misc: remove use of relative directories in overlayDir functions

It turns out that the relative-path support never worked in the first
place.

It had been masked by the fact that we ~never invoke overlayDir with
an absolute path, which caused filepath.Rel to always return an error,
and overlayDir to always fall back to absolute paths.

Since the absolute paths seem to be working fine (and are simpler),
let's stick with those. As far as I can recall, the relative paths
were only a space optimization anyway.

Updates #28387
Updates #30316

Change-Id: Ie8cd28f3c41ca6497ace2799f4193d7f5dde7a37
Reviewed-on: https://go-review.googlesource.com/c/go/+/208481
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

10 files changed, 39 insertions, 68 deletions

diff --git a/misc/cgo/life/overlaydir_test.go b/misc/cgo/life/overlaydir_test.go
index a25b125c7c..034c836248 100644
--- a/misc/cgo/life/overlaydir_test.go
+++ b/misc/cgo/life/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/stdio/overlaydir_test.go b/misc/cgo/stdio/overlaydir_test.go
index 5d6858f960..027ebf17c3 100644
--- a/misc/cgo/stdio/overlaydir_test.go
+++ b/misc/cgo/stdio/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/test/overlaydir_test.go b/misc/cgo/test/overlaydir_test.go
index cad9577ca1..f651979b65 100644
--- a/misc/cgo/test/overlaydir_test.go
+++ b/misc/cgo/test/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/testcarchive/overlaydir_test.go b/misc/cgo/testcarchive/overlaydir_test.go
index ee35dd50f7..67974c5ed8 100644
--- a/misc/cgo/testcarchive/overlaydir_test.go
+++ b/misc/cgo/testcarchive/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/testcshared/overlaydir_test.go b/misc/cgo/testcshared/overlaydir_test.go
index 0c23ec0c15..85d6b44eef 100644
--- a/misc/cgo/testcshared/overlaydir_test.go
+++ b/misc/cgo/testcshared/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/testplugin/overlaydir_test.go b/misc/cgo/testplugin/overlaydir_test.go
index ffb107cf8b..e2c32d83ce 100644
--- a/misc/cgo/testplugin/overlaydir_test.go
+++ b/misc/cgo/testplugin/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/testshared/overlaydir_test.go b/misc/cgo/testshared/overlaydir_test.go
index 3a7c9b04a0..eb587a2d44 100644
--- a/misc/cgo/testshared/overlaydir_test.go
+++ b/misc/cgo/testshared/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/testso/overlaydir_test.go b/misc/cgo/testso/overlaydir_test.go
index 91732d123d..09a1d512f1 100644
--- a/misc/cgo/testso/overlaydir_test.go
+++ b/misc/cgo/testso/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/cgo/testsovar/overlaydir_test.go b/misc/cgo/testsovar/overlaydir_test.go
index 91732d123d..09a1d512f1 100644
--- a/misc/cgo/testsovar/overlaydir_test.go
+++ b/misc/cgo/testsovar/overlaydir_test.go
@@ -21,12 +21,9 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	symBase, err := filepath.Rel(srcRoot, dstRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
-		symBase, err = filepath.Abs(srcRoot)
-		if err != nil {
-			return err
-		}
+		return err
 	}
 
 	return filepath.Walk(srcRoot, func(srcPath string, info os.FileInfo, err error) error {
@@ -52,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}
 
diff --git a/misc/reboot/overlaydir_test.go b/misc/reboot/overlaydir_test.go
index 6e77b2e97b..c446d0891c 100644
--- a/misc/reboot/overlaydir_test.go
+++ b/misc/reboot/overlaydir_test.go
@@ -21,9 +21,7 @@ func overlayDir(dstRoot, srcRoot string) error {
 		return err
 	}
 
-	// If we don't use the absolute path here, exec'ing make.bash fails with
-	// “too many levels of symbolic links”.
-	symBase, err := filepath.Abs(srcRoot)
+	srcRoot, err := filepath.Abs(srcRoot)
 	if err != nil {
 		return err
 	}
@@ -51,11 +49,11 @@ func overlayDir(dstRoot, srcRoot string) error {
 		// Always copy directories (don't symlink them).
 		// If we add a file in the overlay, we don't want to add it in the original.
 		if info.IsDir() {
-			return os.Mkdir(dstPath, perm|0200)
+			return os.MkdirAll(dstPath, perm|0200)
 		}
 
 		// If the OS supports symlinks, use them instead of copying bytes.
-		if err := os.Symlink(filepath.Join(symBase, suffix), dstPath); err == nil {
+		if err := os.Symlink(srcPath, dstPath); err == nil {
 			return nil
 		}