feat(stdio): printf family

include/stdio.h

@@ -25,6 +25,7 @@
 
 #include <vlibc/features.h>
 
+#include <stdarg.h>
 #include <stddef.h>
 #include <sys/types.h>
 
@@ -299,4 +300,36 @@ fopen64(const char *restrict path, const char *restrict mode);
 }
 #endif
 
+/* formatted output (todo 16) */
+
+int
+printf(const char *restrict format, ...);
+int
+fprintf(FILE *restrict stream, const char *restrict format, ...);
+int
+sprintf(char *restrict s, const char *restrict format, ...);
+int
+snprintf(char *restrict s, size_t n, const char *restrict format, ...);
+int
+vprintf(const char *restrict format, va_list ap);
+int
+vfprintf(FILE *restrict stream, const char *restrict format, va_list ap);
+int
+vsprintf(char *restrict s, const char *restrict format, va_list ap);
+int
+vsnprintf(char *restrict s, size_t n, const char *restrict format, va_list ap);
+int
+dprintf(int fd, const char *restrict format, ...);
+int
+vdprintf(int fd, const char *restrict format, va_list ap);
+void
+perror(const char *s);
+
+#if VLIBC_LEVEL_GE(2)
+int
+asprintf(char **restrict strp, const char *restrict format, ...);
+int
+vasprintf(char **restrict strp, const char *restrict format, va_list ap);
+#endif
+
 #endif /* VLIBC_STDIO_H */