forked from omniscale/imposm3
/
lowlevel.go
196 lines (167 loc) · 4.06 KB
/
lowlevel.go
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package pbf
import (
"bytes"
"code.google.com/p/goprotobuf/proto"
"compress/zlib"
structs "encoding/binary"
"errors"
"fmt"
"imposm3/parser/pbf/osmpbf"
"io"
"log"
"os"
"time"
)
type parserError struct {
message string
originalError error
}
func (e *parserError) Error() string {
return fmt.Sprintf("%s: %v", e.message, e.originalError)
}
func newParserError(message string, err error) *parserError {
return &parserError{message, err}
}
var supportedFeatured = map[string]bool{"OsmSchema-V0.6": true, "DenseNodes": true}
func readBlobData(pos Block) ([]byte, error) {
file, err := os.Open(pos.filename)
if err != nil {
return nil, newParserError("file open", err)
}
defer file.Close()
var blob = &osmpbf.Blob{}
blobData := make([]byte, pos.size)
file.Seek(pos.offset, 0)
io.ReadFull(file, blobData)
err = proto.Unmarshal(blobData, blob)
if err != nil {
return nil, newParserError("unmarshaling blob", err)
}
// pbf contains (uncompressed) raw or zlibdata
raw := blob.GetRaw()
if raw == nil {
buf := bytes.NewBuffer(blob.GetZlibData())
r, err := zlib.NewReader(buf)
if err != nil {
return nil, newParserError("zlib error", err)
}
raw = make([]byte, blob.GetRawSize())
_, err = io.ReadFull(r, raw)
if err != nil {
return nil, newParserError("zlib read error", err)
}
}
return raw, nil
}
func readPrimitiveBlock(pos Block) *osmpbf.PrimitiveBlock {
raw, err := readBlobData(pos)
if err != nil {
log.Panic(err)
}
block := &osmpbf.PrimitiveBlock{}
err = proto.Unmarshal(raw, block)
if err != nil {
log.Panic("unmarshaling error: ", err)
}
return block
}
func readAndParseHeaderBlock(pos Block) (*pbfHeader, error) {
raw, err := readBlobData(pos)
if err != nil {
return nil, err
}
header := &osmpbf.HeaderBlock{}
err = proto.Unmarshal(raw, header)
if err != nil {
return nil, err
}
for _, feature := range header.RequiredFeatures {
if supportedFeatured[feature] != true {
return nil, errors.New("cannot parse file, feature " + feature + " not supported")
}
}
result := &pbfHeader{}
timestamp := header.GetOsmosisReplicationTimestamp()
result.Time = time.Unix(timestamp, 0 /* nanoseconds */)
return result, nil
}
type Pbf struct {
file *os.File
Filename string
offset int64
Header *pbfHeader
}
type pbfHeader struct {
Time time.Time
}
func Open(filename string) (f *Pbf, err error) {
file, err := os.Open(filename)
if err != nil {
return nil, err
}
f = &Pbf{Filename: filename, file: file}
err = f.parseHeader()
if err != nil {
file.Close()
return nil, err
}
return f, nil
}
func (pbf *Pbf) Close() error {
return pbf.file.Close()
}
func (pbf *Pbf) parseHeader() error {
offset, size, header := pbf.nextBlock()
if header.GetType() != "OSMHeader" {
panic("invalid block type, expected OSMHeader, got " + header.GetType())
}
var err error
pbf.Header, err = readAndParseHeaderBlock(Block{pbf.Filename, offset, size})
return err
}
func (pbf *Pbf) nextBlock() (offset int64, size int32, header *osmpbf.BlobHeader) {
header = pbf.nextBlobHeader()
size = header.GetDatasize()
offset = pbf.offset
pbf.offset += int64(size)
pbf.file.Seek(pbf.offset, 0)
return offset, size, header
}
func (pbf *Pbf) BlockPositions() (positions chan Block) {
positions = make(chan Block, 8)
go func() {
for {
offset, size, header := pbf.nextBlock()
if size == 0 {
close(positions)
pbf.Close()
return
}
if header.GetType() != "OSMData" {
panic("invalid block type, expected OSMData, got " + header.GetType())
}
positions <- Block{pbf.Filename, offset, size}
}
}()
return
}
func (pbf *Pbf) nextBlobHeaderSize() (size int32) {
pbf.offset += 4
structs.Read(pbf.file, structs.BigEndian, &size)
return
}
func (pbf *Pbf) nextBlobHeader() *osmpbf.BlobHeader {
var blobHeader = &osmpbf.BlobHeader{}
size := pbf.nextBlobHeaderSize()
if size == 0 {
return blobHeader
}
data := make([]byte, size)
io.ReadFull(pbf.file, data)
err := proto.Unmarshal(data, blobHeader)
if err != nil {
log.Fatal("unmarshaling error (header): ", err)
}
pbf.offset += int64(size)
return blobHeader
}