dstring: Add a printf()-style creation API

1 files changed, 28 insertions, 0 deletions

diff --git a/dstring.c b/dstring.c
index 35ea5b2..d7ce456 100644
--- a/dstring.c
+++ b/dstring.c
@@ -15,6 +15,9 @@
  ****************************************************************************/
 
 #include "dstring.h"
+#include <assert.h>
+#include <stdarg.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -117,6 +120,31 @@ int dstrapp(char **str, char c) {
 	return dstrcat_impl(str, &c, 1);
 }
 
+char *dstrprintf(const char *format, ...) {
+	va_list args;
+
+	va_start(args, format);
+	int len = vsnprintf(NULL, 0, format, args);
+	va_end(args);
+
+	assert(len > 0);
+
+	char *str = dstralloc(len);
+	if (!str) {
+		return NULL;
+	}
+
+	va_start(args, format);
+	len = vsnprintf(str, len + 1, format, args);
+	va_end(args);
+
+	struct dstring *header = dstrheader(str);
+	assert(len == header->capacity);
+	header->length = len;
+
+	return str;
+}
+
 void dstrfree(char *dstr) {
 	if (dstr) {
 		free(dstrheader(dstr));