configure: use dlopen instead of ltdl by default

Try dlopen first, then ltdl, or fail to enable dynamically loaded plugins.

dlopen may be disabled with --disable-plugin-dlopen
(not --disable-dlopen because $enable_dlopen is already
 used/set somewhere in the configury)

Requested by IBM, already done in OMPI a while ago.

Closes #262

Signed-off-by: Brice Goglin <[email protected]>

Author: bgoglin

NEWS

@@ -27,6 +27,10 @@ Version 2.2.0
   + Remove support for Intel Xeon Phi (MIC, Knights Corner) co-processors.
 * Tools
   + Add --uid to filter the hwloc-ps output by uid on Linux.
+* Misc
+  + Use the native dlopen instead of libltdl,
+    unless --disable-plugin-dlopen is passed at configure time.
+
 
 Version 2.1.0
 -------------

config/hwloc.m4

@@ -1184,8 +1184,17 @@ return clGetDeviceIDs(0, 0, 0, NULL, NULL);
     AC_MSG_RESULT($hwloc_have_plugins)
 
     if test "x$hwloc_have_plugins" = xyes; then
-      # ltdl (at least 2.4.2) doesn't work on AIX
+      # dlopen and ltdl (at least 2.4.2) doesn't work on AIX
       # posix linkers don't work well with plugins and windows dll constraints
+      if test "x$enable_plugin_dlopen" = x; then
+        if test "x$hwloc_aix" = "xyes"; then
+          AC_MSG_WARN([dlopen does not work on AIX, disabled by default.])
+          enable_plugin_dlopen=no
+        else if test "x$hwloc_windows" = "xyes"; then
+          AC_MSG_WARN([dlopen not supported on non-native Windows build, disabled by default.])
+          enable_plugin_dlopen=no
+        fi fi
+      fi
       if test "x$enable_plugin_ltdl" = x; then
         if test "x$hwloc_aix" = "xyes"; then
           AC_MSG_WARN([ltdl does not work on AIX, disabled by default.])
@@ -1196,27 +1205,37 @@ return clGetDeviceIDs(0, 0, 0, NULL, NULL);
         fi fi
       fi
 
+      # Look for dlopen
+      if test "x$enable_plugin_dlopen" != xno; then
+        HWLOC_CHECK_DLOPEN([hwloc_dlopen_ready], [hwloc_dlopen_libs])
+      fi
       # Look for ltdl
       if test "x$enable_plugin_ltdl" != xno; then
         HWLOC_CHECK_LTDL([hwloc_ltdl_ready], [hwloc_ltdl_libs])
       fi
 
-      # Now use ltdl, or just fail to enable plugins
+      # Now use dlopen by default, or ltdl, or just fail to enable plugins
       AC_MSG_CHECKING([which library to use for loading plugins])
-      if test x$hwloc_ltdl_ready = xyes; then
+      if test "x$hwloc_dlopen_ready" = xyes; then
+        AC_MSG_RESULT([dlopen])
+	hwloc_plugins_load=dlopen
+        # Now enable dlopen libs
+        HWLOC_DL_LIBS="$hwloc_dlopen_libs"
+        AC_SUBST(HWLOC_DL_LIBS)
+      else if test x$hwloc_ltdl_ready = xyes; then
         AC_MSG_RESULT([ltdl])
         hwloc_plugins_load=ltdl
         # Now enable ltdl libs
+        AC_DEFINE([HWLOC_HAVE_LTDL], 1, [Define to 1 if the hwloc library should use ltdl for loading plugins])
         HWLOC_LTDL_LIBS="$hwloc_ltdl_libs"
         AC_SUBST(HWLOC_LTDL_LIBS)
         # Add ltdl static-build dependencies to hwloc.pc
         HWLOC_CHECK_LTDL_DEPS
-	hwloc_plugins_load=ltdl
       else
         AC_MSG_RESULT([none])
-        AC_MSG_WARN([Plugin support requested, but could not enable ltdl])
+        AC_MSG_WARN([Plugin support requested, but could not enable dlopen or ltdl])
         AC_MSG_ERROR([Cannot continue])
-      fi
+      fi fi
 
       AC_DEFINE([HWLOC_HAVE_PLUGINS], 1, [Define to 1 if the hwloc library should support dynamically-loaded plugins])
     fi
@@ -1440,6 +1459,34 @@ AC_DEFUN([_HWLOC_CHECK_DECLS], [
 
 #-----------------------------------------------------------------------
 
+dnl HWLOC_CHECK_DLOPEN
+dnl
+dnl set $1 to yes or not
+dnl set $2 to -ldl or so
+AC_DEFUN([HWLOC_CHECK_DLOPEN], [
+  [$1]=no
+  AC_MSG_CHECKING([for dlopen])
+  AC_LINK_IFELSE([
+    AC_LANG_PROGRAM([[
+      #include <dlfcn.h>
+      #include <stdlib.h>
+      void *handle;
+    ]], [[
+      handle = dlopen(NULL, RTLD_NOW|RTLD_LOCAL);
+    ]])],
+    [AC_MSG_RESULT([yes])
+     [$1]=yes],
+    [AC_MSG_RESULT([no])
+     AC_CHECK_HEADER([dlfcn.h],
+       [AC_CHECK_LIB([dl], [dlopen],
+                     [[$1]=yes
+	             [$2]=-ldl])
+        ])
+    ])
+])
+
+#-----------------------------------------------------------------------
+
 dnl HWLOC_CHECK_LTDL
 dnl
 dnl set $1 to yes or not

config/hwloc_internal.m4

@@ -104,7 +104,13 @@ AC_DEFUN([HWLOC_DEFINE_ARGS],[
                   AS_HELP_STRING([--enable-plugins=name,...],
                                  [Build the given components as dynamically-loaded plugins]))
 
+    # Look for dlopen
+    # Not --disable-dlopen because $enable_dlopen is already used/set
+    AC_ARG_ENABLE([plugin-dlopen],
+                  AC_HELP_STRING([--disable-plugin-dlopen],
+                                 [Do not use dlopen for loading plugins.]))
     # Look for ltdl
+    # Not --disable-ltdl for consistency wrt dlopen above
     AC_ARG_ENABLE([plugin-ltdl],
                   AC_HELP_STRING([--disable-plugin-ltdl],
                                  [Do not use ltdl for loading plugins.]))

doc/hwloc.doxy

@@ -157,7 +157,7 @@ The hwloc core may also benefit from the following development packages:
     The relevant development package is usually <tt>libudev-devel</tt>
     or <tt>libudev-dev</tt>.
 </li>
-<li>libtool's ltdl library for dynamic plugin loading.
+<li>libtool's ltdl library for dynamic plugin loading if the native dlopen cannot be used.
   The relevant development package is usually <tt>libtool-ltdl-devel</tt>
   or <tt>libltdl-dev</tt>.
 </li>
@@ -2710,15 +2710,15 @@ configure script.  You can then invoke hwloc's configuration tests and
 build setup by calling an m4 macro (see below).
 
 Although hwloc dynamic shared object plugins may be used in embedded
-mode, the embedder project will have to manually setup libltdl in its
+mode, the embedder project will have to manually setup dlopen or libltdl in its
 build system so that hwloc can load its plugins at run time.
 Also, embedders should be aware of complications that can arise due to
 public and private linker namespaces (e.g., if the embedder project is
 loaded into a private namespace and then hwloc tries to dynamically
 load its plugins, such loading may fail since the hwloc plugins can't
 find the hwloc symbols they need).
 The embedder project is <b>strongly</b> advised not to use hwloc's
-dynamically loading plugins / libltdl capability.
+dynamically loading plugins / dlopen / libltdl capability.
 
 
 \htmlonly

hwloc.pc.in

@@ -9,4 +9,4 @@ Version: @HWLOC_VERSION@
 Requires.private: @HWLOC_REQUIRES@
 Cflags: -I${includedir}
 Libs: -L${libdir} -lhwloc
-Libs.private: @HWLOC_LIBS@ @HWLOC_LTDL_LIBS@ @HWLOC_LIBS_PRIVATE@
+Libs.private: @HWLOC_LIBS@ @HWLOC_DL_LIBS@ @HWLOC_LTDL_LIBS@ @HWLOC_LIBS_PRIVATE@

hwloc/Makefile.am

@@ -21,7 +21,7 @@ endif
 
 pluginsdir = @HWLOC_PLUGINS_DIR@
 plugins_LTLIBRARIES =
-plugins_ldflags = -module -avoid-version $(HWLOC_LTDL_LIBS)
+plugins_ldflags = -module -avoid-version $(HWLOC_DL_LIBS) $(HWLOC_LTDL_LIBS)
 # Beware that files are not rebuilt automatically when reconfiguring with different paths in these flags.
 AM_CPPFLAGS += -DHWLOC_PLUGINS_PATH="\"$(HWLOC_PLUGINS_PATH)\"" -DRUNSTATEDIR="\"$(HWLOC_runstatedir)\""
 
@@ -199,7 +199,7 @@ endif HWLOC_HAVE_WINDOWS
 # Installable library
 
 libhwloc_la_SOURCES = $(sources)
-libhwloc_la_LDFLAGS = $(ldflags) -version-info $(libhwloc_so_version) $(HWLOC_LIBS) $(HWLOC_LTDL_LIBS) $(HWLOC_LDFLAGS)
+libhwloc_la_LDFLAGS = $(ldflags) -version-info $(libhwloc_so_version) $(HWLOC_LIBS) $(HWLOC_DL_LIBS) $(HWLOC_LTDL_LIBS) $(HWLOC_LDFLAGS)
 
 if HWLOC_HAVE_PLUGINS
 libhwloc_la_LDFLAGS += -export-dynamic

hwloc/components.c

@@ -63,22 +63,136 @@ static pthread_mutex_t hwloc_components_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 #ifdef HWLOC_HAVE_PLUGINS
 
+#ifdef HWLOC_HAVE_LTDL
+/* ltdl-based plugin load */
 #include <ltdl.h>
+typedef lt_dlhandle hwloc_dlhandle;
+#define hwloc_dlinit lt_dlinit
+#define hwloc_dlexit lt_dlexit
+#define hwloc_dlopenext lt_dlopenext
+#define hwloc_dlclose lt_dlclose
+#define hwloc_dlerror lt_dlerror
+#define hwloc_dlsym lt_dlsym
+#define hwloc_dlforeachfile lt_dlforeachfile
+
+#else /* !HWLOC_HAVE_LTDL */
+/* no-ltdl plugin load relies on less portable libdl */
+#include <dlfcn.h>
+typedef void * hwloc_dlhandle;
+static __hwloc_inline int hwloc_dlinit(void) { return 0; }
+static __hwloc_inline int hwloc_dlexit(void) { return 0; }
+#define hwloc_dlclose dlclose
+#define hwloc_dlerror dlerror
+#define hwloc_dlsym dlsym
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <unistd.h>
+
+static hwloc_dlhandle hwloc_dlopenext(const char *_filename)
+{
+  hwloc_dlhandle handle;
+  char *filename = NULL;
+  asprintf(&filename, "%s.so", _filename);
+  if (!filename)
+    return NULL;
+  handle = dlopen(filename, RTLD_NOW|RTLD_LOCAL);
+  free(filename);
+  return handle;
+}
+
+static int
+hwloc_dlforeachfile(const char *_paths,
+		    int (*func)(const char *filename, void *data),
+		    void *data)
+{
+  char *paths = NULL, *path;
+
+  paths = strdup(_paths);
+  if (!paths)
+    return -1;
+
+  path = paths;
+  while (*path) {
+    char *colon;
+    DIR *dir;
+    struct dirent *dirent;
+
+    colon = strchr(path, ':');
+    if (colon)
+      *colon = '\0';
+
+    if (hwloc_plugins_verbose)
+      fprintf(stderr, " Looking under %s\n", path);
+
+    dir = opendir(path);
+    if (!dir)
+      goto next;
+
+    while ((dirent = readdir(dir)) != NULL) {
+      char *abs_name, *suffix;
+      struct stat stbuf;
+      int err;
+
+      err = asprintf(&abs_name, "%s/%s", path, dirent->d_name);
+      if (err < 0)
+	continue;
+
+      err = stat(abs_name, &stbuf);
+      if (err < 0) {
+	free(abs_name);
+        continue;
+      }
+      if (!S_ISREG(stbuf.st_mode)) {
+	free(abs_name);
+	continue;
+      }
+
+      /* Only keep .so files, and remove that suffix to get the component basename */
+      suffix = strrchr(abs_name, '.');
+      if (!suffix || strcmp(suffix, ".so")) {
+	free(abs_name);
+	continue;
+      }
+      *suffix = '\0';
+
+      err = func(abs_name, data);
+      if (err) {
+	free(abs_name);
+	continue;
+      }
+
+      free(abs_name);
+    }
+
+    closedir(dir);
+
+  next:
+    if (!colon)
+      break;
+    path = colon+1;
+  }
+
+  free(paths);
+  return 0;
+}
+#endif /* !HWLOC_HAVE_LTDL */
 
 /* array of pointers to dynamically loaded plugins */
 static struct hwloc__plugin_desc {
   char *name;
   struct hwloc_component *component;
   char *filename;
-  lt_dlhandle handle;
+  hwloc_dlhandle handle;
   struct hwloc__plugin_desc *next;
 } *hwloc_plugins = NULL;
 
 static int
 hwloc__dlforeach_cb(const char *filename, void *_data __hwloc_attribute_unused)
 {
   const char *basename;
-  lt_dlhandle handle;
+  hwloc_dlhandle handle;
   struct hwloc_component *component;
   struct hwloc__plugin_desc *desc, **prevdesc;
   char *componentsymbolname;
@@ -99,10 +213,10 @@ hwloc__dlforeach_cb(const char *filename, void *_data __hwloc_attribute_unused)
   }
 
   /* dlopen and get the component structure */
-  handle = lt_dlopenext(filename);
+  handle = hwloc_dlopenext(filename);
   if (!handle) {
     if (hwloc_plugins_verbose)
-      fprintf(stderr, "Failed to load plugin: %s\n", lt_dlerror());
+      fprintf(stderr, "Failed to load plugin: %s\n", hwloc_dlerror());
     goto out;
   }
 
@@ -114,7 +228,7 @@ hwloc__dlforeach_cb(const char *filename, void *_data __hwloc_attribute_unused)
     goto out_with_handle;
   }
   sprintf(componentsymbolname, "%s_component", basename);
-  component = lt_dlsym(handle, componentsymbolname);
+  component = hwloc_dlsym(handle, componentsymbolname);
   if (!component) {
     if (hwloc_plugins_verbose)
       fprintf(stderr, "Failed to find component symbol `%s'\n",
@@ -175,7 +289,7 @@ hwloc__dlforeach_cb(const char *filename, void *_data __hwloc_attribute_unused)
   return 0;
 
  out_with_handle:
-  lt_dlclose(handle);
+  hwloc_dlclose(handle);
  out:
   return 0;
 }
@@ -191,15 +305,15 @@ hwloc_plugins_exit(void)
   desc = hwloc_plugins;
   while (desc) {
     next = desc->next;
-    lt_dlclose(desc->handle);
+    hwloc_dlclose(desc->handle);
     free(desc->name);
     free(desc->filename);
     free(desc);
     desc = next;
   }
   hwloc_plugins = NULL;
 
-  lt_dlexit();
+  hwloc_dlexit();
 }
 
 static int
@@ -215,7 +329,7 @@ hwloc_plugins_init(void)
 
   hwloc_plugins_blacklist = getenv("HWLOC_PLUGINS_BLACKLIST");
 
-  err = lt_dlinit();
+  err = hwloc_dlinit();
   if (err)
     goto out;
 
@@ -227,7 +341,7 @@ hwloc_plugins_init(void)
 
   if (hwloc_plugins_verbose)
     fprintf(stderr, "Starting plugin dlforeach in %s\n", path);
-  err = lt_dlforeachfile(path, hwloc__dlforeach_cb, NULL);
+  err = hwloc_dlforeachfile(path, hwloc__dlforeach_cb, NULL);
   if (err)
     goto out_with_init;