- explain what magic numbers we're using here.

1 files changed, 6 insertions, 1 deletions

diff --git a/util-linux/freeramdisk.c b/util-linux/freeramdisk.c
index 923a15160..1f010c721 100644
--- a/util-linux/freeramdisk.c
+++ b/util-linux/freeramdisk.c
@@ -18,6 +18,11 @@
 #include <unistd.h>
 #include "busybox.h"
 
+/* From linux/fs.h */
+#define BLKFLSBUF  _IO(0x12,97)
+/* From <linux/fd.h> */
+#define FDFLUSH  _IO(2,0x4b)
+
 int freeramdisk_main(int argc, char **argv)
 {
         int result;
@@ -29,7 +34,7 @@ int freeramdisk_main(int argc, char **argv)
 
         // Act like freeramdisk, fdflush, or both depending on configuration.
         result = ioctl(fd, (ENABLE_FREERAMDISK && bb_applet_name[1]=='r')
-                        || !ENABLE_FDFLUSH ? _IO(0x12,97) : _IO(2,0x4b));
+                        || !ENABLE_FDFLUSH ? BLKFLSBUF : FDFLUSH);
 
         if (ENABLE_FEATURE_CLEAN_UP) close(fd);