Created command: md5sum

Makefile

@@ -6,6 +6,7 @@ SUBDIRS =	basename\
 	cal\
 	cat\
 	echo\
+	md5sum\
 	mkdir\
 	pbd\
 	sleep

md5sum/Makefile

@@ -0,0 +1,9 @@
+# md5sum - calculate RFC1321 hash of files
+
+TARG		= md5sum
+
+include ../std.mk
+
+pre-uninstall:
+
+post-install:

md5sum/md5sum.1

@@ -0,0 +1,13 @@
+.TH MD5SUM 1
+.SH NAME
+md5sum \- compute and check MD5 message digest
+.SH SYNOPSIS
+.B md5sum
+[
+.I file ...
+]
+.SH DESCRIPTION
+Md5sum computes the 32 hex digit RSA Data Security, Inc. MD5 
+Message-Digest Algorithm described in RFC1321. If no files are
+givem, the standard input is summed.
+

md5sum/md5sum.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"os"
+	"fmt"
+	"flag"
+	"crypto/md5"
+	"io/ioutil"
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: md5sum [file ...]\n")
+	os.Exit(1)
+}
+
+func main() {
+	flag.Parse()
+
+	if flag.NArg() == 0 {	// Stdin
+		f := os.Stdin
+		h := md5.New()
+		var buf [64]byte
+
+		for {
+			switch nr, _ := f.Read(buf[:]); true {
+				case nr > 0:
+					_, e := h.Write(buf[0:nr])
+
+					if e != nil {
+						fmt.Fprintf(os.Stderr, "md5sum: error generating hash\n")
+						os.Exit(1)
+					}
+				case nr == 0:
+					s := h.Sum()
+
+					for j := 0; j < len(s); j++ {
+						if s[j] < 0x10 {
+							fmt.Fprintf(os.Stdout, "0%0x", s[j])
+						} else {
+							fmt.Fprintf(os.Stdout, "%0x", s[j])
+						}
+					}
+					fmt.Fprintf(os.Stdout, "  -\n")
+					return
+				case nr < 0:
+					fmt.Fprintf(os.Stderr, "md5sum: error generating hash\n")
+					os.Exit(1)
+			}
+		}
+	} else {
+		h := md5.New()
+
+		for i := 0; i < flag.NArg(); i++ {
+			d, e := ioutil.ReadFile(flag.Arg(i))
+
+			if e != nil {
+				fmt.Fprintf(os.Stderr, "md5sum: cant read file %s\n", flag.Arg(i))
+				os.Exit(1)
+			}
+
+			_, e = h.Write(d)
+
+			if e != nil {
+				fmt.Fprintf(os.Stderr, "md5sum: error generating hash\n")
+				os.Exit(1)
+			}
+
+			s := h.Sum()
+
+			for j := 0; j < len(s); j++ {
+				if s[j] < 0x10 {
+					fmt.Fprintf(os.Stdout, "0%0x", s[j])
+				} else {
+					fmt.Fprintf(os.Stdout, "%0x", s[j])
+				}
+			}
+
+			fmt.Fprintf(os.Stdout, "  %s\n", flag.Arg(i))
+
+			h.Reset()	// Reset has for next file
+		}
+	}
+}
+