Golang coverage with go 1.16 and modules (#5321)

* Fixes go coverage with modules

* Golang coverage html report turning off modules

Otherwise, we get the error
working directory is not part of a module

1 files changed, 126 insertions, 0 deletions

diff --git a/infra/base-images/base-runner/gocoverage/gocovsum/gocovsum.go b/infra/base-images/base-runner/gocoverage/gocovsum/gocovsum.go
new file mode 100644
index 000000000..206600619
--- /dev/null
+++ b/infra/base-images/base-runner/gocoverage/gocovsum/gocovsum.go
@@ -0,0 +1,126 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"log"
+
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"path"
+
+	"golang.org/x/tools/cover"
+)
+
+type CoverageTotal struct {
+	Count     int     `json:"count"`
+	Covered   int     `json:"covered"`
+	Uncovered int     `json:"notcovered"`
+	Percent   float64 `json:"percent"`
+}
+
+type CoverageTotals struct {
+	Functions CoverageTotal `json:"functions,omitempty"`
+	Lines     CoverageTotal `json:"lines,omitempty"`
+	Regions   CoverageTotal `json:"regions,omitempty"`
+}
+
+type CoverageData struct {
+	Totals CoverageTotals `json:"totals,omitempty"`
+}
+
+type PositionInterval struct {
+	start token.Position
+	end   token.Position
+}
+
+type CoverageSummary struct {
+	Data    []CoverageData `json:"data,omitempty"`
+	Type    string         `json:"type,omitempty"`
+	Version string         `json:"version,omitempty"`
+}
+
+func isFunctionCovered(s token.Position, e token.Position, blocks []cover.ProfileBlock) bool {
+	for _, b := range blocks {
+		if b.StartLine >= s.Line && b.StartLine <= e.Line && b.EndLine >= s.Line && b.EndLine <= e.Line {
+			if b.Count > 0 {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func main() {
+	flag.Parse()
+
+	if len(flag.Args()) != 1 {
+		log.Fatalf("needs exactly one argument")
+	}
+	profiles, err := cover.ParseProfiles(flag.Args()[0])
+	if err != nil {
+		log.Fatalf("failed to parse profiles: %v", err)
+	}
+	r := CoverageSummary{}
+	r.Type = "oss-fuzz.go.coverage.json.export"
+	r.Version = "1.0.0"
+	r.Data = make([]CoverageData, 1)
+	gopath := os.Getenv("GOPATH")
+	if len(gopath) == 0 {
+		gopath = os.Getenv("HOME") + "/go"
+	}
+	for _, p := range profiles {
+		fset := token.NewFileSet() // positions are relative to fset
+		f, err := parser.ParseFile(fset, path.Join(gopath, "src", p.FileName), nil, 0)
+		if err != nil {
+			panic(err)
+		}
+		ast.Inspect(f, func(n ast.Node) bool {
+			switch x := n.(type) {
+			case *ast.FuncLit:
+				startf := fset.Position(x.Pos())
+				endf := fset.Position(x.End())
+				r.Data[0].Totals.Functions.Count++
+				if isFunctionCovered(startf, endf, p.Blocks) {
+					r.Data[0].Totals.Functions.Covered++
+				} else {
+					r.Data[0].Totals.Functions.Uncovered++
+				}
+			case *ast.FuncDecl:
+				startf := fset.Position(x.Pos())
+				endf := fset.Position(x.End())
+				r.Data[0].Totals.Functions.Count++
+				if isFunctionCovered(startf, endf, p.Blocks) {
+					r.Data[0].Totals.Functions.Covered++
+				} else {
+					r.Data[0].Totals.Functions.Uncovered++
+				}
+			}
+			return true
+		})
+
+		for _, b := range p.Blocks {
+			r.Data[0].Totals.Regions.Count++
+			if b.Count > 0 {
+				r.Data[0].Totals.Regions.Covered++
+			} else {
+				r.Data[0].Totals.Regions.Uncovered++
+			}
+
+			r.Data[0].Totals.Lines.Count += b.NumStmt
+			if b.Count > 0 {
+				r.Data[0].Totals.Lines.Covered += b.NumStmt
+			} else {
+				r.Data[0].Totals.Lines.Uncovered += b.NumStmt
+			}
+		}
+	}
+	r.Data[0].Totals.Regions.Percent = float64(100*r.Data[0].Totals.Regions.Covered) / float64(r.Data[0].Totals.Regions.Count)
+	r.Data[0].Totals.Lines.Percent = float64(100*r.Data[0].Totals.Lines.Covered) / float64(r.Data[0].Totals.Lines.Count)
+	r.Data[0].Totals.Functions.Percent = float64(100*r.Data[0].Totals.Functions.Covered) / float64(r.Data[0].Totals.Functions.Count)
+	o, _ := json.Marshal(r)
+	fmt.Printf(string(o))
+}