cmd/{cover,go}: avoid use of os.PathListSeparator in cmd/cover flag

Rework the mechanism for passing a list of output files from cmd/go to
cmd/cover when running new-style package-scope coverage
instrumentation (-pkgcfg mode). The old scheme passed a single string
with all output files joined together with os.PathListSeparator, but
this scheme is not viable on plan9, where strings containing the
separator character are not permitted when running exec.Command().
Instead, switch cmd/cover to use an arguments file (a file containing
a list of names) to specify names of instrumented output files. This
fixes the cmd/cover test failures on the plan9 builders.

Updates #51430.

Change-Id: I919f5e0a79500e28648fb9177225a9b938e4fdee
Reviewed-on: https://go-review.googlesource.com/c/go/+/436675
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Run-TryBot: Than McIntosh <[email protected]>

src/cmd/cover/cfg_test.go

@@ -39,18 +39,29 @@ func writePkgConfig(t *testing.T, outdir, tag, ppath, pname string, gran string)
 	return incfg
 }
 
+func writeOutFileList(t *testing.T, infiles []string, outdir, tag string) ([]string, string) {
+	outfilelist := filepath.Join(outdir, tag+"outfilelist.txt")
+	var sb strings.Builder
+	outfs := []string{}
+	for _, inf := range infiles {
+		base := filepath.Base(inf)
+		of := filepath.Join(outdir, tag+".cov."+base)
+		outfs = append(outfs, of)
+		fmt.Fprintf(&sb, "%s\n", of)
+	}
+	if err := os.WriteFile(outfilelist, []byte(sb.String()), 0666); err != nil {
+		t.Fatalf("writing %s: %v", outfilelist, err)
+	}
+	return outfs, outfilelist
+}
+
 func runPkgCover(t *testing.T, outdir string, tag string, incfg string, mode string, infiles []string, errExpected bool) ([]string, string, string) {
 	// Write the pkgcfg file.
 	outcfg := filepath.Join(outdir, "outcfg.txt")
 
 	// Form up the arguments and run the tool.
-	outfiles := []string{}
-	for _, inf := range infiles {
-		base := filepath.Base(inf)
-		outfiles = append(outfiles, filepath.Join(outdir, "cov."+base))
-	}
-	ofs := strings.Join(outfiles, string(os.PathListSeparator))
-	args := []string{"-pkgcfg", incfg, "-mode=" + mode, "-var=var" + tag, "-o", ofs}
+	outfiles, outfilelist := writeOutFileList(t, infiles, outdir, tag)
+	args := []string{"-pkgcfg", incfg, "-mode=" + mode, "-var=var" + tag, "-outfilelist", outfilelist}
 	args = append(args, infiles...)
 	cmd := exec.Command(testcover, args...)
 	if errExpected {

src/cmd/cover/cover.go

@@ -44,10 +44,12 @@ Display coverage percentages to stdout for each function:
 Finally, to generate modified source code with coverage annotations
 for a package (what go test -cover does):
 	go tool cover -mode=set -var=CoverageVariableName \
-		-pkgcfg=<config> -o=<outputfiles> file1.go ... fileN.go
+		-pkgcfg=<config> -outfilelist=<file> file1.go ... fileN.go
 
 where -pkgcfg points to a file containing the package path,
-package name, module path, and related info from "go build".
+package name, module path, and related info from "go build",
+and -outfilelist points to a file containing the filenames
+of the instrumented output files (one per input file).
 See https://pkg.go.dev/internal/coverage#CoverPkgConfig for
 more on the package config.
 `
@@ -61,16 +63,19 @@ func usage() {
 }
 
 var (
-	mode    = flag.String("mode", "", "coverage mode: set, count, atomic")
-	varVar  = flag.String("var", "GoCover", "name of coverage variable to generate")
-	output  = flag.String("o", "", fmt.Sprintf("file(s) for output (if multiple inputs, this is a %q-separated list); defaults to stdout if omitted.", string(os.PathListSeparator)))
-	htmlOut = flag.String("html", "", "generate HTML representation of coverage profile")
-	funcOut = flag.String("func", "", "output coverage profile information for each function")
-	pkgcfg  = flag.String("pkgcfg", "", "enable full-package instrumentation mode using params from specified config file")
+	mode        = flag.String("mode", "", "coverage mode: set, count, atomic")
+	varVar      = flag.String("var", "GoCover", "name of coverage variable to generate")
+	output      = flag.String("o", "", "file for output")
+	outfilelist = flag.String("outfilelist", "", "file containing list of output files (one per line) if -pkgcfg is in use")
+	htmlOut     = flag.String("html", "", "generate HTML representation of coverage profile")
+	funcOut     = flag.String("func", "", "output coverage profile information for each function")
+	pkgcfg      = flag.String("pkgcfg", "", "enable full-package instrumentation mode using params from specified config file")
 )
 
 var pkgconfig coverage.CoverPkgConfig
 
+var outputfiles []string // set whe -pkgcfg is in use
+
 var profile string // The profile to read; the value of -html or -func
 
 var counterStmt func(*File, string) string
@@ -153,18 +158,26 @@ func parseFlags() error {
 			return fmt.Errorf("missing source file(s)")
 		} else {
 			if *pkgcfg != "" {
-				if *output == "" {
-					return fmt.Errorf("supply output file(s) with -o")
+				if *output != "" {
+					return fmt.Errorf("please use '-outfilelist' flag instead of '-o'")
+				}
+				var err error
+				if outputfiles, err = readOutFileList(*outfilelist); err != nil {
+					return err
 				}
 				numInputs := len(flag.Args())
-				numOutputs := len(strings.Split(*output, string(os.PathListSeparator)))
+				numOutputs := len(outputfiles)
 				if numOutputs != numInputs {
 					return fmt.Errorf("number of output files (%d) not equal to number of input files (%d)", numOutputs, numInputs)
 				}
 				if err := readPackageConfig(*pkgcfg); err != nil {
 					return err
 				}
 				return nil
+			} else {
+				if *outfilelist != "" {
+					return fmt.Errorf("'-outfilelist' flag applicable only when -pkgcfg used")
+				}
 			}
 			if flag.NArg() == 1 {
 				return nil
@@ -176,6 +189,14 @@ func parseFlags() error {
 	return fmt.Errorf("too many arguments")
 }
 
+func readOutFileList(path string) ([]string, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("error reading -outfilelist file %q: %v", path, err)
+	}
+	return strings.Split(strings.TrimSpace(string(data)), "\n"), nil
+}
+
 func readPackageConfig(path string) error {
 	data, err := ioutil.ReadFile(path)
 	if err != nil {
@@ -495,7 +516,6 @@ func annotate(names []string) {
 		}
 	}
 	// TODO: process files in parallel here if it matters.
-	outfiles := strings.Split(*output, string(os.PathListSeparator))
 	for k, name := range names {
 		last := false
 		if k == len(names)-1 {
@@ -506,7 +526,7 @@ func annotate(names []string) {
 		isStdout := true
 		if *pkgcfg != "" {
 			var err error
-			fd, err = os.Create(outfiles[k])
+			fd, err = os.Create(outputfiles[k])
 			if err != nil {
 				log.Fatalf("cover: %s", err)
 			}

src/cmd/go/internal/work/exec.go

@@ -691,7 +691,8 @@ OverlayLoop:
 					panic("covermode should be set at this point")
 				}
 				pkgcfg := a.Objdir + "pkgcfg.txt"
-				if err := b.cover2(a, pkgcfg, infiles, outfiles, coverVar, mode); err != nil {
+				covoutfiles := a.Objdir + "coveroutfiles.txt"
+				if err := b.cover2(a, pkgcfg, covoutfiles, infiles, outfiles, coverVar, mode); err != nil {
 					return err
 				}
 			} else {
@@ -1943,22 +1944,22 @@ func (b *Builder) cover(a *Action, dst, src string, varName string) error {
 // cover2 runs, in effect,
 //
 //	go tool cover -pkgcfg=<config file> -mode=b.coverMode -var="varName" -o <outfiles> <infiles>
-func (b *Builder) cover2(a *Action, pkgcfg string, infiles, outfiles []string, varName string, mode string) error {
-	if err := b.writeCoverPkgCfg(a, pkgcfg); err != nil {
+func (b *Builder) cover2(a *Action, pkgcfg, covoutputs string, infiles, outfiles []string, varName string, mode string) error {
+	if err := b.writeCoverPkgInputs(a, pkgcfg, covoutputs, outfiles); err != nil {
 		return err
 	}
 	args := []string{base.Tool("cover"),
 		"-pkgcfg", pkgcfg,
 		"-mode", mode,
 		"-var", varName,
-		"-o", strings.Join(outfiles, string(os.PathListSeparator)),
+		"-outfilelist", covoutputs,
 	}
 	args = append(args, infiles...)
 	return b.run(a, a.Objdir, "cover "+a.Package.ImportPath, nil,
 		cfg.BuildToolexec, args)
 }
 
-func (b *Builder) writeCoverPkgCfg(a *Action, file string) error {
+func (b *Builder) writeCoverPkgInputs(a *Action, pconfigfile string, covoutputsfile string, outfiles []string) error {
 	p := a.Package
 	p.Internal.CoverageCfg = a.Objdir + "coveragecfg"
 	pcfg := coverage.CoverPkgConfig{
@@ -1978,7 +1979,14 @@ func (b *Builder) writeCoverPkgCfg(a *Action, file string) error {
 	if err != nil {
 		return err
 	}
-	return b.writeFile(file, data)
+	if err := b.writeFile(pconfigfile, data); err != nil {
+		return err
+	}
+	var sb strings.Builder
+	for i := range outfiles {
+		fmt.Fprintf(&sb, "%s\n", outfiles[i])
+	}
+	return b.writeFile(covoutputsfile, []byte(sb.String()))
 }
 
 var objectMagic = [][]byte{