Avoid MSVC warnings about dead code in FFI layer

Also fix warning about "insecure" getenv

2 files changed, 29 insertions, 23 deletions

diff --git a/src/lib/utils/os_utils.cpp b/src/lib/utils/os_utils.cpp
index 72de063e8..b37c06d6e 100644
--- a/src/lib/utils/os_utils.cpp
+++ b/src/lib/utils/os_utils.cpp
@@ -384,21 +384,40 @@ size_t OS::get_memory_locking_limit()
    return 0;
    }
 
-const char* OS::read_env_variable(const std::string& name)
+bool OS::read_env_variable(std::string& value_out, const std::string& name)
    {
+   value_out = "";
+
    if(running_in_privileged_state())
-      return nullptr;
+      return false;
 
-   return std::getenv(name.c_str());
+#if defined(BOTAN_TARGET_OS_HAS_WIN32) && defined(BOTAN_BUILD_COMPILER_IS_MSVC)
+   char val[128] = { 0 };
+   size_t req_size = 0;
+   if(getenv_s(&req_size, val, sizeof(val), name.c_str()) == 0)
+      {
+      value_out = std::string(val, req_size);
+      return true;
+      }
+#else
+   if(const char* val = std::getenv(name.c_str()))
+      {
+      value_out = val;
+      return true;
+      }
+#endif
+
+   return false;
    }
 
 size_t OS::read_env_variable_sz(const std::string& name, size_t def)
    {
-   if(const char* env = read_env_variable(name))
+   std::string value;
+   if(read_env_variable(value, name))
       {
       try
          {
-         const size_t val = std::stoul(env, nullptr);
+         const size_t val = std::stoul(value, nullptr);
          return val;
          }
       catch(std::exception&) { /* ignore it */ }
@@ -614,19 +633,6 @@ int OS::run_cpu_instruction_probe(std::function<int ()> probe_fn)
    if(rc != 0)
       throw System_Error("run_cpu_instruction_probe sigaction restore failed", errno);
 
-#elif defined(BOTAN_TARGET_OS_IS_WINDOWS) && defined(BOTAN_TARGET_COMPILER_IS_MSVC)
-
-   // Windows SEH
-   __try
-      {
-      probe_result = probe_fn();
-      }
-   __except(::GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION ?
-            EXCEPTION_EXECUTE_HANDLER : EXCEPTION_CONTINUE_SEARCH)
-      {
-      probe_result = -1;
-      }
-
 #else
    BOTAN_UNUSED(probe_fn);
 #endif
diff --git a/src/lib/utils/os_utils.h b/src/lib/utils/os_utils.h
index 5b8c49f99..d31dcb3ba 100644
--- a/src/lib/utils/os_utils.h
+++ b/src/lib/utils/os_utils.h
@@ -95,12 +95,12 @@ size_t get_memory_locking_limit();
 size_t system_page_size();
 
 /**
-* Read the value of an environment variable. Return nullptr if
-* no such variable is set. If the process seems to be running in
-* a privileged state (such as setuid) then always returns nullptr,
-* similiar to glibc's secure_getenv.
+* Read the value of an environment variable, setting it to value_out if it
+* exists.  Returns false and sets value_out to empty string if no such variable
+* is set. If the process seems to be running in a privileged state (such as
+* setuid) then always returns false and does not examine the environment.
 */
-const char* read_env_variable(const std::string& var_name);
+bool read_env_variable(std::string& value_out, const std::string& var_name);
 
 /**
 * Read the value of an environment variable and convert it to an