Add cksum.

diff --git a/toys/cksum.c b/toys/cksum.c
new file mode 100644 (file)
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);
+}