pkg/uroot: busybox build mode and reproducible archives.

Signed-off-by: Christopher Koch <chrisko@google.com>

.gitignore

@@ -4,6 +4,9 @@
 *.so
 *~
 
+bbsh
+u-root
+
 # Folders
 _obj
 _test

pkg/cpio/newc/newc.go

@@ -231,7 +231,10 @@ func (r *reader) ReadRecord() (cpio.Record, error) {
 
 	content := io.NewSectionReader(r.r, r.pos, int64(hdr.FileSize))
 	r.pos = round4(r.pos + int64(hdr.FileSize))
-	return cpio.Record{cpio.NewReadCloser(content), info}, nil
+	return cpio.Record{
+		Info:       info,
+		ReadCloser: cpio.NewReadCloser(content),
+	}, nil
 }
 
 func init() {

pkg/cpio/types.go

@@ -10,6 +10,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"syscall"
 	"time"
 )
 
@@ -43,6 +44,18 @@ func StaticRecord(contents []byte, info Info) Record {
 	}
 }
 
+// Symlink returns a symlink record at path pointing to target.
+func Symlink(path string, target string) Record {
+	return Record{
+		ReadCloser: ioutil.NopCloser(bytes.NewReader([]byte(target))),
+		Info: Info{
+			FileSize: uint64(len(target)),
+			Mode:     syscall.S_IFLNK | 0777,
+			Name:     path,
+		},
+	}
+}
+
 func NewBytesReadCloser(contents []byte) io.ReadCloser {
 	return ioutil.NopCloser(bytes.NewReader(contents))
 }

pkg/golang/build.go

@@ -6,6 +6,7 @@ import (
 	"go/build"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
 )
 
@@ -22,7 +23,11 @@ func Default() Environ {
 // This currently assumes that packages are named after the directory they are
 // in.
 func (c Environ) FindPackageByPath(path string) (string, error) {
-	p, err := c.Context.ImportDir(path, 0)
+	abs, err := filepath.Abs(path)
+	if err != nil {
+		return "", err
+	}
+	p, err := c.Context.ImportDir(abs, 0)
 	if err != nil {
 		return "", fmt.Errorf("failed to find package in %q: %v", path, err)
 	}