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.
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?
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#define EKEYREVOKED 128 /* Key has been revoked */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.)
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; \
} \
-
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