bp2build: add support for planting unresolved symlinks in the symlink forest.

In the isDir check, there's a possibility that the Stat check fails
because the path is an unresolved symlink. Verify it with Lstat (which
would succeed, since it doesn't follow links), and treat it like a file
if Lstat succeeds.

Test: new integration test
Fixes: 232370097
Change-Id: I9807ca363a5dbdc20639b489b54627bd2cc1ca60

bp2build/symlink_forest.go

@@ -95,13 +95,19 @@ func isDir(path string, fi os.FileInfo) bool {
 		return fi.IsDir()
 	}
 
-	fi2, err := os.Stat(path)
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "Cannot stat '%s': %s\n", path, err)
+	fi2, statErr := os.Stat(path)
+	if statErr == nil {
+		return fi2.IsDir()
+	}
+
+	// Check if this is a dangling symlink. If so, treat it like a file, not a dir.
+	_, lstatErr := os.Lstat(path)
+	if lstatErr != nil {
+		fmt.Fprintf(os.Stderr, "Cannot stat or lstat '%s': %s\n%s\n", path, statErr, lstatErr)
 		os.Exit(1)
 	}
 
-	return fi2.IsDir()
+	return false
 }
 
 // Recursively plants a symlink forest at forestDir. The symlink tree will

tests/bp2build_bazel_test.sh

@@ -169,3 +169,29 @@ EOF
 }
 
 test_cc_correctness
+
+# Regression test for the following failure during symlink forest creation:
+#
+#   Cannot stat '/tmp/st.rr054/foo/bar/unresolved_symlink': stat /tmp/st.rr054/foo/bar/unresolved_symlink: no such file or directory
+#
+function test_bp2build_null_build_with_unresolved_symlink_in_source() {
+  setup
+
+  mkdir -p foo/bar
+  ln -s /tmp/non-existent foo/bar/unresolved_symlink
+  cat > foo/bar/Android.bp <<'EOF'
+filegroup {
+    name: "fg",
+    srcs: ["unresolved_symlink/non-existent-file.txt"],
+  }
+EOF
+
+  run_soong bp2build
+
+  dest=$(readlink -f out/soong/workspace/foo/bar/unresolved_symlink)
+  if [[ "$dest" != "/tmp/non-existent" ]]; then
+    fail "expected to plant an unresolved symlink out/soong/workspace/foo/bar/unresolved_symlink that resolves to /tmp/non-existent"
+  fi
+}
+
+test_bp2build_null_build_with_unresolved_symlink_in_source

tests/lib.sh

@@ -127,6 +127,10 @@ function create_mock_bazel() {
 }
 
 run_bazel() {
+  # Remove the ninja_build output marker file to communicate to buildbot that this is not a regular Ninja build, and its
+  # output should not be parsed as such.
+  rm -rf out/ninja_build
+
   tools/bazel "$@"
 }