libjava/exception.cc

   1 // Functions for Exception Support for Java.
   2
   3 /* Copyright (C) 1998, 1999  Free Software Foundation
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 #include <config.h>
  12
  13 #include <stddef.h>
  14 #include <stdlib.h>
  15
  16 #include <java/lang/Class.h>
  17 #include <java/lang/NullPointerException.h>
  18 #include <gcj/cni.h>
  19 #include <jvm.h>
  20
  21 // eh-common.h needs gansidecl.h.
  22 #include "gansidecl.h"
  23 #include "eh-common.h"
  24
  25 typedef struct {
  26   __eh_info eh_info;
  27   void *value;
  28 } java_eh_info;
  29
  30
  31 /* Language-specific EH info pointer, throw routine, and language/version
  32    info routines. All defined in libgcc2. */
  33
  34 extern "C" java_eh_info **__get_eh_info ();
  35 extern "C" void __throw () __attribute__ ((__noreturn__));
  36 extern "C" void __sjthrow () __attribute__ ((__noreturn__));
  37 extern "C" short __get_eh_table_version (void *table);
  38 extern "C" short __get_eh_table_language (void *table);
  39 extern "C" void *__get_eh_context ();
  40
  41 extern "C" void *
  42 _Jv_type_matcher (java_eh_info *info, void* match_info,
  43                   void *exception_table)
  44 {
  45 #ifndef SJLJ_EXCEPTIONS
  46   /* No exception table implies the old style mechanism, so don't check. */
  47   if (exception_table != NULL
  48       && __get_eh_table_language (exception_table) != EH_LANG_Java)
  49     return NULL;
  50 #endif
  51
  52   /* we don't worry about version info yet, there is only one version! */
  53
  54   if (match_info != NULL)
  55     {
  56       // The match_info is either a (java::lang::Class*) or
  57       // match_info is one more than a (Utf8Const*).
  58       if (sizeof(void*) != sizeof(size_t))
  59         abort();
  60       size_t mi = (size_t) match_info;
  61       if ((mi & 1) != 0)
  62         match_info = _Jv_FindClass ((Utf8Const*) (mi - 1), NULL);
  63       if (! _Jv_IsInstanceOf ((jobject) info->value, (jclass) match_info))
  64         return NULL;
  65     }
  66
  67   return info->value;
  68 }
  69
  70 /* Compiler hook to return a pointer to java exception object. The value
  71    is cleared, so if the exception needs to be rethrown, it should be set
  72    again */
  73
  74 extern "C" void *
  75 _Jv_exception_info (void)
  76 {
  77   java_eh_info *info = *(__get_eh_info ());
  78   void *ptr;
  79
  80   if (info == NULL)
  81     abort ();
  82
  83   ptr = info->value;
  84
  85   /* clear the value so another throw is an error */
  86   info->value = NULL;
  87
  88   return ptr;
  89 }
  90
  91
  92
  93 /* Allocate an exception info structure for java. Called the first time
  94    an exception is thrown. */
  95
  96 extern "C" void
  97 _Jv_eh_alloc ()
  98 {
  99   /* FIXME: we should use _Jv_AllocBytes here.  However, libgcc2
 100      apparently can sometimes free() this value itself.  */
 101   java_eh_info *p = (java_eh_info *) malloc (sizeof (java_eh_info));
 102   if (p == 0)
 103     abort ();
 104
 105   p->value = 0;
 106   java_eh_info ** info_ptr = __get_eh_info ();
 107
 108   /* There should NOT be an exception info pointer already. */
 109   if (*info_ptr != NULL)
 110     abort ();
 111
 112   *info_ptr = p;
 113 }
 114
 115 /* Deallocate the current exception info structure. Called at shutdown time. */
 116
 117 extern "C" void
 118 _Jv_eh_free ()
 119 {
 120   java_eh_info ** info_ptr = __get_eh_info ();
 121   if (*info_ptr == NULL)
 122     abort ();
 123
 124   /* FIXME: ideally we should just let the GC handle this.  */
 125   free (*info_ptr);
 126   *info_ptr = NULL;
 127 }
 128
 129 /* Initialize an __eh_info structure with this libraries matching info. */
 130
 131 extern "C" void
 132 _Jv_setup_eh_info (__eh_info *)
 133 {
 134 }
 135
 136 /* Perform a throw, Java style. Throw will unwind through this call,
 137    so there better not be any handlers or exception thrown here. */
 138
 139 extern "C" void
 140 _Jv_Throw (void *value)
 141 {
 142   if (value == NULL)
 143     value = (void *) new java::lang::NullPointerException ();
 144   java_eh_info *ehinfo = *(__get_eh_info ());
 145   if (ehinfo == NULL)
 146     {
 147       _Jv_eh_alloc ();
 148       ehinfo = *(__get_eh_info ());
 149     }
 150   ehinfo->eh_info.match_function = (__eh_matcher) _Jv_type_matcher;
 151   ehinfo->eh_info.language = EH_LANG_Java;
 152   ehinfo->eh_info.version = 1;
 153   ehinfo->value = value;
 154
 155 /* We're happy with setjmp/longjmp exceptions or region-based
 156    exception handlers: entry points are provided here for both.  */
 157 #ifdef SJLJ_EXCEPTIONS
 158   __sjthrow ();
 159 #else
 160   __throw ();
 161 #endif
 162 }
 163
 164 #ifdef USE_WIN32_SIGNALLING
 165
 166 // This is a mangled version of _Jv_Throw and __sjthrow except
 167 // rather than calling longjmp, it returns a pointer to the jmp buffer
 168
 169 extern "C" int *
 170 win32_get_restart_frame (void *value)
 171 {
 172   struct eh_context *eh = (struct eh_context *)__get_eh_context ();
 173   void ***dhc = &eh->dynamic_handler_chain;
 174
 175   java_eh_info *ehinfo = *(__get_eh_info ());
 176   if (ehinfo == NULL)
 177     {
 178       _Jv_eh_alloc ();
 179       ehinfo = *(__get_eh_info ());
 180     }
 181   ehinfo->eh_info.match_function = (__eh_matcher) _Jv_type_matcher;
 182   ehinfo->eh_info.language = EH_LANG_Java;
 183   ehinfo->eh_info.version = 1;
 184   ehinfo->value = value;
 185
 186   // FIXME: Run clean ups?
 187
 188   int *jmpbuf = (int*)&(*dhc)[2];
 189
 190   *dhc = (void**)(*dhc)[0];
 191
 192   return  jmpbuf;
 193 }
 194
 195 #endif /* USE_WIN32_SIGNALLING */