Add support for searching the local directory

src/find_library.cpp

@@ -21,6 +21,7 @@
 #include <fstream>
 #include <sstream>
 #include <string>
+#include <filesystem>
 
 #include "rcutils/filesystem.h"
 #include "rcutils/get_env.h"
@@ -32,6 +33,7 @@ namespace
 {
 
 #ifdef _WIN32
+#include <windows.h>
 static constexpr char kPathVar[] = "PATH";
 static constexpr char kPathSeparator = ';';
 static constexpr char kSolibPrefix[] = "";
@@ -76,6 +78,19 @@ std::string find_library_path(const std::string & library_name)
   std::string search_path = get_env_var(kPathVar);
   std::list<std::string> search_paths = split(search_path, kPathSeparator);
 
+  #ifdef _WIN32
+  // Support current directory to enable containerized deployments, like Hololens.
+  DWORD len = GetCurrentDirectoryA(0, NULL) + 1;  // How much space is needed for current path?
+  char* currentDir = new char[len];
+  if (currentDir) {
+    if (GetCurrentDirectoryA(len, currentDir) > 0) {
+      search_paths.push_front(currentDir);
+    }
+
+    delete [] currentDir; // no longer needed.
+  }
+  #endif
+
   std::string filename = kSolibPrefix;
   filename += library_name + kSolibExtension;
 

test/test_find_library.cpp

@@ -19,15 +19,22 @@
 #include "gtest/gtest.h"
 
 #include "rcutils/get_env.h"
+#include "rcutils/filesystem.h"
 #include "rcpputils/find_library.hpp"
 
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
 namespace rcpputils
 {
 namespace
 {
 
 TEST(test_find_library, find_library)
 {
+  rcutils_allocator_t allocator = rcutils_get_default_allocator();
+
   // Get ground-truth values from CTest properties.
   std::string expected_library_path;
   {
@@ -67,6 +74,36 @@ TEST(test_find_library, find_library)
     "this_is_a_junk_libray_name_please_dont_define_this_if_you_do_then_"
     "you_are_really_naughty");
   EXPECT_EQ(bad_path, "");
+
+#ifdef _WIN32
+  // On Windows, test find library in the current directory, to support containerized deployments
+
+  const char* currentDir = rcutils_join_path(test_lib_dir, "test_current_path", allocator);
+  EXPECT_NE(currentDir, nullptr);
+
+  const char* testFile = rcutils_join_path(currentDir, "test_win_current_dir.dll", allocator);
+  EXPECT_NE(testFile, nullptr);
+
+  // move a file into the non-current path
+  EXPECT_NE(rcutils_mkdir(currentDir), false);
+  EXPECT_NE(CopyFile(test_lib_actual.c_str(), currentDir, FALSE), FALSE);
+
+  const std::string test_current_dir_fail = find_library_path("test_win_current_dir");
+  EXPECT_EQ(test_current_dir_fail.empty(), true);  // shouldn't be found until we set the current directory.
+
+  DWORD len = GetCurrentDirectoryA(0, NULL) + 1;  // How much space is needed for current path?
+  char* originalCurrentDir = new char[len];
+  GetCurrentDirectoryA(len, originalCurrentDir);
+
+  SetCurrentDirectory(currentDir);
+
+  const std::string test_current_dir_succeed = find_library_path("test_win_current_dir");
+  EXPECT_EQ(test_current_dir_succeed.empty(), false);
+
+  SetCurrentDirectory(currentDir);
+
+  delete [] originalCurrentDir;
+#endif
 }
 
 }  // namespace