src/sigsegv.h.in

   1 /* Page fault handling library.
   2    Copyright (C) 1998-1999, 2002, 2004-2008  Bruno Haible <bruno@clisp.org>
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 #ifndef _SIGSEGV_H
  19 #define _SIGSEGV_H
  20
  21 @FAULT_CONTEXT_INCLUDE@
  22
  23 /* HAVE_SIGSEGV_RECOVERY
  24    is defined if the system supports catching SIGSEGV.  */
  25 #if @HAVE_SIGSEGV_RECOVERY@
  26 # define HAVE_SIGSEGV_RECOVERY 1
  27 #endif
  28
  29 /* HAVE_STACK_OVERFLOW_RECOVERY
  30    is defined if stack overflow can be caught.  */
  31 #if @HAVE_STACK_OVERFLOW_RECOVERY@
  32 # define HAVE_STACK_OVERFLOW_RECOVERY 1
  33 #endif
  34
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 #define LIBSIGSEGV_VERSION 0x0206    /* version number: (major<<8) + minor */
  41 extern int libsigsegv_version;       /* Likewise */
  42
  43 /* -------------------------------------------------------------------------- */
  44
  45 /*
  46  * The type of a global SIGSEGV handler.
  47  * The fault address is passed as argument.
  48  * The access type (read access or write access) is not passed; your handler
  49  * has to know itself how to distinguish these two cases.
  50  * The second argument is 0, meaning it could also be a stack overflow, or 1,
  51  * meaning the handler should seriously try to fix the fault.
  52  * The return value should be nonzero if the handler has done its job
  53  * and no other handler should be called, or 0 if the handler declines
  54  * responsibility for the given address.
  55  */
  56 typedef int (*sigsegv_handler_t) (void* fault_address, int serious);
  57
  58 /*
  59  * Installs a global SIGSEGV handler.
  60  * This should be called once only, and it ignores any previously installed
  61  * SIGSEGV handler.
  62  * Returns 0 on success, or -1 if the system doesn't support catching SIGSEGV.
  63  */
  64 extern int sigsegv_install_handler (sigsegv_handler_t handler);
  65
  66 /*
  67  * Deinstalls the global SIGSEGV handler.
  68  * This goes back to the state where no SIGSEGV handler is installed.
  69  */
  70 extern void sigsegv_deinstall_handler (void);
  71
  72 /*
  73  * Prepares leaving a SIGSEGV handler (through longjmp or similar means).
  74  */
  75 extern void sigsegv_leave_handler (void);
  76
  77 /*
  78  * The type of a context passed to a stack overflow handler.
  79  * This type is system dependent; on some platforms it is an 'ucontext_t *',
  80  * on some platforms it is a 'struct sigcontext *', on others merely an
  81  * opaque 'void *'.
  82  */
  83 typedef @FAULT_CONTEXT@ *stackoverflow_context_t;
  84
  85 /*
  86  * The type of a stack overflow handler.
  87  * Such a handler should perform a longjmp call in order to reduce the amount
  88  * of stack needed. It must not return.
  89  * The emergency argument is 0 when the stack could be repared, or 1 if the
  90  * application should better save its state and exit now.
  91  */
  92 typedef void (*stackoverflow_handler_t) (int emergency, stackoverflow_context_t scp);
  93
  94 /*
  95  * Installs a stack overflow handler.
  96  * The extra_stack argument is a pointer to a pre-allocated area used as a
  97  * stack for executing the handler. It is typically allocated by use of
  98  * `alloca' during `main'. Its size should be sufficiently large.
  99  * The following code determines an appropriate size:
 100  *   #include <signal.h>
 101  *   #ifndef SIGSTKSZ         / * glibc defines SIGSTKSZ for this purpose * /
 102  *   # define SIGSTKSZ 16384  / * on most platforms, 16 KB are sufficient * /
 103  *   #endif
 104  * Returns 0 on success, or -1 if the system doesn't support catching stack
 105  * overflow.
 106  */
 107 extern int stackoverflow_install_handler (stackoverflow_handler_t handler,
 108                                           void* extra_stack, unsigned long extra_stack_size);
 109
 110 /*
 111  * Deinstalls the stack overflow handler.
 112  */
 113 extern void stackoverflow_deinstall_handler (void);
 114
 115 /* -------------------------------------------------------------------------- */
 116
 117 /*
 118  * The following structure and functions permit to define different SIGSEGV
 119  * policies on different address ranges.
 120  */
 121
 122 /*
 123  * The type of a local SIGSEGV handler.
 124  * The fault address is passed as argument.
 125  * The second argument is fixed arbitrary user data.
 126  * The return value should be nonzero if the handler has done its job
 127  * and no other handler should be called, or 0 if the handler declines
 128  * responsibility for the given address.
 129  */
 130 typedef int (*sigsegv_area_handler_t) (void* fault_address, void* user_arg);
 131
 132 /*
 133  * This structure represents a table of memory areas (address range intervals),
 134  * with an local SIGSEGV handler for each.
 135  */
 136 typedef
 137 struct sigsegv_dispatcher {
 138   void* tree;
 139 }
 140 sigsegv_dispatcher;
 141
 142 /*
 143  * Initializes a sigsegv_dispatcher structure.
 144  */
 145 extern void sigsegv_init (sigsegv_dispatcher* dispatcher);
 146
 147 /*
 148  * Adds a local SIGSEGV handler to a sigsegv_dispatcher structure.
 149  * It will cover the interval [address..address+len-1].
 150  * Returns a "ticket" that can be used to remove the handler later.
 151  */
 152 extern void* sigsegv_register (sigsegv_dispatcher* dispatcher,
 153                                void* address, unsigned long len,
 154                                sigsegv_area_handler_t handler, void* handler_arg);
 155
 156 /*
 157  * Removes a local SIGSEGV handler.
 158  */
 159 extern void sigsegv_unregister (sigsegv_dispatcher* dispatcher, void* ticket);
 160
 161 /*
 162  * Call the local SIGSEGV handler responsible for the given fault address.
 163  * Return the handler's return value. 0 means that no handler has been found,
 164  * or that a handler was found but declined responsibility.
 165  */
 166 extern int sigsegv_dispatch (sigsegv_dispatcher* dispatcher, void* fault_address);
 167
 168 /* -------------------------------------------------------------------------- */
 169
 170 #ifdef __cplusplus
 171 }
 172 #endif
 173
 174 #endif /* _SIGSEGV_H */