Suppress UBSan warnings from EXTRACT_.

Yes, the behavior of an access with an improperly-aligned pointer is
undefined according to the C standard, but if we're doing that in an
EXTRACT_ function/macro, we're doing it because we know it's safe and
because it's faster than picking the bytes out one by one and assembling
them, so suppress those warnings.

Pull over libpcap's funcattrs.h and use it to do a bunch of checks for
various function attributes; that defines __has_attribute(), so we can
use it to check for the "suppress sanitizer warnings" attribute.

While we're at it, use other things it defines to specify "this function
never returns", "this function is printf-like", and "this function
argument is a printf-style format argument", rather than using various
configure-script checks.  That should let us declare some function
attributes with Microsoft Visual Studio's compilers.

1 files changed, 122 insertions, 0 deletions

diff --git a/funcattrs.h b/funcattrs.h
new file mode 100644
index 00000000..63d3f565
--- /dev/null
+++ b/funcattrs.h
@@ -0,0 +1,122 @@
+/* -*- Mode: c; tab-width: 8; indent-tabs-mode: 1; c-basic-offset: 8; -*- */
+/*
+ * Copyright (c) 1993, 1994, 1995, 1996, 1997
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the Computer Systems
+ *	Engineering Group at Lawrence Berkeley Laboratory.
+ * 4. Neither the name of the University nor of the Laboratory may be used
+ *    to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lib_funcattrs_h
+#define lib_funcattrs_h
+
+/*
+ * Attributes to apply to functions and their arguments, using various
+ * compiler-specific extensions.
+ */
+
+/*
+ * This was introduced by Clang:
+ *
+ *     http://clang.llvm.org/docs/LanguageExtensions.html#has-attribute
+ *
+ * in some version (which version?); it has been picked up by GCC 5.0.
+ */
+#ifndef __has_attribute
+  /*
+   * It's a macro, so you can check whether it's defined to check
+   * whether it's supported.
+   *
+   * If it's not, define it to always return 0, so that we move on to
+   * the fallback checks.
+   */
+  #define __has_attribute(x) 0
+#endif
+
+/*
+ * NORETURN, before a function declaration, means "this function
+ * never returns".  (It must go before the function declaration, e.g.
+ * "extern NORETURN func(...)" rather than after the function
+ * declaration, as the MSVC version has to go before the declaration.)
+ */
+#if __has_attribute(noreturn) \
+    || (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 205)) \
+    || (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x590)) \
+    || (defined(__xlC__) && __xlC__ >= 0x0A01) \
+    || (defined(__HP_aCC) && __HP_aCC >= 61000)
+  /*
+   * Compiler with support for __attribute((noreturn)), or GCC 2.5 and
+   * later, or Solaris Studio 12 (Sun C 5.9) and later, or IBM XL C 10.1
+   * and later (do any earlier versions of XL C support this?), or
+   * HP aCC A.06.10 and later.
+   */
+  #define NORETURN __attribute((noreturn))
+#elif defined(_MSC_VER)
+  /*
+   * MSVC.
+   */
+  #define NORETURN __declspec(noreturn)
+#else
+  #define NORETURN
+#endif
+
+/*
+ * PRINTFLIKE(x,y), after a function declaration, means "this function
+ * does printf-style formatting, with the xth argument being the format
+ * string and the yth argument being the first argument for the format
+ * string".
+ */
+#if __has_attribute(__format__) \
+    || (defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 203)) \
+    || (defined(__xlC__) && __xlC__ >= 0x0A01) \
+    || (defined(__HP_aCC) && __HP_aCC >= 61000)
+  /*
+   * Compiler with support for it, or GCC 2.3 and later, or IBM XL C 10.1
+   * and later (do any earlier versions of XL C support this?),
+   * or HP aCC A.06.10 and later.
+   */
+  #define PRINTFLIKE(x,y) __attribute__((__format__(__printf__,x,y)))
+#else
+  #define PRINTFLIKE(x,y)
+#endif
+
+/*
+ * For flagging arguments as format strings in MSVC.
+ */
+#if _MSC_VER >= 1400
+ #include <sal.h>
+ #if _MSC_VER > 1400
+  #define FORMAT_STRING(p) _Printf_format_string_ p
+ #else
+  #define FORMAT_STRING(p) __format_string p
+ #endif
+#else
+ #define FORMAT_STRING(p) p
+#endif
+
+#endif /* lib_funcattrs_h */