Added [v]asprintf()

src/core/asprintf.c

+#include <stdint.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+
+/**
+ * Write a formatted string to newly allocated memory.
+ *
+ * @v strp		Pointer to hold allocated string
+ * @v fmt		Format string
+ * @v args		Arguments corresponding to the format string
+ * @ret	len		Length of formatted string
+ */
+int vasprintf ( char **strp, const char *fmt, va_list args ) {
+	size_t len;
+	va_list args_tmp;
+
+	/* Calculate length needed for string */
+	va_copy ( args_tmp, args );
+	len = ( vsnprintf ( NULL, 0, fmt, args_tmp ) + 1 );
+	va_end ( args_tmp );
+
+	/* Allocate and fill string */
+	*strp = malloc ( len );
+	if ( ! *strp )
+		return -ENOMEM;
+	return vsnprintf ( *strp, len, fmt, args );
+}
+
+/**
+ * Write a formatted string to newly allocated memory.
+ *
+ * @v strp		Pointer to hold allocated string
+ * @v fmt		Format string
+ * @v ...		Arguments corresponding to the format string
+ * @ret	len		Length of formatted string
+ */
+int asprintf ( char **strp, const char *fmt, ... ) {
+	va_list args;
+	int len;
+
+	va_start ( args, fmt );
+	len = vasprintf ( strp, fmt, args );
+	va_end ( args );
+	return len;
+}

src/include/stdio.h

 extern int __attribute__ (( format ( printf, 3, 4 ) ))
 snprintf ( char *buf, size_t size, const char *fmt, ... );
 
+extern int __attribute__ (( format ( printf, 2, 3 ) ))
+asprintf ( char **strp, const char *fmt, ... );
+
 extern int vprintf ( const char *fmt, va_list args );
 
 extern int vsnprintf ( char *buf, size_t size, const char *fmt, va_list args );
 
+extern int vasprintf ( char **strp, const char *fmt, va_list args );
+
 /**
  * Write a formatted string to a buffer
  *