Add a MakeSandbox factory function

The new `sapi::MakeSandbox` function simplifies the creation and initialization of Sandbox instances by returning a `absl::StatusOr<std::unique_ptr<SandboxT>>`. The stringop example is updated to demonstrate the use of this new factory function.

PiperOrigin-RevId: 909993578
Change-Id: I900ce6e708ae474bf4cc4e26c89c0060dd03a739

Author: cblichmann

sandboxed_api/examples/stringop/main_stringop.cc

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include <cstring>
+#include <memory>
 #include <string>
 
 #include "gmock/gmock.h"
@@ -67,9 +68,9 @@ TEST(StringopTest, ProtobufStringDuplication) {
 }
 
 TEST(StringopTest, ProtobufStringReversal) {
-  StringopSandbox sandbox;
-  ASSERT_THAT(sandbox.Init(), IsOk());
-  StringopApi api(&sandbox);
+  SAPI_ASSERT_OK_AND_ASSIGN(std::unique_ptr<StringopSandbox> sandbox,
+                            sapi::MakeSandbox<StringopSandbox>());
+  StringopApi api(sandbox.get());
 
   stringop::StringReverse proto;
   proto.set_input("Hello");
@@ -84,9 +85,9 @@ TEST(StringopTest, ProtobufStringReversal) {
 }
 
 TEST(StringopTest, RawStringDuplication) {
-  StringopSandbox sandbox;
-  ASSERT_THAT(sandbox.Init(), IsOk());
-  StringopApi api(&sandbox);
+  SAPI_ASSERT_OK_AND_ASSIGN(std::unique_ptr<StringopSandbox> sandbox,
+                            sapi::MakeSandbox<StringopSandbox>());
+  StringopApi api(sandbox.get());
 
   sapi::v::LenVal param("0123456789", 10);
   SAPI_ASSERT_OK_AND_ASSIGN(int return_value,
@@ -101,9 +102,9 @@ TEST(StringopTest, RawStringDuplication) {
 }
 
 TEST(StringopTest, RawStringReversal) {
-  StringopSandbox sandbox;
-  ASSERT_THAT(sandbox.Init(), IsOk());
-  StringopApi api(&sandbox);
+  SAPI_ASSERT_OK_AND_ASSIGN(std::unique_ptr<StringopSandbox> sandbox,
+                            sapi::MakeSandbox<StringopSandbox>());
+  StringopApi api(sandbox.get());
 
   sapi::v::LenVal param("0123456789", 10);
   {
@@ -121,7 +122,7 @@ TEST(StringopTest, RawStringReversal) {
   {
     // Let's call it again with different data as argument, reusing the
     // existing LenVal object.
-    EXPECT_THAT(param.ResizeData(sandbox.rpc_channel(), 16), IsOk());
+    EXPECT_THAT(param.ResizeData(sandbox->rpc_channel(), 16), IsOk());
     memcpy(param.GetData() + 10, "ABCDEF", 6);
     absl::string_view data(reinterpret_cast<const char*>(param.GetData()),
                            param.GetDataSize());
@@ -139,26 +140,27 @@ TEST(StringopTest, RawStringReversal) {
 }
 
 TEST(StringopTest, RawStringLength) {
-  StringopSandbox sandbox;
-  ASSERT_THAT(sandbox.Init(), IsOk());
-  StringopApi api(&sandbox);
+  SAPI_ASSERT_OK_AND_ASSIGN(std::unique_ptr<StringopSandbox> sandbox,
+                            sapi::MakeSandbox<StringopSandbox>());
+  StringopApi api(sandbox.get());
   SAPI_ASSERT_OK_AND_ASSIGN(void* target_mem_ptr, api.get_raw_c_string());
   SAPI_ASSERT_OK_AND_ASSIGN(size_t len,
-                            sandbox.rpc_channel()->Strlen(target_mem_ptr));
+                            sandbox->rpc_channel()->Strlen(target_mem_ptr));
   EXPECT_THAT(len, Eq(10));
 }
 
 TEST(StringopTest, RawStringReading) {
-  StringopSandbox sandbox;
-  ASSERT_THAT(sandbox.Init(), IsOk());
-  StringopApi api(&sandbox);
+  SAPI_ASSERT_OK_AND_ASSIGN(std::unique_ptr<StringopSandbox> sandbox,
+                            sapi::MakeSandbox<StringopSandbox>());
+  StringopApi api(sandbox.get());
   SAPI_ASSERT_OK_AND_ASSIGN(void* target_mem_ptr, api.get_raw_c_string());
   SAPI_ASSERT_OK_AND_ASSIGN(size_t len,
-                            sandbox.rpc_channel()->Strlen(target_mem_ptr));
+                            sandbox->rpc_channel()->Strlen(target_mem_ptr));
   EXPECT_THAT(len, Eq(10));
 
   SAPI_ASSERT_OK_AND_ASSIGN(
-      std::string data, sandbox.GetCString(sapi::v::RemotePtr(target_mem_ptr)));
+      std::string data,
+      sandbox->GetCString(sapi::v::RemotePtr(target_mem_ptr)));
   EXPECT_THAT(data, StrEq("Ten chars."));
 }
 

sandboxed_api/sandbox.h

@@ -20,6 +20,7 @@
 #include <initializer_list>
 #include <memory>
 #include <string>
+#include <type_traits>
 #include <utility>
 
 #include "absl/base/attributes.h"
@@ -33,12 +34,14 @@
 #include "sandboxed_api/rpcchannel.h"
 #include "sandboxed_api/sandbox2/notify.h"
 #include "sandboxed_api/sandbox_config.h"
+#include "sandboxed_api/util/status_macros.h"
 #include "sandboxed_api/var_abstract.h"
 #include "sandboxed_api/var_reg.h"
 #include "sandboxed_api/vars.h"
 
 namespace sapi {
 namespace internal {
+
 class PtrOrCallable {
  public:
   explicit PtrOrCallable(v::Callable* callable) : callable_(callable) {}
@@ -55,6 +58,7 @@ class PtrOrCallable {
   v::Callable* callable_ = nullptr;
   v::Ptr* ptr_ = nullptr;
 };
+
 }  // namespace internal
 
 // The Sandbox class represents the sandboxed library. It provides users with
@@ -227,6 +231,17 @@ template <typename Backend>
 using SandboxImpl [[deprecated("Use Sandbox instead")]] ABSL_REFACTOR_INLINE =
     Sandbox<Backend>;
 
+// Factory function that creates and initializes a new sandbox instance.
+// SandboxT must be a subclass of SandboxBase.
+template <typename SandboxT, class... Args>
+absl::StatusOr<std::unique_ptr<SandboxT>> MakeSandbox(Args&&... args) {
+  static_assert(std::is_base_of_v<SandboxBase, SandboxT>,
+                "SandboxT must be a subclass of SandboxBase");
+  auto sandbox = std::make_unique<SandboxT>(std::forward<Args>(args)...);
+  SAPI_RETURN_IF_ERROR(sandbox->Init());
+  return sandbox;
+}
+
 }  // namespace sapi
 
 #endif  // SANDBOXED_API_SANDBOX_H_