Merge intoverflow.h into qdefs.h

[xonotic/darkplaces.git] / qdefs.h

diff --git a/qdefs.h b/qdefs.h
index 4421ce1d1093447977d8f60e6435ce04d03523c3..5d0655f77f6e0b519bab330b08678166e20e639f 100644 (file)
--- a/qdefs.h
+++ b/qdefs.h
@@ -1,6 +1,10 @@
 #ifndef QDEFS_H
 #define QDEFS_H
 
+#if defined (__GNUC__) || defined (__clang__) || defined (__TINYC__)
+#define DP_GCC_COMPATIBLE
+#endif
+
 #if (__GNUC__ > 2) || defined (__clang__) || (__TINYC__)
 #define DP_FUNC_PRINTF(n) __attribute__ ((format (printf, n, n+1)))
 #define DP_FUNC_PURE      __attribute__ ((pure))
@@ -11,6 +15,12 @@
 #define DP_FUNC_NORETURN
 #endif
 
+#ifdef DP_GCC_COMPATIBLE
+#define Q_typeof(var) typeof(var)
+#elif defined (MSVC)
+#define Q_typeof(var) decltype(var)
+#endif
+
 #define MAX_NUM_ARGVS  50
 
 #ifdef DP_SMALLMEMORY
@@ -198,4 +208,22 @@
 #define INT_LOSSLESS_FORMAT_CONVERT_U(x) ((uintmax_t)(x))
 #endif
 
+// simple safe library to handle integer overflows when doing buffer size calculations
+// Usage:
+//   - calculate data size using INTOVERFLOW_??? macros
+//   - compare: calculated-size <= INTOVERFLOW_NORMALIZE(buffersize)
+// Functionality:
+//   - all overflows (values > INTOVERFLOW_MAX) and errors are mapped to INTOVERFLOW_MAX
+//   - if any input of an operation is INTOVERFLOW_MAX, INTOVERFLOW_MAX will be returned
+//   - otherwise, regular arithmetics apply
+
+#define INTOVERFLOW_MAX 2147483647
+
+#define INTOVERFLOW_ADD(a,b) (((a) < INTOVERFLOW_MAX && (b) < INTOVERFLOW_MAX && (a) < INTOVERFLOW_MAX - (b)) ? ((a) + (b)) : INTOVERFLOW_MAX)
+#define INTOVERFLOW_SUB(a,b) (((a) < INTOVERFLOW_MAX && (b) < INTOVERFLOW_MAX && (b) <= (a))                  ? ((a) - (b)) : INTOVERFLOW_MAX)
+#define INTOVERFLOW_MUL(a,b) (((a) < INTOVERFLOW_MAX && (b) < INTOVERFLOW_MAX && (a) < INTOVERFLOW_MAX / (b)) ? ((a) * (b)) : INTOVERFLOW_MAX)
+#define INTOVERFLOW_DIV(a,b) (((a) < INTOVERFLOW_MAX && (b) < INTOVERFLOW_MAX && (b) > 0)                     ? ((a) / (b)) : INTOVERFLOW_MAX)
+
+#define INTOVERFLOW_NORMALIZE(a) (((a) < INTOVERFLOW_MAX) ? (a) : (INTOVERFLOW_MAX - 1))
+
 #endif