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According to Jim Meyering on 3/19/2009 3:58 PM:
> * src/dd.c (O_FULLBLOCK): Compute its value via cpp macros that
> expand to less than 3KB of rather than to 180KB(!).
Why use a macro at all? All we have to do is come up with a value that is
bitwise distinct from all the others. In other words, much smaller than
3KB, let alone 180KB.
- --
Don't work too hard, make some time for fun as well!
Eric Blake e...@byu.net
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>From d6a83c9d49c2737a9a0ef9ca7fc4bb9f469e9576 Mon Sep 17 00:00:00 2001
From: Eric Blake <e...@byu.net>
Date: Thu, 19 Mar 2009 22:31:16 -0600
Subject: [PATCH] dd: use a more portable definition of O_FULLBLOCK
* src/dd.c (O_FULLBLOCK): Compute its value without using a 180KB
macro. This avoids triggering a compilation failure with HP-UX's cc.
Reported by Matthew Woehlke.
---
src/dd.c | 35 +++++++++++++++--------------------
1 files changed, 15 insertions(+), 20 deletions(-)
diff --git a/src/dd.c b/src/dd.c
index 9a1c875..ecbcaf5 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -265,30 +265,25 @@ static struct symbol_value const conversions[] =
enum
{
- /* Use a value that is larger than that of any other O_ symbol. */
- O_FULLBLOCK = ((MAX (O_APPEND,
- MAX (O_BINARY,
- MAX (O_CIO,
- MAX (O_DIRECT,
- MAX (O_DIRECTORY,
- MAX (O_DSYNC,
- MAX (O_NOATIME,
- MAX (O_NOCTTY,
- MAX (O_NOFOLLOW,
- MAX (O_NOLINKS,
- MAX (O_NONBLOCK,
- MAX (O_SYNC,
- MAX (O_TEXT, 0)))))))))))))) << 1)
+ /* Use a value that is bitwise distinct from any other O_ symbol. */
+ O_FULLBLOCK = ~(O_APPEND
+ | O_BINARY
+ | O_CIO
+ | O_DIRECT
+ | O_DIRECTORY
+ | O_DSYNC
+ | O_NOATIME
+ | O_NOCTTY
+ | O_NOFOLLOW
+ | O_NOLINKS
+ | O_NONBLOCK
+ | O_SYNC
+ | O_TEXT)
};
-/* Ensure that we didn't shift it off the end. */
+/* Ensure that we got something. */
verify (O_FULLBLOCK != 0);
-#define MULTIPLE_BITS_SET(i) (((i) & ((i) - 1)) != 0)
-
-/* Ensure that this is a single-bit value. */
-verify ( ! MULTIPLE_BITS_SET (O_FULLBLOCK));
-
/* Flags, for iflag="..." and oflag="...". */
static struct symbol_value const flags[] =
{
--
1.6.1.2
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