From 4df6b1ec2f27d0dded28ecc7cde5d12f57e144d9 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Mon, 29 Jun 2015 11:53:51 -0400
Subject: [PATCH] path/filepath: document and test behavior of SkipDir on files
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This behavior is not what we might have designed from the start,
but it has been present since Go 1. Rather than make a visible
behavioral change that might cause programs to work differently
in Go ≤1.4 vs Go ≥1.5, document what SkipDir on a non-directory
has always meant. If code doesn't want this meaning, it is easy
enough not to return SkipDir on non-directories.

Fixes #10533.

Change-Id: Ic0612f032044bc7c69bf62583a02037e4b47530b
Reviewed-on: https://go-review.googlesource.com/11690
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
---
 src/path/filepath/path.go      |  9 +++++----
 src/path/filepath/path_test.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/path/filepath/path.go b/src/path/filepath/path.go
index f9b041bd46..5dc5cfd49e 100644
--- a/src/path/filepath/path.go
+++ b/src/path/filepath/path.go
@@ -335,10 +335,11 @@ var SkipDir = errors.New("skip this directory")
 // If there was a problem walking to the file or directory named by path, the
 // incoming error will describe the problem and the function can decide how
 // to handle that error (and Walk will not descend into that directory). If
-// an error is returned, processing stops. The sole exception is that if path
-// is a directory and the function returns the special value SkipDir, the
-// contents of the directory are skipped and processing continues as usual on
-// the next file.
+// an error is returned, processing stops. The sole exception is when the function
+// returns the special value SkipDir. If the function returns SkipDir when invoked
+// on a directory, Walk skips the directory's contents entirely.
+// If the function returns SkipDir when invoked on a non-directory file,
+// Walk skips the remaining files in the containing directory.
 type WalkFunc func(path string, info os.FileInfo, err error) error
 
 var lstat = os.Lstat // for testing
diff --git a/src/path/filepath/path_test.go b/src/path/filepath/path_test.go
index 4ecaada983..91b6493c51 100644
--- a/src/path/filepath/path_test.go
+++ b/src/path/filepath/path_test.go
@@ -510,6 +510,35 @@ func touch(t *testing.T, name string) {
 	}
 }
 
+func TestWalkSkipDirOnFile(t *testing.T) {
+	td, err := ioutil.TempDir("", "walktest")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(td)
+
+	if err := os.MkdirAll(filepath.Join(td, "dir"), 0755); err != nil {
+		t.Fatal(err)
+	}
+	touch(t, filepath.Join(td, "dir/foo1"))
+	touch(t, filepath.Join(td, "dir/foo2"))
+
+	sawFoo2 := false
+	filepath.Walk(td, func(path string, info os.FileInfo, err error) error {
+		if strings.HasSuffix(path, "foo2") {
+			sawFoo2 = true
+		}
+		if strings.HasSuffix(path, "foo1") {
+			return filepath.SkipDir
+		}
+		return nil
+	})
+
+	if sawFoo2 {
+		t.Errorf("SkipDir on file foo1 did not block processing of foo2")
+	}
+}
+
 func TestWalkFileError(t *testing.T) {
 	td, err := ioutil.TempDir("", "walktest")
 	if err != nil {