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470 lines
15 KiB
Go
470 lines
15 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package webdav
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import (
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"bytes"
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"context"
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"encoding/xml"
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"errors"
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"fmt"
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"io"
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"mime"
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"net/http"
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"os"
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"path/filepath"
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"strconv"
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)
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// Proppatch describes a property update instruction as defined in RFC 4918.
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// See http://www.webdav.org/specs/rfc4918.html#METHOD_PROPPATCH
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type Proppatch struct {
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// Remove specifies whether this patch removes properties. If it does not
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// remove them, it sets them.
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Remove bool
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// Props contains the properties to be set or removed.
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Props []Property
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}
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// Propstat describes a XML propstat element as defined in RFC 4918.
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// See http://www.webdav.org/specs/rfc4918.html#ELEMENT_propstat
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type Propstat struct {
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// Props contains the properties for which Status applies.
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Props []Property
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// Status defines the HTTP status code of the properties in Prop.
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// Allowed values include, but are not limited to the WebDAV status
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// code extensions for HTTP/1.1.
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// http://www.webdav.org/specs/rfc4918.html#status.code.extensions.to.http11
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Status int
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// XMLError contains the XML representation of the optional error element.
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// XML content within this field must not rely on any predefined
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// namespace declarations or prefixes. If empty, the XML error element
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// is omitted.
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XMLError string
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// ResponseDescription contains the contents of the optional
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// responsedescription field. If empty, the XML element is omitted.
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ResponseDescription string
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}
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// makePropstats returns a slice containing those of x and y whose Props slice
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// is non-empty. If both are empty, it returns a slice containing an otherwise
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// zero Propstat whose HTTP status code is 200 OK.
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func makePropstats(x, y Propstat) []Propstat {
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pstats := make([]Propstat, 0, 2)
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if len(x.Props) != 0 {
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pstats = append(pstats, x)
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}
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if len(y.Props) != 0 {
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pstats = append(pstats, y)
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}
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if len(pstats) == 0 {
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pstats = append(pstats, Propstat{
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Status: http.StatusOK,
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})
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}
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return pstats
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}
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// DeadPropsHolder holds the dead properties of a resource.
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//
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// Dead properties are those properties that are explicitly defined. In
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// comparison, live properties, such as DAV:getcontentlength, are implicitly
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// defined by the underlying resource, and cannot be explicitly overridden or
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// removed. See the Terminology section of
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// http://www.webdav.org/specs/rfc4918.html#rfc.section.3
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//
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// There is a whitelist of the names of live properties. This package handles
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// all live properties, and will only pass non-whitelisted names to the Patch
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// method of DeadPropsHolder implementations.
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type DeadPropsHolder interface {
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// DeadProps returns a copy of the dead properties held.
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DeadProps() (map[xml.Name]Property, error)
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// Patch patches the dead properties held.
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//
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// Patching is atomic; either all or no patches succeed. It returns (nil,
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// non-nil) if an internal server error occurred, otherwise the Propstats
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// collectively contain one Property for each proposed patch Property. If
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// all patches succeed, Patch returns a slice of length one and a Propstat
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// element with a 200 OK HTTP status code. If none succeed, for reasons
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// other than an internal server error, no Propstat has status 200 OK.
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//
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// For more details on when various HTTP status codes apply, see
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// http://www.webdav.org/specs/rfc4918.html#PROPPATCH-status
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Patch([]Proppatch) ([]Propstat, error)
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}
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// liveProps contains all supported, protected DAV: properties.
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var liveProps = map[xml.Name]struct {
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// findFn implements the propfind function of this property. If nil,
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// it indicates a hidden property.
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findFn func(context.Context, FileSystem, LockSystem, string, os.FileInfo) (string, error)
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// dir is true if the property applies to directories.
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dir bool
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}{
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{Space: "DAV:", Local: "resourcetype"}: {
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findFn: findResourceType,
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dir: true,
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},
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{Space: "DAV:", Local: "displayname"}: {
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findFn: findDisplayName,
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dir: true,
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},
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{Space: "DAV:", Local: "getcontentlength"}: {
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findFn: findContentLength,
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dir: false,
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},
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{Space: "DAV:", Local: "getlastmodified"}: {
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findFn: findLastModified,
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// http://webdav.org/specs/rfc4918.html#PROPERTY_getlastmodified
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// suggests that getlastmodified should only apply to GETable
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// resources, and this package does not support GET on directories.
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//
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// Nonetheless, some WebDAV clients expect child directories to be
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// sortable by getlastmodified date, so this value is true, not false.
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// See golang.org/issue/15334.
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dir: true,
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},
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{Space: "DAV:", Local: "creationdate"}: {
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findFn: nil,
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dir: false,
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},
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{Space: "DAV:", Local: "getcontentlanguage"}: {
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findFn: nil,
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dir: false,
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},
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{Space: "DAV:", Local: "getcontenttype"}: {
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findFn: findContentType,
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dir: false,
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},
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{Space: "DAV:", Local: "getetag"}: {
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findFn: findETag,
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// findETag implements ETag as the concatenated hex values of a file's
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// modification time and size. This is not a reliable synchronization
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// mechanism for directories, so we do not advertise getetag for DAV
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// collections.
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dir: false,
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},
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// TODO: The lockdiscovery property requires LockSystem to list the
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// active locks on a resource.
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{Space: "DAV:", Local: "lockdiscovery"}: {},
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{Space: "DAV:", Local: "supportedlock"}: {
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findFn: findSupportedLock,
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dir: true,
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},
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}
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// TODO(nigeltao) merge props and allprop?
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// Props returns the status of the properties named pnames for resource name.
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//
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// Each Propstat has a unique status and each property name will only be part
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// of one Propstat element.
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func props(ctx context.Context, fs FileSystem, ls LockSystem, name string, pnames []xml.Name) ([]Propstat, error) {
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f, err := fs.OpenFile(ctx, name, os.O_RDONLY, 0)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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fi, err := f.Stat()
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if err != nil {
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return nil, err
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}
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isDir := fi.IsDir()
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var deadProps map[xml.Name]Property
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if dph, ok := f.(DeadPropsHolder); ok {
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deadProps, err = dph.DeadProps()
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if err != nil {
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return nil, err
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}
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}
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pstatOK := Propstat{Status: http.StatusOK}
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pstatNotFound := Propstat{Status: http.StatusNotFound}
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for _, pn := range pnames {
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// If this file has dead properties, check if they contain pn.
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if dp, ok := deadProps[pn]; ok {
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pstatOK.Props = append(pstatOK.Props, dp)
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continue
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}
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// Otherwise, it must either be a live property or we don't know it.
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if prop := liveProps[pn]; prop.findFn != nil && (prop.dir || !isDir) {
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innerXML, err := prop.findFn(ctx, fs, ls, name, fi)
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if err != nil {
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return nil, err
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}
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pstatOK.Props = append(pstatOK.Props, Property{
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XMLName: pn,
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InnerXML: []byte(innerXML),
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})
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} else {
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pstatNotFound.Props = append(pstatNotFound.Props, Property{
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XMLName: pn,
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})
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}
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}
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return makePropstats(pstatOK, pstatNotFound), nil
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}
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// Propnames returns the property names defined for resource name.
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func propnames(ctx context.Context, fs FileSystem, ls LockSystem, name string) ([]xml.Name, error) {
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f, err := fs.OpenFile(ctx, name, os.O_RDONLY, 0)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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fi, err := f.Stat()
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if err != nil {
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return nil, err
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}
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isDir := fi.IsDir()
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var deadProps map[xml.Name]Property
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if dph, ok := f.(DeadPropsHolder); ok {
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deadProps, err = dph.DeadProps()
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if err != nil {
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return nil, err
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}
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}
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pnames := make([]xml.Name, 0, len(liveProps)+len(deadProps))
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for pn, prop := range liveProps {
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if prop.findFn != nil && (prop.dir || !isDir) {
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pnames = append(pnames, pn)
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}
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}
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for pn := range deadProps {
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pnames = append(pnames, pn)
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}
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return pnames, nil
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}
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// Allprop returns the properties defined for resource name and the properties
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// named in include.
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//
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// Note that RFC 4918 defines 'allprop' to return the DAV: properties defined
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// within the RFC plus dead properties. Other live properties should only be
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// returned if they are named in 'include'.
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//
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// See http://www.webdav.org/specs/rfc4918.html#METHOD_PROPFIND
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func allprop(ctx context.Context, fs FileSystem, ls LockSystem, name string, include []xml.Name) ([]Propstat, error) {
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pnames, err := propnames(ctx, fs, ls, name)
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if err != nil {
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return nil, err
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}
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// Add names from include if they are not already covered in pnames.
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nameset := make(map[xml.Name]bool)
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for _, pn := range pnames {
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nameset[pn] = true
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}
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for _, pn := range include {
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if !nameset[pn] {
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pnames = append(pnames, pn)
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}
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}
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return props(ctx, fs, ls, name, pnames)
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}
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// Patch patches the properties of resource name. The return values are
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// constrained in the same manner as DeadPropsHolder.Patch.
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func patch(ctx context.Context, fs FileSystem, ls LockSystem, name string, patches []Proppatch) ([]Propstat, error) {
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conflict := false
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loop:
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for _, patch := range patches {
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for _, p := range patch.Props {
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if _, ok := liveProps[p.XMLName]; ok {
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conflict = true
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break loop
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}
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}
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}
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if conflict {
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pstatForbidden := Propstat{
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Status: http.StatusForbidden,
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XMLError: `<D:cannot-modify-protected-property xmlns:D="DAV:"/>`,
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}
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pstatFailedDep := Propstat{
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Status: StatusFailedDependency,
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}
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for _, patch := range patches {
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for _, p := range patch.Props {
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if _, ok := liveProps[p.XMLName]; ok {
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pstatForbidden.Props = append(pstatForbidden.Props, Property{XMLName: p.XMLName})
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} else {
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pstatFailedDep.Props = append(pstatFailedDep.Props, Property{XMLName: p.XMLName})
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}
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}
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}
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return makePropstats(pstatForbidden, pstatFailedDep), nil
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}
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f, err := fs.OpenFile(ctx, name, os.O_RDWR, 0)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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if dph, ok := f.(DeadPropsHolder); ok {
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ret, err := dph.Patch(patches)
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if err != nil {
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return nil, err
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}
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// http://www.webdav.org/specs/rfc4918.html#ELEMENT_propstat says that
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// "The contents of the prop XML element must only list the names of
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// properties to which the result in the status element applies."
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for _, pstat := range ret {
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for i, p := range pstat.Props {
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pstat.Props[i] = Property{XMLName: p.XMLName}
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}
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}
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return ret, nil
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}
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// The file doesn't implement the optional DeadPropsHolder interface, so
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// all patches are forbidden.
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pstat := Propstat{Status: http.StatusForbidden}
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for _, patch := range patches {
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for _, p := range patch.Props {
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pstat.Props = append(pstat.Props, Property{XMLName: p.XMLName})
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}
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}
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return []Propstat{pstat}, nil
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}
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func escapeXML(s string) string {
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for i := 0; i < len(s); i++ {
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// As an optimization, if s contains only ASCII letters, digits or a
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// few special characters, the escaped value is s itself and we don't
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// need to allocate a buffer and convert between string and []byte.
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switch c := s[i]; {
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case c == ' ' || c == '_' ||
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('+' <= c && c <= '9') || // Digits as well as + , - . and /
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('A' <= c && c <= 'Z') ||
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('a' <= c && c <= 'z'):
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continue
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}
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// Otherwise, go through the full escaping process.
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var buf bytes.Buffer
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xml.EscapeText(&buf, []byte(s))
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return buf.String()
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}
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return s
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}
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func findResourceType(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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if fi.IsDir() {
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return `<D:collection xmlns:D="DAV:"/>`, nil
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}
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return "", nil
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}
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func findDisplayName(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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if slashClean(name) == "/" {
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// Hide the real name of a possibly prefixed root directory.
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return "", nil
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}
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return escapeXML(fi.Name()), nil
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}
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func findContentLength(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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return strconv.FormatInt(fi.Size(), 10), nil
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}
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func findLastModified(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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return fi.ModTime().UTC().Format(http.TimeFormat), nil
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}
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// ErrNotImplemented should be returned by optional interfaces if they
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// want the original implementation to be used.
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var ErrNotImplemented = errors.New("not implemented")
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// ContentTyper is an optional interface for the os.FileInfo
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// objects returned by the FileSystem.
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//
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// If this interface is defined then it will be used to read the
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// content type from the object.
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//
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// If this interface is not defined the file will be opened and the
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// content type will be guessed from the initial contents of the file.
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type ContentTyper interface {
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// ContentType returns the content type for the file.
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//
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// If this returns error ErrNotImplemented then the error will
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// be ignored and the base implementation will be used
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// instead.
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ContentType(ctx context.Context) (string, error)
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}
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func findContentType(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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if do, ok := fi.(ContentTyper); ok {
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ctype, err := do.ContentType(ctx)
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if err != ErrNotImplemented {
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return ctype, err
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}
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}
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f, err := fs.OpenFile(ctx, name, os.O_RDONLY, 0)
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if err != nil {
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return "", err
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}
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defer f.Close()
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// This implementation is based on serveContent's code in the standard net/http package.
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ctype := mime.TypeByExtension(filepath.Ext(name))
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if ctype != "" {
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return ctype, nil
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}
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// Read a chunk to decide between utf-8 text and binary.
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var buf [512]byte
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n, err := io.ReadFull(f, buf[:])
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if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
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return "", err
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}
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ctype = http.DetectContentType(buf[:n])
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// Rewind file.
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_, err = f.Seek(0, os.SEEK_SET)
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return ctype, err
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}
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// ETager is an optional interface for the os.FileInfo objects
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// returned by the FileSystem.
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//
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// If this interface is defined then it will be used to read the ETag
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// for the object.
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//
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// If this interface is not defined an ETag will be computed using the
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// ModTime() and the Size() methods of the os.FileInfo object.
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type ETager interface {
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// ETag returns an ETag for the file. This should be of the
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// form "value" or W/"value"
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//
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// If this returns error ErrNotImplemented then the error will
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// be ignored and the base implementation will be used
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// instead.
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ETag(ctx context.Context) (string, error)
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}
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func findETag(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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if do, ok := fi.(ETager); ok {
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etag, err := do.ETag(ctx)
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if err != ErrNotImplemented {
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return etag, err
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}
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}
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// The Apache http 2.4 web server by default concatenates the
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// modification time and size of a file. We replicate the heuristic
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// with nanosecond granularity.
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return fmt.Sprintf(`"%x%x"`, fi.ModTime().UnixNano(), fi.Size()), nil
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}
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func findSupportedLock(ctx context.Context, fs FileSystem, ls LockSystem, name string, fi os.FileInfo) (string, error) {
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return `` +
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`<D:lockentry xmlns:D="DAV:">` +
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`<D:lockscope><D:exclusive/></D:lockscope>` +
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`<D:locktype><D:write/></D:locktype>` +
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`</D:lockentry>`, nil
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}
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