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
 126 static int
 127 dynl_obj_print (SCM exp, SCM port, scm_print_state *pstate)
 128 {
 129   scm_puts ("#<dynamic-object ", port);
 130   scm_iprin1 (DYNL_FILENAME (exp), port, pstate);
 131   if (DYNL_HANDLE (exp) == NULL)
 132     scm_puts (" (unlinked)", port);
 133   scm_putc ('>', port);
 134   return 1;
 135 }
 136
 137
 138 SCM_DEFINE (scm_dynamic_link, "dynamic-link", 1, 0, 0,
 139             (SCM filename),
 140             "Find the shared object (shared library) denoted by\n"
 141             "@var{filename} and link it into the running Guile\n"
 142             "application.  The returned\n"
 143             "scheme object is a ``handle'' for the library which can\n"
 144             "be passed to @code{dynamic-func}, @code{dynamic-call} etc.\n\n"
 145             "Searching for object files is system dependent.  Normally,\n"
 146             "if @var{filename} does have an explicit directory it will\n"
 147             "be searched for in locations\n"
 148             "such as @file{/usr/lib} and @file{/usr/local/lib}.")
 149 #define FUNC_NAME s_scm_dynamic_link
 150 {
 151   void *handle;
 152   char *file;
 153
 154   scm_dynwind_begin (0);
 155   file = scm_to_locale_string (filename);
 156   scm_dynwind_free (file);
 157   handle = sysdep_dynl_link (file, FUNC_NAME);
 158   scm_dynwind_end ();
 159   SCM_RETURN_NEWSMOB2 (scm_tc16_dynamic_obj, SCM_UNPACK (filename), handle);
 160 }
 161 #undef FUNC_NAME
 162
 163
 164 SCM_DEFINE (scm_dynamic_object_p, "dynamic-object?", 1, 0, 0,
 165             (SCM obj),
 166             "Return @code{#t} if @var{obj} is a dynamic object handle,\n"
 167             "or @code{#f} otherwise.")
 168 #define FUNC_NAME s_scm_dynamic_object_p
 169 {
 170   return scm_from_bool (SCM_TYP16_PREDICATE (scm_tc16_dynamic_obj, obj));
 171 }
 172 #undef FUNC_NAME
 173
 174
 175 SCM_DEFINE (scm_dynamic_unlink, "dynamic-unlink", 1, 0, 0,
 176             (SCM dobj),
 177             "Unlink a dynamic object from the application, if possible.  The\n"
 178             "object must have been linked by @code{dynamic-link}, with \n"
 179             "@var{dobj} the corresponding handle.  After this procedure\n"
 180             "is called, the handle can no longer be used to access the\n"
 181             "object.")
 182 #define FUNC_NAME s_scm_dynamic_unlink
 183 {
 184   /*fixme* GC-problem */
 185   SCM_VALIDATE_SMOB (SCM_ARG1, dobj, dynamic_obj);
 186   if (DYNL_HANDLE (dobj) == NULL) {
 187     SCM_MISC_ERROR ("Already unlinked: ~S", scm_list_1 (dobj));
 188   } else {
 189     sysdep_dynl_unlink (DYNL_HANDLE (dobj), FUNC_NAME);
 190     SET_DYNL_HANDLE (dobj, NULL);
 191     return SCM_UNSPECIFIED;
 192   }
 193 }
 194 #undef FUNC_NAME
 195
 196
 197 SCM_DEFINE (scm_dynamic_func, "dynamic-func", 2, 0, 0,
 198             (SCM name, SCM dobj),
 199             "Return a ``handle'' for the function @var{name} in the\n"
 200             "shared object referred to by @var{dobj}.  The handle\n"
 201             "can be passed to @code{dynamic-call} to actually\n"
 202             "call the function.\n\n"
 203             "Regardless whether your C compiler prepends an underscore\n"
 204             "@samp{_} to the global names in a program, you should\n"
 205             "@strong{not} include this underscore in @var{name}\n"
 206             "since it will be added automatically when necessary.")
 207 #define FUNC_NAME s_scm_dynamic_func
 208 {
 209   /* The returned handle is formed by casting the address of the function to a
 210    * long value and converting this to a scheme number
 211    */
 212
 213   void (*func) ();
 214
 215   SCM_VALIDATE_STRING (1, name);
 216   /*fixme* GC-problem */
 217   SCM_VALIDATE_SMOB (SCM_ARG2, dobj, dynamic_obj);
 218   if (DYNL_HANDLE (dobj) == NULL) {
 219     SCM_MISC_ERROR ("Already unlinked: ~S", dobj);
 220   } else {
 221     char *chars;
 222
 223     scm_dynwind_begin (0);
 224     chars = scm_to_locale_string (name);
 225     scm_dynwind_free (chars);
 226     func = (void (*) ()) sysdep_dynl_func (chars, DYNL_HANDLE (dobj),
 227                                            FUNC_NAME);
 228     scm_dynwind_end ();
 229     return scm_from_ulong ((unsigned long) func);
 230   }
 231 }
 232 #undef FUNC_NAME
 233
 234
 235 SCM_DEFINE (scm_dynamic_call, "dynamic-call", 2, 0, 0,
 236             (SCM func, SCM dobj),
 237             "Call a C function in a dynamic object.  Two styles of\n"
 238             "invocation are supported:\n\n"
 239             "@itemize @bullet\n"
 240             "@item @var{func} can be a function handle returned by\n"
 241             "@code{dynamic-func}.  In this case @var{dobj} is\n"
 242             "ignored\n"
 243             "@item @var{func} can be a string with the name of the\n"
 244             "function to call, with @var{dobj} the handle of the\n"
 245             "dynamic object in which to find the function.\n"
 246             "This is equivalent to\n"
 247             "@smallexample\n\n"
 248             "(dynamic-call (dynamic-func @var{func} @var{dobj}) #f)\n"
 249             "@end smallexample\n"
 250             "@end itemize\n\n"
 251             "In either case, the function is passed no arguments\n"
 252             "and its return value is ignored.")
 253 #define FUNC_NAME s_scm_dynamic_call
 254 {
 255   void (*fptr) ();
 256
 257   if (scm_is_string (func))
 258     func = scm_dynamic_func (func, dobj);
 259   fptr = (void (*) ()) scm_to_ulong (func);
 260   fptr ();
 261   return SCM_UNSPECIFIED;
 262 }
 263 #undef FUNC_NAME
 264
 265 static void
 266 free_string_pointers (void *data)
 267 {
 268   scm_i_free_string_pointers ((char **)data);
 269 }
 270
 271 SCM_DEFINE (scm_dynamic_args_call, "dynamic-args-call", 3, 0, 0,
 272             (SCM func, SCM dobj, SCM args),
 273             "Call the C function indicated by @var{func} and @var{dobj},\n"
 274             "just like @code{dynamic-call}, but pass it some arguments and\n"
 275             "return its return value.  The C function is expected to take\n"
 276             "two arguments and return an @code{int}, just like @code{main}:\n"
 277             "@smallexample\n"
 278             "int c_func (int argc, char **argv);\n"
 279             "@end smallexample\n\n"
 280             "The parameter @var{args} must be a list of strings and is\n"
 281             "converted into an array of @code{char *}.  The array is passed\n"
 282             "in @var{argv} and its size in @var{argc}.  The return value is\n"
 283             "converted to a Scheme number and returned from the call to\n"
 284             "@code{dynamic-args-call}.")
 285 #define FUNC_NAME s_scm_dynamic_args_call
 286 {
 287   int (*fptr) (int argc, char **argv);
 288   int result, argc;
 289   char **argv;
 290
 291   scm_dynwind_begin (0);
 292
 293   if (scm_is_string (func))
 294     func = scm_dynamic_func (func, dobj);
 295
 296   fptr = (int (*) (int, char **)) scm_to_ulong (func);
 297
 298   argv = scm_i_allocate_string_pointers (args);
 299   scm_dynwind_unwind_handler (free_string_pointers, argv,
 300                               SCM_F_WIND_EXPLICITLY);
 301   for (argc = 0; argv[argc]; argc++)
 302     ;
 303   result = (*fptr) (argc, argv);
 304
 305   scm_dynwind_end ();
 306   return scm_from_int (result);
 307 }
 308 #undef FUNC_NAME
 309
 310 void
 311 scm_init_dynamic_linking ()
 312 {
 313   scm_tc16_dynamic_obj = scm_make_smob_type ("dynamic-object", 0);
 314   scm_set_smob_print (scm_tc16_dynamic_obj, dynl_obj_print);
 315   sysdep_dynl_init ();
 316 #include "libguile/dynl.x"
 317 }
 318
 319 /*
 320   Local Variables:
 321   c-file-style: "gnu"
 322   End:
 323 */