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
  16 #include <java/lang/Class.h>
  17 #include <java/lang/NullPointerException.h>
  18 #include <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" short __get_eh_table_version (void *table);
  37 extern "C" short __get_eh_table_language (void *table);
  38
  39
  40 extern "C" void * malloc (size_t);
  41 extern "C" void free (void *);
  42
  43
  44 extern "C" void *
  45 _Jv_type_matcher (java_eh_info *info, void* match_info,
  46                   void *exception_table)
  47 {
  48   if (__get_eh_table_language (exception_table) != EH_LANG_Java)
  49     return NULL;
  50
  51   /* we don't worry about version info yet, there is only one version! */
  52
  53   if (match_info != NULL)
  54     {
  55       // The match_info is either a (java::lang::Class*) or
  56       // match_info is one more than a (Utf8Const*).
  57       if (sizeof(void*) != sizeof(size_t))
  58         abort();
  59       size_t mi = (size_t) match_info;
  60       if ((mi & 1) != 0)
  61         match_info = _Jv_FindClass ((Utf8Const*) (mi - 1), NULL);
  62       if (! _Jv_IsInstanceOf ((jobject) info->value, (jclass) match_info))
  63         return NULL;
  64     }
  65
  66   return info->value;
  67 }
  68
  69 /* Compiler hook to return a pointer to java exception object. The value
  70    is cleared, so if the exception needs to be rethrown, it should be set
  71    again */
  72
  73 extern "C" void *
  74 _Jv_exception_info (void)
  75 {
  76   java_eh_info *info = *(__get_eh_info ());
  77   void *ptr;
  78
  79   if (info == NULL)
  80     abort ();
  81
  82   ptr = info->value;
  83
  84   /* clear the value so another throw is an error */
  85   info->value = NULL;
  86
  87   return ptr;
  88 }
  89
  90
  91
  92 /* Allocate an exception info structure for java. Called the first time
  93    an exception is thrown. */
  94
  95 extern "C" void
  96 _Jv_eh_alloc ()
  97 {
  98   /* FIXME: we should use _Jv_AllocBytes here.  However, libgcc2
  99      apparently can sometimes free() this value itself.  */
 100   java_eh_info *p = (java_eh_info *) malloc (sizeof (java_eh_info));
 101   if (p == 0)
 102     terminate ();
 103
 104   p->value = 0;
 105   java_eh_info ** info_ptr = __get_eh_info ();
 106
 107   /* There should NOT be an exception info pointer already. */
 108   if (*info_ptr != NULL)
 109     abort ();
 110
 111   *info_ptr = p;
 112 }
 113
 114 /* Deallocate the current exception info structure. Called at shutdown time. */
 115
 116 extern "C" void
 117 _Jv_eh_free ()
 118 {
 119   java_eh_info ** info_ptr = __get_eh_info ();
 120   if (*info_ptr == NULL)
 121     abort ();
 122
 123   /* FIXME: ideally we should just let the GC handle this.  */
 124   free (*info_ptr);
 125   *info_ptr = NULL;
 126 }
 127
 128 /* Perform a throw, Java style. Throw will unwind through this call, so
 129    there better not be any handlers or exception thrown here. */
 130
 131
 132 /* Initialize an __eh_info structure with this libraries matching info. */
 133
 134 extern "C" void
 135 _Jv_setup_eh_info (__eh_info *)
 136 {
 137 }
 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   __throw();
 155 }