added wxVaCopy() and use it to fix wxVsnprintf() crash (see bug 1017651)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29604 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/function.tex

@@ -237,6 +237,7 @@ the corresponding topic.
 \helpref{wxUnix2DosFilename}{wxunix2dosfilename}\\
 \helpref{wxUnsetEnv}{wxunsetenv}\\
 \helpref{wxUsleep}{wxusleep}\\
+\helpref{wxVaCopy}{wxvacopy}\\
 \helpref{wxVsnprintf}{wxvsnprintf}\\
 \helpref{wxWakeUpIdle}{wxwakeupidle}\\
 \helpref{wxWriteResource}{wxwriteresource}\\
@@ -2977,6 +2978,19 @@ allows to define unsigned 64 bit compile time constants:
 \helpref{wxLL}{wxll}, \helpref{wxLongLong}{wxlonglong}
 
 
+\membersection{wxVaCopy}\label{wxvacopy}
+
+\func{void}{wxVaCopy}{\param{va\_list }{argptrDst}, \param{va\_list}{argptrSrc}}
+
+This macro is the same as the standard C99 \texttt{va\_copy} for the compilers
+which support it or its replacement for those that don't. It must be used to
+preserve the value of a \texttt{va\_list} object if you need to use it after
+passing it to another function because it can be modified by the latter.
+
+As with \texttt{va\_start}, each call to \texttt{wxVaCopy} must have a matching 
+\texttt{va\_end}.
+
+
 \membersection{::wxWriteResource}\label{wxwriteresource}
 
 \func{bool}{wxWriteResource}{\param{const wxString\& }{section}, \param{const wxString\& }{entry},

include/wx/defs.h

@@ -323,6 +323,50 @@ typedef int wxWindowID;
     #endif
 #endif
 
+/* provide replacement for C99 va_copy() if the compiler doesn't have it */
+
+/* could be already defined by configure or the user */
+#ifndef wxVaCopy
+    /* if va_copy is a macro or configure detected that we have it, use it */
+    #if defined(va_copy) || defined(HAVE_VA_COPY)
+        #define wxVaCopy va_copy
+    #else /* no va_copy, try to provide a replacement */
+        /*
+           configure tries to determine whether va_list is an array or struct
+           type, but it may not be used under Windows, so deal with a few
+           special cases.
+         */
+
+        #ifdef __WATCOMC__
+            /* Watcom uses array type for va_list except for PPC and Alpha */
+            #if !defined(__PPC__) && !defined(__AXP__)
+                #define VA_LIST_IS_ARRAY
+            #endif
+        #endif /* __WATCOMC__ */
+
+        #if defined(__PPC__) && (defined(_CALL_SYSV) || defined (_WIN32))
+            /*
+                PPC using SysV ABI and NT/PPC are special in that they use an
+                extra level of indirection.
+             */
+            #define VA_LIST_IS_POINTER
+        #endif /* SysV or Win32 on __PPC__ */
+
+        /*
+            note that we use memmove(), not memcpy(), in case anybody tries
+            to do wxVaCopy(ap, ap)
+         */
+        #if defined(VA_LIST_IS_POINTER)
+            #define wxVaCopy(d, s)  memmove(*(d), *(s), sizeof(va_list))
+        #elif defined(VA_LIST_IS_ARRAY)
+            #define wxVaCopy(d, s) memmove((d), (s), sizeof(va_list))
+        #else /* we can only hope that va_lists are simple lvalues */
+            #define wxVaCopy(d, s) ((d) = (s))
+        #endif
+    #endif /* va_copy/!va_copy */
+#endif // wxVaCopy
+
+
 /*  ---------------------------------------------------------------------------- */
 /*  portable calling conventions macros */
 /*  ---------------------------------------------------------------------------- */

src/common/string.cpp

@@ -1727,7 +1727,12 @@ int wxString::PrintfV(const wxChar* pszFormat, va_list argptr)
                 return -1;
             }
 
-            len = wxVsnprintf(buf, size, pszFormat, argptr);
+            // wxVsnprintf() may modify the original arg pointer, so pass it
+            // only a copy
+            va_list argptrcopy;
+            wxVaCopy(argptrcopy, argptr);
+            len = wxVsnprintf(buf, size, pszFormat, argptrcopy);
+            va_end(argptrcopy);
 
             // some implementations of vsnprintf() don't NUL terminate
             // the string if there is not enough space for it so