Add FIONWRITE to allow applications to sniff the amount of writable space on a descriptor. Implement this for serial devices only.

2026-07-01 23:50:35 +08:00 · 2013-01-03 00:33:22 -08:00
parent c08135ffef
commit e787fa5bce
2 changed files with 25 additions and 0 deletions
@@ -110,6 +110,10 @@
                                           * OUT: Bytes readable from this fd
                                           */

+#define FIONWRITE       _FIOC(0x0005)     /* IN:  Location to return value (int *)
+                                           * OUT: Bytes writable to this fd
+                                           */
+
 /* NuttX file system ioctl definitions **************************************/

 #define _DIOCVALID(c)   (_IOC_TYPE(c)==_DIOCBASE)