Add printf like behaviour to assert

1 files changed, 46 insertions, 6 deletions

diff --git a/arch/x86_64/include/arch/exception_handling/assert.hpp b/arch/x86_64/include/arch/exception_handling/assert.hpp
index f355a61..152e653 100644
--- a/arch/x86_64/include/arch/exception_handling/assert.hpp
+++ b/arch/x86_64/include/arch/exception_handling/assert.hpp
@@ -1,16 +1,56 @@
 #ifndef TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_ASSERT_HPP
 #define TEACHOS_ARCH_X86_64_EXCEPTION_HANDLING_ASSERT_HPP
 
+#include "arch/exception_handling/panic.hpp"
+
+#include <stdio.h>
+
 namespace teachos::arch::exception_handling
 {
+  namespace
+  {
+    char constexpr FAILED_MESSAGE[] = "Invalid arguments passed to format specifiers (%) in exception_handling::assert";
+  }
+
   /**
-   * @brief assert a condition to be true, if not do not continue
-   * execution of the code and print message to screen
+   * @brief Assert a condition to be true, if not do not continue
+   * execution of the code and print the formatted message to screen.
    *
-   * @param condition
-   * @param message
+   * @param condition Condition we want to be true.
+   * @param format Formatting message that the given arguments will be inserted into.
+   * @param ...args Arguments that will be formatted and inserted into the resulting string, replacing their respective
+   * specifiers. Uses the printf specifiers see https://cplusplus.com/reference/cstdio/printf/ for more information.
    */
-  auto assert(bool condition, char const * message) -> void;
+  template<typename... Args>
+  auto assert(bool condition, char const * format, Args const &... args) -> void
+  {
+    if (condition)
+    {
+      return;
+    }
+    else if constexpr (sizeof...(args) == 0)
+    {
+      panic("Assertion Violation: ", format);
+    }
+
+    // Result is what would have been written if the passed buffer would have been large enough not counting null
+    // character, or if an error occured while creating the string a negative number is returned instead. To ensure this
+    // will not crash the system when creating an array with negative size we assert beforehand with a clear error
+    // message.
+    int const size = snprintf(nullptr, 0U, format, args...) + 1U;
+    if (size < 0)
+    {
+      panic("Assertion Violation: ", FAILED_MESSAGE);
+    }
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wvla"
+    char arguments[size] = {};
+#pragma GCC diagnostic pop
+    int const written_characters = snprintf(arguments, size, format, args...);
+    // Written characters is expected to be one less, because of the null termination character.
+    bool const result = (written_characters == (size - 1));
+    panic("Assertion Violation: ", result ? arguments : FAILED_MESSAGE);
+  }
 }  // namespace teachos::arch::exception_handling
 
-#endif
\ No newline at end of file
+#endif