File uuid.obscpio of Package distribution-container

07070100000000000081a40000000000000000000000016328304800000c1b000000000000000000000000000000000000000d00000000uuid/uuid.go// Package uuid provides simple UUID generation. Only version 4 style UUIDs
// can be generated.
//
// Please see http://tools.ietf.org/html/rfc4122 for details on UUIDs.
package uuid

import (
	"crypto/rand"
	"fmt"
	"io"
	"os"
	"syscall"
	"time"
)

const (
	// Bits is the number of bits in a UUID
	Bits = 128

	// Size is the number of bytes in a UUID
	Size = Bits / 8

	format = "%08x-%04x-%04x-%04x-%012x"
)

var (
	// ErrUUIDInvalid indicates a parsed string is not a valid uuid.
	ErrUUIDInvalid = fmt.Errorf("invalid uuid")

	// Loggerf can be used to override the default logging destination. Such
	// log messages in this library should be logged at warning or higher.
	Loggerf = func(format string, args ...interface{}) {}
)

// UUID represents a UUID value. UUIDs can be compared and set to other values
// and accessed by byte.
type UUID [Size]byte

// Generate creates a new, version 4 uuid.
func Generate() (u UUID) {
	const (
		// ensures we backoff for less than 450ms total. Use the following to
		// select new value, in units of 10ms:
		// 	n*(n+1)/2 = d -> n^2 + n - 2d -> n = (sqrt(8d + 1) - 1)/2
		maxretries = 9
		backoff    = time.Millisecond * 10
	)

	var (
		totalBackoff time.Duration
		count        int
		retries      int
	)

	for {
		// This should never block but the read may fail. Because of this,
		// we just try to read the random number generator until we get
		// something. This is a very rare condition but may happen.
		b := time.Duration(retries) * backoff
		time.Sleep(b)
		totalBackoff += b

		n, err := io.ReadFull(rand.Reader, u[count:])
		if err != nil {
			if retryOnError(err) && retries < maxretries {
				count += n
				retries++
				Loggerf("error generating version 4 uuid, retrying: %v", err)
				continue
			}

			// Any other errors represent a system problem. What did someone
			// do to /dev/urandom?
			panic(fmt.Errorf("error reading random number generator, retried for %v: %v", totalBackoff.String(), err))
		}

		break
	}

	u[6] = (u[6] & 0x0f) | 0x40 // set version byte
	u[8] = (u[8] & 0x3f) | 0x80 // set high order byte 0b10{8,9,a,b}

	return u
}

// Parse attempts to extract a uuid from the string or returns an error.
func Parse(s string) (u UUID, err error) {
	if len(s) != 36 {
		return UUID{}, ErrUUIDInvalid
	}

	// create stack addresses for each section of the uuid.
	p := make([][]byte, 5)

	if _, err := fmt.Sscanf(s, format, &p[0], &p[1], &p[2], &p[3], &p[4]); err != nil {
		return u, err
	}

	copy(u[0:4], p[0])
	copy(u[4:6], p[1])
	copy(u[6:8], p[2])
	copy(u[8:10], p[3])
	copy(u[10:16], p[4])

	return
}

func (u UUID) String() string {
	return fmt.Sprintf(format, u[:4], u[4:6], u[6:8], u[8:10], u[10:])
}

// retryOnError tries to detect whether or not retrying would be fruitful.
func retryOnError(err error) bool {
	switch err := err.(type) {
	case *os.PathError:
		return retryOnError(err.Err) // unpack the target error
	case syscall.Errno:
		if err == syscall.EPERM {
			// EPERM represents an entropy pool exhaustion, a condition under
			// which we backoff and retry.
			return true
		}
	}

	return false
}
07070100000001000081a40000000000000000000000016328304800000437000000000000000000000000000000000000001200000000uuid/uuid_test.gopackage uuid

import (
	"testing"
)

const iterations = 1000

func TestUUID4Generation(t *testing.T) {
	for i := 0; i < iterations; i++ {
		u := Generate()

		if u[6]&0xf0 != 0x40 {
			t.Fatalf("version byte not correctly set: %v, %08b %08b", u, u[6], u[6]&0xf0)
		}

		if u[8]&0xc0 != 0x80 {
			t.Fatalf("top order 8th byte not correctly set: %v, %b", u, u[8])
		}
	}
}

func TestParseAndEquality(t *testing.T) {
	for i := 0; i < iterations; i++ {
		u := Generate()

		parsed, err := Parse(u.String())
		if err != nil {
			t.Fatalf("error parsing uuid %v: %v", u, err)
		}

		if parsed != u {
			t.Fatalf("parsing round trip failed: %v != %v", parsed, u)
		}
	}

	for _, c := range []string{
		"bad",
		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",    // correct length, incorrect format
		"  20cc7775-2671-43c7-8742-51d1cfa23258",  // leading space
		"20cc7775-2671-43c7-8742-51d1cfa23258   ", // trailing space
		"00000000-0000-0000-0000-x00000000000",    // out of range character
	} {
		if _, err := Parse(c); err == nil {
			t.Fatalf("parsing %q should have failed", c)
		}
	}
}
07070100000002000041ed0000000000000000000000016328304800000000000000000000000000000000000000000000000500000000uuid07070100000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000b00000000TRAILER!!!