libjava/exception.cc

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