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 <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
  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 #ifndef SJLJ_EXCEPTIONS
  49   /* No exception table implies the old style mechanism, so don't check. */
  50   if (exception_table != NULL
  51       && __get_eh_table_language (exception_table) != EH_LANG_Java)
  52     return NULL;
  53 #endif
  54
  55   /* we don't worry about version info yet, there is only one version! */
  56
  57   if (match_info != NULL)
  58     {
  59       // The match_info is either a (java::lang::Class*) or
  60       // match_info is one more than a (Utf8Const*).
  61       if (sizeof(void*) != sizeof(size_t))
  62         abort();
  63       size_t mi = (size_t) match_info;
  64       if ((mi & 1) != 0)
  65         match_info = _Jv_FindClass ((Utf8Const*) (mi - 1), NULL);
  66       if (! _Jv_IsInstanceOf ((jobject) info->value, (jclass) match_info))
  67         return NULL;
  68     }
  69
  70   return info->value;
  71 }
  72
  73 /* Compiler hook to return a pointer to java exception object. The value
  74    is cleared, so if the exception needs to be rethrown, it should be set
  75    again */
  76
  77 extern "C" void *
  78 _Jv_exception_info (void)
  79 {
  80   java_eh_info *info = *(__get_eh_info ());
  81   void *ptr;
  82
  83   if (info == NULL)
  84     abort ();
  85
  86   ptr = info->value;
  87
  88   /* clear the value so another throw is an error */
  89   info->value = NULL;
  90
  91   return ptr;
  92 }
  93
  94
  95
  96 /* Allocate an exception info structure for java. Called the first time
  97    an exception is thrown. */
  98
  99 extern "C" void
 100 _Jv_eh_alloc ()
 101 {
 102   /* FIXME: we should use _Jv_AllocBytes here.  However, libgcc2
 103      apparently can sometimes free() this value itself.  */
 104   java_eh_info *p = (java_eh_info *) malloc (sizeof (java_eh_info));
 105   if (p == 0)
 106     terminate ();
 107
 108   p->value = 0;
 109   java_eh_info ** info_ptr = __get_eh_info ();
 110
 111   /* There should NOT be an exception info pointer already. */
 112   if (*info_ptr != NULL)
 113     abort ();
 114
 115   *info_ptr = p;
 116 }
 117
 118 /* Deallocate the current exception info structure. Called at shutdown time. */
 119
 120 extern "C" void
 121 _Jv_eh_free ()
 122 {
 123   java_eh_info ** info_ptr = __get_eh_info ();
 124   if (*info_ptr == NULL)
 125     abort ();
 126
 127   /* FIXME: ideally we should just let the GC handle this.  */
 128   free (*info_ptr);
 129   *info_ptr = NULL;
 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 /* Perform a throw, Java style. Throw will unwind through this call,
 140    so there better not be any handlers or exception thrown here. */
 141
 142 extern "C" void
 143 _Jv_Throw (void *value)
 144 {
 145   if (value == NULL)
 146     value = (void *) new java::lang::NullPointerException ();
 147   java_eh_info *ehinfo = *(__get_eh_info ());
 148   if (ehinfo == NULL)
 149     {
 150       _Jv_eh_alloc ();
 151       ehinfo = *(__get_eh_info ());
 152     }
 153   ehinfo->eh_info.match_function = (__eh_matcher) _Jv_type_matcher;
 154   ehinfo->eh_info.language = EH_LANG_Java;
 155   ehinfo->eh_info.version = 1;
 156   ehinfo->value = value;
 157
 158 /* We're happy with setjmp/longjmp exceptions or region-based
 159    exception handlers: entry points are provided here for both.  */
 160 #ifdef SJLJ_EXCEPTIONS
 161   __sjthrow ();
 162 #else
 163   __throw ();
 164 #endif
 165 }