Add OS::read_env_variable

Combines the priv check and the getenv call on one.

3 files changed, 22 insertions, 9 deletions

diff --git a/src/lib/ffi/ffi.cpp b/src/lib/ffi/ffi.cpp
index cfc2cb2d5..b0c1f6e71 100644
--- a/src/lib/ffi/ffi.cpp
+++ b/src/lib/ffi/ffi.cpp
@@ -18,7 +18,7 @@ namespace Botan_FFI {
 
 int ffi_error_exception_thrown(const char* func_name, const char* exn, int rc)
    {
-   if(Botan::OS::running_in_privileged_state() == false && std::getenv("BOTAN_FFI_PRINT_EXCEPTIONS") != nullptr)
+   if(Botan::OS::read_env_variable("BOTAN_FFI_PRINT_EXCEPTIONS") != nullptr)
       {
       std::fprintf(stderr, "in %s exception '%s' returning %d\n", func_name, exn, rc);
       }
diff --git a/src/lib/utils/os_utils.cpp b/src/lib/utils/os_utils.cpp
index 265d4aac2..e5267cad6 100644
--- a/src/lib/utils/os_utils.cpp
+++ b/src/lib/utils/os_utils.cpp
@@ -267,17 +267,14 @@ size_t OS::get_memory_locking_limit()
    /*
    * Allow override via env variable
    */
-   if(OS::running_in_privileged_state() == false)
+   if(const char* env = read_env_variable("BOTAN_MLOCK_POOL_SIZE"))
       {
-      if(const char* env = std::getenv("BOTAN_MLOCK_POOL_SIZE"))
+      try
          {
-         try
-            {
-            const size_t user_req = std::stoul(env, nullptr);
-            mlock_requested = std::min(user_req, mlock_requested);
-            }
-         catch(std::exception&) { /* ignore it */ }
+         const size_t user_req = std::stoul(env, nullptr);
+         mlock_requested = std::min(user_req, mlock_requested);
          }
+      catch(std::exception&) { /* ignore it */ }
       }
 
    if(mlock_requested > 0)
@@ -328,6 +325,14 @@ size_t OS::get_memory_locking_limit()
    return 0;
    }
 
+const char* OS::read_env_variable(const std::string& name)
+   {
+   if(running_in_privileged_state())
+      return nullptr;
+
+   return std::getenv(name.c_str());
+   }
+
 void* OS::allocate_locked_pages(size_t length)
    {
 #if defined(BOTAN_TARGET_OS_HAS_POSIX1) && defined(BOTAN_TARGET_OS_HAS_POSIX_MLOCK)
diff --git a/src/lib/utils/os_utils.h b/src/lib/utils/os_utils.h
index 24cbdd5a3..a6044dd18 100644
--- a/src/lib/utils/os_utils.h
+++ b/src/lib/utils/os_utils.h
@@ -80,6 +80,14 @@ 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.
+*/
+const char* read_env_variable(const std::string& var_name);
+
+/**
 * Request so many bytes of page-aligned RAM locked into memory using
 * mlock, VirtualLock, or similar. Returns null on failure. The memory
 * returned is zeroed. Free it with free_locked_pages.