURE;
+		}
+		if (len<1) break;
+
+		llen += len;
+		for (i=0; i<len; i++) crc=cksum(crc, toybuf[i]);
+	}
+
+	// CRC the length
+
+	llen2 = llen;
+	while (llen) {
+		crc = cksum(crc, llen);
+		llen >>= 8;
+	}
+
+	printf("%u %"PRIu64, ~crc, llen2);
+	if (strcmp("-", name)) printf(" %s", name);
+	xputc('\n');
+}
+
+void cksum_main(void)
+{
+	crc_init(TT.crc_table);
+	loopfiles(toys.optargs, do_cksum);
+}
-- 
2.7.4