On Thu, Feb 01, 2007 at 02:45:09PM +0100, Bernhard Fischer wrote:
>On Thu, Feb 01, 2007 at 01:31:18PM +0100, Joakim Tjernlund wrote:
>>O
>>> Well, do we -ENOSYS if something isn't available?
>>> If so, then we should rather
>>> #ifdef __NR_readahead
>>> [snip current code]
>>> #else
>>> ssize_t readahead(int fd, off_t offset, size_t count)
>>> {
>>> __set_errno(ENOSYS);
>>> return -1;
>>> }
>>> link_warning(readahead,"not available")
>>> #endif
>>>
>>> Wondering if there should be a generic internal helper stub for
>>> the ENOSYS;ret -1 case..
>>
>>This can make cross compiling painful since you can't tell if
>>readahead is present or not.
>>On the other hand, a well behaved app will handle this dynamically ...
>
>Either way, behaviour should imho be consistent, and it is not, from a
>quick grep for ENOSYS. Didn't really look, admittedly.
>
>Not stubbing unsupported functions out sounds smaller. Deciding what
>route to take, either to stub them out or making them not available
>isn't my call, though.
[replying to this old thread]
So.. what do people think should be done in this respect?
I'm attaching a proposal that allows for conveniently adding stubs by
doing this:
--- 8< ---
#include <bits/syscall-stub.h>
#define __SYSCALL_STUB __NR_pivot_root
#include <sys/syscall.h>
int pivot_root(const char *new_root, const char *put_old);
_syscall2(int, pivot_root, const char *, new_root, const char *, put_old);
--- 8< ---
instead of manually providing a __set_errno(ENOSYS);return -1; stub
It converts a few conditional syscalls to this proposed scheme as an
example.
This way we could even have a config-option that decides if there should
be any stubs or none (not talking about alternative impls, they are of
no interrest for now).
Opinions?
Index: include/sys/syscall.h
===================================================================
--- include/sys/syscall.h (revision 22022)
+++ include/sys/syscall.h (working copy)
@@ -31,6 +31,11 @@
#include <features.h>
#include <bits/sysnum.h>
#if defined _LIBC && (defined IS_IN_libc || defined NOT_IN_libc)
+# if defined __SYSCALL_STUB && __SYSCALL_STUB
+ /* Syscall exists, no stub needed. */
+# undef __SYSCALL_STUB
+# endif
+
# include <bits/syscalls.h>
#endif
Index: libc/sysdeps/linux/common/access.c
===================================================================
--- libc/sysdeps/linux/common/access.c (revision 22022)
+++ libc/sysdeps/linux/common/access.c (working copy)
@@ -7,6 +7,8 @@
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_access
#include <sys/syscall.h>
#include <unistd.h>
_syscall2(int, access, const char *, pathname, int, mode);
Index: libc/sysdeps/linux/common/bdflush.c
===================================================================
--- libc/sysdeps/linux/common/bdflush.c (revision 22022)
+++ libc/sysdeps/linux/common/bdflush.c (working copy)
@@ -7,15 +7,9 @@
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_bdflush
#include <sys/syscall.h>
#include <sys/kdaemon.h>
-#ifdef __NR_bdflush
_syscall2(int, bdflush, int, __func, long int, __data);
-#else
-int bdflush(int __func, long int __data)
-{
- __set_errno(ENOSYS);
- return -1;
-}
-#endif
Index: libc/sysdeps/linux/common/capget.c
===================================================================
--- libc/sysdeps/linux/common/capget.c (revision 22022)
+++ libc/sysdeps/linux/common/capget.c (working copy)
@@ -6,15 +6,9 @@
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
-
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_capget
#include <sys/syscall.h>
+
int capget(void *header, void *data);
-#ifdef __NR_capget
_syscall2(int, capget, void *, header, void *, data);
-#else
-int capget(void *header, void *data)
-{
- __set_errno(ENOSYS);
- return -1;
-}
-#endif
Index: libc/sysdeps/linux/common/adjtimex.c
===================================================================
--- libc/sysdeps/linux/common/adjtimex.c (revision 22022)
+++ libc/sysdeps/linux/common/adjtimex.c (working copy)
@@ -7,6 +7,8 @@
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_adjtimex
#include <sys/syscall.h>
#include <sys/timex.h>
Index: libc/sysdeps/linux/common/capset.c
===================================================================
--- libc/sysdeps/linux/common/capset.c (revision 22022)
+++ libc/sysdeps/linux/common/capset.c (working copy)
@@ -6,15 +6,9 @@
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
-
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_capset
#include <sys/syscall.h>
+
int capset(void *header, const void *data);
-#ifdef __NR_capset
_syscall2(int, capset, void *, header, const void *, data);
-#else
-int capset(void *header, const void *data)
-{
- __set_errno(ENOSYS);
- return -1;
-}
-#endif
Index: libc/sysdeps/linux/common/delete_module.c
===================================================================
--- libc/sysdeps/linux/common/delete_module.c (revision 22022)
+++ libc/sysdeps/linux/common/delete_module.c (working copy)
@@ -6,14 +6,9 @@
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_delete_module
#include <sys/syscall.h>
+
int delete_module(const char *name);
-#ifdef __NR_delete_module
_syscall1(int, delete_module, const char *, name);
-#else
-int delete_module(const char *name)
-{
- __set_errno(ENOSYS);
- return -1;
-}
-#endif
Index: libc/sysdeps/linux/common/pivot_root.c
===================================================================
--- libc/sysdeps/linux/common/pivot_root.c (revision 22022)
+++ libc/sysdeps/linux/common/pivot_root.c (working copy)
@@ -7,15 +7,9 @@
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
+#include <bits/syscall-stub.h>
+#define __SYSCALL_STUB __NR_pivot_root
#include <sys/syscall.h>
int pivot_root(const char *new_root, const char *put_old);
-#ifdef __NR_pivot_root
_syscall2(int, pivot_root, const char *, new_root, const char *, put_old);
-#else
-int pivot_root(const char *new_root, const char *put_old)
-{
- __set_errno(ENOSYS);
- return -1;
-}
-#endif
Index: libc/sysdeps/linux/i386/bits/syscalls.h
===================================================================
--- libc/sysdeps/linux/i386/bits/syscalls.h (revision 22022)
+++ libc/sysdeps/linux/i386/bits/syscalls.h (working copy)
@@ -12,8 +12,7 @@
#ifndef __ASSEMBLER__
#include <errno.h>
-
-#define SYS_ify(syscall_name) (__NR_##syscall_name)
+#include <bits/syscall-stub.h>
#define INTERNAL_SYSCALL_DECL(err) do { } while (0)
@@ -106,35 +105,40 @@ __asm__ (".L__X'%ebx = 1\n\t"
#define _syscall0(type,name) \
type name(void) \
{ \
-return (type) (INLINE_SYSCALL(name, 0)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 0)); \
}
#undef _syscall1
#define _syscall1(type,name,type1,arg1) \
type name(type1 arg1) \
{ \
-return (type) (INLINE_SYSCALL(name, 1, arg1)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 1, arg1)); \
}
+
#undef _syscall2
+#define INLINE_SYSCALL2(name, arg1, arg2) \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 2, arg1, arg2));
+
#define _syscall2(type,name,type1,arg1,type2,arg2) \
type name(type1 arg1,type2 arg2) \
{ \
-return (type) (INLINE_SYSCALL(name, 2, arg1, arg2)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 2, arg1, arg2)); \
}
+
#undef _syscall3
#define _syscall3(type,name,type1,arg1,type2,arg2,type3,arg3) \
type name(type1 arg1,type2 arg2,type3 arg3) \
{ \
-return (type) (INLINE_SYSCALL(name, 3, arg1, arg2, arg3)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 3, arg1, arg2, arg3)); \
}
#undef _syscall4
#define _syscall4(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) \
type name (type1 arg1, type2 arg2, type3 arg3, type4 arg4) \
{ \
-return (type) (INLINE_SYSCALL(name, 4, arg1, arg2, arg3, arg4)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 4, arg1, arg2, arg3, arg4)); \
}
#undef _syscall5
@@ -142,7 +146,7 @@ return (type) (INLINE_SYSCALL(name, 4, a
type5,arg5) \
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5) \
{ \
-return (type) (INLINE_SYSCALL(name, 5, arg1, arg2, arg3, arg4, arg5)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 5, arg1, arg2, arg3, arg4, arg5)); \
}
#undef _syscall6
@@ -150,9 +154,13 @@ return (type) (INLINE_SYSCALL(name, 5, a
type5,arg5,type6,arg6) \
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5, type6 arg6) \
{ \
-return (type) (INLINE_SYSCALL(name, 6, arg1, arg2, arg3, arg4, arg5, arg6)); \
+EMIT_INLINE_SYSCALL(type) (INLINE_SYSCALL(name, 6, arg1, arg2, arg3, arg4, arg5, arg6)); \
}
- #define INLINE_SYSCALL(name, nr, args...) \
+
+#if !defined __SYSCALL_STUB
+#warning NO STUB
+#define EMIT_INLINE_SYSCALL(type) return (type)
+#define INLINE_SYSCALL(name, nr, args...) \
({ \
unsigned int _resultvar = INTERNAL_SYSCALL (name, , nr, args); \
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (_resultvar, ), 0)) \
@@ -161,6 +169,15 @@ return (type) (INLINE_SYSCALL(name, 6, a
_resultvar = 0xffffffff; \
} \
(int) _resultvar; })
+#else
+#warning do STUB
+#define EMIT_INLINE_SYSCALL(type)
+#define INLINE_SYSCALL(name, nr, args...) \
+ ({ \
+ __set_errno(ENOSYS); \
+ return -1; \
+ })
+#endif
#define INTERNAL_SYSCALL(name, err, nr, args...) \
({ \
Index: libc/sysdeps/linux/i386/bits/syscall-stub.h
===================================================================
--- libc/sysdeps/linux/i386/bits/syscall-stub.h (revision 0)
+++ libc/sysdeps/linux/i386/bits/syscall-stub.h (revision 0)
@@ -0,0 +1,17 @@
+#ifndef __SYSCALL_STUB_H__
+#define __SYSCALL_STUB_H__ 1
+
+#define SYS_ify(syscall_name) (__NR_##syscall_name)
+
+/* XXX: drop this! */
+#ifndef _SYSCALL_H
+#define _SYSCALL_H 42
+#endif
+
+#include <bits/sysnum.h>
+
+#if _SYSCALL_H == 42
+#undef _SYSCALL_H
+#endif
+
+#endif /* __SYSCALL_STUB_H__ */
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