vty api: add vty_out_va()

Provide a va_list type vty_out() variant, to be able to pass on variable
arguments from other function signatures to vty_out().

This will be used by Ibd6b1ed7f1bd6e1f2e0fde53352055a4468f23e5 for osmo_tdef.

Change-Id: Ie6e6f11a6b794f3cb686350c1ed678e4d5bbbb75

include/osmocom/vty/vty.h

@@ -193,6 +193,7 @@ void vty_reset (void);
 struct vty *vty_new (void);
 struct vty *vty_create (int vty_sock, void *priv);
 int vty_out (struct vty *, const char *, ...) VTY_PRINTF_ATTRIBUTE(2, 3);
+int vty_out_va(struct vty *vty, const char *format, va_list ap);
 int vty_out_newline(struct vty *);
 int vty_read(struct vty *vty);
 //void vty_time_print (struct vty *, int);

src/vty/vty.c

@@ -249,26 +249,19 @@ int vty_shell(struct vty *vty)
 	return vty->type == VTY_SHELL ? 1 : 0;
 }
 
-
-/*! VTY standard output function
- *  \param[in] vty VTY to which we should print
- *  \param[in] format variable-length format string
- */
-int vty_out(struct vty *vty, const char *format, ...)
+int vty_out_va(struct vty *vty, const char *format, va_list ap)
 {
-	va_list args;
 	int len = 0;
 	int size = 1024;
 	char buf[1024];
 	char *p = NULL;
 
 	if (vty_shell(vty)) {
-		va_start(args, format);
-		vprintf(format, args);
-		va_end(args);
+		vprintf(format, ap);
 	} else {
+		va_list args;
 		/* Try to write to initial buffer.  */
-		va_start(args, format);
+		va_copy(args, ap);
 		len = vsnprintf(buf, sizeof buf, format, args);
 		va_end(args);
 
@@ -284,7 +277,7 @@ int vty_out(struct vty *vty, const char *format, ...)
 				if (!p)
 					return -1;
 
-				va_start(args, format);
+				va_copy(args, ap);
 				len = vsnprintf(p, size, format, args);
 				va_end(args);
 
@@ -310,6 +303,20 @@ int vty_out(struct vty *vty, const char *format, ...)
 	return len;
 }
 
+/*! VTY standard output function
+ *  \param[in] vty VTY to which we should print
+ *  \param[in] format variable-length format string
+ */
+int vty_out(struct vty *vty, const char *format, ...)
+{
+	va_list args;
+	int rc;
+	va_start(args, format);
+	rc = vty_out_va(vty, format, args);
+	va_end(args);
+	return rc;
+}
+
 /*! print a newline on the given VTY */
 int vty_out_newline(struct vty *vty)
 {