cmd/internal/goobj: add test case for object file reader

Add test in which a input Go object file contains a very large number
of relocations (more than 1<<20).

Updates #41621.

Change-Id: If1ebf3c4fefbf55ddec4e05c5299e7c48fc697d8
Reviewed-on: https://go-review.googlesource.com/c/go/+/278493
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Trust: Than McIntosh <thanm@google.com>

diff --git a/src/cmd/internal/goobj/objfile_test.go b/src/cmd/internal/goobj/objfile_test.go
index c6fd427c150dec5ef251dd0125160bcd9a570279..99d02a1bf1d1117be3d2ca89a24feb4893361deb 100644 (file)
--- a/src/cmd/internal/goobj/objfile_test.go
+++ b/src/cmd/internal/goobj/objfile_test.go
@@ -9,6 +9,11 @@ import (
        "bytes"
        "cmd/internal/bio"
        "cmd/internal/objabi"
+       "fmt"
+       "internal/testenv"
+       "io/ioutil"
+       "os"
+       "os/exec"
        "testing"
 )
 
@@ -69,3 +74,60 @@ func TestReadWrite(t *testing.T) {
                t.Errorf("read Aux2 mismatch: got %v %v", a2.Type(), a2.Sym())
        }
 }
+
+var issue41621prolog = `
+package main
+var lines = []string{
+`
+
+var issue41621epilog = `
+}
+func getLines() []string {
+       return lines
+}
+func main() {
+       println(getLines())
+}
+`
+
+func TestIssue41621LargeNumberOfRelocations(t *testing.T) {
+       if testing.Short() || (objabi.GOARCH != "amd64") {
+               t.Skipf("Skipping large number of relocations test in short mode or on %s", objabi.GOARCH)
+       }
+       testenv.MustHaveGoBuild(t)
+
+       tmpdir, err := ioutil.TempDir("", "lotsofrelocs")
+       if err != nil {
+               t.Fatalf("can't create temp directory: %v\n", err)
+       }
+       defer os.RemoveAll(tmpdir)
+
+       // Emit testcase.
+       var w bytes.Buffer
+       fmt.Fprintf(&w, issue41621prolog)
+       for i := 0; i < 1048576+13; i++ {
+               fmt.Fprintf(&w, "\t\"%d\",\n", i)
+       }
+       fmt.Fprintf(&w, issue41621epilog)
+       err = ioutil.WriteFile(tmpdir+"/large.go", w.Bytes(), 0666)
+       if err != nil {
+               t.Fatalf("can't write output: %v\n", err)
+       }
+
+       // Emit go.mod
+       w.Reset()
+       fmt.Fprintf(&w, "module issue41621\n\ngo 1.12\n")
+       err = ioutil.WriteFile(tmpdir+"/go.mod", w.Bytes(), 0666)
+       if err != nil {
+               t.Fatalf("can't write output: %v\n", err)
+       }
+       w.Reset()
+
+       // Build.
+       cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "large")
+       cmd.Dir = tmpdir
+       out, err := cmd.CombinedOutput()
+       if err != nil {
+               t.Fatalf("Build failed: %v, output: %s", err, out)
+       }
+}