github.com/rck/u-root@v0.0.0-20180106144920-7eb602e381bb/pkg/uroot/cpio.go (about)

     1  // Copyright 2015-2017 the u-root Authors. All rights reserved
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package uroot
     6  
     7  import (
     8  	"github.com/u-root/u-root/pkg/cpio"
     9  	_ "github.com/u-root/u-root/pkg/cpio/newc"
    10  	"github.com/u-root/u-root/pkg/ramfs"
    11  )
    12  
    13  // CPIOArchiver is an implementation of Archiver for the cpio format.
    14  type CPIOArchiver struct {
    15  	// Format is the name of the cpio format to use.
    16  	Format string
    17  }
    18  
    19  // DefaultExtension implements Archiver.DefaultExtension.
    20  func (ca CPIOArchiver) DefaultExtension() string {
    21  	return "cpio"
    22  }
    23  
    24  // Archive implements Archiver.Archive.
    25  func (ca CPIOArchiver) Archive(opts ArchiveOpts) error {
    26  	archiver, err := cpio.Format(ca.Format)
    27  	if err != nil {
    28  		return err
    29  	}
    30  
    31  	init, err := ramfs.NewInitramfs(archiver.Writer(opts.OutputFile))
    32  	if err != nil {
    33  		return err
    34  	}
    35  
    36  	if opts.BaseArchive != nil {
    37  		transform := cpio.MakeReproducible
    38  
    39  		// Rename init to inito if there is another init.
    40  		if !opts.UseExistingInit && opts.Contains("init") {
    41  			transform = func(r cpio.Record) cpio.Record {
    42  				if r.Name == "init" {
    43  					r.Name = "inito"
    44  				}
    45  				return cpio.MakeReproducible(r)
    46  			}
    47  		}
    48  
    49  		if err := init.Concat(archiver.Reader(opts.BaseArchive), transform); err != nil {
    50  			return err
    51  		}
    52  	}
    53  
    54  	// Reproducible builds: Files should be added to the archive in the
    55  	// same order.
    56  	for _, path := range opts.ArchiveFiles.SortedKeys() {
    57  		if record, ok := opts.ArchiveFiles.Records[path]; ok {
    58  			if err := init.WriteRecord(record); err != nil {
    59  				return err
    60  			}
    61  		}
    62  		if src, ok := opts.ArchiveFiles.Files[path]; ok {
    63  			if err := init.WriteFile(src, path); err != nil {
    64  				return err
    65  			}
    66  		}
    67  	}
    68  	return init.WriteTrailer()
    69  }