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 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  19  */
  20
  21
  22
  23 /* "dynl.c" dynamically link&load object files.
  24    Author: Aubrey Jaffer
  25    Modified for libguile by Marius Vollmer */
  26
  27 #if 0 /* Disabled until we know for sure that it isn't needed */
  28 /* XXX - This is only here to drag in a definition of __eprintf. This
  29    is needed for proper operation of dynamic linking. The real
  30    solution would probably be a shared libgcc. */
  31
  32 #undef NDEBUG
  33 #include <assert.h>
  34
  35 static void
  36 maybe_drag_in_eprintf ()
  37 {
  38   assert (!maybe_drag_in_eprintf);
  39 }
  40 #endif
  41
  42 #include <stdio.h>
  43 #include <string.h>
  44
  45 #include "libguile/_scm.h"
  46 #include "libguile/dynl.h"
  47 #include "libguile/smob.h"
  48 #include "libguile/keywords.h"
  49 #include "libguile/ports.h"
  50 #include "libguile/strings.h"
  51 #include "libguile/deprecation.h"
  52 #include "libguile/lang.h"
  53 #include "libguile/validate.h"
  54 #include "libguile/dynwind.h"
  55
  56 #include "guile-ltdl.h"
  57
  58 /*
  59   From the libtool manual: "Note that libltdl is not threadsafe,
  60   i.e. a multithreaded application has to use a mutex for libltdl.".
  61
  62   Guile does not currently support pre-emptive threads, so there is
  63   no mutex.  Previously SCM_DEFER_INTS and SCM_ALLOW_INTS were used:
  64   they are mentioned here in case somebody is grepping for thread
  65   problems ;)
  66 */
  67
  68 static void *
  69 sysdep_dynl_link (const char *fname, const char *subr)
  70 {
  71   scm_lt_dlhandle handle;
  72   handle = scm_lt_dlopenext (fname);
  73   if (NULL == handle)
  74     {
  75       SCM fn;
  76       SCM msg;
  77
  78       fn = scm_makfrom0str (fname);
  79       msg = scm_makfrom0str (scm_lt_dlerror ());
  80       scm_misc_error (subr, "file: ~S, message: ~S", scm_list_2 (fn, msg));
  81     }
  82   return (void *) handle;
  83 }
  84
  85 static void
  86 sysdep_dynl_unlink (void *handle, const char *subr)
  87 {
  88   if (scm_lt_dlclose ((scm_lt_dlhandle) handle))
  89     {
  90       scm_misc_error (subr, (char *) scm_lt_dlerror (), SCM_EOL);
  91     }
  92 }
  93
  94 static void *
  95 sysdep_dynl_func (const char *symb, void *handle, const char *subr)
  96 {
  97   void *fptr;
  98
  99   fptr = scm_lt_dlsym ((scm_lt_dlhandle) handle, symb);
 100   if (!fptr)
 101     {
 102       scm_misc_error (subr, (char *) scm_lt_dlerror (), SCM_EOL);
 103     }
 104   return fptr;
 105 }
 106
 107 static void
 108 sysdep_dynl_init ()
 109 {
 110   scm_lt_dlinit ();
 111 }
 112
 113 scm_t_bits scm_tc16_dynamic_obj;
 114
 115 #define DYNL_FILENAME         SCM_SMOB_OBJECT
 116 #define DYNL_HANDLE(x)        ((void *) SCM_SMOB_DATA_2 (x))
 117 #define SET_DYNL_HANDLE(x, v) (SCM_SET_SMOB_DATA_2 ((x), (scm_t_bits) (v)))
 118
 119
 120 static SCM
 121 dynl_obj_mark (SCM ptr)
 122 {
 123   return DYNL_FILENAME (ptr);
 124 }
 125
 126
 127 static int
 128 dynl_obj_print (SCM exp, SCM port, scm_print_state *pstate)
 129 {
 130   scm_puts ("#<dynamic-object ", port);
 131   scm_iprin1 (DYNL_FILENAME (exp), port, pstate);
 132   if (DYNL_HANDLE (exp) == NULL)
 133     scm_puts (" (unlinked)", port);
 134   scm_putc ('>', port);
 135   return 1;
 136 }
 137
 138
 139 SCM_DEFINE (scm_dynamic_link, "dynamic-link", 1, 0, 0,
 140             (SCM filename),
 141             "Find the shared object (shared library) denoted by\n"
 142             "@var{filename} and link it into the running Guile\n"
 143             "application.  The returned\n"
 144             "scheme object is a ``handle'' for the library which can\n"
 145             "be passed to @code{dynamic-func}, @code{dynamic-call} etc.\n\n"
 146             "Searching for object files is system dependent.  Normally,\n"
 147             "if @var{filename} does have an explicit directory it will\n"
 148             "be searched for in locations\n"
 149             "such as @file{/usr/lib} and @file{/usr/local/lib}.")
 150 #define FUNC_NAME s_scm_dynamic_link
 151 {
 152   void *handle;
 153   char *file;
 154
 155   scm_frame_begin (0);
 156   file = scm_to_locale_string (filename);
 157   scm_frame_free (file);
 158   handle = sysdep_dynl_link (file, FUNC_NAME);
 159   scm_frame_end ();
 160   SCM_RETURN_NEWSMOB2 (scm_tc16_dynamic_obj, SCM_UNPACK (filename), handle);
 161 }
 162 #undef FUNC_NAME
 163
 164
 165 SCM_DEFINE (scm_dynamic_object_p, "dynamic-object?", 1, 0, 0,
 166             (SCM obj),
 167             "Return @code{#t} if @var{obj} is a dynamic object handle,\n"
 168             "or @code{#f} otherwise.")
 169 #define FUNC_NAME s_scm_dynamic_object_p
 170 {
 171   return scm_from_bool (SCM_TYP16_PREDICATE (scm_tc16_dynamic_obj, obj));
 172 }
 173 #undef FUNC_NAME
 174
 175
 176 SCM_DEFINE (scm_dynamic_unlink, "dynamic-unlink", 1, 0, 0,
 177             (SCM dobj),
 178             "Unlink a dynamic object from the application, if possible.  The\n"
 179             "object must have been linked by @code{dynamic-link}, with \n"
 180             "@var{dobj} the corresponding handle.  After this procedure\n"
 181             "is called, the handle can no longer be used to access the\n"
 182             "object.")
 183 #define FUNC_NAME s_scm_dynamic_unlink
 184 {
 185   /*fixme* GC-problem */
 186   SCM_VALIDATE_SMOB (SCM_ARG1, dobj, dynamic_obj);
 187   if (DYNL_HANDLE (dobj) == NULL) {
 188     SCM_MISC_ERROR ("Already unlinked: ~S", scm_list_1 (dobj));
 189   } else {
 190     sysdep_dynl_unlink (DYNL_HANDLE (dobj), FUNC_NAME);
 191     SET_DYNL_HANDLE (dobj, NULL);
 192     return SCM_UNSPECIFIED;
 193   }
 194 }
 195 #undef FUNC_NAME
 196
 197
 198 SCM_DEFINE (scm_dynamic_func, "dynamic-func", 2, 0, 0,
 199             (SCM name, SCM dobj),
 200             "Return a ``handle'' for the function @var{name} in the\n"
 201             "shared object referred to by @var{dobj}.  The handle\n"
 202             "can be passed to @code{dynamic-call} to actually\n"
 203             "call the function.\n\n"
 204             "Regardless whether your C compiler prepends an underscore\n"
 205             "@samp{_} to the global names in a program, you should\n"
 206             "@strong{not} include this underscore in @var{name}\n"
 207             "since it will be added automatically when necessary.")
 208 #define FUNC_NAME s_scm_dynamic_func
 209 {
 210   /* The returned handle is formed by casting the address of the function to a
 211    * long value and converting this to a scheme number
 212    */
 213
 214   void (*func) ();
 215
 216   SCM_VALIDATE_STRING (1, name);
 217   /*fixme* GC-problem */
 218   SCM_VALIDATE_SMOB (SCM_ARG2, dobj, dynamic_obj);
 219   if (DYNL_HANDLE (dobj) == NULL) {
 220     SCM_MISC_ERROR ("Already unlinked: ~S", dobj);
 221   } else {
 222     char *chars;
 223
 224     scm_frame_begin (0);
 225     chars = scm_to_locale_string (name);
 226     scm_frame_free (chars);
 227     func = (void (*) ()) sysdep_dynl_func (chars, DYNL_HANDLE (dobj),
 228                                            FUNC_NAME);
 229     scm_frame_end ();
 230     return scm_from_ulong ((unsigned long) func);
 231   }
 232 }
 233 #undef FUNC_NAME
 234
 235
 236 SCM_DEFINE (scm_dynamic_call, "dynamic-call", 2, 0, 0,
 237             (SCM func, SCM dobj),
 238             "Call a C function in a dynamic object.  Two styles of\n"
 239             "invocation are supported:\n\n"
 240             "@itemize @bullet\n"
 241             "@item @var{func} can be a function handle returned by\n"
 242             "@code{dynamic-func}.  In this case @var{dobj} is\n"
 243             "ignored\n"
 244             "@item @var{func} can be a string with the name of the\n"
 245             "function to call, with @var{dobj} the handle of the\n"
 246             "dynamic object in which to find the function.\n"
 247             "This is equivalent to\n"
 248             "@smallexample\n\n"
 249             "(dynamic-call (dynamic-func @var{func} @var{dobj}) #f)\n"
 250             "@end smallexample\n"
 251             "@end itemize\n\n"
 252             "In either case, the function is passed no arguments\n"
 253             "and its return value is ignored.")
 254 #define FUNC_NAME s_scm_dynamic_call
 255 {
 256   void (*fptr) ();
 257
 258   if (scm_is_string (func))
 259     func = scm_dynamic_func (func, dobj);
 260   fptr = (void (*) ()) scm_to_ulong (func);
 261   fptr ();
 262   return SCM_UNSPECIFIED;
 263 }
 264 #undef FUNC_NAME
 265
 266 static void
 267 free_string_pointers (void *data)
 268 {
 269   scm_i_free_string_pointers ((char **)data);
 270 }
 271
 272 SCM_DEFINE (scm_dynamic_args_call, "dynamic-args-call", 3, 0, 0,
 273             (SCM func, SCM dobj, SCM args),
 274             "Call the C function indicated by @var{func} and @var{dobj},\n"
 275             "just like @code{dynamic-call}, but pass it some arguments and\n"
 276             "return its return value.  The C function is expected to take\n"
 277             "two arguments and return an @code{int}, just like @code{main}:\n"
 278             "@smallexample\n"
 279             "int c_func (int argc, char **argv);\n"
 280             "@end smallexample\n\n"
 281             "The parameter @var{args} must be a list of strings and is\n"
 282             "converted into an array of @code{char *}.  The array is passed\n"
 283             "in @var{argv} and its size in @var{argc}.  The return value is\n"
 284             "converted to a Scheme number and returned from the call to\n"
 285             "@code{dynamic-args-call}.")
 286 #define FUNC_NAME s_scm_dynamic_args_call
 287 {
 288   int (*fptr) (int argc, char **argv);
 289   int result, argc;
 290   char **argv;
 291
 292   scm_frame_begin (0);
 293
 294   if (scm_is_string (func))
 295     func = scm_dynamic_func (func, dobj);
 296
 297   fptr = (int (*) (int, char **)) scm_to_ulong (func);
 298
 299   argv = scm_i_allocate_string_pointers (args);
 300   scm_frame_unwind_handler (free_string_pointers, argv,
 301                             SCM_F_WIND_EXPLICITLY);
 302   for (argc = 0; argv[argc]; argc++)
 303     ;
 304   result = (*fptr) (argc, argv);
 305
 306   scm_frame_end ();
 307   return scm_from_int (result);
 308 }
 309 #undef FUNC_NAME
 310
 311 void
 312 scm_init_dynamic_linking ()
 313 {
 314   scm_tc16_dynamic_obj = scm_make_smob_type ("dynamic-object", 0);
 315   scm_set_smob_mark (scm_tc16_dynamic_obj, dynl_obj_mark);
 316   scm_set_smob_print (scm_tc16_dynamic_obj, dynl_obj_print);
 317   sysdep_dynl_init ();
 318 #include "libguile/dynl.x"
 319 }
 320
 321 /*
 322   Local Variables:
 323   c-file-style: "gnu"
 324   End:
 325 */