Move mmap binary reader to UNIX only architectures, fixes #122

binary.go

@@ -7,8 +7,6 @@ import (
 	"io"
 	"math"
 	"os"
-	"runtime"
-	"syscall"
 )
 
 const PageSize = 4096
@@ -341,77 +339,6 @@ type IBinaryReader interface {
 	Bytes(int, int64) ([]byte, error)
 }
 
-type binaryReaderMmap struct {
-	data []byte
-}
-
-func newBinaryReaderMmap(filename string) (*binaryReaderMmap, error) {
-	f, err := os.Open(filename)
-	if err != nil {
-		return nil, err
-	}
-	defer f.Close()
-
-	fi, err := f.Stat()
-	if err != nil {
-		return nil, err
-	}
-
-	size := fi.Size()
-	if size == 0 {
-		// Treat (size == 0) as a special case, avoiding the syscall, since
-		// "man 2 mmap" says "the length... must be greater than 0".
-		//
-		// As we do not call syscall.Mmap, there is no need to call
-		// runtime.SetFinalizer to enforce a balancing syscall.Munmap.
-		return &binaryReaderMmap{
-			data: make([]byte, 0),
-		}, nil
-	} else if size < 0 {
-		return nil, fmt.Errorf("mmap: file %q has negative size", filename)
-	} else if size != int64(int(size)) {
-		return nil, fmt.Errorf("mmap: file %q is too large", filename)
-	}
-
-	data, err := syscall.Mmap(int(f.Fd()), 0, int(size), syscall.PROT_READ, syscall.MAP_SHARED)
-	if err != nil {
-		return nil, err
-	}
-	r := &binaryReaderMmap{data}
-	runtime.SetFinalizer(r, (*binaryReaderMmap).Close)
-	return r, nil
-}
-
-// Close closes the reader.
-func (r *binaryReaderMmap) Close() error {
-	if r.data == nil {
-		return nil
-	} else if len(r.data) == 0 {
-		r.data = nil
-		return nil
-	}
-	data := r.data
-	r.data = nil
-	runtime.SetFinalizer(r, nil)
-	return syscall.Munmap(data)
-}
-
-// Len returns the length of the underlying memory-mapped file.
-func (r *binaryReaderMmap) Len() int {
-	return len(r.data)
-}
-
-func (r *binaryReaderMmap) Bytes(n int, off int64) ([]byte, error) {
-	if r.data == nil {
-		return nil, errors.New("mmap: closed")
-	} else if off < 0 || int64(len(r.data)) < off {
-		return nil, fmt.Errorf("mmap: invalid offset %d", off)
-	} else if int64(len(r.data)-n) < off {
-		return r.data[off:len(r.data):len(r.data)], io.EOF
-	}
-	return r.data[off : off+int64(n) : off+int64(n)], nil
-}
-
 type binaryReaderFile struct {
 	f    *os.File
 	size int64

binary_unix.go

@@ -0,0 +1,83 @@
+//go:build unix
+
+package parse
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"syscall"
+)
+
+type binaryReaderMmap struct {
+	data []byte
+}
+
+func newBinaryReaderMmap(filename string) (*binaryReaderMmap, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	fi, err := f.Stat()
+	if err != nil {
+		return nil, err
+	}
+
+	size := fi.Size()
+	if size == 0 {
+		// Treat (size == 0) as a special case, avoiding the syscall, since
+		// "man 2 mmap" says "the length... must be greater than 0".
+		//
+		// As we do not call syscall.Mmap, there is no need to call
+		// runtime.SetFinalizer to enforce a balancing syscall.Munmap.
+		return &binaryReaderMmap{
+			data: make([]byte, 0),
+		}, nil
+	} else if size < 0 {
+		return nil, fmt.Errorf("mmap: file %q has negative size", filename)
+	} else if size != int64(int(size)) {
+		return nil, fmt.Errorf("mmap: file %q is too large", filename)
+	}
+
+	data, err := syscall.Mmap(int(f.Fd()), 0, int(size), syscall.PROT_READ, syscall.MAP_SHARED)
+	if err != nil {
+		return nil, err
+	}
+	r := &binaryReaderMmap{data}
+	runtime.SetFinalizer(r, (*binaryReaderMmap).Close)
+	return r, nil
+}
+
+// Close closes the reader.
+func (r *binaryReaderMmap) Close() error {
+	if r.data == nil {
+		return nil
+	} else if len(r.data) == 0 {
+		r.data = nil
+		return nil
+	}
+	data := r.data
+	r.data = nil
+	runtime.SetFinalizer(r, nil)
+	return syscall.Munmap(data)
+}
+
+// Len returns the length of the underlying memory-mapped file.
+func (r *binaryReaderMmap) Len() int {
+	return len(r.data)
+}
+
+func (r *binaryReaderMmap) Bytes(n int, off int64) ([]byte, error) {
+	if r.data == nil {
+		return nil, errors.New("mmap: closed")
+	} else if off < 0 || int64(len(r.data)) < off {
+		return nil, fmt.Errorf("mmap: invalid offset %d", off)
+	} else if int64(len(r.data)-n) < off {
+		return r.data[off:len(r.data):len(r.data)], io.EOF
+	}
+	return r.data[off : off+int64(n) : off+int64(n)], nil
+}