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 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
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but 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 02110-1301 USA
  19  */
  20
  21
  22
  23 #ifdef HAVE_CONFIG_H
  24 # include <config.h>
  25 #endif
  26
  27 /* "dynl.c" dynamically link&load object files.
  28    Author: Aubrey Jaffer
  29    Modified for libguile by Marius Vollmer */
  30
  31 #if 0 /* Disabled until we know for sure that it isn't needed */
  32 /* XXX - This is only here to drag in a definition of __eprintf. This
  33    is needed for proper operation of dynamic linking. The real
  34    solution would probably be a shared libgcc. */
  35
  36 #undef NDEBUG
  37 #include <assert.h>
  38
  39 static void
  40 maybe_drag_in_eprintf ()
  41 {
  42   assert (!maybe_drag_in_eprintf);
  43 }
  44 #endif
  45
  46 #include <stdio.h>
  47 #include <string.h>
  48
  49 #include "libguile/_scm.h"
  50 #include "libguile/dynl.h"
  51 #include "libguile/smob.h"
  52 #include "libguile/keywords.h"
  53 #include "libguile/ports.h"
  54 #include "libguile/strings.h"
  55 #include "libguile/deprecation.h"
  56 #include "libguile/lang.h"
  57 #include "libguile/validate.h"
  58 #include "libguile/dynwind.h"
  59
  60 #include <ltdl.h>
  61
  62 /*
  63   From the libtool manual: "Note that libltdl is not threadsafe,
  64   i.e. a multithreaded application has to use a mutex for libltdl.".
  65
  66   Guile does not currently support pre-emptive threads, so there is no
  67   mutex.  Previously SCM_CRITICAL_SECTION_START and
  68   SCM_CRITICAL_SECTION_END were used: they are mentioned here in case
  69   somebody is grepping for thread problems ;)
  70 */
  71 /* njrev: not threadsafe, protection needed as described above */
  72
  73 static void *
  74 sysdep_dynl_link (const char *fname, const char *subr)
  75 {
  76   lt_dlhandle handle;
  77   handle = lt_dlopenext (fname);
  78   if (NULL == handle)
  79     {
  80       SCM fn;
  81       SCM msg;
  82
  83       fn = scm_from_locale_string (fname);
  84       msg = scm_from_locale_string (lt_dlerror ());
  85       scm_misc_error (subr, "file: ~S, message: ~S", scm_list_2 (fn, msg));
  86     }
  87   return (void *) handle;
  88 }
  89
  90 static void
  91 sysdep_dynl_unlink (void *handle, const char *subr)
  92 {
  93   if (lt_dlclose ((lt_dlhandle) handle))
  94     {
  95       scm_misc_error (subr, (char *) lt_dlerror (), SCM_EOL);
  96     }
  97 }
  98
  99 static void *
 100 sysdep_dynl_func (const char *symb, void *handle, const char *subr)
 101 {
 102   void *fptr;
 103
 104   fptr = lt_dlsym ((lt_dlhandle) handle, symb);
 105   if (!fptr)
 106     {
 107       scm_misc_error (subr, (char *) lt_dlerror (), SCM_EOL);
 108     }
 109   return fptr;
 110 }
 111
 112 static void
 113 sysdep_dynl_init ()
 114 {
 115   lt_dlinit ();
 116 }
 117
 118 scm_t_bits scm_tc16_dynamic_obj;
 119
 120 #define DYNL_FILENAME         SCM_SMOB_OBJECT
 121 #define DYNL_HANDLE(x)        ((void *) SCM_SMOB_DATA_2 (x))
 122 #define SET_DYNL_HANDLE(x, v) (SCM_SET_SMOB_DATA_2 ((x), (scm_t_bits) (v)))
 123
 124
 125 static SCM
 126 dynl_obj_mark (SCM ptr)
 127 {
 128   return DYNL_FILENAME (ptr);
 129 }
 130
 131
 132 static int
 133 dynl_obj_print (SCM exp, SCM port, scm_print_state *pstate)
 134 {
 135   scm_puts ("#<dynamic-object ", port);
 136   scm_iprin1 (DYNL_FILENAME (exp), port, pstate);
 137   if (DYNL_HANDLE (exp) == NULL)
 138     scm_puts (" (unlinked)", port);
 139   scm_putc ('>', port);
 140   return 1;
 141 }
 142
 143
 144 SCM_DEFINE (scm_dynamic_link, "dynamic-link", 1, 0, 0,
 145             (SCM filename),
 146             "Find the shared object (shared library) denoted by\n"
 147             "@var{filename} and link it into the running Guile\n"
 148             "application.  The returned\n"
 149             "scheme object is a ``handle'' for the library which can\n"
 150             "be passed to @code{dynamic-func}, @code{dynamic-call} etc.\n\n"
 151             "Searching for object files is system dependent.  Normally,\n"
 152             "if @var{filename} does have an explicit directory it will\n"
 153             "be searched for in locations\n"
 154             "such as @file{/usr/lib} and @file{/usr/local/lib}.")
 155 #define FUNC_NAME s_scm_dynamic_link
 156 {
 157   void *handle;
 158   char *file;
 159
 160   scm_dynwind_begin (0);
 161   file = scm_to_locale_string (filename);
 162   scm_dynwind_free (file);
 163   handle = sysdep_dynl_link (file, FUNC_NAME);
 164   scm_dynwind_end ();
 165   SCM_RETURN_NEWSMOB2 (scm_tc16_dynamic_obj, SCM_UNPACK (filename), handle);
 166 }
 167 #undef FUNC_NAME
 168
 169
 170 SCM_DEFINE (scm_dynamic_object_p, "dynamic-object?", 1, 0, 0,
 171             (SCM obj),
 172             "Return @code{#t} if @var{obj} is a dynamic object handle,\n"
 173             "or @code{#f} otherwise.")
 174 #define FUNC_NAME s_scm_dynamic_object_p
 175 {
 176   return scm_from_bool (SCM_TYP16_PREDICATE (scm_tc16_dynamic_obj, obj));
 177 }
 178 #undef FUNC_NAME
 179
 180
 181 SCM_DEFINE (scm_dynamic_unlink, "dynamic-unlink", 1, 0, 0,
 182             (SCM dobj),
 183             "Unlink a dynamic object from the application, if possible.  The\n"
 184             "object must have been linked by @code{dynamic-link}, with \n"
 185             "@var{dobj} the corresponding handle.  After this procedure\n"
 186             "is called, the handle can no longer be used to access the\n"
 187             "object.")
 188 #define FUNC_NAME s_scm_dynamic_unlink
 189 {
 190   /*fixme* GC-problem */
 191   SCM_VALIDATE_SMOB (SCM_ARG1, dobj, dynamic_obj);
 192   if (DYNL_HANDLE (dobj) == NULL) {
 193     SCM_MISC_ERROR ("Already unlinked: ~S", scm_list_1 (dobj));
 194   } else {
 195     sysdep_dynl_unlink (DYNL_HANDLE (dobj), FUNC_NAME);
 196     SET_DYNL_HANDLE (dobj, NULL);
 197     return SCM_UNSPECIFIED;
 198   }
 199 }
 200 #undef FUNC_NAME
 201
 202
 203 SCM_DEFINE (scm_dynamic_func, "dynamic-func", 2, 0, 0,
 204             (SCM name, SCM dobj),
 205             "Return a ``handle'' for the function @var{name} in the\n"
 206             "shared object referred to by @var{dobj}.  The handle\n"
 207             "can be passed to @code{dynamic-call} to actually\n"
 208             "call the function.\n\n"
 209             "Regardless whether your C compiler prepends an underscore\n"
 210             "@samp{_} to the global names in a program, you should\n"
 211             "@strong{not} include this underscore in @var{name}\n"
 212             "since it will be added automatically when necessary.")
 213 #define FUNC_NAME s_scm_dynamic_func
 214 {
 215   /* The returned handle is formed by casting the address of the function to a
 216    * long value and converting this to a scheme number
 217    */
 218
 219   void (*func) ();
 220
 221   SCM_VALIDATE_STRING (1, name);
 222   /*fixme* GC-problem */
 223   SCM_VALIDATE_SMOB (SCM_ARG2, dobj, dynamic_obj);
 224   if (DYNL_HANDLE (dobj) == NULL) {
 225     SCM_MISC_ERROR ("Already unlinked: ~S", dobj);
 226   } else {
 227     char *chars;
 228
 229     scm_dynwind_begin (0);
 230     chars = scm_to_locale_string (name);
 231     scm_dynwind_free (chars);
 232     func = (void (*) ()) sysdep_dynl_func (chars, DYNL_HANDLE (dobj),
 233                                            FUNC_NAME);
 234     scm_dynwind_end ();
 235     return scm_from_ulong ((unsigned long) func);
 236   }
 237 }
 238 #undef FUNC_NAME
 239
 240
 241 SCM_DEFINE (scm_dynamic_call, "dynamic-call", 2, 0, 0,
 242             (SCM func, SCM dobj),
 243             "Call a C function in a dynamic object.  Two styles of\n"
 244             "invocation are supported:\n\n"
 245             "@itemize @bullet\n"
 246             "@item @var{func} can be a function handle returned by\n"
 247             "@code{dynamic-func}.  In this case @var{dobj} is\n"
 248             "ignored\n"
 249             "@item @var{func} can be a string with the name of the\n"
 250             "function to call, with @var{dobj} the handle of the\n"
 251             "dynamic object in which to find the function.\n"
 252             "This is equivalent to\n"
 253             "@smallexample\n\n"
 254             "(dynamic-call (dynamic-func @var{func} @var{dobj}) #f)\n"
 255             "@end smallexample\n"
 256             "@end itemize\n\n"
 257             "In either case, the function is passed no arguments\n"
 258             "and its return value is ignored.")
 259 #define FUNC_NAME s_scm_dynamic_call
 260 {
 261   void (*fptr) ();
 262
 263   if (scm_is_string (func))
 264     func = scm_dynamic_func (func, dobj);
 265   fptr = (void (*) ()) scm_to_ulong (func);
 266   fptr ();
 267   return SCM_UNSPECIFIED;
 268 }
 269 #undef FUNC_NAME
 270
 271 static void
 272 free_string_pointers (void *data)
 273 {
 274   scm_i_free_string_pointers ((char **)data);
 275 }
 276
 277 SCM_DEFINE (scm_dynamic_args_call, "dynamic-args-call", 3, 0, 0,
 278             (SCM func, SCM dobj, SCM args),
 279             "Call the C function indicated by @var{func} and @var{dobj},\n"
 280             "just like @code{dynamic-call}, but pass it some arguments and\n"
 281             "return its return value.  The C function is expected to take\n"
 282             "two arguments and return an @code{int}, just like @code{main}:\n"
 283             "@smallexample\n"
 284             "int c_func (int argc, char **argv);\n"
 285             "@end smallexample\n\n"
 286             "The parameter @var{args} must be a list of strings and is\n"
 287             "converted into an array of @code{char *}.  The array is passed\n"
 288             "in @var{argv} and its size in @var{argc}.  The return value is\n"
 289             "converted to a Scheme number and returned from the call to\n"
 290             "@code{dynamic-args-call}.")
 291 #define FUNC_NAME s_scm_dynamic_args_call
 292 {
 293   int (*fptr) (int argc, char **argv);
 294   int result, argc;
 295   char **argv;
 296
 297   scm_dynwind_begin (0);
 298
 299   if (scm_is_string (func))
 300     func = scm_dynamic_func (func, dobj);
 301
 302   fptr = (int (*) (int, char **)) scm_to_ulong (func);
 303
 304   argv = scm_i_allocate_string_pointers (args);
 305   scm_dynwind_unwind_handler (free_string_pointers, argv,
 306                               SCM_F_WIND_EXPLICITLY);
 307   for (argc = 0; argv[argc]; argc++)
 308     ;
 309   result = (*fptr) (argc, argv);
 310
 311   scm_dynwind_end ();
 312   return scm_from_int (result);
 313 }
 314 #undef FUNC_NAME
 315
 316 void
 317 scm_init_dynamic_linking ()
 318 {
 319   scm_tc16_dynamic_obj = scm_make_smob_type ("dynamic-object", 0);
 320   scm_set_smob_mark (scm_tc16_dynamic_obj, dynl_obj_mark);
 321   scm_set_smob_print (scm_tc16_dynamic_obj, dynl_obj_print);
 322   sysdep_dynl_init ();
 323 #include "libguile/dynl.x"
 324 }
 325
 326 /*
 327   Local Variables:
 328   c-file-style: "gnu"
 329   End:
 330 */