// ParseAR parses an archive file from r and returns a map from filename to
// contents, or else an error.

ParseAR parses an archive file from r and returns a map from filename to
contents, or else an error.
// ParseAR parses an archive file from r and returns a map from filename to // contents or else an error .
func ParseAR(r io.Reader) (map[string][]byte, error) {
	const expectedMagic = "!<arch>\n"
	var magic [len(expectedMagic)]byte
	if _, err := io.ReadFull(r, magic[:]); err != nil {
		return nil, err
	}
	if string(magic[:]) != expectedMagic {
		return nil, errors.New("ar: not an archive file")
	}
	const filenameTableName = "//"
	const symbolTableName = "/"
	var longFilenameTable []byte
	ret := make(map[string][]byte)
	for {
		var header [60]byte
		if _, err := io.ReadFull(r, header[:]); err != nil {
			if err == io.EOF {
				break
			}
			return nil, errors.New("ar: error reading file header: " + err.Error())
		}
		name := strings.TrimRight(string(header[:16]), " ")
		sizeStr := strings.TrimRight(string(header[48:58]), "\x00 ")
		size, err := strconv.ParseUint(sizeStr, 10, 64)
		if err != nil {
			return nil, errors.New("ar: failed to parse file size: " + err.Error())
		}
		storedSize := size
		if storedSize%2 == 1 {
			storedSize++
		}
		contents := make([]byte, storedSize)
		if _, err := io.ReadFull(r, contents); err != nil {
			return nil, errors.New("ar: error reading file contents: " + err.Error())
		}
		contents = contents[:size]
		switch {
		case name == filenameTableName:
			if longFilenameTable != nil {
				return nil, errors.New("ar: two filename tables found")
			}
			longFilenameTable = contents
			continue
		case name == symbolTableName:
			continue
		case len(name) > 1 && name[0] == '/':
			if longFilenameTable == nil {
				return nil, errors.New("ar: long filename reference found before filename table")
			}
			offset, err := strconv.ParseUint(name[1:], 10, 64)
			if err != nil {
				return nil, errors.New("ar: failed to parse filename offset: " + err.Error())
			}
			if offset > uint64((^uint(0))>>1) {
				return nil, errors.New("ar: filename offset overflow")
			}
			if int(offset) > len(longFilenameTable) {
				return nil, errors.New("ar: filename offset out of bounds")
			}
			filename := longFilenameTable[offset:]
			if i := bytes.IndexAny(filename, "/\x00"); i < 0 {
				return nil, errors.New("ar: unterminated filename in table")
			} else {
				filename = filename[:i]
			}
			name = string(filename)
		default:
			name = strings.TrimRight(name, "/")
		}
		var namelen uint
		n, err := fmt.Sscanf(name, "#1/%d", &namelen)
		if err == nil && n == 1 && len(contents) >= int(namelen) {
			name = string(contents[:namelen])
			contents = contents[namelen:]
			var null int
			for ; null < len(name); null++ {
				if name[null] == 0 {
					break
				}
			}
			name = name[:null]
		}
		if name == "__.SYMDEF" || name == "__.SYMDEF SORTED" {
			continue
		}
		ret[name] = contents
	}
	return ret, nil
}
func ParseAR ( r io . Reader ) ( map [ string ] [ ] byte , error ) { const expectedMagic = " \n " var magic [ len ( expectedMagic ) ] byte if _ , err := io . ReadFull ( r , magic [ : ] ) ; err != nil { return nil , err } if string ( magic [ : ] ) != expectedMagic { return nil , errors . New ( " " ) } const filenameTableName = " " const symbolTableName = " " var longFilenameTable [ ] byte ret := make ( map [ string ] [ ] byte ) for { var header [ 60 ] byte if _ , err := io . ReadFull ( r , header [ : ] ) ; err != nil { if err == io . EOF { break } return nil , errors . New ( " " + err . Error ( ) ) } name := strings . TrimRight ( string ( header [ : 16 ] ) , " " ) sizeStr := strings . TrimRight ( string ( header [ 48 : 58 ] ) , " \x00 " ) size , err := strconv . ParseUint ( sizeStr , 10 , 64 ) if err != nil { return nil , errors . New ( " " + err . Error ( ) ) } storedSize := size if storedSize % 2 == 1 { storedSize ++ } contents := make ( [ ] byte , storedSize ) if _ , err := io . ReadFull ( r , contents ) ; err != nil { return nil , errors . New ( " " + err . Error ( ) ) } contents = contents [ : size ] switch { case name == filenameTableName : if longFilenameTable != nil { return nil , errors . New ( " " ) } longFilenameTable = contents continue case name == symbolTableName : continue case len ( name ) > 1 && name [ 0 ] == '/' : if longFilenameTable == nil { return nil , errors . New ( " " ) } offset , err := strconv . ParseUint ( name [ 1 : ] , 10 , 64 ) if err != nil { return nil , errors . New ( " " + err . Error ( ) ) } if offset > uint64 ( ( ^ uint ( 0 ) ) >> 1 ) { return nil , errors . New ( " " ) } if int ( offset ) > len ( longFilenameTable ) { return nil , errors . New ( " " ) } filename := longFilenameTable [ offset : ] if i := bytes . IndexAny ( filename , " \x00 " ) ; i < 0 { return nil , errors . New ( " " ) } else { filename = filename [ : i ] } name = string ( filename ) default : name = strings . TrimRight ( name , " " ) } var namelen uint n , err := fmt . Sscanf ( name , " " , & namelen ) if err == nil && n == 1 && len ( contents ) >= int ( namelen ) { name = string ( contents [ : namelen ] ) contents = contents [ namelen : ] var null int for ; null < len ( name ) ; null ++ { if name [ null ] == 0 { break } } name = name [ : null ] } if name == " " || name == " " { continue } ret [ name ] = contents } return ret , nil }
ParseAR parses an archive file from r and returns a map from filename to
contents, or else an error.
ParseAR parses an archive file from r and returns a map from filename to contents or else an error .
// See https://en.wikipedia.org/wiki/Ar_(Unix)#File_format_details
 // File contents are padded to a multiple of two bytes
 // A long filename is stored as "/" followed by a
 // base-10 offset in the filename table.
 // Windows terminates filenames with NUL characters,
 // while sysv/GNU uses /.
 // Post-processing for BSD:
 // https://en.wikipedia.org/wiki/Ar_(Unix)#BSD_variant
 //
 // If the name is of the form #1/XXX, XXX identifies the length of the
 // name, and the name itself is stored as a prefix of the data, possibly
 // null-padded.
 // Names can be null padded; find the first null (if any). Note that
 // this also handles the case of a null followed by non-null
 // characters. It's not clear whether those can ever show up in
 // practice, but we might as well handle them in case they can show
 // up.
