224 lines
7.9 KiB
Go
224 lines
7.9 KiB
Go
/*
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* Minio Cloud Storage, (C) 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package main
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import (
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"net/http"
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"strings"
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"time"
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)
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// Validates the preconditions. Returns true if object content need not be written to http.ResponseWriter.
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func checkPreconditions(r *http.Request, w http.ResponseWriter, objInfo ObjectInfo) bool {
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// Return false for methods other than GET and HEAD.
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if r.Method != "GET" && r.Method != "HEAD" {
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return false
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}
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// Headers to be set of object content is not going to be written to the client.
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writeHeaders := func() {
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// set common headers
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setCommonHeaders(w)
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// set object-related metadata headers
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w.Header().Set("Last-Modified", objInfo.ModTime.UTC().Format(http.TimeFormat))
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if objInfo.MD5Sum != "" {
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w.Header().Set("ETag", "\""+objInfo.MD5Sum+"\"")
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}
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}
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// If-Modified-Since : Return the object only if it has been modified since the specified time,
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// otherwise return a 304 (not modified).
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ifModifiedSinceHeader := r.Header.Get("If-Modified-Since")
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if ifModifiedSinceHeader != "" {
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if !ifModifiedSince(objInfo.ModTime, ifModifiedSinceHeader) {
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// If the object is not modified since the specified time.
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writeHeaders()
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w.WriteHeader(http.StatusNotModified)
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return true
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}
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}
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// If-Unmodified-Since : Return the object only if it has not been modified since the specified
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// time, otherwise return a 412 (precondition failed).
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ifUnmodifiedSinceHeader := r.Header.Get("If-Unmodified-Since")
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if ifUnmodifiedSinceHeader != "" {
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if ifModifiedSince(objInfo.ModTime, ifUnmodifiedSinceHeader) {
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// If the object is modified since the specified time.
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writeHeaders()
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writeErrorResponse(w, r, ErrPreconditionFailed, r.URL.Path)
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return true
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}
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}
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// If-Match : Return the object only if its entity tag (ETag) is the same as the one specified;
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// otherwise return a 412 (precondition failed).
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ifMatchETagHeader := r.Header.Get("If-Match")
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if ifMatchETagHeader != "" {
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if !isETagEqual(objInfo.MD5Sum, ifMatchETagHeader) {
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// If the object ETag does not match with the specified ETag.
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writeHeaders()
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writeErrorResponse(w, r, ErrPreconditionFailed, r.URL.Path)
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return true
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}
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}
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// If-None-Match : Return the object only if its entity tag (ETag) is different from the
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// one specified otherwise, return a 304 (not modified).
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ifNoneMatchETagHeader := r.Header.Get("If-None-Match")
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if ifNoneMatchETagHeader != "" {
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if isETagEqual(objInfo.MD5Sum, ifNoneMatchETagHeader) {
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// If the object ETag matches with the specified ETag.
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writeHeaders()
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w.WriteHeader(http.StatusNotModified)
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return true
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}
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}
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// Object content should be written to http.ResponseWriter
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return false
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}
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// returns true if object was modified after givenTime.
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func ifModifiedSince(objTime time.Time, givenTimeStr string) bool {
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if objTime.IsZero() || objTime.Equal(time.Unix(0, 0)) {
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// If the object doesn't have a modtime (IsZero), or the modtime
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// is obviously garbage (Unix time == 0), then ignore modtimes
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// and don't process the If-Modified-Since header.
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return false
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}
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givenTime, err := time.Parse(http.TimeFormat, givenTimeStr)
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if err != nil {
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return true
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}
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// The Date-Modified header truncates sub-second precision, so
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// use mtime < t+1s instead of mtime <= t to check for unmodified.
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if objTime.After(givenTime.Add(1 * time.Second)) {
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return true
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}
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return false
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}
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// canonicalizeETag returns ETag with leading and trailing double-quotes removed,
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// if any present
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func canonicalizeETag(etag string) string {
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canonicalETag := strings.TrimPrefix(etag, "\"")
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return strings.TrimSuffix(canonicalETag, "\"")
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}
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// isETagEqual return true if the canonical representations of two ETag strings
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// are equal, false otherwise
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func isETagEqual(left, right string) bool {
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return canonicalizeETag(left) == canonicalizeETag(right)
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}
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// checkCopySource implements x-amz-copy-source-if-modified-since and
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// x-amz-copy-source-if-unmodified-since checks.
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//
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// modtime is the modification time of the resource to be served, or
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// IsZero(). return value is whether this request is now complete.
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func checkCopySourceLastModified(w http.ResponseWriter, r *http.Request, modtime time.Time) bool {
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// writer always has quoted string
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// transform reader's etag to
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if r.Method != "PUT" {
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return false
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}
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if modtime.IsZero() || modtime.Equal(time.Unix(0, 0)) {
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// If the object doesn't have a modtime (IsZero), or the modtime
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// is obviously garbage (Unix time == 0), then ignore modtimes
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// and don't process the If-Modified-Since header.
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return false
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}
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// The Date-Modified header truncates sub-second precision, so
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// use mtime < t+1s instead of mtime <= t to check for unmodified.
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if _, ok := r.Header["x-amz-copy-source-if-modified-since"]; ok {
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// Return the object only if it has been modified since the
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// specified time, otherwise return a 304 error (not modified).
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t, err := time.Parse(http.TimeFormat, r.Header.Get("x-amz-copy-source-if-modified-since"))
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if err == nil && modtime.Before(t.Add(1*time.Second)) {
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h := w.Header()
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// Remove Content headers if set
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delete(h, "Content-Type")
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delete(h, "Content-Length")
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delete(h, "Content-Range")
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w.WriteHeader(http.StatusNotModified)
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return true
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}
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} else if _, ok := r.Header["x-amz-copy-source-if-unmodified-since"]; ok {
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// Return the object only if it has not been modified since the
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// specified time, otherwise return a 412 error (precondition failed).
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t, err := time.Parse(http.TimeFormat, r.Header.Get("x-amz-copy-source-if-unmodified-since"))
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if err == nil && modtime.After(t.Add(1*time.Second)) {
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h := w.Header()
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// Remove Content headers if set
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delete(h, "Content-Type")
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delete(h, "Content-Length")
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delete(h, "Content-Range")
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writeErrorResponse(w, r, ErrPreconditionFailed, r.URL.Path)
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return true
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}
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}
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w.Header().Set("Last-Modified", modtime.UTC().Format(http.TimeFormat))
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return false
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}
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// checkCopySourceETag implements x-amz-copy-source-if-match and
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// x-amz-copy-source-if-none-match checks.
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//
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// The ETag must have been previously set in the ResponseWriter's
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// headers. The return value is whether this request is now considered
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// complete.
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func checkCopySourceETag(w http.ResponseWriter, r *http.Request) bool {
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// writer always has quoted string
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// transform reader's etag to
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if r.Method != "PUT" {
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return false
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}
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etag := w.Header().Get("ETag")
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// Tag must be provided...
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if etag == "" {
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return false
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}
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if inm := r.Header.Get("x-amz-copy-source-if-none-match"); inm != "" {
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// Return the object only if its entity tag (ETag) is
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// different from the one specified; otherwise, the
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// request returns a 412 HTTP status code error (failed precondition).
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if isETagEqual(inm, etag) || isETagEqual(inm, "*") {
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h := w.Header()
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// Remove Content headers if set
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delete(h, "Content-Type")
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delete(h, "Content-Length")
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delete(h, "Content-Range")
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writeErrorResponse(w, r, ErrPreconditionFailed, r.URL.Path)
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return true
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}
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} else if inm := r.Header.Get("x-amz-copy-source-if-match"); !isETagEqual(inm, "") {
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// Return the object only if its entity tag (ETag) is the same
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// as the one specified; otherwise, return a 412 (precondition failed).
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if !isETagEqual(inm, etag) {
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h := w.Header()
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// Remove Content headers if set
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delete(h, "Content-Type")
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delete(h, "Content-Length")
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delete(h, "Content-Range")
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writeErrorResponse(w, r, ErrPreconditionFailed, r.URL.Path)
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return true
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}
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}
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return false
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}
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