1 files changed, 22 insertions, 79 deletions

diff --git a/libgo/go/cmd/go/internal/version/version.go b/libgo/go/cmd/go/internal/version/version.go
index 58cbd32e78d..52502e95c6d 100644
--- a/libgo/go/cmd/go/internal/version/version.go
+++ b/libgo/go/cmd/go/internal/version/version.go
@@ -8,7 +8,8 @@ package version
 import (
 	"bytes"
 	"context"
-	"encoding/binary"
+	"debug/buildinfo"
+	"errors"
 	"fmt"
 	"io/fs"
 	"os"
@@ -62,8 +63,14 @@ func runVersion(ctx context.Context, cmd *base.Command, args []string) {
 		// a reasonable use case. For example, imagine GOFLAGS=-v to
 		// turn "verbose mode" on for all Go commands, which should not
 		// break "go version".
-		if (!base.InGOFLAGS("-m") && *versionM) || (!base.InGOFLAGS("-v") && *versionV) {
-			fmt.Fprintf(os.Stderr, "go version: flags can only be used with arguments\n")
+		var argOnlyFlag string
+		if !base.InGOFLAGS("-m") && *versionM {
+			argOnlyFlag = "-m"
+		} else if !base.InGOFLAGS("-v") && *versionV {
+			argOnlyFlag = "-v"
+		}
+		if argOnlyFlag != "" {
+			fmt.Fprintf(os.Stderr, "go: 'go version' only accepts %s flag with arguments\n", argOnlyFlag)
 			base.SetExitStatus(2)
 			return
 		}
@@ -135,90 +142,26 @@ func scanFile(file string, info fs.FileInfo, mustPrint bool) {
 		return
 	}
 
-	x, err := openExe(file)
+	bi, err := buildinfo.ReadFile(file)
 	if err != nil {
 		if mustPrint {
-			fmt.Fprintf(os.Stderr, "%s: %v\n", file, err)
-		}
-		return
-	}
-	defer x.Close()
-
-	vers, mod := findVers(x)
-	if vers == "" {
-		if mustPrint {
-			fmt.Fprintf(os.Stderr, "%s: go version not found\n", file)
+			if pathErr := (*os.PathError)(nil); errors.As(err, &pathErr) && filepath.Clean(pathErr.Path) == filepath.Clean(file) {
+				fmt.Fprintf(os.Stderr, "%v\n", file)
+			} else {
+				fmt.Fprintf(os.Stderr, "%s: %v\n", file, err)
+			}
 		}
 		return
 	}
 
-	fmt.Printf("%s: %s\n", file, vers)
-	if *versionM && mod != "" {
-		fmt.Printf("\t%s\n", strings.ReplaceAll(mod[:len(mod)-1], "\n", "\n\t"))
-	}
-}
-
-// The build info blob left by the linker is identified by
-// a 16-byte header, consisting of buildInfoMagic (14 bytes),
-// the binary's pointer size (1 byte),
-// and whether the binary is big endian (1 byte).
-var buildInfoMagic = []byte("\xff Go buildinf:")
-
-// findVers finds and returns the Go version and module version information
-// in the executable x.
-func findVers(x exe) (vers, mod string) {
-	// Read the first 64kB of text to find the build info blob.
-	text := x.DataStart()
-	data, err := x.ReadData(text, 64*1024)
+	fmt.Printf("%s: %s\n", file, bi.GoVersion)
+	bi.GoVersion = "" // suppress printing go version again
+	mod, err := bi.MarshalText()
 	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s: formatting build info: %v\n", file, err)
 		return
 	}
-	for ; !bytes.HasPrefix(data, buildInfoMagic); data = data[32:] {
-		if len(data) < 32 {
-			return
-		}
-	}
-
-	// Decode the blob.
-	ptrSize := int(data[14])
-	bigEndian := data[15] != 0
-	var bo binary.ByteOrder
-	if bigEndian {
-		bo = binary.BigEndian
-	} else {
-		bo = binary.LittleEndian
-	}
-	var readPtr func([]byte) uint64
-	if ptrSize == 4 {
-		readPtr = func(b []byte) uint64 { return uint64(bo.Uint32(b)) }
-	} else {
-		readPtr = bo.Uint64
-	}
-	vers = readString(x, ptrSize, readPtr, readPtr(data[16:]))
-	if vers == "" {
-		return
-	}
-	mod = readString(x, ptrSize, readPtr, readPtr(data[16+ptrSize:]))
-	if len(mod) >= 33 && mod[len(mod)-17] == '\n' {
-		// Strip module framing.
-		mod = mod[16 : len(mod)-16]
-	} else {
-		mod = ""
-	}
-	return
-}
-
-// readString returns the string at address addr in the executable x.
-func readString(x exe, ptrSize int, readPtr func([]byte) uint64, addr uint64) string {
-	hdr, err := x.ReadData(addr, uint64(2*ptrSize))
-	if err != nil || len(hdr) < 2*ptrSize {
-		return ""
-	}
-	dataAddr := readPtr(hdr)
-	dataLen := readPtr(hdr[ptrSize:])
-	data, err := x.ReadData(dataAddr, dataLen)
-	if err != nil || uint64(len(data)) < dataLen {
-		return ""
+	if *versionM && len(mod) > 0 {
+		fmt.Printf("\t%s\n", bytes.ReplaceAll(mod[:len(mod)-1], []byte("\n"), []byte("\n\t")))
 	}
-	return string(data)
 }