libguile/dynl.c

   1 /* dynl.c - dynamic linking
   2  *
   3  * Copyright (C) 1990, 91, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002,
   4  * 2003, 2008, 2009, 2010 Free Software Foundation, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public License
   8  * as published by the Free Software Foundation; either version 3 of
   9  * the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19  * 02110-1301 USA
  20  */
  21
  22
  23
  24 #ifdef HAVE_CONFIG_H
  25 # include <config.h>
  26 #endif
  27
  28 /* "dynl.c" dynamically link&load object files.
  29    Author: Aubrey Jaffer
  30    Modified for libguile by Marius Vollmer */
  31
  32 #if 0 /* Disabled until we know for sure that it isn't needed */
  33 /* XXX - This is only here to drag in a definition of __eprintf. This
  34    is needed for proper operation of dynamic linking. The real
  35    solution would probably be a shared libgcc. */
  36
  37 #undef NDEBUG
  38 #include <assert.h>
  39
  40 static void
  41 maybe_drag_in_eprintf ()
  42 {
  43   assert (!maybe_drag_in_eprintf);
  44 }
  45 #endif
  46
  47 #include <stdio.h>
  48 #include <string.h>
  49
  50 #include "libguile/_scm.h"
  51 #include "libguile/libpath.h"
  52 #include "libguile/dynl.h"
  53 #include "libguile/smob.h"
  54 #include "libguile/keywords.h"
  55 #include "libguile/ports.h"
  56 #include "libguile/strings.h"
  57 #include "libguile/deprecation.h"
  58 #include "libguile/validate.h"
  59 #include "libguile/dynwind.h"
  60 #include "libguile/foreign.h"
  61
  62 #include <ltdl.h>
  63
  64 /*
  65   From the libtool manual: "Note that libltdl is not threadsafe,
  66   i.e. a multithreaded application has to use a mutex for libltdl.".
  67
  68   Guile does not currently support pre-emptive threads, so there is no
  69   mutex.  Previously SCM_CRITICAL_SECTION_START and
  70   SCM_CRITICAL_SECTION_END were used: they are mentioned here in case
  71   somebody is grepping for thread problems ;)
  72 */
  73 /* njrev: not threadsafe, protection needed as described above */
  74
  75 static void *
  76 sysdep_dynl_link (const char *fname, const char *subr)
  77 {
  78   lt_dlhandle handle;
  79
  80   if (fname != NULL)
  81     handle = lt_dlopenext (fname);
  82   else
  83     /* Return a handle for the program as a whole.  */
  84     handle = lt_dlopen (NULL);
  85
  86   if (NULL == handle)
  87     {
  88       SCM fn;
  89       SCM msg;
  90
  91       fn = fname != NULL ? scm_from_locale_string (fname) : SCM_BOOL_F;
  92       msg = scm_from_locale_string (lt_dlerror ());
  93       scm_misc_error (subr, "file: ~S, message: ~S", scm_list_2 (fn, msg));
  94     }
  95
  96   return (void *) handle;
  97 }
  98
  99 static void
 100 sysdep_dynl_unlink (void *handle, const char *subr)
 101 {
 102   if (lt_dlclose ((lt_dlhandle) handle))
 103     {
 104       scm_misc_error (subr, (char *) lt_dlerror (), SCM_EOL);
 105     }
 106 }
 107
 108 static void *
 109 sysdep_dynl_value (const char *symb, void *handle, const char *subr)
 110 {
 111   void *fptr;
 112
 113   fptr = lt_dlsym ((lt_dlhandle) handle, symb);
 114   if (!fptr)
 115     {
 116       scm_misc_error (subr, (char *) lt_dlerror (), SCM_EOL);
 117     }
 118   return fptr;
 119 }
 120
 121 static void
 122 sysdep_dynl_init ()
 123 {
 124   char *env;
 125
 126   lt_dlinit ();
 127
 128   env = getenv ("GUILE_SYSTEM_EXTENSIONS_PATH");
 129   if (env && strcmp (env, "") == 0)
 130     /* special-case interpret system-ltdl-path=="" as meaning no system path,
 131        which is the case during the build */
 132     ;
 133   else if (env)
 134     /* FIXME: should this be a colon-separated path? Or is the only point to
 135        allow the build system to turn off the installed extensions path? */
 136     lt_dladdsearchdir (env);
 137   else
 138     {
 139       lt_dladdsearchdir (SCM_LIB_DIR);
 140       lt_dladdsearchdir (SCM_EXTENSIONS_DIR);
 141     }
 142 }
 143
 144 scm_t_bits scm_tc16_dynamic_obj;
 145
 146 #define DYNL_FILENAME         SCM_SMOB_OBJECT
 147 #define DYNL_HANDLE(x)        ((void *) SCM_SMOB_DATA_2 (x))
 148 #define SET_DYNL_HANDLE(x, v) (SCM_SET_SMOB_DATA_2 ((x), (scm_t_bits) (v)))
 149
 150
 151
 152 static int
 153 dynl_obj_print (SCM exp, SCM port, scm_print_state *pstate)
 154 {
 155   scm_puts ("#<dynamic-object ", port);
 156   scm_iprin1 (DYNL_FILENAME (exp), port, pstate);
 157   if (DYNL_HANDLE (exp) == NULL)
 158     scm_puts (" (unlinked)", port);
 159   scm_putc ('>', port);
 160   return 1;
 161 }
 162
 163
 164 SCM_DEFINE (scm_dynamic_link, "dynamic-link", 0, 1, 0,
 165             (SCM filename),
 166             "Find the shared object (shared library) denoted by\n"
 167             "@var{filename} and link it into the running Guile\n"
 168             "application.  The returned\n"
 169             "scheme object is a ``handle'' for the library which can\n"
 170             "be passed to @code{dynamic-func}, @code{dynamic-call} etc.\n\n"
 171             "Searching for object files is system dependent.  Normally,\n"
 172             "if @var{filename} does have an explicit directory it will\n"
 173             "be searched for in locations\n"
 174             "such as @file{/usr/lib} and @file{/usr/local/lib}.\n\n"
 175             "When @var{filename} is omitted, a @dfn{global symbol handle} is\n"
 176             "returned.  This handle provides access to the symbols\n"
 177             "available to the program at run-time, including those exported\n"
 178             "by the program itself and the shared libraries already loaded.\n")
 179 #define FUNC_NAME s_scm_dynamic_link
 180 {
 181   void *handle;
 182   char *file;
 183
 184   scm_dynwind_begin (0);
 185
 186   if (SCM_UNBNDP (filename))
 187     file = NULL;
 188   else
 189     {
 190       file = scm_to_locale_string (filename);
 191       scm_dynwind_free (file);
 192     }
 193
 194   handle = sysdep_dynl_link (file, FUNC_NAME);
 195   scm_dynwind_end ();
 196
 197   SCM_RETURN_NEWSMOB2 (scm_tc16_dynamic_obj,
 198                        SCM_UNBNDP (filename)
 199                        ? SCM_UNPACK (SCM_BOOL_F) : SCM_UNPACK (filename),
 200                        handle);
 201 }
 202 #undef FUNC_NAME
 203
 204
 205 SCM_DEFINE (scm_dynamic_object_p, "dynamic-object?", 1, 0, 0,
 206             (SCM obj),
 207             "Return @code{#t} if @var{obj} is a dynamic object handle,\n"
 208             "or @code{#f} otherwise.")
 209 #define FUNC_NAME s_scm_dynamic_object_p
 210 {
 211   return scm_from_bool (SCM_TYP16_PREDICATE (scm_tc16_dynamic_obj, obj));
 212 }
 213 #undef FUNC_NAME
 214
 215
 216 SCM_DEFINE (scm_dynamic_unlink, "dynamic-unlink", 1, 0, 0,
 217             (SCM dobj),
 218             "Unlink a dynamic object from the application, if possible.  The\n"
 219             "object must have been linked by @code{dynamic-link}, with \n"
 220             "@var{dobj} the corresponding handle.  After this procedure\n"
 221             "is called, the handle can no longer be used to access the\n"
 222             "object.")
 223 #define FUNC_NAME s_scm_dynamic_unlink
 224 {
 225   /*fixme* GC-problem */
 226   SCM_VALIDATE_SMOB (SCM_ARG1, dobj, dynamic_obj);
 227   if (DYNL_HANDLE (dobj) == NULL) {
 228     SCM_MISC_ERROR ("Already unlinked: ~S", scm_list_1 (dobj));
 229   } else {
 230     sysdep_dynl_unlink (DYNL_HANDLE (dobj), FUNC_NAME);
 231     SET_DYNL_HANDLE (dobj, NULL);
 232     return SCM_UNSPECIFIED;
 233   }
 234 }
 235 #undef FUNC_NAME
 236
 237
 238 SCM_DEFINE (scm_dynamic_pointer, "dynamic-pointer", 2, 0, 0,
 239             (SCM name, SCM dobj),
 240             "Return a ``wrapped pointer'' to the symbol @var{name}\n"
 241             "in the shared object referred to by @var{dobj}.  The returned\n"
 242             "pointer points to a C object.\n\n"
 243             "Regardless whether your C compiler prepends an underscore\n"
 244             "@samp{_} to the global names in a program, you should\n"
 245             "@strong{not} include this underscore in @var{name}\n"
 246             "since it will be added automatically when necessary.")
 247 #define FUNC_NAME s_scm_dynamic_pointer
 248 {
 249   void *val;
 250
 251   SCM_VALIDATE_STRING (1, name);
 252   SCM_VALIDATE_SMOB (SCM_ARG2, dobj, dynamic_obj);
 253
 254   if (DYNL_HANDLE (dobj) == NULL)
 255     SCM_MISC_ERROR ("Already unlinked: ~S", dobj);
 256   else
 257     {
 258       char *chars;
 259
 260       scm_dynwind_begin (0);
 261       chars = scm_to_locale_string (name);
 262       scm_dynwind_free (chars);
 263       val = sysdep_dynl_value (chars, DYNL_HANDLE (dobj), FUNC_NAME);
 264       scm_dynwind_end ();
 265
 266       return scm_from_pointer (val, NULL);
 267     }
 268 }
 269 #undef FUNC_NAME
 270
 271
 272 SCM_DEFINE (scm_dynamic_func, "dynamic-func", 2, 0, 0,
 273             (SCM name, SCM dobj),
 274             "Return a ``handle'' for the function @var{name} in the\n"
 275             "shared object referred to by @var{dobj}.  The handle\n"
 276             "can be passed to @code{dynamic-call} to actually\n"
 277             "call the function.\n\n"
 278             "Regardless whether your C compiler prepends an underscore\n"
 279             "@samp{_} to the global names in a program, you should\n"
 280             "@strong{not} include this underscore in @var{name}\n"
 281             "since it will be added automatically when necessary.")
 282 #define FUNC_NAME s_scm_dynamic_func
 283 {
 284   return scm_dynamic_pointer (name, dobj);
 285 }
 286 #undef FUNC_NAME
 287
 288
 289 SCM_DEFINE (scm_dynamic_call, "dynamic-call", 2, 0, 0,
 290             (SCM func, SCM dobj),
 291             "Call a C function in a dynamic object.  Two styles of\n"
 292             "invocation are supported:\n\n"
 293             "@itemize @bullet\n"
 294             "@item @var{func} can be a function handle returned by\n"
 295             "@code{dynamic-func}.  In this case @var{dobj} is\n"
 296             "ignored\n"
 297             "@item @var{func} can be a string with the name of the\n"
 298             "function to call, with @var{dobj} the handle of the\n"
 299             "dynamic object in which to find the function.\n"
 300             "This is equivalent to\n"
 301             "@smallexample\n\n"
 302             "(dynamic-call (dynamic-func @var{func} @var{dobj}) #f)\n"
 303             "@end smallexample\n"
 304             "@end itemize\n\n"
 305             "In either case, the function is passed no arguments\n"
 306             "and its return value is ignored.")
 307 #define FUNC_NAME s_scm_dynamic_call
 308 {
 309   void (*fptr) (void);
 310
 311   if (scm_is_string (func))
 312     func = scm_dynamic_func (func, dobj);
 313   SCM_VALIDATE_POINTER (SCM_ARG1, func);
 314
 315   fptr = SCM_POINTER_VALUE (func);
 316   fptr ();
 317   return SCM_UNSPECIFIED;
 318 }
 319 #undef FUNC_NAME
 320
 321 void
 322 scm_init_dynamic_linking ()
 323 {
 324   scm_tc16_dynamic_obj = scm_make_smob_type ("dynamic-object", 0);
 325   scm_set_smob_print (scm_tc16_dynamic_obj, dynl_obj_print);
 326   sysdep_dynl_init ();
 327 #include "libguile/dynl.x"
 328 }
 329
 330 /*
 331   Local Variables:
 332   c-file-style: "gnu"
 333   End:
 334 */