abstract getting filename, and add docs

diff --git a/src/build/dlopen.c b/src/build/dlopen.c
index ad85f0ea88bae61b740a2db25cc00304572583a3..01cbb9f65bed1661f033fa5b9e523a783f30b50f 100644 (file)
--- a/src/build/dlopen.c
+++ b/src/build/dlopen.c
@@ -169,7 +169,45 @@ static void *check_path(char *filename, char const *name, size_t namelen,
        return check_symbol(handle, symbol);
 }
 
+/*
+ *     Get the filename from the linker information.  We don't care
+ *     about the filename we used to open the library.  If the linker
+ *     information differs from the filename we used, well, there's
+ *     little we can do about that.
+ */
+static char *get_filename(void *handle)
+{
+       struct link_map *link_map = NULL;
+
+#ifdef __linux__
+       /*
+        *      RTLD_DI_ORIGIN returns the folder.  This
+        *      function returns the full pathname.  And,
+        *      returns a "struct link_map" which
+        *      coincidentally is also what's available on
+        *      OSX.
+        */
+       (void) dlinfo(handle, RTLD_DI_LINKMAP, &link_map);
+#else
+
+       /*
+        *      On OSX, the handle is just a `struct link_map`
+        *      pointer.  So we cast the handle to that, and
+        *      access the fields directly.
+        */
+       link_map = (struct link_map *) handle;
+#endif
+
+       if (!link_map) return NULL;
+
+       return strdup(link_map->l_name);
+}
+
+
 /** Call dlopen as a GNU make function
+ *
+ *  This function opens a library (without extension!), and returns
+ *  the directory where the library was found.
  *
  *     $(dlopen libfoo)
  *             open it, letting the dynamic linker figure it out
@@ -347,37 +385,7 @@ static char *make_dlopen(UNUSED char const *nm, unsigned int argc, char **argv)
        lib->handle = handle;
        lib->name = libname;
 
-       /*
-        *      Set lib->filename from the linker information.  We
-        *      don't care about the filename we used to open the
-        *      library.  If the linker information differs from the
-        *      filename we used, well, there's little we can do about
-        *      that.
-        */
-       {
-               struct link_map *link_map = NULL;
-
-#ifdef __linux__
-               /*
-                *      RTLD_DI_ORIGIN returns the folder.  This
-                *      function returns the full pathname.  And,
-                *      returns a "struct link_map" which
-                *      coincidentally is also what's available on
-                *      OSX.
-                */
-               (void) dlinfo(handle, RTLD_DI_LINKMAP, &link_map);
-#else
-
-               /*
-                *      On OSX, the handle is just a `struct link_map`
-                *      pointer.  So we cast the handle to that, and
-                *      access the fields directly.
-                */
-               link_map = (struct link_map *) handle;
-#endif
-
-               if (link_map) lib->filename = strdup(link_map->l_name);
-        }
+       lib->filename = get_filename(handle);
 
        libs = lib;