Merge pull request #108 from tri-adam/build-context

Build Context Upload/Delete

Author: tri-adam

client/archive.go

@@ -0,0 +1,175 @@
+// Copyright (c) 2022, Sylabs Inc. All rights reserved.
+// This software is licensed under a 3-clause BSD license. Please consult the
+// LICENSE.md file distributed with the sources of this project regarding your
+// rights to use or distribute this software.
+
+package client
+
+import (
+	"archive/tar"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+type archiver struct {
+	fs       fs.FS
+	w        *tar.Writer
+	archived map[string]struct{}
+}
+
+// newArchiver returns an archiver that will write an archive to w.
+func newArchiver(fsys fs.FS, w io.Writer) *archiver {
+	return &archiver{
+		fs:       fsys,
+		w:        tar.NewWriter(w),
+		archived: make(map[string]struct{}),
+	}
+}
+
+var errUnsupportedType = errors.New("unsupported file type")
+
+// writeEntry writes the named path from the file system to the archive.
+func (ar *archiver) writeEntry(name string) (err error) {
+	// If entry already exists, skip it.
+	if _, ok := ar.archived[name]; ok {
+		return nil
+	}
+	defer func() {
+		if err == nil {
+			ar.archived[name] = struct{}{}
+		}
+	}()
+
+	// Get file info.
+	fi, err := fs.Stat(ar.fs, name)
+	if err != nil {
+		return err
+	}
+
+	// Populate TAR header based on file info, and normalize name.
+	h, err := tar.FileInfoHeader(fi, "")
+	if err != nil {
+		return err
+	}
+	h.Name = filepath.ToSlash(name)
+
+	// Check that we're writing a supported type, and make any necessary adjustments.
+	switch h.Typeflag {
+	case tar.TypeReg:
+		// Nothing to do.
+
+	case tar.TypeSymlink:
+		// Always follow symbolic links.
+		h.Typeflag = tar.TypeReg
+		h.Linkname = ""
+		h.Size = fi.Size()
+
+	case tar.TypeDir:
+		// Normalize name.
+		if !strings.HasSuffix(h.Name, "/") {
+			h.Name += "/"
+		}
+
+	default:
+		return fmt.Errorf("%v: %w (%v)", name, errUnsupportedType, h.Typeflag)
+	}
+
+	// Write TAR header.
+	if err := ar.w.WriteHeader(h); err != nil {
+		return err
+	}
+
+	// Write file contents, if applicable.
+	if h.Typeflag == tar.TypeReg && h.Size > 0 {
+		f, err := ar.fs.Open(name)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+
+		if _, err := io.Copy(ar.w, f); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// walkDirFunc returns a WalkDirFunc that writes each path to ar.
+func (ar *archiver) walkDirFunc() fs.WalkDirFunc {
+	return func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if path == "." {
+			return nil
+		}
+
+		return ar.writeEntry(path)
+	}
+}
+
+// writeDirAll writes an entry for directory name to the archive, along with any necessary parents.
+func (ar *archiver) writeDirAll(name string) error {
+	if name == "." {
+		return nil
+	}
+
+	if _, ok := ar.archived[name]; ok {
+		return nil // Path already archived, no need to recurse.
+	}
+
+	// Recursively create parent(s).
+	if err := ar.writeDirAll(path.Dir(name)); err != nil {
+		return err
+	}
+
+	return ar.writeEntry(name)
+}
+
+// WriteFiles writes all files matching pattern from the file system to the archive. If the named
+// path is a directory, its contents are recursively added using fs.WalkDir.
+func (ar *archiver) WriteFiles(pattern string) error {
+	names, err := fs.Glob(ar.fs, pattern)
+	if err != nil {
+		return err
+	}
+
+	if len(names) == 0 {
+		return fmt.Errorf("%v: %w", pattern, fs.ErrNotExist)
+	}
+
+	for _, name := range names {
+		// Ensure parent directory exists in archive.
+		if err := ar.writeDirAll(path.Dir(name)); err != nil {
+			return err
+		}
+
+		fi, err := fs.Stat(ar.fs, name)
+		if err != nil {
+			return err
+		}
+
+		// If name refers to a directory, walk it, adding entries. Otherwise, add a single entry.
+		if fi.IsDir() {
+			if err := fs.WalkDir(ar.fs, name, ar.walkDirFunc()); err != nil {
+				return err
+			}
+		} else if err := ar.writeEntry(name); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Close closes the archive.
+func (ar *archiver) Close() error {
+	return ar.w.Close()
+}