1 files changed, 149 insertions, 9 deletions

diff --git a/src/lib/libc/include/namespace.h b/src/lib/libc/include/namespace.h
index 4a51f15ddf..b0cad502a3 100644
--- a/src/lib/libc/include/namespace.h
+++ b/src/lib/libc/include/namespace.h
@@ -1,18 +1,158 @@
-/*      $OpenBSD: namespace.h,v 1.2 1996/08/19 08:28:08 tholo Exp $     */
+/*      $OpenBSD: namespace.h,v 1.3 2015/08/31 02:53:56 guenther Exp $  */
 
+#ifndef _LIBC_NAMESPACE_H_
+#define _LIBC_NAMESPACE_H_
+
+/* These will be replaced with symbol renaming ala PROTO_NORMAL */
 #define catclose        _catclose
 #define catgets         _catgets
 #define catopen         _catopen
-#define err             _err
-#define errx            _errx
 #define strtoq          _strtoq
 #define strtouq         _strtouq
 #define sys_errlist     _sys_errlist
 #define sys_nerr        _sys_nerr
 #define sys_siglist     _sys_siglist
-#define verr            _verr
-#define verrx           _verrx
-#define vwarn           _vwarn
-#define vwarnx          _vwarnx
-#define warn            _warn
-#define warnx           _warnx
+
+/*
+ * Copyright (c) 2015 Philip Guenther <guenther@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * The goal: calls from inside libc to other libc functions should be via
+ * identifiers that are of hidden visibility and--to avoid confusion--are
+ * in the reserved namespace.  By doing this these calls are protected
+ * from overriding by applications and on many platforms can avoid creation
+ * or use of GOT or PLT entries.  I've chosen a prefix of underbar-C-underbar
+ * ("_libc_") for this.  These will not be declared directly; instead, the
+ * gcc "asm labels" extension will be used rename the function.
+ *
+ * For syscalls which are cancellation points, such as wait4(), there
+ * are identifiers that do not provide cancellation:
+ *      _libc_wait4             hidden alias, for use internal to libc only
+ *      _thread_sys_wait4       global name, for use outside libc only
+ * ...and identifiers that do provide cancellation:
+ *      wait4                   weak alias, for general use
+ *      _libc_wait4_cancel      hidden alias, for use internal to libc only
+ * Inside libc, the bare name ("wait4") binds to the version *without*
+ * cancellation; the few times where cancellation is desired it can be
+ * obtained by calling CANCEL(x) instead of just x.
+ *
+ * Some other calls need to be wrapped for reasons other than cancellation,
+ * such as to provide functionality beyond the underlying syscall (e.g.,
+ * setlogin).  For these, there are identifiers for the raw call, without
+ * the wrapping:
+ *      _libc_setlogin          hidden alias, for use internal to libc only
+ *      _thread_sys_setlogin    global name, for use outside libc only
+ * ...and identifiers that do provide the libc wrapping:
+ *      setlogin                weak alias, for general use
+ *      _libc_setlogin_wrap     hidden alias, for use internal to libc only
+ * Inside libc, the bare name ("setlogin") binds to the wrapper; when the
+ * raw version is necessary it can be obtained by calling HIDDEN(x) instead of
+ * just x.
+ *
+ * For syscalls which are not cancellation points, such as getpid(),
+ * the identifiers are just:
+ *      _libc_getpid            hidden alias, for use internal to libc only
+ *      _thread_sys_getpid      global name, for use outside libc only
+ *      getpid                  weak alias, for use outside libc only
+ *
+ * By using gcc's "asm label" extension, we can usually avoid having
+ * to type those prefixes in the .h and .c files.  However, for those
+ * cases where a non-default binding is necessary we can use these macros
+ * to get the desired identifier:
+ *
+ *   CANCEL(x)
+ *      This expands to the internal, hidden name of a cancellation
+ *      wrapper: _libc_x_cancel.  ex: CANCEL(fsync)(fd)
+ *
+ *   WRAP(x)
+ *      This expands to the internal, hidden name of a non-cancellation
+ *      wrapper: _libc_x_wrap.  ex: WRAP(sigpending)(set)
+ *
+ *
+ * In order to actually set up the desired asm labels, we use these in
+ * the internal .h files:
+ *   PROTO_NORMAL(x)            Symbols used both internally and externally
+ *      This makes gcc convert use of x to use _libc_x instead
+ *      ex: PROTO_NORMAL(getpid)
+ *
+ *   PROTO_STD_DEPRECATED(x)    Standard C symbols that we don't want to use
+ *      This just marks the symbol as deprecated, with no renaming.
+ *      ex: PROTO_STD_DEPRECATED(strcpy)
+ *
+ *   PROTO_DEPRECATED(x)        Symbols not in ISO C that we don't want to use
+ *      This marks the symbol as both weak and deprecated, with no renaming
+ *      ex: PROTO_DEPRECATED(creat)
+ *
+ *   PROTO_CANCEL(x)            Functions that have cancellation wrappers
+ *      Like PROTO_NORMAL(x), but also declares _libc_x_cancel
+ *      ex: PROTO_CANCEL(wait4)
+ *
+ *   PROTO_WRAP(x)              Functions that have wrappers for other reasons
+ *      This makes gcc convert use of x to use _libc_x_wrap instead.
+ *      ex: PROTO_WRAP(setlogin)
+ *
+ *
+ * Finally, to create the expected aliases, we use these in the .c files
+ * where the definitions are:
+ *   DEF_STRONG(x)              Symbols reserved to or specified by ISO C
+ *      This defines x as a strong alias for _libc_x; this must only
+ *      be used for symbols that are reserved by the C standard
+ *      (or reserved in the external identifier namespace).
+ *      Matches with PROTO_NORMAL()
+ *      ex: DEF_STRONG(fopen)
+ *
+ *   DEF_WEAK(x)                Symbols used internally and not in ISO C
+ *      This defines x as a weak alias for _libc_x
+ *      Matches with PROTO_NORMAL()
+ *      ex: DEF_WEAK(lseek)
+ *
+ *   DEF_CANCEL(x)              Symbols that have a cancellation wrapper
+ *      This defines x as a weak alias for _libc_x_cancel.
+ *      Matches with PROTO_CANCEL()
+ *      ex: DEF_CANCEL(read)
+ *
+ *   DEF_WRAP(x)
+ *      This defines x as a weak alias for _libc_x_wrap.
+ *      Matches with PROTO_WRAP()
+ *      ex: DEF_WRAP(setlogin)
+ *
+ *   DEF_SYS(x)
+ *      This defines _thread_sys_x as a strong alias for _libc_x.  This should
+ *      only be needed for syscalls that have C instead of asm stubs.
+ *      Matches with PROTO_NORMAL(), PROTO_CANCEL(), or PROTO_WRAP()
+ *      ex: DEF_SYS(pread)
+ */
+
+#define HIDDEN(x)               _libc_##x
+#define CANCEL(x)               _libc_##x##_cancel
+#define WRAP(x)                 _libc_##x##_wrap
+#define HIDDEN_STRING(x)        "_libc_" __STRING(x)
+#define WRAP_STRING(x)          "_libc_" __STRING(x) "_wrap"
+
+#define PROTO_NORMAL(x)         __dso_hidden typeof(x) x asm(HIDDEN_STRING(x))
+#define PROTO_STD_DEPRECATED(x) typeof(x) x __attribute__((deprecated))
+#define PROTO_DEPRECATED(x)     typeof(x) x __attribute__((deprecated, weak))
+#define PROTO_CANCEL(x)         PROTO_NORMAL(x), CANCEL(x)
+#define PROTO_WRAP(x)           __dso_hidden typeof(x) x asm(WRAP_STRING(x))
+
+#define DEF_STRONG(x)           __strong_alias(x, HIDDEN(x))
+#define DEF_WEAK(x)             __weak_alias(x, HIDDEN(x))
+#define DEF_CANCEL(x)           __weak_alias(x, CANCEL(x))
+#define DEF_WRAP(x)             __weak_alias(x, WRAP(x))
+#define DEF_SYS(x)              __strong_alias(_thread_sys_##x, HIDDEN(x))
+
+#endif  /* _LIBC_NAMESPACE_H_ */
+