syscall: Fix Getwd on Windows to correctly handle long paths.

Fixes #60051.

Change-Id: Ia68ca0493912cb09d8c1d36a144bf0725842af1d
Reviewed-on: https://go-review.googlesource.com/c/go/+/502415
Auto-Submit: Bryan Mills <bcmills@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/src/syscall/syscall_windows_test.go b/src/syscall/syscall_windows_test.go
index 7b31a863c3..81285e9a38 100644
--- a/src/syscall/syscall_windows_test.go
+++ b/src/syscall/syscall_windows_test.go
@@ -180,6 +180,30 @@ int main(int argc, char *argv[])
 	}
 }
 
+func TestGetwd_DoesNotPanicWhenPathIsLong(t *testing.T) {
+	// Regression test for https://github.com/golang/go/issues/60051.
+
+	// The length of a filename is also limited, so we can't reproduce the
+	// crash by creating a single directory with a very long name; we need two
+	// layers.
+	a200 := strings.Repeat("a", 200)
+	dirname := filepath.Join(t.TempDir(), a200, a200)
+
+	err := os.MkdirAll(dirname, 0o700)
+	if err != nil {
+		t.Skipf("MkdirAll failed: %v", err)
+	}
+	err = os.Chdir(dirname)
+	if err != nil {
+		t.Skipf("Chdir failed: %v", err)
+	}
+	// Change out of the temporary directory so that we don't inhibit its
+	// removal during test cleanup.
+	defer os.Chdir(`\`)
+
+	syscall.Getwd()
+}
+
 func FuzzUTF16FromString(f *testing.F) {
 	f.Add("hi")           // ASCII
 	f.Add("â")            // latin1