use weak symbols

1 files changed, 49 insertions, 45 deletions

diff --git a/lib/libc/arch/i386/SYS.h b/lib/libc/arch/i386/SYS.h
index 17a43ecf593..7e117eca688 100644
--- a/lib/libc/arch/i386/SYS.h
+++ b/lib/libc/arch/i386/SYS.h
@@ -33,70 +33,74 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$OpenBSD: SYS.h,v 1.5 1999/01/06 05:36:17 d Exp $
+ *	$OpenBSD: SYS.h,v 1.6 2000/01/06 08:50:35 d Exp $
  */
 
 #include <machine/asm.h>
 #include <sys/syscall.h>
 
+/*
+ * Design note:
+ *
+ * System calls entry points are really named _thread_sys_{syscall},
+ * and weakly aliased to the name {syscall}. This allows the thread
+ * library to replace system calls at link time.
+ */
+
+#ifdef _NO_WEAK_ALIASES
+
+#ifdef _THREAD_SAFE
+/* Use _thread_sys_{syscall} when compiled with -D_THREAD_SAFE */
+#ifdef __STDC__
+#define	SYSENTRY(x)	ENTRY(_thread_sys_ ## x)
+#else /* ! __STDC__ */
+#define	SYSENTRY(x)	ENTRY(_thread_sys_ /**/ x)
+#endif /* ! __STDC__ */
+#else /* ! _THREAD_SAFE */
+/* Use {syscall} when compiling without -D_THREAD_SAFE */
+#define SYSENTRY(x)	ENTRY(x)
+#endif /* ! _THREAD_SAFE */
+
+#else /* WEAK_ALIASES */
+
+/* Use both _thread_sys_{syscall} and [weak] {syscall}. */
+
 #ifdef __STDC__
-# define    __ENTRY(p,x)	ENTRY(p##x)
-# define    __DO_SYSCALL(x)				\
-				movl $(SYS_##x),%eax;	\
-				int $0x80
-# define    __LABEL2(p,x)	_C_LABEL(p##x)
-#else
-# define    __ENTRY(p,x)	ENTRY(p/**/x)
-# define    __DO_SYSCALL(x)				\
-				movl $(SYS_/**/x),%eax;	\
-				int $0x80
-# define    __LABEL2(p,x)	_C_LABEL(p/**/x)
-#endif
+#define	SYSENTRY(x)					\
+			ENTRY(_thread_sys_ ## x)	\
+			.weak _C_LABEL(x);		\
+			_C_LABEL(x) = _C_LABEL(_thread_sys_ ## x)
+#else /* ! __STDC__ */
+#define	SYSENTRY(x)					\
+			ENTRY(_thread_sys_/**/x)	\
+			.weak _C_LABEL(x);		\
+			_C_LABEL(x) = _C_LABEL(_thread_sys_/**/x)
+#endif /* ! __STDC__ */
+#endif /* WEAK_ALIASES */
+
+#define	__DO_SYSCALL(x)					\
+			movl $(__CONCAT(SYS_,x)),%eax;	\
+			int $0x80
 
 /* perform a syscall, set errno */
-#define	    __SYSCALL(p,x)				\
+#define	SYSCALL(x)					\
 			.text;				\
 			.align 2;			\
 		2:					\
 			jmp PIC_PLT(cerror);		\
-		__ENTRY(p,x);				\
+		SYSENTRY(x);				\
 			__DO_SYSCALL(x);		\
 			jc 2b
 
 /* perform a syscall, set errno, return */
-# define    __RSYSCALL(p,x)	__SYSCALL(p,x); ret
+#define	RSYSCALL(x)					\
+			SYSCALL(x); 			\
+			ret
 
 /* perform a syscall, return */
-# define    __PSEUDO(p,x,y)				\
-		__ENTRY(p,x);				\
+#define	PSEUDO(x,y)					\
+		SYSENTRY(x);				\
 			__DO_SYSCALL(y);		\
 			ret
 
-/*
- * Design note:
- *
- * When the syscalls need to be renamed so they can be handled
- * specially by the threaded library, these macros insert `_thread_sys_'
- * in front of their name. This avoids the need to #ifdef _THREAD_SAFE 
- * everywhere that the renamed function needs to be called.
- */
-#ifdef _THREAD_SAFE
-/*
- * For the thread_safe versions, we prepend _thread_sys_ to the function
- * name so that the 'C' wrapper can go around the real name.
- */
-# define SYSCALL(x)	__SYSCALL(_thread_sys_,x)
-# define RSYSCALL(x)	__RSYSCALL(_thread_sys_,x)
-# define PSEUDO(x,y)	__PSEUDO(_thread_sys_,x,y)
-# define SYSENTRY(x)	__ENTRY(_thread_sys_,x)
-#else _THREAD_SAFE
-/*
- * The non-threaded library defaults to traditional syscalls where
- * the function name matches the syscall name.
- */
-# define SYSCALL(x)	__SYSCALL(,x)
-# define RSYSCALL(x)	__RSYSCALL(,x)
-# define PSEUDO(x,y)	__PSEUDO(,x,y)
-# define SYSENTRY(x)	__ENTRY(,x)
-#endif _THREAD_SAFE
 	.globl	cerror