Remove _THREAD_SAFE and make libc thread-safe by default by

adding (weak definitions to) stubs for some of the pthread
functions.  If the threads library is linked in, the real
pthread functions will pulled in.

Use the following convention for system calls wrapped by the
threads library:
	__sys_foo - actual system call
	_foo - weak definition to __sys_foo
	foo - weak definition to __sys_foo

Change all libc uses of system calls wrapped by the threads
library from foo to _foo.  In order to define the prototypes
for _foo(), we introduce namespace.h and un-namespace.h
(suggested by bde).  All files that need to reference these
system calls, should include namespace.h before any standard
includes, then include un-namespace.h after the standard
includes and before any local includes.  <db.h> is an exception
and shouldn't be included in between namespace.h and
un-namespace.h  namespace.h will define foo to _foo, and
un-namespace.h will undefine foo.

Try to eliminate some of the recursive calls to MT-safe
functions in libc/stdio in preparation for adding a mutex
to FILE.  We have recursive mutexes, but would like to avoid
using them if possible.

Remove uneeded includes of <errno.h> from a few files.

Add $FreeBSD$ to a few files in order to pass commitprep.

Approved by:	-arch

1 files changed, 13 insertions, 22 deletions

diff --git a/lib/libc/alpha/SYS.h b/lib/libc/alpha/SYS.h
index 923300b..d53e1fb 100644
--- a/lib/libc/alpha/SYS.h
+++ b/lib/libc/alpha/SYS.h
@@ -83,50 +83,41 @@ END(label);
  * Design note:
  *
  * The macros PSYSCALL() and PRSYSCALL() are intended for use where a
- * syscall needs to be renamed in the threaded library. When building
- * a normal library, they default to the traditional SYSCALL() and
- * RSYSCALL(). This avoids the need to #ifdef _THREAD_SAFE everywhere
- * that the renamed function needs to be called.
+ * syscall needs to be renamed in the threaded library.
  */
-#ifdef _THREAD_SAFE
 /*
- * For the thread_safe versions, we prepend _thread_sys_ to the function
+ * For the thread_safe versions, we prepend __sys_ to the function
  * name so that the 'C' wrapper can go around the real name.
  */
+#define	PNAME(name)	__CONCAT(__sys_,name)
+
 #define	PCALL(name)						\
-	CALL(___CONCAT(_thread_sys_,name))
+	CALL(PNAME(name))
 
 #define	PLEAF(name, args)					\
-LEAF(___CONCAT(_thread_sys_,name),args)
+LEAF(PNAME(name),args)
 
 #define	PEND(name)						\
-END(___CONCAT(_thread_sys_,name))
+END(PNAME(name))
 
 #define	PSYSCALL(name)						\
 PLEAF(name,0);				/* XXX # of args? */	\
+	WEAK_ALIAS(name, PNAME(name));				\
+	WEAK_ALIAS(__CONCAT(_,name), PNAME(name));		\
 	CALLSYS_ERROR(name)
 
 #define	PRSYSCALL(name)						\
 PLEAF(name,0);				/* XXX # of args? */	\
+	WEAK_ALIAS(name, PNAME(name));				\
+	WEAK_ALIAS(__CONCAT(_,name), PNAME(name));		\
 	CALLSYS_ERROR(name)					\
 	RET;							\
 PEND(name)
 
 #define	PPSEUDO(label,name)					\
 PLEAF(label,0);				/* XXX # of args? */	\
+	WEAK_ALIAS(label, PNAME(label));			\
+	WEAK_ALIAS(__CONCAT(_,label), PNAME(label));		\
 	CALLSYS_ERROR(name);					\
 	RET;							\
 PEND(label)
-
-#else
-/*
- * The non-threaded library defaults to traditional syscalls where
- * the function name matches the syscall name.
- */
-#define	PSYSCALL(x)	SYSCALL(x)
-#define	PRSYSCALL(x)	RSYSCALL(x)
-#define	PPSEUDO(x,y)	PSEUDO(x,y)
-#define	PLEAF(x,y)	LEAF(x,y)
-#define	PEND(x)		END(x)
-#define	PCALL(x)	CALL(x)
-#endif