From 854f733c4931f8b227e940e2375bc5f99fbb11b0 Mon Sep 17 00:00:00 2001
From: Willi Goesgens <willi@arangodb.com>
Date: Wed, 21 Jan 2015 15:03:21 +0100
Subject: [PATCH] Exceptions:   - Assert that the associated errorcode has
 format options so if you call a THROW-macro with parameters these don't get
 lost unheard.   - Add new macro which offers format strings, so you can throw
 standard errors with custom messages.

---
 arangod/Utils/Exception.cpp | 34 ++++++++++++++++++++++++++++++++++
 arangod/Utils/Exception.h   | 17 +++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/arangod/Utils/Exception.cpp b/arangod/Utils/Exception.cpp
index a699010f61..94c376909c 100644
--- a/arangod/Utils/Exception.cpp
+++ b/arangod/Utils/Exception.cpp
@@ -117,6 +117,9 @@ char const* Exception::what () const throw () {
   return _errorMessage.c_str();
 }
 
+
+
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief construct an error message from a template string
 ////////////////////////////////////////////////////////////////////////////////
@@ -126,6 +129,11 @@ std::string Exception::FillExceptionString (int code,
   char const* format = TRI_errno_string(code);
   TRI_ASSERT(format != nullptr);
 
+#ifdef TRI_ENABLE_MAINTAINER_MODE
+  // Obviously the formatstring of the error code has to support parameters.
+  TRI_ASSERT(strchr(format, '%') != nullptr);
+#endif
+
   char buffer[1024];
   va_list ap;
   va_start(ap, code);
@@ -136,6 +144,32 @@ std::string Exception::FillExceptionString (int code,
   return std::string(buffer);
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief construct an error message from a template string
+////////////////////////////////////////////////////////////////////////////////
+        
+std::string Exception::FillFormatExceptionString (char const* format,
+                                                  ...) {
+  TRI_ASSERT(format != nullptr);
+
+#ifdef TRI_ENABLE_MAINTAINER_MODE
+  // Format #1 should come from the macro...
+  TRI_ASSERT(strchr(format, '%') != nullptr);
+  // Obviously the user has to give us a format string.
+  TRI_ASSERT(strchr(strchr(format, '%'), '%') != nullptr);
+#endif
+
+  char buffer[1024];
+  va_list ap;
+  va_start(ap, format);
+  vsnprintf(buffer, sizeof(buffer) - 1, format, ap);
+  va_end(ap);
+  buffer[sizeof(buffer) - 1] = '\0'; // Windows
+
+  return std::string(buffer);
+}
+
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief controls whether a backtrace is created for each exception
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/Utils/Exception.h b/arangod/Utils/Exception.h
index 2c1430097c..a4e8fa98fd 100644
--- a/arangod/Utils/Exception.h
+++ b/arangod/Utils/Exception.h
@@ -54,6 +54,21 @@
 #define THROW_ARANGO_EXCEPTION_PARAMS(code, ...)                               \
   throw triagens::arango::Exception(code, triagens::arango::Exception::FillExceptionString(code, __VA_ARGS__), __FILE__, __LINE__)
 
+
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief throws an arango exception with an error code and arbitrary 
+/// arguments (to be inserted in printf-style manner)
+////////////////////////////////////////////////////////////////////////////////
+
+#define THROW_ARANGO_EXCEPTION_FORMAT(code, format, ...)                 \
+  throw triagens::arango::Exception(code,                               \
+                                    triagens::arango::Exception::FillFormatExceptionString( \
+                                                                                           "%s: " format,\
+                                                                                           TRI_errno_string(code), \
+                                                                                           __VA_ARGS__),\
+                                    __FILE__, __LINE__)
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief throws an arango exception with an error code and an already-built
 /// error message
@@ -105,6 +120,8 @@ namespace triagens {
         }
 
         static std::string FillExceptionString (int, ...);
+        static std::string FillFormatExceptionString (char const * format,
+                                                      ...);
 
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief controls whether a backtrace is created for each exception