--- /dev/null
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package coverage
+
+import (
+ "fmt"
+ "internal/coverage"
+ "io"
+ "reflect"
+ "unsafe"
+)
+
+// EmitMetaDataToDir writes a coverage meta-data file for the
+// currently running program to the directory specified in 'dir'. An
+// error will be returned if the operation can't be completed
+// successfully (for example, if the currently running program was not
+// built with "-cover", or if the directory does not exist).
+func EmitMetaDataToDir(dir string) error {
+ if !finalHashComputed {
+ return fmt.Errorf("error: no meta-data available (binary not built with -cover?)")
+ }
+ return emitMetaDataToDirectory(dir, getCovMetaList())
+}
+
+// EmitMetaDataToWriter writes the meta-data content (the payload that
+// would normally be emitted to a meta-data file) for currently
+// running program to the the writer 'w'. An error will be returned if
+// the operation can't be completed successfully (for example, if the
+// currently running program was not built with "-cover", or if a
+// write fails).
+func EmitMetaDataToWriter(w io.Writer) error {
+ if w == nil {
+ return fmt.Errorf("error: nil writer in EmitMetaDataToWriter")
+ }
+ if !finalHashComputed {
+ return fmt.Errorf("error: no meta-data available (binary not built with -cover?)")
+ }
+ ml := getCovMetaList()
+ return writeMetaData(w, ml, cmode, cgran, finalHash)
+}
+
+// EmitCounterDataToDir writes a coverage counter-data file for the
+// currently running program to the directory specified in 'dir'. An
+// error will be returned if the operation can't be completed
+// successfully (for example, if the currently running program was not
+// built with "-cover", or if the directory does not exist). The
+// counter data written will be a snapshot taken at the point of the
+// call.
+func EmitCounterDataToDir(dir string) error {
+ return emitCounterDataToDirectory(dir)
+}
+
+// EmitCounterDataToWriter writes coverage counter-data content for
+// the currently running program to the writer 'w'. An error will be
+// returned if the operation can't be completed successfully (for
+// example, if the currently running program was not built with
+// "-cover", or if a write fails). The counter data written will be a
+// snapshot taken at the point of the invocation.
+func EmitCounterDataToWriter(w io.Writer) error {
+ if w == nil {
+ return fmt.Errorf("error: nil writer in EmitCounterDataToWriter")
+ }
+ // Ask the runtime for the list of coverage counter symbols.
+ cl := getCovCounterList()
+ if len(cl) == 0 {
+ return fmt.Errorf("program not built with -cover")
+ }
+ if !finalHashComputed {
+ return fmt.Errorf("meta-data not written yet, unable to write counter data")
+ }
+
+ pm := getCovPkgMap()
+ s := &emitState{
+ counterlist: cl,
+ pkgmap: pm,
+ }
+ return s.emitCounterDataToWriter(w)
+}
+
+// ClearCoverageCounters clears/resets all coverage counter variables
+// in the currently running program. It returns an error if the
+// program in question was not built with the "-cover" flag. Clearing
+// of coverage counters is also not supported for programs not using
+// atomic counter mode (see more detailed comments below for the
+// rationale here).
+func ClearCoverageCounters() error {
+ cl := getCovCounterList()
+ if len(cl) == 0 {
+ return fmt.Errorf("program not built with -cover")
+ }
+ if cmode != coverage.CtrModeAtomic {
+ return fmt.Errorf("ClearCoverageCounters invoked for program build with -covermode=%s (please use -covermode=atomic)", cmode.String())
+ }
+
+ // Implementation note: this function would be faster and simpler
+ // if we could just zero out the entire counter array, but for the
+ // moment we go through and zero out just the slots in the array
+ // corresponding to the counter values. We do this to avoid the
+ // following bad scenario: suppose that a user builds their Go
+ // program with "-cover", and that program has a function (call it
+ // main.XYZ) that invokes ClearCoverageCounters:
+ //
+ // func XYZ() {
+ // ... do some stuff ...
+ // coverage.ClearCoverageCounters()
+ // if someCondition { <<--- HERE
+ // ...
+ // }
+ // }
+ //
+ // At the point where ClearCoverageCounters executes, main.XYZ has
+ // not yet finished running, thus as soon as the call returns the
+ // line marked "HERE" above will trigger the writing of a non-zero
+ // value into main.XYZ's counter slab. However since we've just
+ // finished clearing the entire counter segment, we will have lost
+ // the values in the prolog portion of main.XYZ's counter slab
+ // (nctrs, pkgid, funcid). This means that later on at the end of
+ // program execution as we walk through the entire counter array
+ // for the program looking for executed functions, we'll zoom past
+ // main.XYZ's prolog (which was zero'd) and hit the non-zero
+ // counter value corresponding to the "HERE" block, which will then
+ // be interpreted as the start of another live function. Things
+ // will go downhill from there.
+ //
+ // This same scenario is also a potential risk if the program is
+ // running on an architecture that permits reordering of writes/stores,
+ // since the inconsistency described above could arise here. Example
+ // scenario:
+ //
+ // func ABC() {
+ // ... // prolog
+ // if alwaysTrue() {
+ // XYZ() // counter update here
+ // }
+ // }
+ //
+ // In the instrumented version of ABC, the prolog of the function
+ // will contain a series of stores to the initial portion of the
+ // counter array to write number-of-counters, pkgid, funcid. Later
+ // in the function there is also a store to increment a counter
+ // for the block containing the call to XYZ(). If the CPU is
+ // allowed to reorder stores and decides to issue the XYZ store
+ // before the prolog stores, this could be observable as an
+ // inconsistency similar to the one above. Hence the requirement
+ // for atomic counter mode: according to package atomic docs,
+ // "...operations that happen in a specific order on one thread,
+ // will always be observed to happen in exactly that order by
+ // another thread". Thus we can be sure that there will be no
+ // inconsistency when reading the counter array from the thread
+ // running ClearCoverageCounters.
+
+ var sd []uint32
+
+ bufHdr := (*reflect.SliceHeader)(unsafe.Pointer(&sd))
+ for _, c := range cl {
+ bufHdr.Data = uintptr(unsafe.Pointer(c.Counters))
+ bufHdr.Len = int(c.Len)
+ bufHdr.Cap = int(c.Len)
+ for i := 0; i < len(sd); i++ {
+ // Skip ahead until the next non-zero value.
+ if sd[i] == 0 {
+ continue
+ }
+ // We found a function that was executed; clear its counters.
+ nCtrs := sd[i]
+ for j := 0; j < int(nCtrs); j++ {
+ sd[i+coverage.FirstCtrOffset+j] = 0
+ }
+ // Move to next function.
+ i += coverage.FirstCtrOffset + int(nCtrs) - 1
+ }
+ }
+ return nil
+}
--- /dev/null
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package coverage
+
+import (
+ "fmt"
+ "internal/coverage"
+ "internal/goexperiment"
+ "internal/testenv"
+ "os"
+ "os/exec"
+ "path/filepath"
+ "strings"
+ "testing"
+)
+
+// Set to true for debugging (linux only).
+const fixedTestDir = false
+
+func TestCoverageApis(t *testing.T) {
+ if !goexperiment.CoverageRedesign {
+ t.Skipf("skipping new coverage tests (experiment not enabled)")
+ }
+ testenv.MustHaveGoBuild(t)
+ dir := t.TempDir()
+ if fixedTestDir {
+ dir = "/tmp/qqqzzz"
+ os.RemoveAll(dir)
+ mkdir(t, dir)
+ }
+
+ // Build harness.
+ bdir := mkdir(t, filepath.Join(dir, "build"))
+ hargs := []string{"-cover", "-coverpkg=all"}
+ if testing.CoverMode() != "" {
+ hargs = append(hargs, "-covermode="+testing.CoverMode())
+ }
+ harnessPath := buildHarness(t, bdir, hargs)
+
+ t.Logf("harness path is %s", harnessPath)
+
+ // Sub-tests for each API we want to inspect, plus
+ // extras for error testing.
+ t.Run("emitToDir", func(t *testing.T) {
+ t.Parallel()
+ testEmitToDir(t, harnessPath, dir)
+ })
+ t.Run("emitToWriter", func(t *testing.T) {
+ t.Parallel()
+ testEmitToWriter(t, harnessPath, dir)
+ })
+ t.Run("emitToNonexistentDir", func(t *testing.T) {
+ t.Parallel()
+ testEmitToNonexistentDir(t, harnessPath, dir)
+ })
+ t.Run("emitToNilWriter", func(t *testing.T) {
+ t.Parallel()
+ testEmitToNilWriter(t, harnessPath, dir)
+ })
+ t.Run("emitToFailingWriter", func(t *testing.T) {
+ t.Parallel()
+ testEmitToFailingWriter(t, harnessPath, dir)
+ })
+ t.Run("emitWithCounterClear", func(t *testing.T) {
+ t.Parallel()
+ testEmitWithCounterClear(t, harnessPath, dir)
+ })
+
+}
+
+// upmergeCoverData helps improve coverage data for this package
+// itself. If this test itself is being invoked with "-cover", then
+// what we'd like is for package coverage data (that is, coverage for
+// routines in "runtime/coverage") to be incorporated into the test
+// run from the "harness.exe" runs we've just done. We can accomplish
+// this by doing a merge from the harness gocoverdir's to the test
+// gocoverdir.
+func upmergeCoverData(t *testing.T, gocoverdir string) {
+ if testing.CoverMode() == "" {
+ return
+ }
+ testGoCoverDir := os.Getenv("GOCOVERDIR")
+ if testGoCoverDir == "" {
+ return
+ }
+ args := []string{"tool", "covdata", "merge", "-pkg=runtime/coverage",
+ "-o", testGoCoverDir, "-i", gocoverdir}
+ t.Logf("up-merge of covdata from %s to %s", gocoverdir, testGoCoverDir)
+ t.Logf("executing: go %+v", args)
+ cmd := exec.Command(testenv.GoToolPath(t), args...)
+ if b, err := cmd.CombinedOutput(); err != nil {
+ t.Fatalf("covdata merge failed (%v): %s", err, b)
+ }
+}
+
+// buildHarness builds the helper program "harness.exe".
+func buildHarness(t *testing.T, dir string, opts []string) string {
+ harnessPath := filepath.Join(dir, "harness.exe")
+ harnessSrc := filepath.Join("testdata", "harness.go")
+ args := []string{"build", "-o", harnessPath}
+ args = append(args, opts...)
+ args = append(args, harnessSrc)
+ //t.Logf("harness build: go %+v\n", args)
+ cmd := exec.Command(testenv.GoToolPath(t), args...)
+ if b, err := cmd.CombinedOutput(); err != nil {
+ t.Fatalf("build failed (%v): %s", err, b)
+ }
+ return harnessPath
+}
+
+func mkdir(t *testing.T, d string) string {
+ t.Helper()
+ if err := os.Mkdir(d, 0777); err != nil {
+ t.Fatalf("mkdir failed: %v", err)
+ }
+ return d
+}
+
+// updateGoCoverDir updates the specified environment 'env' to set
+// GOCOVERDIR to 'gcd' (if setGoCoverDir is TRUE) or removes
+// GOCOVERDIR from the environment (if setGoCoverDir is false).
+func updateGoCoverDir(env []string, gcd string, setGoCoverDir bool) []string {
+ rv := []string{}
+ found := false
+ for _, v := range env {
+ if strings.HasPrefix(v, "GOCOVERDIR=") {
+ if !setGoCoverDir {
+ continue
+ }
+ v = "GOCOVERDIR=" + gcd
+ found = true
+ }
+ rv = append(rv, v)
+ }
+ if !found && setGoCoverDir {
+ rv = append(rv, "GOCOVERDIR="+gcd)
+ }
+ return rv
+}
+
+func runHarness(t *testing.T, harnessPath string, tp string, setGoCoverDir bool, rdir, edir string) (string, error) {
+ t.Logf("running: %s -tp %s -o %s with rdir=%s and GOCOVERDIR=%v", harnessPath, tp, edir, rdir, setGoCoverDir)
+ cmd := exec.Command(harnessPath, "-tp", tp, "-o", edir)
+ cmd.Dir = rdir
+ cmd.Env = updateGoCoverDir(os.Environ(), rdir, setGoCoverDir)
+ b, err := cmd.CombinedOutput()
+ //t.Logf("harness run output: %s\n", string(b))
+ return string(b), err
+}
+
+func testForSpecificFunctions(t *testing.T, dir string, want []string, avoid []string) string {
+ args := []string{"tool", "covdata", "debugdump",
+ "-live", "-pkg=main", "-i=" + dir}
+ t.Logf("running: go %v\n", args)
+ cmd := exec.Command(testenv.GoToolPath(t), args...)
+ b, err := cmd.CombinedOutput()
+ if err != nil {
+ t.Fatalf("'go tool covdata failed (%v): %s", err, b)
+ }
+ output := string(b)
+ rval := ""
+ for _, f := range want {
+ wf := "Func: " + f
+ if strings.Contains(output, wf) {
+ continue
+ }
+ rval += fmt.Sprintf("error: output should contain %q but does not\n", wf)
+ }
+ for _, f := range avoid {
+ wf := "Func: " + f
+ if strings.Contains(output, wf) {
+ rval += fmt.Sprintf("error: output should not contain %q but does\n", wf)
+ }
+ }
+ return rval
+}
+
+func withAndWithoutRunner(f func(setit bool, tag string)) {
+ // Run 'f' with and without GOCOVERDIR set.
+ for i := 0; i < 2; i++ {
+ tag := "x"
+ setGoCoverDir := true
+ if i == 0 {
+ setGoCoverDir = false
+ tag = "y"
+ }
+ f(setGoCoverDir, tag)
+ }
+}
+
+func mktestdirs(t *testing.T, tag, tp, dir string) (string, string) {
+ t.Helper()
+ rdir := mkdir(t, filepath.Join(dir, tp+"-rdir-"+tag))
+ edir := mkdir(t, filepath.Join(dir, tp+"-edir-"+tag))
+ return rdir, edir
+}
+
+func testEmitToDir(t *testing.T, harnessPath string, dir string) {
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+ tp := "emitToDir"
+ rdir, edir := mktestdirs(t, tag, tp, dir)
+ output, err := runHarness(t, harnessPath, tp,
+ setGoCoverDir, rdir, edir)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp emitDir': %v", err)
+ }
+
+ // Just check to make sure meta-data file and counter data file were
+ // written. Another alternative would be to run "go tool covdata"
+ // or equivalent, but for now, this is what we've got.
+ dents, err := os.ReadDir(edir)
+ if err != nil {
+ t.Fatalf("os.ReadDir(%s) failed: %v", edir, err)
+ }
+ mfc := 0
+ cdc := 0
+ for _, e := range dents {
+ if e.IsDir() {
+ continue
+ }
+ if strings.HasPrefix(e.Name(), coverage.MetaFilePref) {
+ mfc++
+ } else if strings.HasPrefix(e.Name(), coverage.CounterFilePref) {
+ cdc++
+ }
+ }
+ wantmf := 1
+ wantcf := 1
+ if mfc != wantmf {
+ t.Errorf("EmitToDir: want %d meta-data files, got %d\n", wantmf, mfc)
+ }
+ if cdc != wantcf {
+ t.Errorf("EmitToDir: want %d counter-data files, got %d\n", wantcf, cdc)
+ }
+ upmergeCoverData(t, edir)
+ upmergeCoverData(t, rdir)
+ })
+}
+
+func testEmitToWriter(t *testing.T, harnessPath string, dir string) {
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+ tp := "emitToWriter"
+ rdir, edir := mktestdirs(t, tag, tp, dir)
+ output, err := runHarness(t, harnessPath, tp, setGoCoverDir, rdir, edir)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp %s': %v", tp, err)
+ }
+ want := []string{"main", tp}
+ avoid := []string{"final"}
+ if msg := testForSpecificFunctions(t, edir, want, avoid); msg != "" {
+ t.Errorf("coverage data from %q output match failed: %s", tp, msg)
+ }
+ upmergeCoverData(t, edir)
+ upmergeCoverData(t, rdir)
+ })
+}
+
+func testEmitToNonexistentDir(t *testing.T, harnessPath string, dir string) {
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+ tp := "emitToNonexistentDir"
+ rdir, edir := mktestdirs(t, tag, tp, dir)
+ output, err := runHarness(t, harnessPath, tp, setGoCoverDir, rdir, edir)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp %s': %v", tp, err)
+ }
+ upmergeCoverData(t, edir)
+ upmergeCoverData(t, rdir)
+ })
+}
+
+func testEmitToUnwritableDir(t *testing.T, harnessPath string, dir string) {
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+
+ tp := "emitToUnwritableDir"
+ rdir, edir := mktestdirs(t, tag, tp, dir)
+
+ // Make edir unwritable.
+ if err := os.Chmod(edir, 0555); err != nil {
+ t.Fatalf("chmod failed: %v", err)
+ }
+ defer os.Chmod(edir, 0777)
+
+ output, err := runHarness(t, harnessPath, tp, setGoCoverDir, rdir, edir)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp %s': %v", tp, err)
+ }
+ upmergeCoverData(t, edir)
+ upmergeCoverData(t, rdir)
+ })
+}
+
+func testEmitToNilWriter(t *testing.T, harnessPath string, dir string) {
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+ tp := "emitToNilWriter"
+ rdir, edir := mktestdirs(t, tag, tp, dir)
+ output, err := runHarness(t, harnessPath, tp, setGoCoverDir, rdir, edir)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp %s': %v", tp, err)
+ }
+ upmergeCoverData(t, edir)
+ upmergeCoverData(t, rdir)
+ })
+}
+
+func testEmitToFailingWriter(t *testing.T, harnessPath string, dir string) {
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+ tp := "emitToFailingWriter"
+ rdir, edir := mktestdirs(t, tag, tp, dir)
+ output, err := runHarness(t, harnessPath, tp, setGoCoverDir, rdir, edir)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp %s': %v", tp, err)
+ }
+ upmergeCoverData(t, edir)
+ upmergeCoverData(t, rdir)
+ })
+}
+
+func testEmitWithCounterClear(t *testing.T, harnessPath string, dir string) {
+ // Ensure that we have two versions of the harness: one built with
+ // -covermode=atomic and one built with -covermode=set (we need
+ // both modes to test all of the functionality).
+ var nonatomicHarnessPath, atomicHarnessPath string
+ if testing.CoverMode() != "atomic" {
+ nonatomicHarnessPath = harnessPath
+ bdir2 := mkdir(t, filepath.Join(dir, "build2"))
+ hargs := []string{"-covermode=atomic", "-coverpkg=all"}
+ atomicHarnessPath = buildHarness(t, bdir2, hargs)
+ } else {
+ atomicHarnessPath = harnessPath
+ mode := "set"
+ if testing.CoverMode() != "" && testing.CoverMode() != "atomic" {
+ mode = testing.CoverMode()
+ }
+ // Build a special nonatomic covermode version of the harness
+ // (we need both modes to test all of the functionality).
+ bdir2 := mkdir(t, filepath.Join(dir, "build2"))
+ hargs := []string{"-covermode=" + mode, "-coverpkg=all"}
+ nonatomicHarnessPath = buildHarness(t, bdir2, hargs)
+ }
+
+ withAndWithoutRunner(func(setGoCoverDir bool, tag string) {
+ // First a run with the nonatomic harness path, which we
+ // expect to fail.
+ tp := "emitWithCounterClear"
+ rdir1, edir1 := mktestdirs(t, tag, tp+"1", dir)
+ output, err := runHarness(t, nonatomicHarnessPath, tp,
+ setGoCoverDir, rdir1, edir1)
+ if err == nil {
+ t.Logf("%s", output)
+ t.Fatalf("running '%s -tp %s': unexpected success",
+ nonatomicHarnessPath, tp)
+ }
+
+ // Next a run with the atomic harness path, which we
+ // expect to succeed.
+ rdir2, edir2 := mktestdirs(t, tag, tp+"2", dir)
+ output, err = runHarness(t, atomicHarnessPath, tp,
+ setGoCoverDir, rdir2, edir2)
+ if err != nil {
+ t.Logf("%s", output)
+ t.Fatalf("running 'harness -tp %s': %v", tp, err)
+ }
+ want := []string{tp, "postClear"}
+ avoid := []string{"preClear", "main", "final"}
+ if msg := testForSpecificFunctions(t, edir2, want, avoid); msg != "" {
+ t.Logf("%s", output)
+ t.Errorf("coverage data from %q output match failed: %s", tp, msg)
+ }
+
+ if testing.CoverMode() == "atomic" {
+ upmergeCoverData(t, edir2)
+ upmergeCoverData(t, rdir2)
+ } else {
+ upmergeCoverData(t, edir1)
+ upmergeCoverData(t, rdir1)
+ }
+ })
+}
+
+func TestApisOnNocoverBinary(t *testing.T) {
+ testenv.MustHaveGoBuild(t)
+ dir := t.TempDir()
+
+ // Build harness with no -cover.
+ bdir := mkdir(t, filepath.Join(dir, "nocover"))
+ edir := mkdir(t, filepath.Join(dir, "emitDirNo"))
+ harnessPath := buildHarness(t, bdir, nil)
+ output, err := runHarness(t, harnessPath, "emitToDir", false, edir, edir)
+ if err == nil {
+ t.Fatalf("expected error on TestApisOnNocoverBinary harness run")
+ }
+ const want = "not built with -cover"
+ if !strings.Contains(output, want) {
+ t.Errorf("error output does not contain %q: %s", want, output)
+ }
+}
--- /dev/null
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+ "flag"
+ "fmt"
+ "internal/coverage/slicewriter"
+ "io"
+ "io/ioutil"
+ "log"
+ "path/filepath"
+ "runtime/coverage"
+ "strings"
+)
+
+var verbflag = flag.Int("v", 0, "Verbose trace output level")
+var testpointflag = flag.String("tp", "", "Testpoint to run")
+var outdirflag = flag.String("o", "", "Output dir into which to emit")
+
+func emitToWriter() {
+ log.SetPrefix("emitToWriter: ")
+ var slwm slicewriter.WriteSeeker
+ if err := coverage.EmitMetaDataToWriter(&slwm); err != nil {
+ log.Fatalf("error: EmitMetaDataToWriter returns %v", err)
+ }
+ mf := filepath.Join(*outdirflag, "covmeta.0abcdef")
+ if err := ioutil.WriteFile(mf, slwm.BytesWritten(), 0666); err != nil {
+ log.Fatalf("error: writing %s: %v", mf, err)
+ }
+ var slwc slicewriter.WriteSeeker
+ if err := coverage.EmitCounterDataToWriter(&slwc); err != nil {
+ log.Fatalf("error: EmitCounterDataToWriter returns %v", err)
+ }
+ cf := filepath.Join(*outdirflag, "covcounters.0abcdef.99.77")
+ if err := ioutil.WriteFile(cf, slwc.BytesWritten(), 0666); err != nil {
+ log.Fatalf("error: writing %s: %v", cf, err)
+ }
+}
+
+func emitToDir() {
+ log.SetPrefix("emitToDir: ")
+ if err := coverage.EmitMetaDataToDir(*outdirflag); err != nil {
+ log.Fatalf("error: EmitMetaDataToDir returns %v", err)
+ }
+ if err := coverage.EmitCounterDataToDir(*outdirflag); err != nil {
+ log.Fatalf("error: EmitCounterDataToDir returns %v", err)
+ }
+}
+
+func emitToNonexistentDir() {
+ log.SetPrefix("emitToNonexistentDir: ")
+
+ want := []string{
+ "no such file or directory", // linux-ish
+ "system cannot find the file specified", // windows
+ }
+
+ checkWant := func(which string, got string) {
+ found := false
+ for _, w := range want {
+ if strings.Contains(got, w) {
+ found = true
+ break
+ }
+ }
+ if !found {
+ log.Fatalf("%s emit to bad dir: got error:\n %v\nwanted error with one of:\n %+v", which, got, want)
+ }
+ }
+
+ // Mangle the output directory to produce something nonexistent.
+ mangled := *outdirflag + "_MANGLED"
+ if err := coverage.EmitMetaDataToDir(mangled); err == nil {
+ log.Fatal("expected error from EmitMetaDataToDir to nonexistent dir")
+ } else {
+ got := fmt.Sprintf("%v", err)
+ checkWant("meta data", got)
+ }
+
+ // Now try to emit counter data file to a bad dir.
+ if err := coverage.EmitCounterDataToDir(mangled); err == nil {
+ log.Fatal("expected error emitting counter data to bad dir")
+ } else {
+ got := fmt.Sprintf("%v", err)
+ checkWant("counter data", got)
+ }
+}
+
+func emitToUnwritableDir() {
+ log.SetPrefix("emitToUnwritableDir: ")
+
+ want := "permission denied"
+
+ if err := coverage.EmitMetaDataToDir(*outdirflag); err == nil {
+ log.Fatal("expected error from EmitMetaDataToDir to unwritable dir")
+ } else {
+ got := fmt.Sprintf("%v", err)
+ if !strings.Contains(got, want) {
+ log.Fatalf("meta-data emit to unwritable dir: wanted error containing %q got %q", want, got)
+ }
+ }
+
+ // Similarly with writing counter data.
+ if err := coverage.EmitCounterDataToDir(*outdirflag); err == nil {
+ log.Fatal("expected error emitting counter data to unwritable dir")
+ } else {
+ got := fmt.Sprintf("%v", err)
+ if !strings.Contains(got, want) {
+ log.Fatalf("emitting counter data to unwritable dir: wanted error containing %q got %q", want, got)
+ }
+ }
+}
+
+func emitToNilWriter() {
+ log.SetPrefix("emitToWriter: ")
+ want := "nil writer"
+ var bad io.WriteSeeker
+ if err := coverage.EmitMetaDataToWriter(bad); err == nil {
+ log.Fatal("expected error passing nil writer for meta emit")
+ } else {
+ got := fmt.Sprintf("%v", err)
+ if !strings.Contains(got, want) {
+ log.Fatalf("emitting meta-data passing nil writer: wanted error containing %q got %q", want, got)
+ }
+ }
+
+ if err := coverage.EmitCounterDataToWriter(bad); err == nil {
+ log.Fatal("expected error passing nil writer for counter emit")
+ } else {
+ got := fmt.Sprintf("%v", err)
+ if !strings.Contains(got, want) {
+ log.Fatalf("emitting counter data passing nil writer: wanted error containing %q got %q", want, got)
+ }
+ }
+}
+
+type failingWriter struct {
+ writeCount int
+ writeLimit int
+ slws slicewriter.WriteSeeker
+}
+
+func (f *failingWriter) Write(p []byte) (n int, err error) {
+ c := f.writeCount
+ f.writeCount++
+ if f.writeLimit < 0 || c < f.writeLimit {
+ return f.slws.Write(p)
+ }
+ return 0, fmt.Errorf("manufactured write error")
+}
+
+func (f *failingWriter) Seek(offset int64, whence int) (int64, error) {
+ return f.slws.Seek(offset, whence)
+}
+
+func (f *failingWriter) reset(lim int) {
+ f.writeCount = 0
+ f.writeLimit = lim
+ f.slws = slicewriter.WriteSeeker{}
+}
+
+func writeStressTest(tag string, testf func(testf *failingWriter) error) {
+ // Invoke the function initially without the write limit
+ // set, to capture the number of writes performed.
+ fw := &failingWriter{writeLimit: -1}
+ testf(fw)
+
+ // Now that we know how many writes are going to happen, run the
+ // function repeatedly, each time with a Write operation set to
+ // fail at a new spot. The goal here is to make sure that:
+ // A) an error is reported, and B) nothing crashes.
+ tot := fw.writeCount
+ for i := 0; i < tot; i++ {
+ fw.reset(i)
+ err := testf(fw)
+ if err == nil {
+ log.Fatalf("no error from write %d tag %s", i, tag)
+ }
+ }
+}
+
+func postClear() int {
+ return 42
+}
+
+func preClear() int {
+ return 42
+}
+
+// This test is designed to ensure that write errors are properly
+// handled by the code that writes out coverage data. It repeatedly
+// invokes the 'emit to writer' apis using a specially crafted writer
+// that captures the total number of expected writes, then replays the
+// execution N times with a manufactured write error at the
+// appropriate spot.
+func emitToFailingWriter() {
+ log.SetPrefix("emitToFailingWriter: ")
+
+ writeStressTest("emit-meta", func(f *failingWriter) error {
+ return coverage.EmitMetaDataToWriter(f)
+ })
+ writeStressTest("emit-counter", func(f *failingWriter) error {
+ return coverage.EmitCounterDataToWriter(f)
+ })
+}
+
+func emitWithCounterClear() {
+ log.SetPrefix("emitWitCounterClear: ")
+ preClear()
+ if err := coverage.ClearCoverageCounters(); err != nil {
+ log.Fatalf("clear failed: %v", err)
+ }
+ postClear()
+ if err := coverage.EmitMetaDataToDir(*outdirflag); err != nil {
+ log.Fatalf("error: EmitMetaDataToDir returns %v", err)
+ }
+ if err := coverage.EmitCounterDataToDir(*outdirflag); err != nil {
+ log.Fatalf("error: EmitCounterDataToDir returns %v", err)
+ }
+}
+
+func final() int {
+ println("I run last.")
+ return 43
+}
+
+func main() {
+ log.SetFlags(0)
+ flag.Parse()
+ if *testpointflag == "" {
+ log.Fatalf("error: no testpoint (use -tp flag)")
+ }
+ if *outdirflag == "" {
+ log.Fatalf("error: no output dir specified (use -o flag)")
+ }
+ switch *testpointflag {
+ case "emitToDir":
+ emitToDir()
+ case "emitToWriter":
+ emitToWriter()
+ case "emitToNonexistentDir":
+ emitToNonexistentDir()
+ case "emitToUnwritableDir":
+ emitToUnwritableDir()
+ case "emitToNilWriter":
+ emitToNilWriter()
+ case "emitToFailingWriter":
+ emitToFailingWriter()
+ case "emitWithCounterClear":
+ emitWithCounterClear()
+ default:
+ log.Fatalf("error: unknown testpoint %q", *testpointflag)
+ }
+ final()
+}