Use pcap_snprintf() instead of snprintf().

[libpcap] / pcap-int.h

diff --git a/pcap-int.h b/pcap-int.h
index dff1900cb0d4f5e858416cd34e83fb0fb2838942..091b041938d2b2e37d6defa8d00948894f99abd1 100644 (file)
--- a/pcap-int.h
+++ b/pcap-int.h
@@ -380,14 +380,52 @@ int       pcap_read(pcap_t *, int cnt, pcap_handler, u_char *);
 
 #include <stdarg.h>
 
-#if !defined(HAVE_SNPRINTF)
-#define snprintf pcap_snprintf
-extern int snprintf (char *, size_t, const char *, ...);
+/*
+ * 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
+
+/*
+ * 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.
+ *
+ * We also want to allow this to be built with versions of Visual Studio
+ * prior to VS 2015, so we can't rely on snprintf() being present.
+ *
+ * And we want to make sure that, if we support plugins in the future,
+ * a routine with C99 snprintf() behavior will be available to them.
+ * We also don't want it to collide with the C library snprintf() if
+ * there is one.
+ *
+ * So we make pcap_snprintf() and pcap_vsnprintf() available, either by
+ * #defining them to be snprintf or vsnprintf, respectively, or by
+ * defining our own versions and exporting them.
+ */
+#ifdef HAVE_SNPRINTF
+#define pcap_snprintf snprintf
+#else
+extern int pcap_snprintf(char *, size_t, FORMAT_STRING(const char *), ...);
 #endif
 
-#if !defined(HAVE_VSNPRINTF)
-#define vsnprintf pcap_vsnprintf
-extern int vsnprintf (char *, size_t, const char *, va_list ap);
+#ifdef HAVE_VSNPRINTF
+#define pcap_vsnprintf vsnprintf
+#else
+extern int pcap_vsnprintf(char *, size_t, const char *, va_list ap);
 #endif
 
 /*