Code to complete executables in PATH

tools/completion/files.go

@@ -8,6 +8,8 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"golang.org/x/sys/unix"
 )
 
 var _ = fmt.Print
@@ -54,3 +56,21 @@ func complete_files(prefix string, callback CompleteFilesCallback) error {
 
 	return nil
 }
+
+func complete_executables_in_path(prefix string, paths ...string) []string {
+	ans := make([]string, 0, 1024)
+	if len(paths) == 0 {
+		paths = filepath.SplitList(os.Getenv("PATH"))
+	}
+	for _, dir := range paths {
+		entries, err := os.ReadDir(dir)
+		if err == nil {
+			for _, e := range entries {
+				if strings.HasPrefix(e.Name(), prefix) && !e.IsDir() && unix.Access(filepath.Join(dir, e.Name()), unix.X_OK) == nil {
+					ans = append(ans, e.Name())
+				}
+			}
+		}
+	}
+	return ans
+}

tools/completion/files_test.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"reflect"
 	"sort"
+	"strings"
 	"testing"
 )
 
@@ -19,11 +20,16 @@ func TestCompleteFiles(t *testing.T) {
 		defer os.Chdir(cwd)
 	}
 	os.Chdir(tdir)
-	os.Create(filepath.Join(tdir, "one.txt"))
-	os.Create(filepath.Join(tdir, "two.txt"))
+
+	create := func(parts ...string) {
+		f, _ := os.Create(filepath.Join(tdir, filepath.Join(parts...)))
+		f.Close()
+	}
+	create("one.txt")
+	create("two.txt")
 	os.Mkdir(filepath.Join(tdir, "odir"), 0700)
-	os.Create(filepath.Join(tdir, "odir", "three.txt"))
-	os.Create(filepath.Join(tdir, "odir", "four.txt"))
+	create("odir", "three.txt")
+	create("odir", "four.txt")
 
 	test_candidates := func(prefix string, expected ...string) {
 		if expected == nil {
@@ -77,3 +83,36 @@ func TestCompleteFiles(t *testing.T) {
 	test_candidates("x")
 
 }
+
+func TestCompleteExecutables(t *testing.T) {
+	tdir := t.TempDir()
+	create := func(base string, name string, mode os.FileMode) {
+		f, _ := os.OpenFile(filepath.Join(tdir, base, name), os.O_CREATE, mode)
+		f.Close()
+	}
+	os.Mkdir(filepath.Join(tdir, "one"), 0700)
+	os.Mkdir(filepath.Join(tdir, "two"), 0700)
+
+	create("", "not-in-path", 0700)
+	create("one", "one-exec", 0700)
+	create("one", "one-not-exec", 0600)
+	create("two", "two-exec", 0700)
+	os.Symlink(filepath.Join(tdir, "two", "two-exec"), filepath.Join(tdir, "one", "s"))
+	os.Symlink(filepath.Join(tdir, "one", "one-not-exec"), filepath.Join(tdir, "one", "n"))
+
+	t.Setenv("PATH", strings.Join([]string{filepath.Join(tdir, "one"), filepath.Join(tdir, "two")}, string(os.PathListSeparator)))
+	test_candidates := func(prefix string, expected ...string) {
+		if expected == nil {
+			expected = make([]string, 0)
+		}
+		actual := complete_executables_in_path(prefix)
+		sort.Strings(expected)
+		sort.Strings(actual)
+		if !reflect.DeepEqual(expected, actual) {
+			t.Fatalf("Did not get expected completion candidates for prefix: %#v\nExpected: %#v\nActual:   %#v", prefix, expected, actual)
+		}
+	}
+	test_candidates("", "one-exec", "two-exec", "s")
+	test_candidates("o", "one-exec")
+	test_candidates("x")
+}