makeshift/internal/archive/archive.go

package archive

import (
	"archive/tar"
	"compress/gzip"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"

	makeshift "git.towk2.me/towk/makeshift/pkg"
)

func Create(filenames []string, buf io.Writer, hooks []makeshift.Hook) error {
	// Create new Writers for gzip and tar
	// These writers are chained. Writing to the tar writer will
	// write to the gzip writer which in turn will write to
	// the "buf" writer
	gw := gzip.NewWriter(buf)
	defer gw.Close()
	tw := tar.NewWriter(gw)
	defer tw.Close()

	// Iterate over files and add them to the tar archive
	for _, filename := range filenames {
		err := addToArchive(tw, filename, hooks)
		if err != nil {
			return err
		}
	}

	return nil
}

func Expand(tarname, xpath string) error {
	tarfile, err := os.Open(tarname)
	if err != nil {
		return err
	}
	defer tarfile.Close()
	// absPath, err := filepath.Abs(xpath)
	// if err != nil {
	// 	return err
	// }
	tr := tar.NewReader(tarfile)
	if strings.HasSuffix(tarname, ".gz") {
		gz, err := gzip.NewReader(tarfile)
		if err != nil {
			return fmt.Errorf("failed to create new gzip reader: %v", err)
		}
		defer gz.Close()
		tr = tar.NewReader(gz)
	}

	// untar each segment
	for {
		header, err := tr.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return fmt.Errorf("failed to get next tar header: %v", err)
		}

		// determine proper file path info
		var (
			fileinfo = header.FileInfo()
			filename = header.Name
			file     *os.File
			abspath  string
			dirpath  string
		)

		// absFileName := filepath.Join(absPath, filename) // if a dir, create it, then go to next segment
		if fileinfo.Mode().IsDir() {
			if err := os.MkdirAll(filename, 0o755); err != nil {
				return fmt.Errorf("failed to make directory '%s': %v", filename, err)
			}
			continue
		}

		dirpath = filepath.Dir(filename)
		if err = os.MkdirAll(dirpath, 0o777); err != nil {
			return fmt.Errorf("failed to make directory '%s': %v", err)
		}

		// create new file with original file mode
		abspath, err = filepath.Abs(filename)
		if err != nil {
			return fmt.Errorf("failed to get absolute path: %v", err)
		}
		file, err = os.OpenFile(
			abspath,
			os.O_RDWR|os.O_CREATE|os.O_TRUNC,
			fileinfo.Mode().Perm(),
		)
		if err != nil {
			return fmt.Errorf("failed to open file: %v", err)
		}
		// fmt.Printf("x %s\n", filename)

		// copy the contents to the new file
		n, err := io.Copy(file, tr)
		if err != nil {
			return fmt.Errorf("failed to copy file: %v", err)
		}
		if err = file.Close(); err != nil {
			return fmt.Errorf("failed to close file: %v", err)
		}
		if n != fileinfo.Size() {
			return fmt.Errorf("wrote %d, want %d", n, fileinfo.Size())
		}
	}
	return nil
}

func addToArchive(tw *tar.Writer, filename string, hooks []makeshift.Hook) error {
	var (
		tempfile = fmt.Sprintf("%s.tmp", filename)
		file     *os.File
		contents []byte
		data     any
		err      error
	)
	// run pre-hooks to modify the contents of the file
	// before archiving using plugins
	for _, hook := range hooks {
		// set the file in the data store before running hook
		contents, err = os.ReadFile(filename)
		if err != nil {
			return fmt.Errorf("failed to read '%s' to download: %v", filename, err)
		}
		hook.Data.Set("file", contents)

		err = hook.Run()
		if err != nil {
			return err
		}

		// create temporary file to use to add to archive
		hook = hooks[len(hooks)-1]
		data, err = hook.Data.Get("out")
		if err != nil {
			return fmt.Errorf("failed to get output data from '%s' plugin: %v", hook.Plugin.Name(), err)
		}

		err = os.WriteFile(tempfile, data.([]byte), 0o777)
		if err != nil {
			return fmt.Errorf("failed to write temporary file: %v", err)
		}
	}

	// use original file if no hooks to write archive
	if len(hooks) == 0 {
		file, err = os.Open(filename)
	} else {
		file, err = os.Open(tempfile)
	}
	if err != nil {
		return fmt.Errorf("failed to open archive file: %v", err)
	}
	defer file.Close()

	// get FileInfo for file size, mode, etc.
	info, err := file.Stat()
	if err != nil {
		return err
	}

	// skip file if it's a directory
	if info.IsDir() {
		return nil
	}

	// create a tar Header from the FileInfo data
	header, err := tar.FileInfoHeader(info, info.Name())
	if err != nil {
		return fmt.Errorf("failed to create FileInfoHeader: %v", err)
	}

	// use full path as name (FileInfoHeader only takes the basename) to
	// preserve directory structure
	// see for more info: https://golang.org/src/archive/tar/common.go?#L626
	header.Name = filename

	// Write file header to the tar archive
	err = tw.WriteHeader(header)
	if err != nil {
		return err
	}

	// copy file content to tar archive
	if len(hooks) == 0 {
		_, err = io.Copy(tw, file)
	} else {
		_, err = io.Copy(tw, strings.NewReader(string(data.([]byte))))
	}
	if err != nil {
		return err
	}

	// delete the temporary file since we're done with it
	if len(hooks) != 0 {
		err = os.Remove(tempfile)
		if err != nil {
			return err
		}
	}

	return nil
}