Merge pull request #454 from peterstace/411-use-unsafeslice-for-wkb-h…

…andling

#411 use safer method when converting between byte and float slices

.ci/docker-compose-cmppg.yml

@@ -8,7 +8,7 @@ services:
       timeout: '1s'
       retries: 50
   tests:
-    image: golang:1.14
+    image: golang:1.17
     working_dir: /go/src/github.com/peterstace/simplefeatures
     entrypoint: go test -test.count=1 -test.timeout=30m -test.run=. ./internal/cmprefimpl/cmppg
     volumes:

.ci/docker-compose-pgscan.yml

@@ -8,7 +8,7 @@ services:
       timeout: '1s'
       retries: 50
   tests:
-    image: golang:1.14
+    image: golang:1.17
     working_dir: /go/src/github.com/peterstace/simplefeatures
     entrypoint: go test -test.count=1 -test.timeout=30m -test.run=. ./internal/pgscan
     volumes:

.ci/docker-compose-unit.yml

@@ -1,7 +1,7 @@
 version: "2.1"
 services:
   tests:
-    image: golang:1.15
+    image: golang:1.17
     working_dir: /go/src/github.com/peterstace/simplefeatures
     entrypoint: go test -covermode=count -coverprofile=coverage.out -test.count=1 -test.run=. ./geom ./rtree
     volumes:

.ci/geos.Dockerfile

@@ -1,5 +1,5 @@
-FROM golang:1.14
+FROM golang:1.17-buster
 RUN apt-get -y update && \
 	apt-get install -y libgeos-dev=3.7.1-1 && \
 	rm -rf /var/lib/apt/lists/*
-ENV PATH=/usr/lib/go-1.15/bin:${PATH}
+ENV PATH=/usr/lib/go-1.17/bin:${PATH}

.ci/golint.Dockerfile

@@ -1,2 +1,2 @@
-FROM golang:1.14
+FROM golang:1.17
 RUN go get -u golang.org/x/lint/golint

CHANGELOG.md

@@ -11,6 +11,9 @@
 - Add a new `DumpRings` method to the `Polygon` type, which gives the rings of
   the polygon as a slice of `LineString`s.
 
+- Uses `unsafe.Slice` for internal WKB conversions. This increases the minimum
+  Go version required to use simplefeatures from 1.14 to 1.17.
+
 ## v0.37.0
 
 2022-03-29

geom/wkb_marshal.go

@@ -4,7 +4,6 @@ import (
 	"encoding/binary"
 	"fmt"
 	"math"
-	"reflect"
 	"unsafe"
 )
 
@@ -87,10 +86,8 @@ func (m *wkbMarshaler) writeSequence(seq Sequence) {
 // floatsAsBytes reinterprets the floats slice as a bytes slice in a similar
 // manner to reinterpret_cast in C++.
 func floatsAsBytes(floats []float64) []byte {
-	var byts []byte
-	hdr := (*reflect.SliceHeader)(unsafe.Pointer(&byts))
-	hdr.Data = (*reflect.SliceHeader)(unsafe.Pointer(&floats)).Data
-	hdr.Len = 8 * len(floats)
-	hdr.Cap = 8 * cap(floats)
-	return byts
+	if len(floats) == 0 {
+		return nil
+	}
+	return unsafe.Slice((*byte)(unsafe.Pointer(&floats[0])), 8*len(floats))
 }

geom/wkb_parser.go

@@ -4,7 +4,6 @@ import (
 	"encoding/binary"
 	"fmt"
 	"math"
-	"reflect"
 	"unsafe"
 )
 
@@ -224,12 +223,10 @@ func (p *wkbParser) parseLineString(ctype CoordinatesType) (LineString, error) {
 // bytesAsFloats reinterprets the bytes slice as a float64 slice in a similar
 // manner to reinterpret_cast in C++.
 func bytesAsFloats(byts []byte) []float64 {
-	var floats []float64
-	hdr := (*reflect.SliceHeader)(unsafe.Pointer(&floats))
-	hdr.Data = (*reflect.SliceHeader)(unsafe.Pointer(&byts)).Data
-	hdr.Len = len(byts) / 8
-	hdr.Cap = cap(byts) / 8
-	return floats
+	if len(byts) == 0 {
+		return nil
+	}
+	return unsafe.Slice((*float64)(unsafe.Pointer(&byts[0])), len(byts)/8)
 }
 
 // flipEndianessStride8 flips the endianess of the input bytes, assuming that

go.mod

@@ -1,5 +1,5 @@
 module github.com/peterstace/simplefeatures
 
-go 1.14
+go 1.17
 
 require github.com/lib/pq v1.1.1