cmd/compile/internal/importer: minimize Import differences

Minimizes the differences with go/internal/gcimporter.Import.

Note that the copy in cmd/compile/internal/importer is currently
only used in tests.

The delta between the two Import functions is now just types vs types2.

Change-Id: I5e94d3aa5bbdb78252e47310c95807f63e27ef3d
Reviewed-on: https://go-review.googlesource.com/c/go/+/626698
Commit-Queue: Tim King <taking@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/compile/internal/importer/gcimporter.go b/src/cmd/compile/internal/importer/gcimporter.go
index 47a0d7c0bf31ec0a800eb6ff4ad453e267187ccb..fa780d386a92e4e61d85f948b6527a0ea2fa19c6 100644 (file)
--- a/src/cmd/compile/internal/importer/gcimporter.go
+++ b/src/cmd/compile/internal/importer/gcimporter.go
@@ -14,6 +14,7 @@ import (
        "fmt"
        "go/build"
        "internal/pkgbits"
+       "internal/saferio"
        "io"
        "os"
        "os/exec"
@@ -216,23 +217,11 @@ func Import(packages map[string]*types2.Package, path, srcDir string, lookup fun
                err = fmt.Errorf("import %q: old textual export format no longer supported (recompile package)", path)
 
        case "$$B\n":
-               // TODO(taking): minimize code delta with src/go/internal/gcimporter.Import.
-               var data []byte
-               var r io.Reader = buf
-               if size >= 0 {
-                       r = io.LimitReader(r, int64(size))
-               }
-               data, err = io.ReadAll(r)
-               if err != nil {
-                       break
-               }
-
-               if len(data) == 0 {
-                       err = fmt.Errorf("import %q: missing export data", path)
-                       break
+               var exportFormat byte
+               if exportFormat, err = buf.ReadByte(); err != nil {
+                       return
                }
-               exportFormat := data[0]
-               s := string(data[1:])
+               size--
 
                // The unified export format starts with a 'u'; the indexed export
                // format starts with an 'i'; and the older binary export format
@@ -241,7 +230,18 @@ func Import(packages map[string]*types2.Package, path, srcDir string, lookup fun
                switch exportFormat {
                case 'u':
                        // exported strings may contain "\n$$\n" - search backwards
+                       var data []byte
+                       var r io.Reader = buf
+                       if size >= 0 {
+                               if data, err = saferio.ReadData(r, uint64(size)); err != nil {
+                                       return
+                               }
+                       } else if data, err = io.ReadAll(r); err != nil {
+                               return
+                       }
+                       s := string(data)
                        s = s[:strings.LastIndex(s, "\n$$\n")]
+
                        input := pkgbits.NewPkgDecoder(id, s)
                        pkg = ReadPackage(nil, packages, input)
                default:

diff --git a/src/go/internal/gcimporter/gcimporter.go b/src/go/internal/gcimporter/gcimporter.go
index f86b20da8d0d36b7699f3a9f4f411f0bdbc2d444..a07fd8a6de622850e7ca94b099cc9ae8f48b1a43 100644 (file)
--- a/src/go/internal/gcimporter/gcimporter.go
+++ b/src/go/internal/gcimporter/gcimporter.go
@@ -23,9 +23,6 @@ import (
        "sync"
 )
 
-// debugging/development support
-const debug = false
-
 var exportMap sync.Map // package dir → func() (string, error)
 
 // lookupGorootExport returns the location of the export data