Use notary library for trusted image fetch and signing

Add a trusted flag to force the cli to resolve a tag into a digest via the notary trust library and pull by digest.
On push the flag the trust flag will indicate the digest and size of a manifest should be signed and push to a notary server.
If a tag is given, the cli will resolve the tag into a digest and pull by digest.
After pulling, if a tag is given the cli makes a request to tag the image.

Use certificate directory for notary requests

Read certificates using same logic used by daemon for registry requests.

Catch JSON syntax errors from Notary client

When an uncaught error occurs in Notary it may show up in Docker as a JSON syntax error, causing a confusing error message to the user.
Provide a generic error when a JSON syntax error occurs.

Catch expiration errors and wrap in additional context.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

ansiescape/split.go

@@ -0,0 +1,89 @@
+package ansiescape
+
+import "bytes"
+
+// dropCR drops a leading or terminal \r from the data.
+func dropCR(data []byte) []byte {
+	if len(data) > 0 && data[len(data)-1] == '\r' {
+		data = data[0 : len(data)-1]
+	}
+	if len(data) > 0 && data[0] == '\r' {
+		data = data[1:]
+	}
+	return data
+}
+
+// escapeSequenceLength calculates the length of an ANSI escape sequence
+// If there is not enough characters to match a sequence, -1 is returned,
+// if there is no valid sequence 0 is returned, otherwise the number
+// of bytes in the sequence is returned. Only returns length for
+// line moving sequences.
+func escapeSequenceLength(data []byte) int {
+	next := 0
+	if len(data) <= next {
+		return -1
+	}
+	if data[next] != '[' {
+		return 0
+	}
+	for {
+		next = next + 1
+		if len(data) <= next {
+			return -1
+		}
+		if (data[next] > '9' || data[next] < '0') && data[next] != ';' {
+			break
+		}
+	}
+	if len(data) <= next {
+		return -1
+	}
+	// Only match line moving codes
+	switch data[next] {
+	case 'A', 'B', 'E', 'F', 'H', 'h':
+		return next + 1
+	}
+
+	return 0
+}
+
+// ScanANSILines is a scanner function which splits the
+// input based on ANSI escape codes and new lines.
+func ScanANSILines(data []byte, atEOF bool) (advance int, token []byte, err error) {
+	if atEOF && len(data) == 0 {
+		return 0, nil, nil
+	}
+
+	// Look for line moving escape sequence
+	if i := bytes.IndexByte(data, '\x1b'); i >= 0 {
+		last := 0
+		for i >= 0 {
+			last = last + i
+
+			// get length of ANSI escape sequence
+			sl := escapeSequenceLength(data[last+1:])
+			if sl == -1 {
+				return 0, nil, nil
+			}
+			if sl == 0 {
+				// If no relevant sequence was found, skip
+				last = last + 1
+				i = bytes.IndexByte(data[last:], '\x1b')
+				continue
+			}
+
+			return last + 1 + sl, dropCR(data[0:(last)]), nil
+		}
+	}
+	if i := bytes.IndexByte(data, '\n'); i >= 0 {
+		// No escape sequence, check for new line
+		return i + 1, dropCR(data[0:i]), nil
+	}
+
+	// If we're at EOF, we have a final, non-terminated line. Return it.
+	if atEOF {
+		return len(data), dropCR(data), nil
+	}
+	// Request more data.
+	return 0, nil, nil
+}

ansiescape/split_test.go

@@ -0,0 +1,53 @@
+package ansiescape
+
+import (
+	"bufio"
+	"strings"
+	"testing"
+)
+
+func TestSplit(t *testing.T) {
+	lines := []string{
+		"test line 1",
+		"another test line",
+		"some test line",
+		"line with non-cursor moving sequence \x1b[1T", // Scroll Down
+		"line with \x1b[31;1mcolor\x1b[0m then reset",  // "color" in Bold Red
+		"cursor forward \x1b[1C and backward \x1b[1D",
+		"invalid sequence \x1babcd",
+		"",
+		"after empty",
+	}
+	splitSequences := []string{
+		"\x1b[1A",   // Cursor up
+		"\x1b[1B",   // Cursor down
+		"\x1b[1E",   // Cursor next line
+		"\x1b[1F",   // Cursor previous line
+		"\x1b[1;1H", // Move cursor to position
+		"\x1b[1;1h", // Move cursor to position
+		"\n",
+		"\r\n",
+		"\n\r",
+		"\x1b[1A\r",
+		"\r\x1b[1A",
+	}
+
+	for _, sequence := range splitSequences {
+		scanner := bufio.NewScanner(strings.NewReader(strings.Join(lines, sequence)))
+		scanner.Split(ScanANSILines)
+		i := 0
+		for scanner.Scan() {
+			if i >= len(lines) {
+				t.Fatalf("Too many scanned lines")
+			}
+			scanned := scanner.Text()
+			if scanned != lines[i] {
+				t.Fatalf("Wrong line scanned with sequence %q\n\tExpected: %q\n\tActual:   %q", sequence, lines[i], scanned)
+			}
+			i++
+		}
+		if i < len(lines) {
+			t.Errorf("Wrong number of lines for sequence %q: %d, expected %d", sequence, i, len(lines))
+		}
+	}
+}