util.c handling of return value of vsnprintf

At two points in util.c, there is code that use vsnprintf
if available, otherwise vsprintf.  The handling of the return
value does not reflect which function has been called.
The patch tries to improve this.

1 files changed, 16 insertions, 4 deletions

diff --git a/util.c b/util.c
index 67a5cbe4d1..8d9d2e48a2 100644
--- a/util.c
+++ b/util.c
@@ -6267,8 +6267,14 @@ Perl_my_snprintf(char *buffer, const Size_t len, const char *format, ...)
     retval = vsprintf(buffer, format, ap);
 #endif
     va_end(ap);
-    /* vsnprintf() shows failure with >= len, vsprintf() with < 0 */
-    if (retval < 0 || (len > 0 && (Size_t)retval >= len))
+    /* vsprintf() shows failure with < 0 */
+    if (retval < 0
+#ifdef HAS_VSNPRINTF
+    /* vsnprintf() shows failure with >= len */
+        ||
+        (len > 0 && (Size_t)retval >= len) 
+#endif
+    )
 	Perl_croak(aTHX_ "panic: my_snprintf buffer overflow");
     return retval;
 }
@@ -6307,8 +6313,14 @@ Perl_my_vsnprintf(char *buffer, const Size_t len, const char *format, va_list ap
     retval = vsprintf(buffer, format, ap);
 # endif
 #endif /* #ifdef NEED_VA_COPY */
-    /* vsnprintf() shows failure with >= len, vsprintf() with < 0 */
-    if (retval < 0 || (len > 0 && (Size_t)retval >= len))
+    /* vsprintf() shows failure with < 0 */
+    if (retval < 0
+#ifdef HAS_VSNPRINTF
+    /* vsnprintf() shows failure with >= len */
+        ||
+        (len > 0 && (Size_t)retval >= len) 
+#endif
+    )
 	Perl_croak(aTHX_ "panic: my_vsnprintf buffer overflow");
     return retval;
 }