- explain what magic numbers we're using here.

diff --git a/util-linux/freeramdisk.c b/util-linux/freeramdisk.c
index 923a1516009aa544e8451f0e78d03edca7760296..1f010c721896a5ebca83af0f72d4b08134d6df1f 100644 (file)
--- 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);