mirror of
https://github.com/rclone/rclone
synced 2024-12-10 22:33:56 +01:00
263 lines
6.9 KiB
Go
263 lines
6.9 KiB
Go
// Define the options for Open
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package fs
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import (
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"fmt"
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"net/http"
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"strconv"
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"strings"
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"github.com/ncw/rclone/fs/hash"
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"github.com/pkg/errors"
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)
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// OpenOption is an interface describing options for Open
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type OpenOption interface {
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fmt.Stringer
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// Header returns the option as an HTTP header
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Header() (key string, value string)
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// Mandatory returns whether this option can be ignored or not
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Mandatory() bool
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}
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// RangeOption defines an HTTP Range option with start and end. If
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// either start or end are < 0 then they will be omitted.
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//
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// End may be bigger than the Size of the object in which case it will
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// be capped to the size of the object.
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//
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// Note that the End is inclusive, so to fetch 100 bytes you would use
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// RangeOption{Start: 0, End: 99}
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//
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// If Start is specified but End is not then it will fetch from Start
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// to the end of the file.
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//
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// If End is specified, but Start is not then it will fetch the last
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// End bytes.
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//
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// Examples:
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//
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// RangeOption{Start: 0, End: 99} - fetch the first 100 bytes
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// RangeOption{Start: 100, End: 199} - fetch the second 100 bytes
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// RangeOption{Start: 100} - fetch bytes from offset 100 to the end
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// RangeOption{End: 100} - fetch the last 100 bytes
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//
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// A RangeOption implements a single byte-range-spec from
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// https://tools.ietf.org/html/rfc7233#section-2.1
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type RangeOption struct {
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Start int64
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End int64
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}
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// Header formats the option as an http header
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func (o *RangeOption) Header() (key string, value string) {
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key = "Range"
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value = "bytes="
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if o.Start >= 0 {
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value += strconv.FormatInt(o.Start, 10)
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}
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value += "-"
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if o.End >= 0 {
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value += strconv.FormatInt(o.End, 10)
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}
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return key, value
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}
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// ParseRangeOption parses a RangeOption from a Range: header.
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// It only accepts single ranges.
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func ParseRangeOption(s string) (po *RangeOption, err error) {
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const preamble = "bytes="
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if !strings.HasPrefix(s, preamble) {
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return nil, errors.New("Range: header invalid: doesn't start with " + preamble)
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}
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s = s[len(preamble):]
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if strings.IndexRune(s, ',') >= 0 {
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return nil, errors.New("Range: header invalid: contains multiple ranges which isn't supported")
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}
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dash := strings.IndexRune(s, '-')
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if dash < 0 {
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return nil, errors.New("Range: header invalid: contains no '-'")
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}
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start, end := strings.TrimSpace(s[:dash]), strings.TrimSpace(s[dash+1:])
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o := RangeOption{Start: -1, End: -1}
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if start != "" {
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o.Start, err = strconv.ParseInt(start, 10, 64)
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if err != nil || o.Start < 0 {
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return nil, errors.New("Range: header invalid: bad start")
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}
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}
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if end != "" {
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o.End, err = strconv.ParseInt(end, 10, 64)
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if err != nil || o.End < 0 {
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return nil, errors.New("Range: header invalid: bad end")
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}
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}
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return &o, nil
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}
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// String formats the option into human readable form
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func (o *RangeOption) String() string {
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return fmt.Sprintf("RangeOption(%d,%d)", o.Start, o.End)
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}
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// Mandatory returns whether the option must be parsed or can be ignored
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func (o *RangeOption) Mandatory() bool {
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return true
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}
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// Decode interprets the RangeOption into an offset and a limit
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//
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// The offset is the start of the stream and the limit is how many
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// bytes should be read from it. If the limit is -1 then the stream
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// should be read to the end.
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func (o *RangeOption) Decode(size int64) (offset, limit int64) {
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if o.Start >= 0 {
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offset = o.Start
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if o.End >= 0 {
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limit = o.End - o.Start + 1
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} else {
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limit = -1
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}
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} else {
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if o.End >= 0 {
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offset = size - o.End
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} else {
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offset = 0
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}
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limit = -1
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}
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return offset, limit
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}
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// FixRangeOption looks through the slice of options and adjusts any
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// RangeOption~s found that request a fetch from the end into an
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// absolute fetch using the size passed in and makes sure the range does
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// not exceed filesize. Some remotes (eg Onedrive, Box) don't support
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// range requests which index from the end.
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func FixRangeOption(options []OpenOption, size int64) {
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for i := range options {
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option := options[i]
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if x, ok := option.(*RangeOption); ok {
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// If start is < 0 then fetch from the end
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if x.Start < 0 {
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x = &RangeOption{Start: size - x.End, End: -1}
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options[i] = x
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}
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if x.End > size {
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x = &RangeOption{Start: x.Start, End: size}
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options[i] = x
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}
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}
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}
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}
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// SeekOption defines an HTTP Range option with start only.
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type SeekOption struct {
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Offset int64
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}
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// Header formats the option as an http header
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func (o *SeekOption) Header() (key string, value string) {
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key = "Range"
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value = fmt.Sprintf("bytes=%d-", o.Offset)
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return key, value
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}
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// String formats the option into human readable form
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func (o *SeekOption) String() string {
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return fmt.Sprintf("SeekOption(%d)", o.Offset)
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}
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// Mandatory returns whether the option must be parsed or can be ignored
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func (o *SeekOption) Mandatory() bool {
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return true
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}
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// HTTPOption defines a general purpose HTTP option
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type HTTPOption struct {
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Key string
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Value string
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}
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// Header formats the option as an http header
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func (o *HTTPOption) Header() (key string, value string) {
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return o.Key, o.Value
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}
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// String formats the option into human readable form
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func (o *HTTPOption) String() string {
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return fmt.Sprintf("HTTPOption(%q,%q)", o.Key, o.Value)
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}
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// Mandatory returns whether the option must be parsed or can be ignored
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func (o *HTTPOption) Mandatory() bool {
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return false
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}
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// HashesOption defines an option used to tell the local fs to limit
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// the number of hashes it calculates.
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type HashesOption struct {
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Hashes hash.Set
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}
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// Header formats the option as an http header
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func (o *HashesOption) Header() (key string, value string) {
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return "", ""
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}
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// String formats the option into human readable form
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func (o *HashesOption) String() string {
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return fmt.Sprintf("HashesOption(%v)", o.Hashes)
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}
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// Mandatory returns whether the option must be parsed or can be ignored
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func (o *HashesOption) Mandatory() bool {
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return false
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}
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// OpenOptionAddHeaders adds each header found in options to the
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// headers map provided the key was non empty.
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func OpenOptionAddHeaders(options []OpenOption, headers map[string]string) {
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for _, option := range options {
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key, value := option.Header()
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if key != "" && value != "" {
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headers[key] = value
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}
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}
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}
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// OpenOptionHeaders adds each header found in options to the
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// headers map provided the key was non empty.
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//
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// It returns a nil map if options was empty
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func OpenOptionHeaders(options []OpenOption) (headers map[string]string) {
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if len(options) == 0 {
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return nil
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}
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headers = make(map[string]string, len(options))
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OpenOptionAddHeaders(options, headers)
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return headers
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}
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// OpenOptionAddHTTPHeaders Sets each header found in options to the
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// http.Header map provided the key was non empty.
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func OpenOptionAddHTTPHeaders(headers http.Header, options []OpenOption) {
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for _, option := range options {
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key, value := option.Header()
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if key != "" && value != "" {
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headers.Set(key, value)
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}
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}
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}
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// check interface
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var (
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_ OpenOption = (*RangeOption)(nil)
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_ OpenOption = (*SeekOption)(nil)
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_ OpenOption = (*HTTPOption)(nil)
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)
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