[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [21034] branches/blender2.5/blender/source /blender/blenlib/intern/BLI_dynstr.c: 2.5: fix for crash in BLI_dynstr_appendf, each vsnprintf call

[Brecht Van Lommel]

Revision: 21034
          http://projects.blender.org/plugins/scmsvn/viewcvs.php?view=rev&root=bf-blender&revision=21034
Author:   blendix
Date:     2009-06-20 16:53:30 +0200 (Sat, 20 Jun 2009)

Log Message:
-----------
2.5: fix for crash in BLI_dynstr_appendf, each vsnprintf call
apparently needs its own va_start/va_end.

Modified Paths:
--------------
    branches/blender2.5/blender/source/blender/blenlib/intern/BLI_dynstr.c

Modified: branches/blender2.5/blender/source/blender/blenlib/intern/BLI_dynstr.c
===================================================================
--- branches/blender2.5/blender/source/blender/blenlib/intern/BLI_dynstr.c	2009-06-20 14:01:34 UTC (rev 21033)
+++ branches/blender2.5/blender/source/blender/blenlib/intern/BLI_dynstr.c	2009-06-20 14:53:30 UTC (rev 21034)
@@ -92,7 +92,7 @@
 		if(len == sizeof(fixedmessage))
 			message= fixedmessage;
 		else
-			message= MEM_callocN(sizeof(char)*len+1, "BLI_dynstr_appendf");
+			message= MEM_callocN(sizeof(char)*(len+1), "BLI_dynstr_appendf");
 
 		retval= vsnprintf(message, len, format, args);
 
@@ -132,10 +132,54 @@
 void BLI_dynstr_appendf(DynStr *ds, const char *format, ...)
 {
 	va_list args;
+	char *message, fixedmessage[256];
+	int len= 256, maxlen= 65536, retval;
 
-	va_start(args, format);
-	BLI_dynstr_vappendf(ds, format, args);
-	va_end(args);
+	/* note that it's tempting to just call BLI_dynstr_vappendf here
+	 * and avoid code duplication, that crashes on some system because
+	 * va_start/va_end have to be called for each vsnprintf call */
+
+	while(1) {
+		if(len == sizeof(fixedmessage))
+			message= fixedmessage;
+		else
+			message= MEM_callocN(sizeof(char)*(len+1), "BLI_dynstr_appendf");
+
+		va_start(args, format);
+		retval= vsnprintf(message, len, format, args);
+		va_end(args);
+
+		if(retval == -1) {
+			/* -1 means not enough space, but on windows it may also mean
+			 * there is a formatting error, so we impose a maximum length */
+			if(message != fixedmessage)
+				MEM_freeN(message);
+			message= NULL;
+
+			len *= 2;
+			if(len > maxlen) {
+				fprintf(stderr, "BLI_dynstr_append text too long or format error.\n");
+				break;
+			}
+		}
+		else if(retval > len) {
+			/* in C99 the actual length required is returned */
+			if(message != fixedmessage)
+				MEM_freeN(message);
+			message= NULL;
+
+			len= retval;
+		}
+		else
+			break;
+	}
+
+	if(message) {
+		BLI_dynstr_append(ds, message);
+
+		if(message != fixedmessage)
+			MEM_freeN(message);
+	}
 }
 
 int BLI_dynstr_get_len(DynStr *ds) {