whatcanGOwrong

go/pkg/mod/mvdan.cc/gofumpt@v0.7.0/ulimit_linux_test.go

@@ -0,0 +1,91 @@
+// Copyright (c) 2019, Daniel Martí <mvdan@mvdan.cc>
+// See LICENSE for licensing information
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"testing"
+
+	"github.com/go-quicktest/qt"
+	"golang.org/x/sys/unix"
+)
+
+func init() {
+	// Here rather than in TestMain, to reuse the unix build tag.
+	if limit := os.Getenv("TEST_WITH_FILE_LIMIT"); limit != "" {
+		n, err := strconv.ParseUint(limit, 10, 64)
+		if err != nil {
+			panic(err)
+		}
+		rlimit := unix.Rlimit{Cur: n, Max: n}
+		if err := unix.Setrlimit(unix.RLIMIT_NOFILE, &rlimit); err != nil {
+			panic(err)
+		}
+		os.Exit(main1())
+	}
+}
+
+func TestWithLowOpenFileLimit(t *testing.T) {
+	// Safe to run in parallel, as we only change the limit for child processes.
+	t.Parallel()
+
+	tempDir := t.TempDir()
+	testBinary, err := os.Executable()
+	qt.Assert(t, qt.IsNil(err))
+
+	const (
+		// Enough directories to run into the ulimit.
+		// Enough number of files in total to run into the ulimit.
+		numberDirs        = 500
+		numberFilesPerDir = 20
+		numberFilesTotal  = numberDirs * numberFilesPerDir
+	)
+	t.Logf("writing %d tiny Go files", numberFilesTotal)
+	var allGoFiles []string
+	for i := 0; i < numberDirs; i++ {
+		// Prefix "p", so the package name is a valid identifier.
+		// Add one go.mod file per directory as well,
+		// which will help catch data races when loading module info.
+		dirName := fmt.Sprintf("p%03d", i)
+		dirPath := filepath.Join(tempDir, dirName)
+		err := os.MkdirAll(dirPath, 0o777)
+		qt.Assert(t, qt.IsNil(err))
+
+		err = os.WriteFile(filepath.Join(dirPath, "go.mod"),
+			[]byte(fmt.Sprintf("module %s\n\ngo 1.16", dirName)), 0o666)
+		qt.Assert(t, qt.IsNil(err))
+
+		for j := 0; j < numberFilesPerDir; j++ {
+			filePath := filepath.Join(dirPath, fmt.Sprintf("%03d.go", j))
+			err := os.WriteFile(filePath,
+				// Extra newlines so that "-l" prints all paths.
+				[]byte(fmt.Sprintf("package %s\n\n\n", dirName)), 0o666)
+			qt.Assert(t, qt.IsNil(err))
+			allGoFiles = append(allGoFiles, filePath)
+		}
+	}
+	if len(allGoFiles) != numberFilesTotal {
+		panic("allGoFiles doesn't have the expected number of files?")
+	}
+	runGofmt := func(paths ...string) {
+		t.Logf("running with %d paths", len(paths))
+		cmd := exec.Command(testBinary, append([]string{"-l"}, paths...)...)
+		// 256 is a relatively common low limit, e.g. on Mac.
+		cmd.Env = append(os.Environ(), "TEST_WITH_FILE_LIMIT=256")
+		out, err := cmd.Output()
+		var stderr []byte
+		if err, _ := err.(*exec.ExitError); err != nil {
+			stderr = err.Stderr
+		}
+		qt.Assert(t, qt.IsNil(err), qt.Commentf("stderr:\n%s", stderr))
+		qt.Assert(t, qt.Equals(bytes.Count(out, []byte("\n")), len(allGoFiles)))
+	}
+	runGofmt(tempDir)
+	runGofmt(allGoFiles...)
+}