cmd/dist: use of elf package adds 300k to dist binary size

[bradfitz]

The cmd/dist binary imports the elf package (and thus the dwarf) binary, just for one use:

                case strings.Contains(out, "mips64"):
                        file, err := elf.Open(os.Args[0])
                        if err != nil {
                                fatal("failed to open %s to determine endianness: %v", os.Args[0], err)
                        }
                        if file.FileHeader.ByteOrder == binary.BigEndian {
                                gohostarch = "mips64"
                        } else {
                                gohostarch = "mips64le"
                        }

... for detecting the host architecture.

Can that be done cheaper?

(noticed while looking at reducing the GOROOT_BOOTSTRAP tarball size sent to builders)

Not super high priority, of course.

[minux]

Yes, to determine the endian cmd/dist only needs to read the 6th byte of the elf file.

[gopherbot]

CL https://golang.org/cl/21662 mentions this issue.