Add pemit to convert data to PEM.

cmd/pemit/README

@@ -0,0 +1,41 @@
+pemit
+
+This is a utility to pem-encode data. It requires a PEM type to be
+specified via the `-t` flag. Any number of files may be specified on
+the command line; alternatively, if no arguments are provided or the
+only argument is "-", pemit will read from standard input.
+
+Example of standard input:
+	$ dd if=/dev/zero bs=32 count=1 | pemit -t "NULL DATA" 
+	1+0 records in
+	1+0 records out
+	32 bytes (32 B) copied, 8.8908e-05 s, 360 kB/s
+	-----BEGIN NULL DATA-----
+	AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
+	-----END NULL DATA-----
+	$ dd if=/dev/zero bs=32 count=1 | pemit -t "NULL DATA" -
+	1+0 records in
+	1+0 records out
+	32 bytes (32 B) copied, 3.1041e-05 s, 1.0 MB/s
+	-----BEGIN NULL DATA-----
+	AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
+	-----END NULL DATA-----
+
+Using files:
+        $ dd if=/dev/zero of=fileA bs=32 count=1
+	1+0 records in
+	1+0 records out
+	32 bytes (32 B) copied, 9.0908e-05 s, 352 kB/s
+        $ dd if=/dev/zero of=fileB bs=32 count=1
+	1+0 records in
+	1+0 records out
+	32 bytes (32 B) copied, 9.0908e-05 s, 352 kB/s
+	$ pemit -t NULL\ DATA fileA      
+	-----BEGIN NULL DATA-----
+	AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=
+	-----END NULL DATA-----
+	$ pemit -t NULL\ DATA fileA fileB
+	-----BEGIN NULL DATA-----
+	AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+	AAAAAAAAAAAAAAAAAAAAAA==
+	-----END NULL DATA-----

cmd/pemit/main.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"bytes"
+	"encoding/pem"
+	"flag"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/kisom/goutils/assert"
+	"github.com/kisom/goutils/die"
+	"github.com/kisom/goutils/lib"
+)
+
+func usage(w io.Writer) {
+	fmt.Fprintf(w, `Usage: %s [-h] -t type sources
+
+	Flags:
+		-h	Display this help message.
+		-t type	Set the PEM type. This is required.
+
+	Sources may be a list of files or a single '-'. A single dash
+	(or no arguments) will cause %s to use standard input.
+`, lib.ProgName(), lib.ProgName())
+}
+
+func init() {
+	flag.Usage = func() { usage(os.Stderr) }
+}
+
+func copyFile(path string, buf *bytes.Buffer) error {
+	assert.Bool(buf != nil, "buffer should not be nil")
+	file, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(buf, file)
+	file.Close()
+	return err
+}
+
+func main() {
+	var pemType string
+	flag.StringVar(&pemType, "t", "", "Specify the `PEM type`.")
+	flag.Parse()
+
+	die.When(len(pemType) == 0, "no PEM type specified.")
+
+	buf := &bytes.Buffer{}
+	argc := flag.NArg()
+	var err error
+
+	switch {
+	case argc == 0:
+		_, err = io.Copy(buf, os.Stdin)
+		if err != nil {
+			lib.Err(lib.ExitFailure, err, "failed to read input")
+		}
+	case argc == 1:
+		path := flag.Arg(0)
+		if path == "-" {
+			_, err = io.Copy(buf, os.Stdin)
+		} else {
+			err = copyFile(path, buf)
+		}
+
+		if err != nil {
+			lib.Err(lib.ExitFailure, err, "failed to read input")
+		}
+	case argc > 1:
+		for i := 0; i < argc; i++ {
+			path := flag.Arg(i)
+			err = copyFile(path, buf)
+			if err != nil {
+				lib.Err(lib.ExitFailure, err, "reading file failed")
+			}
+		}
+	default:
+		panic("shouldn't be here")
+	}
+
+	p := &pem.Block{
+		Type:  pemType,
+		Bytes: buf.Bytes(),
+	}
+
+	encoded := string(pem.EncodeToMemory(p))
+	fmt.Print(encoded)
+}