mirror of https://github.com/perkeep/perkeep.git
103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
/*
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Copyright 2011 Google Inc.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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 index
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import (
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"json"
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"os"
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"camli/magic"
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"camli/schema"
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)
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// maxSniffSize is how much of a blob to buffer in memory for both
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// MIME sniffing (in which case 1MB is way overkill) and also for
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// holding a schema blob in memory for analysis in later steps (where
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// 1MB is about the max size a claim can be, with about 1023K (of
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// slack space)
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const maxSniffSize = 1024 * 1024
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type BlobSniffer struct {
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header []byte
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written int64
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camli *schema.Superset
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mimeType *string
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}
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func (sn *BlobSniffer) Superset() (*schema.Superset, bool) {
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return sn.camli, sn.camli != nil
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}
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func (sn *BlobSniffer) Write(d []byte) (int, os.Error) {
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sn.written += int64(len(d))
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if len(sn.header) < maxSniffSize {
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n := maxSniffSize - len(sn.header)
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if len(d) < n {
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n = len(d)
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}
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sn.header = append(sn.header, d[:n]...)
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}
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return len(d), nil
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}
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func (sn *BlobSniffer) IsTruncated() bool {
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return sn.written > maxSniffSize
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}
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func (sn *BlobSniffer) Body() (string, os.Error) {
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if sn.IsTruncated() {
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return "", os.NewError("was truncated")
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}
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return string(sn.header), nil
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}
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// returns content type or empty string if unknown
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func (sn *BlobSniffer) MimeType() string {
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if sn.mimeType != nil {
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return *sn.mimeType
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}
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return ""
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}
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func (sn *BlobSniffer) Parse() {
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// Try to parse it as JSON
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// TODO: move this into the magic library? Is the magic library Camli-specific
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// or to be upstreamed elsewhere?
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if sn.bufferIsCamliJson() {
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str := "application/json; camliType=" + sn.camli.Type
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sn.mimeType = &str
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}
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if mime := magic.MimeType(sn.header); mime != "" {
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sn.mimeType = &mime
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}
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}
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func (sn *BlobSniffer) bufferIsCamliJson() bool {
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buf := sn.header
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if len(buf) < 2 || buf[0] != '{' {
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return false
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}
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camli := new(schema.Superset)
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err := json.Unmarshal(buf, camli)
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if err != nil {
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return false
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}
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sn.camli = camli
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return true
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}
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