2 files changed, 34 insertions, 2 deletions

diff --git a/lib/libc/gen/dlfcn.c b/lib/libc/gen/dlfcn.c
index 79021e76b1e4..38b9553679a4 100644
--- a/lib/libc/gen/dlfcn.c
+++ b/lib/libc/gen/dlfcn.c
@@ -23,7 +23,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: dlfcn.c,v 1.1 1998/02/09 06:05:24 jdp Exp $
+ *	$Id: dlfcn.c,v 1.2 1998/03/07 19:57:05 jdp Exp $
  */
 
 /*
@@ -94,6 +94,14 @@ dlsym(void *handle, const char *name)
 	return NULL;
 }
 
+#pragma weak dlversion
+int
+dlversion(void)
+{
+	_rtld_error(sorry);
+	return 0;
+}
+
 #else /* a.out format */
 
 #include <sys/types.h>
@@ -165,4 +173,11 @@ dlsym(void *handle, const char *name)
 		return (__ldso_entry->dlsym)(handle, name);
 }
 
+/* We don't support dlversion() on a.out systems. */
+int
+dlversion(void)
+{
+	return 0;
+}
+
 #endif /* __ELF__ */
diff --git a/lib/libc/gen/dlopen.3 b/lib/libc/gen/dlopen.3
index 9e848f9e8428..e56e3aeb9b98 100644
--- a/lib/libc/gen/dlopen.3
+++ b/lib/libc/gen/dlopen.3
@@ -34,7 +34,7 @@
 .Os FreeBSD
 .Dt DLOPEN 3
 .Sh NAME
-.Nm dlopen, dlsym, dlerror, dlclose
+.Nm dlopen, dlsym, dlerror, dlclose, dlversion
 .Nd programmatic interface to the dynamic linker
 .Sh SYNOPSIS
 .Fd #include <dlfcn.h>
@@ -46,6 +46,8 @@
 .Fn dlerror "void"
 .Ft int
 .Fn dlclose "void *handle"
+.Ft int
+.Fn dlversion "void"
 .Sh DESCRIPTION
 These functions provide a simple programmatic interface to the services of the
 dynamic linker.
@@ -219,6 +221,19 @@ The object-intrinsic functions
 and
 .Fn _fini
 are called with no arguments, and are not expected to return values.
+.Pp
+.Fn dlversion
+returns the version number of the dynamic linker.  Interpreted
+as a decimal number, the version number has the form
+.Em rrrsss .
+.Em rrr
+corresponds to the base operating system release version, e.g., 400
+for release 4.0.0.
+.Em sss
+is a serial number that increases monotonically within each release
+version.  If the installed dynamic linker is too old to support
+.Fn dlversion ,
+0 is returned.
 .Sh NOTES
 ELF executables need to be linked
 using the
@@ -234,6 +249,8 @@ and
 return the null pointer in the event of errors.
 .Fn dlclose
 returns 0 on success, or -1 if an error occurred.
+.Fn dlversion
+returns 0 if the dynamic linker is too old to support it.
 Whenever an error has been detected, a message detailing it can be
 retrieved via a call to
 .Fn dlerror .