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  * The handler is run at a moment when nothing about the global state of the
  57  * program is known. Therefore it cannot use facilities that manipulate global
  58  * variables or locks. In particular, it cannot use malloc(); use mmap()
  59  * instead. It cannot use fopen(); use open() instead. Etc. All global
  60  * variables that are accessed by the handler should be marked 'volatile'.
  61  */
  62 typedef int (*sigsegv_handler_t) (void* fault_address, int serious);
  63
  64 /*
  65  * Installs a global SIGSEGV handler.
  66  * This should be called once only, and it ignores any previously installed
  67  * SIGSEGV handler.
  68  * Returns 0 on success, or -1 if the system doesn't support catching SIGSEGV.
  69  */
  70 extern int sigsegv_install_handler (sigsegv_handler_t handler);
  71
  72 /*
  73  * Deinstalls the global SIGSEGV handler.
  74  * This goes back to the state where no SIGSEGV handler is installed.
  75  */
  76 extern void sigsegv_deinstall_handler (void);
  77
  78 #if LIBSIGSEGV_VERSION >= 0x0206
  79 /*
  80  * Prepares leaving a SIGSEGV handler (through longjmp or similar means).
  81  * Control is transferred by calling CONTINUATION with CONT_ARG1, CONT_ARG2,
  82  * CONT_ARG3 as arguments.
  83  * CONTINUATION must not return.
  84  * The sigsegv_leave_handler function may return if called from a SIGSEGV
  85  * handler; its return value should be used as the handler's return value.
  86  * The sigsegv_leave_handler function does not return if called from a
  87  * stack overflow handler.
  88  */
  89 extern int sigsegv_leave_handler (void (*continuation) (void*, void*, void*), void* cont_arg1, void* cont_arg2, void* cont_arg3);
  90 #else /* older versions of libsigsegv */
  91 /*
  92  * Prepares leaving a SIGSEGV handler (through longjmp or similar means).
  93  * Limitation: This function could only be called once on MacOS X.
  94  */
  95 extern void sigsegv_leave_handler (void);
  96 #endif
  97
  98 /*
  99  * The type of a context passed to a stack overflow handler.
 100  * This type is system dependent; on some platforms it is an 'ucontext_t *',
 101  * on some platforms it is a 'struct sigcontext *', on others merely an
 102  * opaque 'void *'.
 103  */
 104 typedef @FAULT_CONTEXT@ *stackoverflow_context_t;
 105
 106 /*
 107  * The type of a stack overflow handler.
 108  * Such a handler should perform a longjmp call in order to reduce the amount
 109  * of stack needed. It must not return.
 110  * The emergency argument is 0 when the stack could be repared, or 1 if the
 111  * application should better save its state and exit now.
 112  *
 113  * The handler is run at a moment when nothing about the global state of the
 114  * program is known. Therefore it cannot use facilities that manipulate global
 115  * variables or locks. In particular, it cannot use malloc(); use mmap()
 116  * instead. It cannot use fopen(); use open() instead. Etc. All global
 117  * variables that are accessed by the handler should be marked 'volatile'.
 118  */
 119 typedef void (*stackoverflow_handler_t) (int emergency, stackoverflow_context_t scp);
 120
 121 /*
 122  * Installs a stack overflow handler.
 123  * The extra_stack argument is a pointer to a pre-allocated area used as a
 124  * stack for executing the handler. It is typically allocated by use of
 125  * `alloca' during `main'. Its size should be sufficiently large.
 126  * The following code determines an appropriate size:
 127  *   #include <signal.h>
 128  *   #ifndef SIGSTKSZ         / * glibc defines SIGSTKSZ for this purpose * /
 129  *   # define SIGSTKSZ 16384  / * on most platforms, 16 KB are sufficient * /
 130  *   #endif
 131  * Returns 0 on success, or -1 if the system doesn't support catching stack
 132  * overflow.
 133  */
 134 extern int stackoverflow_install_handler (stackoverflow_handler_t handler,
 135                                           void* extra_stack, unsigned long extra_stack_size);
 136
 137 /*
 138  * Deinstalls the stack overflow handler.
 139  */
 140 extern void stackoverflow_deinstall_handler (void);
 141
 142 /* -------------------------------------------------------------------------- */
 143
 144 /*
 145  * The following structure and functions permit to define different SIGSEGV
 146  * policies on different address ranges.
 147  */
 148
 149 /*
 150  * The type of a local SIGSEGV handler.
 151  * The fault address is passed as argument.
 152  * The second argument is fixed arbitrary user data.
 153  * The return value should be nonzero if the handler has done its job
 154  * and no other handler should be called, or 0 if the handler declines
 155  * responsibility for the given address.
 156  */
 157 typedef int (*sigsegv_area_handler_t) (void* fault_address, void* user_arg);
 158
 159 /*
 160  * This structure represents a table of memory areas (address range intervals),
 161  * with an local SIGSEGV handler for each.
 162  */
 163 typedef
 164 struct sigsegv_dispatcher {
 165   void* tree;
 166 }
 167 sigsegv_dispatcher;
 168
 169 /*
 170  * Initializes a sigsegv_dispatcher structure.
 171  */
 172 extern void sigsegv_init (sigsegv_dispatcher* dispatcher);
 173
 174 /*
 175  * Adds a local SIGSEGV handler to a sigsegv_dispatcher structure.
 176  * It will cover the interval [address..address+len-1].
 177  * Returns a "ticket" that can be used to remove the handler later.
 178  */
 179 extern void* sigsegv_register (sigsegv_dispatcher* dispatcher,
 180                                void* address, unsigned long len,
 181                                sigsegv_area_handler_t handler, void* handler_arg);
 182
 183 /*
 184  * Removes a local SIGSEGV handler.
 185  */
 186 extern void sigsegv_unregister (sigsegv_dispatcher* dispatcher, void* ticket);
 187
 188 /*
 189  * Call the local SIGSEGV handler responsible for the given fault address.
 190  * Return the handler's return value. 0 means that no handler has been found,
 191  * or that a handler was found but declined responsibility.
 192  */
 193 extern int sigsegv_dispatch (sigsegv_dispatcher* dispatcher, void* fault_address);
 194
 195 /* -------------------------------------------------------------------------- */
 196
 197 #ifdef __cplusplus
 198 }
 199 #endif
 200
 201 #endif /* _SIGSEGV_H */