zip: Implement Insert (append files)

Close #397

Also minor tweaks

README.md

@@ -18,7 +18,7 @@ Introducing **Archiver 4.0** - a cross-platform, multi-format archive utility an
 - Create and extract archive files
 - Walk or traverse into archive files
 - Extract only specific files from archives
-- Insert (append) into .tar files
+- Insert (append) into .tar and .zip archives
 - Read from password-protected 7-Zip files
 - Numerous archive and compression formats supported
 - Extensible (add more formats just by registering them)
@@ -301,9 +301,9 @@ defer decompressor.Close()
 // reads from decompressor will be decompressed
 ```
 
-### Append to tarball
+### Append to tarball and zip archives
 
-Tar archives can be appended to without creating a whole new archive by calling `Insert()` on a tar stream. However, this requires that the tarball is not compressed (due to complexities with modifying compression dictionaries).
+Tar and Zip archives can be appended to without creating a whole new archive by calling `Insert()` on a tar or zip stream. However, for tarballs, this requires that the tarball is not compressed (due to complexities with modifying compression dictionaries).
 
 Here is an example that appends a file to a tarball on disk:
 
@@ -325,3 +325,5 @@ if err != nil {
 }
 ```
 
+The code is similar for inserting into a Zip archive, except you'll call `Insert()` on the `Zip` type instead.
+

archiver.go

@@ -27,6 +27,11 @@ type File struct {
 	// it is such a common field and we want to preserve
 	// format-agnosticism (no type assertions) for basic
 	// operations.
+	//
+	// EXPERIMENTAL: If inserting a file into an archive,
+	// and this is left blank, the implementation of the
+	// archive format can default to using the file's base
+	// name.
 	NameInArchive string
 
 	// For symbolic and hard links, the target of the link.
@@ -224,7 +229,7 @@ func openAndCopyFile(file File, w io.Writer) error {
 	// When file is in use and size is being written to, creating the compressed
 	// file will fail with "archive/tar: write too long." Using CopyN gracefully
 	// handles this.
-	_, err = io.CopyN(w, fileReader, file.Size())
+	_, err = io.Copy(w, fileReader)
 	if err != nil && err != io.EOF {
 		return err
 	}

go.mod

@@ -1,6 +1,8 @@
 module github.com/mholt/archiver/v4
 
-go 1.20
+go 1.21.3
+
+toolchain go1.22.0
 
 require (
 	github.com/andybalholm/brotli v1.0.5
@@ -13,6 +15,7 @@ require (
 )
 
 require (
+	github.com/STARRY-S/zip v0.1.0
 	github.com/bodgit/sevenzip v1.4.3
 	github.com/golang/snappy v0.0.4
 	github.com/pierrec/lz4/v4 v4.1.18

go.sum

@@ -17,6 +17,8 @@ cloud.google.com/go/storage v1.5.0/go.mod h1:tpKbwo567HUNpVclU5sGELwQWBDZ8gh0Zeo
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/STARRY-S/zip v0.1.0 h1:eUER3jKmHKXjv+iy3BekLa+QnNSo1Lqz4eTzYBcGDqo=
+github.com/STARRY-S/zip v0.1.0/go.mod h1:qj/mTZkvb3AvfGQ2e775/3AODRvB4peSw8KNMvrM8/I=
 github.com/andybalholm/brotli v1.0.5 h1:8uQZIdzKmjc/iuPu7O2ioW48L81FgatrcpfFmiq/cCs=
 github.com/andybalholm/brotli v1.0.5/go.mod h1:fO7iG3H7G2nSZ7m0zPUDn85XEX2GTukHGRSepvi9Eig=
 github.com/bodgit/plumbing v1.3.0 h1:pf9Itz1JOQgn7vEOE7v7nlEfBykYqvUYioC61TwWCFU=
@@ -104,6 +106,7 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/therootcompany/xz v1.0.1 h1:CmOtsn1CbtmyYiusbfmhmkpAAETj0wBIH6kCYaX+xzw=
 github.com/therootcompany/xz v1.0.1/go.mod h1:3K3UH1yCKgBneZYhuQUvJ9HPD19UEXEI0BWbMn8qNMY=
 github.com/ulikunitz/xz v0.5.6/go.mod h1:2bypXElzHzzJZwzH67Y6wb67pO62Rzfn7BSiF4ABRW8=

interfaces.go

@@ -94,6 +94,7 @@ type Extractor interface {
 }
 
 // Inserter can insert files into an existing archive.
+// EXPERIMENTAL: This API is subject to change.
 type Inserter interface {
 	// Insert inserts the files into archive.
 	//

tar.go

@@ -84,6 +84,9 @@ func (t Tar) writeFileToArchive(ctx context.Context, tw *tar.Writer, file File)
 		return fmt.Errorf("file %s: creating header: %w", file.NameInArchive, err)
 	}
 	hdr.Name = file.NameInArchive // complete path, since FileInfoHeader() only has base name
+	if hdr.Name == "" {
+		hdr.Name = file.Name() // assume base name of file I guess
+	}
 	if t.NumericUIDGID {
 		hdr.Uname = ""
 		hdr.Gname = ""

zip.go

@@ -11,6 +11,8 @@ import (
 	"path"
 	"strings"
 
+	szip "github.com/STARRY-S/zip"
+
 	"github.com/dsnet/compress/bzip2"
 	"github.com/klauspost/compress/zip"
 	"github.com/klauspost/compress/zstd"
@@ -137,6 +139,9 @@ func (z Zip) archiveOneFile(ctx context.Context, zw *zip.Writer, idx int, file F
 		return fmt.Errorf("getting info for file %d: %s: %w", idx, file.Name(), err)
 	}
 	hdr.Name = file.NameInArchive // complete path, since FileInfoHeader() only has base name
+	if hdr.Name == "" {
+		hdr.Name = file.Name() // assume base name of file I guess
+	}
 
 	// customize header based on file properties
 	if file.IsDir() {
@@ -256,6 +261,66 @@ func (z Zip) decodeText(hdr *zip.FileHeader) {
 	}
 }
 
+// Insert appends the listed files into the provided Zip archive stream.
+func (z Zip) Insert(ctx context.Context, into io.ReadWriteSeeker, files []File) error {
+	// following very simple example at https://github.com/STARRY-S/zip?tab=readme-ov-file#usage
+	zu, err := szip.NewUpdater(into)
+	if err != nil {
+		return err
+	}
+	defer zu.Close()
+
+	for idx, file := range files {
+		if err := ctx.Err(); err != nil {
+			return err // honor context cancellation
+		}
+
+		hdr, err := szip.FileInfoHeader(file)
+		if err != nil {
+			return fmt.Errorf("getting info for file %d: %s: %w", idx, file.NameInArchive, err)
+		}
+		hdr.Name = file.NameInArchive // complete path, since FileInfoHeader() only has base name
+		if hdr.Name == "" {
+			hdr.Name = file.Name() // assume base name of file I guess
+		}
+
+		// customize header based on file properties
+		if file.IsDir() {
+			if !strings.HasSuffix(hdr.Name, "/") {
+				hdr.Name += "/" // required
+			}
+			hdr.Method = zip.Store
+		} else if z.SelectiveCompression {
+			// only enable compression on compressable files
+			ext := strings.ToLower(path.Ext(hdr.Name))
+			if _, ok := compressedFormats[ext]; ok {
+				hdr.Method = zip.Store
+			} else {
+				hdr.Method = z.Compression
+			}
+		}
+
+		w, err := zu.AppendHeaderAt(hdr, -1)
+		if err != nil {
+			return fmt.Errorf("inserting file header: %d: %s: %w", idx, file.Name(), err)
+		}
+
+		// directories have no file body
+		if file.IsDir() {
+			return nil
+		}
+		if err := openAndCopyFile(file, w); err != nil {
+			if z.ContinueOnError && ctx.Err() == nil {
+				log.Printf("[ERROR] appending file %d into archive: %s: %v", idx, file.Name(), err)
+				continue
+			}
+			return fmt.Errorf("copying inserted file %d: %s: %w", idx, file.Name(), err)
+		}
+	}
+
+	return nil
+}
+
 type seekReaderAt interface {
 	io.ReaderAt
 	io.Seeker