X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/45fc519a2ac35af5805204418c370136aa0db1f7..c0af6af3011d4c55bdadf3dd76cd5fc1115c50d0:/netdissect-stdinc.h

diff --git a/netdissect-stdinc.h b/netdissect-stdinc.h
index a05e1cfe..8f1e5727 100644
--- 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 */
 
@@ -278,53 +294,65 @@ typedef char* caddr_t;
 #endif /* _WIN32 */
 
 /*
- * Used to declare a structure unaligned, so that the C compiler,
- * if necessary, generates code that doesn't assume alignment.
- * This is required because there is no guarantee that the packet
- * data we get from libpcap/WinPcap is properly aligned.
- *
- * This assumes that, for all compilers that support __attribute__((packed)),
- * for all instruction set architectures requiring strict alignment, declaring
- * a structure with that attribute causes the compiler to generate code that
- * handles misaligned 2-byte, 4-byte, and 8-byte integral quantities.
- *
- * It does not (yet) handle compilers where you can get the compiler
- * to generate code of that sort by some other means.
- *
- * This is required in order to, for example, keep the compiler from
- * generating, for
- *
- *	if (bp->bp_htype == 1 && bp->bp_hlen == 6 && bp->bp_op == BOOTPREQUEST) {
- *
- * in print-bootp.c, code that loads the first 4-byte word of a
- * "struct bootp", masking out the bp_hops field, and comparing the result
- * against 0x01010600.
+ * 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.
  *
- * Note: this also requires that padding be put into the structure,
- * at least for compilers where it's implemented as __attribute__((packed)).
+ * 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.
  *
- * XXX - now that we're using nd_ types that are just arrays of bytes, is
- * this still necessary?  Are there any compilers that align structures,
- * none of whose members require more than byte alignment, on more than
- * one-byte boundaries, and assume a structure is aligned on such a
- * boundary?  (I have vague memories of either m68k or ARM compilers
- * aligning on at least 2-byte boundaries.)
+ * We assume all UN*Xes that have snprintf() and vsnprintf() provide
+ * C99 behavior.
  */
-#if ND_IS_AT_LEAST_GNUC_VERSION(2,0) || \
-    ND_IS_AT_LEAST_XL_C_VERSION(6,0)
-  /*
-   * GCC 2.0 or later, or a compiler that claims to be GCC 2.0 or later,
-   * or IBM XL C 6.0 or later.
-   *
-   * Use __attribute__((packed)).
-   */
-  #define ND_UNALIGNED	__attribute__((packed))
-#else
+#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__) */
   /*
-   * Nothing.
+   * 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
    */
-  #define ND_UNALIGNED
-#endif
+  #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.
@@ -484,11 +512,6 @@ struct in6_addr {
  * end of Apple deprecation workaround macros
  */
 
-/*
- * Function attributes, for various compilers.
- */
-#include "funcattrs.h"
-
 /*
  * Statement attributes, for various compilers.
  *
@@ -496,8 +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