libc: implement asprintf

1 files changed, 24 insertions, 0 deletions

diff --git a/src/libc/stdio/asprintf.c b/src/libc/stdio/asprintf.c
new file mode 100644
index 0000000..ee24e38
--- /dev/null
+++ b/src/libc/stdio/asprintf.c
@@ -0,0 +1,24 @@
+#include <shared/mem.h>
+#include <shared/printf.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int asprintf(char **restrict sp, const char *restrict fmt, ...) {
+	int ret;
+	va_list argp;
+	va_start(argp, fmt);
+	ret = vasprintf(sp, fmt, argp);
+	va_end(argp);
+	return ret;
+}
+int vasprintf(char **restrict sp, const char *restrict fmt, va_list ap) {
+	va_list ap2;
+	va_copy(ap2, ap);
+	int ret = vsnprintf(NULL, 0, fmt, ap2);
+	va_end(ap2);
+
+	if (ret < 0) return ret;
+	*sp = malloc(ret+1);
+	if (*sp == NULL) return -1;
+	return vsnprintf(*sp, ret+1, fmt, ap);
+}