Make FindFiles ignore (trivial) errors (#217)

Fixes #99

Author: mahadzaryab1

script.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"hash"
 	"io"
+	"io/fs"
 	"math"
 	"net/http"
 	"os"
@@ -76,8 +77,9 @@ func File(path string) *Pipe {
 }
 
 // FindFiles creates a pipe listing all the files in the directory dir and its
-// subdirectories recursively, one per line, like Unix find(1). If dir doesn't
-// exist or can't be read, the pipe's error status will be set.
+// subdirectories recursively, one per line, like Unix find(1).
+// Errors are ignored unless no files are found (in which case the pipe's error
+// status will be set to the last error encountered).
 //
 // Each line of the output consists of a slash-separated path, starting with
 // the initial directory. For example, if the directory looks like this:
@@ -92,17 +94,19 @@ func File(path string) *Pipe {
 //	test/2.txt
 func FindFiles(dir string) *Pipe {
 	var paths []string
-	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+	var innerErr error
+	fs.WalkDir(os.DirFS(dir), ".", func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
-			return err
+			innerErr = err
+			return fs.SkipDir
 		}
-		if !info.IsDir() {
-			paths = append(paths, path)
+		if !d.IsDir() {
+			paths = append(paths, filepath.Join(dir, path))
 		}
 		return nil
 	})
-	if err != nil {
-		return NewPipe().WithError(err)
+	if innerErr != nil && len(paths) == 0 {
+		return NewPipe().WithError(innerErr)
 	}
 	return Slice(paths)
 }

script_unix_test.go

@@ -3,6 +3,8 @@
 package script_test
 
 import (
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/bitfield/script"
@@ -106,6 +108,30 @@ func TestExecPipesDataToExternalCommandAndGetsExpectedOutput(t *testing.T) {
 	}
 }
 
+func TestFindFiles_DoesNotErrorWhenSubDirectoryIsNotReadable(t *testing.T) {
+	t.Parallel()
+	tmpDir := t.TempDir()
+	restrictedDirPath := filepath.Join(tmpDir, "a_restricted_dir")
+	if err := os.Mkdir(restrictedDirPath, 0o000); err != nil {
+		t.Fatal(err)
+	}
+	fileAPath := filepath.Join(tmpDir, "file_a.txt")
+	if err := os.WriteFile(fileAPath, []byte("hello world!"), os.ModePerm); err != nil {
+		t.Fatal(err)
+	}
+	got, err := script.FindFiles(tmpDir).String()
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := fileAPath + "\n"
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !cmp.Equal(want, got) {
+		t.Fatal(cmp.Diff(want, got))
+	}
+}
+
 func ExampleExec_ok() {
 	script.Exec("echo Hello, world!").Stdout()
 	// Output: