Move the trampolines for dlopen and related functions from crt0.o

into libc.  This reduces the size of every dynamically linked
executable by 248 bytes, and it reduces the size of static executables
by a lesser amount.  It also eliminates some global namespace
pollution.

With this change in place, the source for dlfcn.h should probably
be moved to "/usr/src/include".  I'll save that for another day.

Compatibility note:  Programs which use dlopen, if compiled on
systems with this change, will not run on systems with a libc from
prior to this change.  Very few programs use dlopen, so I think
that is OK.

1 files changed, 96 insertions, 0 deletions

diff --git a/lib/libc/gen/dlfcn.c b/lib/libc/gen/dlfcn.c
new file mode 100644
index 0000000..3f00346
--- /dev/null
+++ b/lib/libc/gen/dlfcn.c
@@ -0,0 +1,96 @@
+/*-
+ * Copyright (c) 1998 John D. Polstra
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	$Id$
+ */
+
+/*
+ * Trampolines to services provided by the dynamic linker.
+ */
+
+#include <sys/types.h>
+#include <nlist.h>		/* XXX - Required by link.h */
+#include <dlfcn.h>
+#include <link.h>
+#include <stddef.h>
+
+/*
+ * These variables are set by code in crt0.o.  For compatibility with
+ * old executables, they must be common, not extern.
+ */
+struct ld_entry	*__ldso_entry;		/* Entry points to dynamic linker */
+int		 __ldso_version;	/* Dynamic linker version number */
+
+void *
+dlopen(name, mode)
+	const char	*name;
+	int		 mode;
+{
+	if (__ldso_entry == NULL)
+		return NULL;
+	return (__ldso_entry->dlopen)(name, mode);
+}
+
+int
+dlclose(fd)
+	void		*fd;
+{
+	if (__ldso_entry == NULL)
+		return -1;
+	return (__ldso_entry->dlclose)(fd);
+}
+
+void *
+dlsym(fd, name)
+	void		*fd;
+	const char	*name;
+{
+	if (__ldso_entry == NULL)
+		return NULL;
+	if (__ldso_version >= LDSO_VERSION_HAS_DLSYM3) {
+		void *retaddr = *(&fd - 1);  /* XXX - ABI/machine dependent */
+		return (__ldso_entry->dlsym3)(fd, name, retaddr);
+	} else
+		return (__ldso_entry->dlsym)(fd, name);
+}
+
+
+const char *
+dlerror()
+{
+	if (__ldso_entry == NULL)
+		return "Service unavailable";
+	return (__ldso_entry->dlerror)();
+}
+
+int
+dladdr(addr, dlip)
+	const void	*addr;
+	Dl_info		*dlip;
+{
+	if (__ldso_entry == NULL || __ldso_version < LDSO_VERSION_HAS_DLADDR)
+		return 0;
+	return (__ldso_entry->dladdr)(addr, dlip);
+}