From: Willy Tarreau <w@1wt.eu>
Date: Fri, 25 Feb 2022 07:45:52 +0000 (+0100)
Subject: DEBUG: cleanup BUG_ON() configuration
X-Git-Tag: v2.6-dev2~9
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=be0dbba6ecda5c882ee4e0db4923f8a67e4a85e9;p=thirdparty%2Fhaproxy.git

DEBUG: cleanup BUG_ON() configuration

The BUG_ON() macro handling is complicated because it relies on a
conditional CRASH_NOW() macro whose definition depends on DEBUG_STRICT
and DEBUG_STRICT_NOCRASH. Let's rethink the whole thing differently,
and instead make the underlying _BUG_ON() macro take a crash argument
to decide whether to crash or not, as well as a prefix and a suffix for
the message, that will allow to distinguish between variants. Now the
suffix is set to a message explaining we don't crash when needed.
This also allows to get rid of the CRASH_NOW() macro and to define
much simpler new macros.
---

diff --git a/include/haproxy/bug.h b/include/haproxy/bug.h
index a360d5b1ab..ddf55e8057 100644
--- a/include/haproxy/bug.h
+++ b/include/haproxy/bug.h
@@ -50,29 +50,34 @@
 #define ABORT_NOW() do { DUMP_TRACE(); (*(volatile int*)1=0); } while (0)
 #endif
 
+/* This is the generic low-level macro dealing with conditional warnings and
+ * bugs. The caller decides whether to crash or not and what prefix and suffix
+ * to pass.
+ */
+#define _BUG_ON(cond, file, line, crash, pfx, sfx)			\
+	__BUG_ON(cond, file, line, crash, pfx, sfx)
+
+#define __BUG_ON(cond, file, line, crash, pfx, sfx)                     \
+	do {                                                            \
+		if (unlikely(cond)) {					\
+			const char msg[] = "\n" pfx "condition \"" #cond "\" matched at " file ":" #line "" sfx "\n"; \
+			DISGUISE(write(2, msg, __builtin_strlen(msg)));	\
+			if (crash)					\
+				ABORT_NOW();				\
+			else						\
+				DUMP_TRACE();				\
+		}							\
+	} while (0)
+
 /* BUG_ON: complains if <cond> is true when DEBUG_STRICT or DEBUG_STRICT_NOCRASH
  * are set, does nothing otherwise. With DEBUG_STRICT in addition it immediately
  * crashes using ABORT_NOW() above.
  */
-#if defined(DEBUG_STRICT) || defined(DEBUG_STRICT_NOCRASH)
 #if defined(DEBUG_STRICT)
-#define CRASH_NOW() ABORT_NOW()
-#else
-#define CRASH_NOW() do { DUMP_TRACE(); } while (0)
-#endif
-
-#define BUG_ON(cond) _BUG_ON(cond, __FILE__, __LINE__)
-#define _BUG_ON(cond, file, line) __BUG_ON(cond, file, line)
-#define __BUG_ON(cond, file, line)                                             \
-	do {                                                                   \
-		if (unlikely(cond)) {					       \
-			const char msg[] = "\nFATAL: bug condition \"" #cond "\" matched at " file ":" #line "\n"; \
-			DISGUISE(write(2, msg, __builtin_strlen(msg)));        \
-			CRASH_NOW();                                           \
-		}                                                              \
-	} while (0)
+#define BUG_ON(cond) _BUG_ON(cond, __FILE__, __LINE__, 1, "FATAL: bug ", "")
+#elif defined(DEBUG_STRICT_NOCRASH)
+#define BUG_ON(cond) _BUG_ON(cond, __FILE__, __LINE__, 0, "FATAL: bug ", " (not crashing but process is untrusted now)")
 #else
-#undef CRASH_NOW
 #define BUG_ON(cond)
 #endif