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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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 <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 no
  63   mutex.  Previously SCM_CRITICAL_SECTION_START and
  64   SCM_CRITICAL_SECTION_END were used: they are mentioned here in case
  65   somebody is grepping for thread problems ;)
  66 */
  67 /* njrev: not threadsafe, protection needed as described above */
  68
  69 static void *
  70 sysdep_dynl_link (const char *fname, const char *subr)
  71 {
  72   lt_dlhandle handle;
  73   handle = lt_dlopenext (fname);
  74   if (NULL == handle)
  75     {
  76       SCM fn;
  77       SCM msg;
  78
  79       fn = scm_from_locale_string (fname);
  80       msg = scm_from_locale_string (lt_dlerror ());
  81       scm_misc_error (subr, "file: ~S, message: ~S", scm_list_2 (fn, msg));
  82     }
  83   return (void *) handle;
  84 }
  85
  86 static void
  87 sysdep_dynl_unlink (void *handle, const char *subr)
  88 {
  89   if (lt_dlclose ((lt_dlhandle) handle))
  90     {
  91       scm_misc_error (subr, (char *) lt_dlerror (), SCM_EOL);
  92     }
  93 }
  94
  95 static void *
  96 sysdep_dynl_func (const char *symb, void *handle, const char *subr)
  97 {
  98   void *fptr;
  99
 100   fptr = lt_dlsym ((lt_dlhandle) handle, symb);
 101   if (!fptr)
 102     {
 103       scm_misc_error (subr, (char *) lt_dlerror (), SCM_EOL);
 104     }
 105   return fptr;
 106 }
 107
 108 static void
 109 sysdep_dynl_init ()
 110 {
 111   lt_dlinit ();
 112 }
 113
 114 scm_t_bits scm_tc16_dynamic_obj;
 115
 116 #define DYNL_FILENAME         SCM_SMOB_OBJECT
 117 #define DYNL_HANDLE(x)        ((void *) SCM_SMOB_DATA_2 (x))
 118 #define SET_DYNL_HANDLE(x, v) (SCM_SET_SMOB_DATA_2 ((x), (scm_t_bits) (v)))
 119
 120
 121
 122 static int
 123 dynl_obj_print (SCM exp, SCM port, scm_print_state *pstate)
 124 {
 125   scm_puts ("#<dynamic-object ", port);
 126   scm_iprin1 (DYNL_FILENAME (exp), port, pstate);
 127   if (DYNL_HANDLE (exp) == NULL)
 128     scm_puts (" (unlinked)", port);
 129   scm_putc ('>', port);
 130   return 1;
 131 }
 132
 133
 134 SCM_DEFINE (scm_dynamic_link, "dynamic-link", 1, 0, 0,
 135             (SCM filename),
 136             "Find the shared object (shared library) denoted by\n"
 137             "@var{filename} and link it into the running Guile\n"
 138             "application.  The returned\n"
 139             "scheme object is a ``handle'' for the library which can\n"
 140             "be passed to @code{dynamic-func}, @code{dynamic-call} etc.\n\n"
 141             "Searching for object files is system dependent.  Normally,\n"
 142             "if @var{filename} does have an explicit directory it will\n"
 143             "be searched for in locations\n"
 144             "such as @file{/usr/lib} and @file{/usr/local/lib}.")
 145 #define FUNC_NAME s_scm_dynamic_link
 146 {
 147   void *handle;
 148   char *file;
 149
 150   scm_dynwind_begin (0);
 151   file = scm_to_locale_string (filename);
 152   scm_dynwind_free (file);
 153   handle = sysdep_dynl_link (file, FUNC_NAME);
 154   scm_dynwind_end ();
 155   SCM_RETURN_NEWSMOB2 (scm_tc16_dynamic_obj, SCM_UNPACK (filename), handle);
 156 }
 157 #undef FUNC_NAME
 158
 159
 160 SCM_DEFINE (scm_dynamic_object_p, "dynamic-object?", 1, 0, 0,
 161             (SCM obj),
 162             "Return @code{#t} if @var{obj} is a dynamic object handle,\n"
 163             "or @code{#f} otherwise.")
 164 #define FUNC_NAME s_scm_dynamic_object_p
 165 {
 166   return scm_from_bool (SCM_TYP16_PREDICATE (scm_tc16_dynamic_obj, obj));
 167 }
 168 #undef FUNC_NAME
 169
 170
 171 SCM_DEFINE (scm_dynamic_unlink, "dynamic-unlink", 1, 0, 0,
 172             (SCM dobj),
 173             "Unlink a dynamic object from the application, if possible.  The\n"
 174             "object must have been linked by @code{dynamic-link}, with \n"
 175             "@var{dobj} the corresponding handle.  After this procedure\n"
 176             "is called, the handle can no longer be used to access the\n"
 177             "object.")
 178 #define FUNC_NAME s_scm_dynamic_unlink
 179 {
 180   /*fixme* GC-problem */
 181   SCM_VALIDATE_SMOB (SCM_ARG1, dobj, dynamic_obj);
 182   if (DYNL_HANDLE (dobj) == NULL) {
 183     SCM_MISC_ERROR ("Already unlinked: ~S", scm_list_1 (dobj));
 184   } else {
 185     sysdep_dynl_unlink (DYNL_HANDLE (dobj), FUNC_NAME);
 186     SET_DYNL_HANDLE (dobj, NULL);
 187     return SCM_UNSPECIFIED;
 188   }
 189 }
 190 #undef FUNC_NAME
 191
 192
 193 SCM_DEFINE (scm_dynamic_func, "dynamic-func", 2, 0, 0,
 194             (SCM name, SCM dobj),
 195             "Return a ``handle'' for the function @var{name} in the\n"
 196             "shared object referred to by @var{dobj}.  The handle\n"
 197             "can be passed to @code{dynamic-call} to actually\n"
 198             "call the function.\n\n"
 199             "Regardless whether your C compiler prepends an underscore\n"
 200             "@samp{_} to the global names in a program, you should\n"
 201             "@strong{not} include this underscore in @var{name}\n"
 202             "since it will be added automatically when necessary.")
 203 #define FUNC_NAME s_scm_dynamic_func
 204 {
 205   /* The returned handle is formed by casting the address of the function to a
 206    * long value and converting this to a scheme number
 207    */
 208
 209   void (*func) ();
 210
 211   SCM_VALIDATE_STRING (1, name);
 212   /*fixme* GC-problem */
 213   SCM_VALIDATE_SMOB (SCM_ARG2, dobj, dynamic_obj);
 214   if (DYNL_HANDLE (dobj) == NULL) {
 215     SCM_MISC_ERROR ("Already unlinked: ~S", dobj);
 216   } else {
 217     char *chars;
 218
 219     scm_dynwind_begin (0);
 220     chars = scm_to_locale_string (name);
 221     scm_dynwind_free (chars);
 222     func = (void (*) ()) sysdep_dynl_func (chars, DYNL_HANDLE (dobj),
 223                                            FUNC_NAME);
 224     scm_dynwind_end ();
 225     return scm_from_ulong ((unsigned long) func);
 226   }
 227 }
 228 #undef FUNC_NAME
 229
 230
 231 SCM_DEFINE (scm_dynamic_call, "dynamic-call", 2, 0, 0,
 232             (SCM func, SCM dobj),
 233             "Call a C function in a dynamic object.  Two styles of\n"
 234             "invocation are supported:\n\n"
 235             "@itemize @bullet\n"
 236             "@item @var{func} can be a function handle returned by\n"
 237             "@code{dynamic-func}.  In this case @var{dobj} is\n"
 238             "ignored\n"
 239             "@item @var{func} can be a string with the name of the\n"
 240             "function to call, with @var{dobj} the handle of the\n"
 241             "dynamic object in which to find the function.\n"
 242             "This is equivalent to\n"
 243             "@smallexample\n\n"
 244             "(dynamic-call (dynamic-func @var{func} @var{dobj}) #f)\n"
 245             "@end smallexample\n"
 246             "@end itemize\n\n"
 247             "In either case, the function is passed no arguments\n"
 248             "and its return value is ignored.")
 249 #define FUNC_NAME s_scm_dynamic_call
 250 {
 251   void (*fptr) ();
 252
 253   if (scm_is_string (func))
 254     func = scm_dynamic_func (func, dobj);
 255   fptr = (void (*) ()) scm_to_ulong (func);
 256   fptr ();
 257   return SCM_UNSPECIFIED;
 258 }
 259 #undef FUNC_NAME
 260
 261 static void
 262 free_string_pointers (void *data)
 263 {
 264   scm_i_free_string_pointers ((char **)data);
 265 }
 266
 267 SCM_DEFINE (scm_dynamic_args_call, "dynamic-args-call", 3, 0, 0,
 268             (SCM func, SCM dobj, SCM args),
 269             "Call the C function indicated by @var{func} and @var{dobj},\n"
 270             "just like @code{dynamic-call}, but pass it some arguments and\n"
 271             "return its return value.  The C function is expected to take\n"
 272             "two arguments and return an @code{int}, just like @code{main}:\n"
 273             "@smallexample\n"
 274             "int c_func (int argc, char **argv);\n"
 275             "@end smallexample\n\n"
 276             "The parameter @var{args} must be a list of strings and is\n"
 277             "converted into an array of @code{char *}.  The array is passed\n"
 278             "in @var{argv} and its size in @var{argc}.  The return value is\n"
 279             "converted to a Scheme number and returned from the call to\n"
 280             "@code{dynamic-args-call}.")
 281 #define FUNC_NAME s_scm_dynamic_args_call
 282 {
 283   int (*fptr) (int argc, char **argv);
 284   int result, argc;
 285   char **argv;
 286
 287   scm_dynwind_begin (0);
 288
 289   if (scm_is_string (func))
 290     func = scm_dynamic_func (func, dobj);
 291
 292   fptr = (int (*) (int, char **)) scm_to_ulong (func);
 293
 294   argv = scm_i_allocate_string_pointers (args);
 295   scm_dynwind_unwind_handler (free_string_pointers, argv,
 296                               SCM_F_WIND_EXPLICITLY);
 297   for (argc = 0; argv[argc]; argc++)
 298     ;
 299   result = (*fptr) (argc, argv);
 300
 301   scm_dynwind_end ();
 302   return scm_from_int (result);
 303 }
 304 #undef FUNC_NAME
 305
 306 void
 307 scm_init_dynamic_linking ()
 308 {
 309   scm_tc16_dynamic_obj = scm_make_smob_type ("dynamic-object", 0);
 310   scm_set_smob_print (scm_tc16_dynamic_obj, dynl_obj_print);
 311   sysdep_dynl_init ();
 312 #include "libguile/dynl.x"
 313 }
 314
 315 /*
 316   Local Variables:
 317   c-file-style: "gnu"
 318   End:
 319 */