Merge pull request #760 from leres/master

[tcpdump] / netdissect-stdinc.h

diff --git a/netdissect-stdinc.h b/netdissect-stdinc.h
index 8ef4e2a704326f1577f264e0c2af6c87f40e0e76..8f1e5727642d04687887f0a9fe2fc86ae3a14bb3 100644 (file)
--- a/netdissect-stdinc.h
+++ b/netdissect-stdinc.h
@@ -209,12 +209,30 @@
 #endif
 
 #ifdef _MSC_VER
-#define stat _stat
-#define open _open
-#define fstat _fstat
-#define read _read
-#define close _close
-#define O_RDONLY _O_RDONLY
+  /*
+   * Microsoft tries to avoid polluting the C namespace with UN*Xisms,
+   * by adding a preceding underscore; we *want* the UN*Xisms, so add
+   * #defines to let us use them.
+   */
+  #define isascii __isascii
+  #define isatty _isatty
+  #define stat _stat
+  #define strdup _strdup
+  #define open _open
+  #define fstat _fstat
+  #define read _read
+  #define close _close
+  #define O_RDONLY _O_RDONLY
+
+  /*
+   * If <crtdbg.h> has been included, and _DEBUG is defined, and
+   * __STDC__ is zero, <crtdbg.h> will define strdup() to call
+   * _strdup_dbg().  So if it's already defined, don't redefine
+   * it.
+   */
+  #ifndef strdup
+    #define strdup _strdup
+  #endif
 #endif  /* _MSC_VER */
 
 /*
@@ -243,8 +261,6 @@ typedef char* caddr_t;
 #endif /* caddr_t */
 
 #define MAXHOSTNAMELEN 64
-#define snprintf _snprintf
-#define vsnprintf _vsnprintf
 
 #else /* _WIN32 */
 
@@ -277,6 +293,67 @@ typedef char* caddr_t;
 
 #endif /* _WIN32 */
 
+/*
+ * Function attributes, for various compilers.
+ */
+#include "funcattrs.h"
+
+/*
+ * On Windows, snprintf(), with that name and with C99 behavior - i.e.,
+ * guaranteeing that the formatted string is null-terminated - didn't
+ * appear until Visual Studio 2015.  Prior to that, the C runtime had
+ * only _snprintf(), which *doesn't* guarantee that the string is
+ * null-terminated if it is truncated due to the buffer being too
+ * small.  We therefore can't just define snprintf to be _snprintf
+ * and define vsnprintf to be _vsnprintf, as we're relying on null-
+ * termination of strings in all cases.
+ *
+ * Furthermore, some versions of Visual Studio prior to Visual
+ * Studio 2015 had vsnprintf() (but not snprintf()!), but those
+ * versions don't guarantee null termination, either.
+ *
+ * We assume all UN*Xes that have snprintf() and vsnprintf() provide
+ * C99 behavior.
+ */
+#if defined(_MSC_VER) || defined(__MINGW32__)
+  #if defined(_MSC_VER) && _MSC_VER >= 1900
+    /*
+     * VS 2015 or newer; just use the C runtime's snprintf() and
+     * vsnprintf().
+     */
+    #define nd_snprintf                snprintf
+    #define nd_vsnprintf       vsnprintf
+  #else /* defined(_MSC_VER) && _MSC_VER >= 1900 */
+    /*
+     * VS prior to 2015, or MingGW; assume we have _snprintf_s() and
+     * _vsnprintf_s(), which guarantee null termination.
+     */
+    #define nd_snprintf(buf, buflen, ...) \
+        _snprintf_s(buf, buflen, _TRUNCATE, __VA_ARGS__)
+    #define nd_vsnprintf(buf, buflen, fmt, ap) \
+        _vsnprintf_s(buf, buflen, _TRUNCATE, fmt, ap)
+  #endif /* defined(_MSC_VER) && _MSC_VER >= 1900 */
+#else /* defined(_MSC_VER) || defined(__MINGW32__) */
+  /*
+   * Some other compiler, which we assume to be a UN*X compiler.
+   * Use the system's snprintf() if we have it, otherwise use
+   * our own implementation
+   */
+  #ifdef HAVE_SNPRINTF
+    #define nd_snprintf                snprintf
+  #else /* HAVE_SNPRINTF */
+    int nd_snprintf (char *str, size_t sz, FORMAT_STRING(const char *format), ...)
+        PRINTFLIKE(3, 4);
+  #endif /* HAVE_SNPRINTF */
+
+  #ifdef HAVE_VSNPRINTF
+    #define nd_vsnprintf       vsnprintf
+  #else /* HAVE_VSNPRINTF */
+    int nd_vsnprintf (char *str, size_t sz, FORMAT_STRING(const char *format),
+        va_list ap) PRINTFLIKE(3, 0);
+  #endif /* HAVE_VSNPRINTF */
+#endif /* defined(_MSC_VER) || defined(__MINGW32__) */
+
 /*
  * fopen() read and write modes for text files and binary files.
  */
@@ -435,11 +512,6 @@ struct in6_addr {
  * end of Apple deprecation workaround macros
  */
 
-/*
- * Function attributes, for various compilers.
- */
-#include "funcattrs.h"
-
 /*
  * Statement attributes, for various compilers.
  *
@@ -447,8 +519,16 @@ struct in6_addr {
  * it also implement __has_attribute() (for example, GCC 5.0 and later
  * have __has_attribute(), and the "fallthrough" attribute was introduced
  * in GCC 7).
+ *
+ * Unfortunately, Clang does this wrong - a statement
+ *
+ *    __attribute__ ((fallthrough));
+ *
+ * produces bogus -Wmissing-declaration "declaration does not declare
+ * anything" warnings (dear Clang: that's not a declaration, it's an
+ * empty statement).  GCC, however, has no trouble with this.
  */
-#if __has_attribute(fallthrough)
+#if __has_attribute(fallthrough) && !defined(__clang__)
 #  define ND_FALL_THROUGH __attribute__ ((fallthrough))
 #else
 #  define ND_FALL_THROUGH