On Tue, 20 Jun 2006 18:40:10 +0900 (JST) Masatake YAMATO wrote:
> Hi,
>
> __syscall_return in unistd.h is maintained?
>
> In the macro the value returned from system call is
> compared with the maximum error number defined in a header file
> to know the call is successful or not. However, the maximum error number
> is hard-coded and is not updated.
Ack, this certainly needs some care & fixing.
> Here is an example(i386):
>
> /*
> * user-visible error numbers are in the range -1 - -128: see
> * <asm-i386/errno.h>
> */
> #define __syscall_return(type, res) \
> do { \
> if ((unsigned long)(res) >= (unsigned long)(-(128 + 1))) { \
> errno = -(res); \
> res = -1; \
> } \
>
> The comment says the maximum errno is 128.
> However, the actual C code says 128 + 1. What does "+ 1" mean?
I don't understand the -1 either. A few asm-*/unistd.h files
use that, but most of them do not.
> Look at <asm-i386/errno.h>:
>
> #ifndef _I386_ERRNO_H
> #define _I386_ERRNO_H
>
> #include <asm-generic/errno.h>
>
> #endif
>
> The look at <asm-generic/errno.h>:
>
> #define EKEYREVOKED 128 /* Key has been revoked */
> #define EKEYREJECTED 129 /* Key was rejected by service */
>
> /* for robust mutexes */
> #define EOWNERDEAD 130 /* Owner died */
> #define ENOTRECOVERABLE 131 /* State not recoverable */
>
> Here the maximum errno is 131.
>
>
> In many architectures, <asm-foo/errno.h> just includes
> <asm-generic/errno.h>. So I think <asm-generic/errno.h> should
> exports the real maximum errno and the other headers can
> use it. So in many cases, we can just maintain
> the real maximum errno in <asm-generic/errno.h>.
>
> Here is the patch for i386. If this patch is approved, I will write
> patches for the other architectures. (However, it may be better to be
> done by each architecture's maintainer.)
I like the patch.
> Signed-off-by: Masatake YAMATO <[email protected]>
>
> diff --git a/include/asm-generic/errno.h b/include/asm-generic/errno.h
> index e8852c0..4e1238e 100644
> --- a/include/asm-generic/errno.h
> +++ b/include/asm-generic/errno.h
> @@ -106,4 +106,8 @@ #define EKEYREJECTED 129 /* Key was reje
> #define EOWNERDEAD 130 /* Owner died */
> #define ENOTRECOVERABLE 131 /* State not recoverable */
>
> +/*
> + * If you add a new error, Don't forget to update `GENERIC_ERRNO_MAX'
> + */
> +#define GENERIC_ERRNO_MAX ENOTRECOVERABLE
> #endif
> diff --git a/include/asm-i386/errno.h b/include/asm-i386/errno.h
> index 969b343..9892b2d 100644
> --- a/include/asm-i386/errno.h
> +++ b/include/asm-i386/errno.h
> @@ -2,5 +2,5 @@ #ifndef _I386_ERRNO_H
> #define _I386_ERRNO_H
>
> #include <asm-generic/errno.h>
> -
> +#define i386_ERRNO_MAX GENERIC_ERRNO_MAX
> #endif
> diff --git a/include/asm-i386/unistd.h b/include/asm-i386/unistd.h
> index eb4b152..f52ec68 100644
> --- a/include/asm-i386/unistd.h
> +++ b/include/asm-i386/unistd.h
> @@ -326,12 +326,13 @@ #define __NR_vmsplice 316
> #define NR_syscalls 317
>
> /*
> - * user-visible error numbers are in the range -1 - -128: see
> - * <asm-i386/errno.h>
> + * user-visible error numbers are in the range -1 - -i386_ERRNO_MAX
> */
> +#include <asm-i386/errno.h>
> +
> #define __syscall_return(type, res) \
> do { \
> - if ((unsigned long)(res) >= (unsigned long)(-(128 + 1))) { \
> + if ((unsigned long)(res) >= (unsigned long)(-(i386_ERRNO_MAX))) { \
> errno = -(res); \
> res = -1; \
> } \
> -
Thanks.
---
~Randy
-
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