[sanitizer] Improve VSNPrintf internal diagnostics

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h

@@ -292,14 +292,16 @@ void NORETURN CheckFailed(const char *file, int line, const char *cond,
                           u64 v1, u64 v2);
 
 // Check macro
-#define RAW_CHECK_MSG(expr, msg) do { \
-  if (UNLIKELY(!(expr))) { \
-    RawWrite(msg); \
-    Die(); \
-  } \
-} while (0)
+#define RAW_CHECK_MSG(expr, msg, ...)          \
+  do {                                         \
+    if (UNLIKELY(!(expr))) {                   \
+      const char* msgs[] = {msg, __VA_ARGS__}; \
+      for (const char* m : msgs) RawWrite(m);  \
+      Die();                                   \
+    }                                          \
+  } while (0)
 
-#define RAW_CHECK(expr) RAW_CHECK_MSG(expr, #expr)
+#define RAW_CHECK(expr, ...) RAW_CHECK_MSG(expr, #expr "\n", __VA_ARGS__)
 
 #define CHECK_IMPL(c1, op, c2) \
   do { \

compiler-rt/lib/sanitizer_common/sanitizer_printf.cpp

@@ -129,7 +129,7 @@ int VSNPrintf(char *buff, int buff_length,
               const char *format, va_list args) {
   static const char *kPrintfFormatsHelp =
       "Supported Printf formats: %([0-9]*)?(z|l|ll)?{d,u,x,X}; %p; "
-      "%[-]([0-9]*)?(\\.\\*)?s; %c\n";
+      "%[-]([0-9]*)?(\\.\\*)?s; %c\nProvided format: ";
   RAW_CHECK(format);
   RAW_CHECK(buff_length > 0);
   const char *buff_end = &buff[buff_length - 1];
@@ -191,30 +191,30 @@ int VSNPrintf(char *buff, int buff_length,
         break;
       }
       case 'p': {
-        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
+        RAW_CHECK(!have_flags, kPrintfFormatsHelp, format);
         result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
         break;
       }
       case 's': {
-        RAW_CHECK_MSG(!have_length, kPrintfFormatsHelp);
+        RAW_CHECK(!have_length, kPrintfFormatsHelp, format);
         // Only left-justified width is supported.
         CHECK(!have_width || left_justified);
         result += AppendString(&buff, buff_end, left_justified ? -width : width,
                                precision, va_arg(args, char*));
         break;
       }
       case 'c': {
-        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
+        RAW_CHECK(!have_flags, kPrintfFormatsHelp, format);
         result += AppendChar(&buff, buff_end, va_arg(args, int));
         break;
       }
       case '%' : {
-        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
+        RAW_CHECK(!have_flags, kPrintfFormatsHelp, format);
         result += AppendChar(&buff, buff_end, '%');
         break;
       }
       default: {
-        RAW_CHECK_MSG(false, kPrintfFormatsHelp);
+        RAW_CHECK(false, kPrintfFormatsHelp, format);
       }
     }
   }