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/* Page fault handling library.
Copyright (C) 1998-2021 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible. */
#ifndef _SIGSEGV_H
#define _SIGSEGV_H
/* Get size_t. */
#include <stddef.h>
/* Define the fault context structure. */
#if defined __linux__ || defined __ANDROID__ \
|| (defined __FreeBSD__ && (defined __arm__ || defined __armhf__ || defined __arm64__)) \
|| defined __NetBSD__ \
|| defined _AIX || defined __sun \
|| defined __CYGWIN__
/* Linux, FreeBSD, NetBSD, AIX, Solaris, Cygwin */
# include <ucontext.h>
#elif (defined __APPLE__ && defined __MACH__)
/* macOS */
# include <sys/ucontext.h>
#elif defined __HAIKU__
/* Haiku */
# include <signal.h>
#endif
/* Correct the value of SIGSTKSZ on some systems.
glibc >= 2.34: When _GNU_SOURCE is defined, SIGSTKSZ is no longer a
compile-time constant. But most programs need a simple constant.
AIX 64-bit: original value 4096 is too small.
HP-UX: original value 8192 is too small.
Solaris 11/x86_64: original value 8192 is too small. */
#include <signal.h>
#if __GLIBC__ >= 2
# undef SIGSTKSZ
# if defined __ia64__
# define SIGSTKSZ 262144
# else
# define SIGSTKSZ 65536
# endif
#endif
#if defined _AIX && defined _ARCH_PPC64
# undef SIGSTKSZ
# define SIGSTKSZ 8192
#endif
#if defined __hpux || (defined __sun && (defined __x86_64__ || defined __amd64__))
# undef SIGSTKSZ
# define SIGSTKSZ 16384
#endif
/* HAVE_SIGSEGV_RECOVERY
is defined if the system supports catching SIGSEGV. */
#if defined __linux__ || defined __ANDROID__ || defined __GNU__ \
|| defined __FreeBSD_kernel__ || (defined __FreeBSD__ && !(defined __sparc__ || defined __sparc64__)) || defined __DragonFly__ \
|| defined __NetBSD__ \
|| defined __OpenBSD__ \
|| (defined __APPLE__ && defined __MACH__) \
|| defined _AIX || defined __sgi || defined __sun \
|| defined __CYGWIN__ || defined __HAIKU__
/* Linux, Hurd, GNU/kFreeBSD, FreeBSD, NetBSD, OpenBSD, macOS, AIX, IRIX, Solaris, Cygwin, Haiku */
# define HAVE_SIGSEGV_RECOVERY 1
#endif
/* HAVE_STACK_OVERFLOW_RECOVERY
is defined if stack overflow can be caught. */
#if defined __linux__ || defined __ANDROID__ || defined __GNU__ \
|| defined __FreeBSD_kernel__ || (defined __FreeBSD__ && !(defined __sparc__ || defined __sparc64__)) || defined __DragonFly__ \
|| (defined __NetBSD__ && !(defined __sparc__ || defined __sparc64__)) \
|| defined __OpenBSD__ \
|| (defined __APPLE__ && defined __MACH__) \
|| defined _AIX || defined __sgi || defined __sun \
|| defined __CYGWIN__ || defined __HAIKU__
/* Linux, Hurd, GNU/kFreeBSD, FreeBSD, NetBSD, OpenBSD, macOS, AIX, IRIX, Solaris, Cygwin, Haiku */
# define HAVE_STACK_OVERFLOW_RECOVERY 1
#endif
#ifdef __cplusplus
extern "C" {
#endif
#define LIBSIGSEGV_VERSION 0x020D /* version number: (major<<8) + minor */
extern int libsigsegv_version; /* Likewise */
/* -------------------------------------------------------------------------- */
#if 1 /* really only HAVE_SIGSEGV_RECOVERY */
/*
* The mask of bits that are set to zero in a fault address that gets passed
* to a global SIGSEGV handler.
* On some platforms, the precise fault address is not known, only the memory
* page into which the fault address falls. This is apparently allowed by POSIX:
* <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/signal.h.html>
* says: "For some implementations, the value of si_addr may be inaccurate."
* In this case, the returned fault address is rounded down to a multiple of
* getpagesize() = sysconf(_SC_PAGESIZE).
* On such platforms, we define SIGSEGV_FAULT_ADDRESS_ALIGNMENT to be an upper
* bound for getpagesize() (and, like getpagesize(), also a power of 2).
* On the platforms where the returned fault address is the precise one, we
* define SIGSEGV_FAULT_ADDRESS_ALIGNMENT to 1.
*/
# if defined __NetBSD__ && (defined __sparc__ || defined __sparc64__)
/* getpagesize () is 0x1000 or 0x2000, depending on hardware. */
# define SIGSEGV_FAULT_ADDRESS_ALIGNMENT 0x2000UL
# elif defined __linux__ && (defined __s390__ || defined __s390x__)
/* getpagesize () is 0x1000. */
# define SIGSEGV_FAULT_ADDRESS_ALIGNMENT 0x1000UL
# else
# define SIGSEGV_FAULT_ADDRESS_ALIGNMENT 1UL
# endif
/*
* The type of a global SIGSEGV handler.
* The fault address, with the bits (SIGSEGV_FAULT_ADDRESS_ALIGNMENT - 1)
* cleared, is passed as argument.
* The access type (read access or write access) is not passed; your handler
* has to know itself how to distinguish these two cases.
* The second argument is 0, meaning it could also be a stack overflow, or 1,
* meaning the handler should seriously try to fix the fault.
* The return value should be nonzero if the handler has done its job
* and no other handler should be called, or 0 if the handler declines
* responsibility for the given address.
*
* The handler is run at a moment when nothing about the global state of the
* program is known. Therefore it cannot use facilities that manipulate global
* variables or locks. In particular, it cannot use malloc(); use mmap()
* instead. It cannot use fopen(); use open() instead. Etc. All global
* variables that are accessed by the handler should be marked 'volatile'.
*/
typedef int (*sigsegv_handler_t) (void* fault_address, int serious);
/*
* Installs a global SIGSEGV handler.
* This should be called once only, and it ignores any previously installed
* SIGSEGV handler.
* Returns 0 on success, or -1 if the system doesn't support catching SIGSEGV.
*/
extern int sigsegv_install_handler (sigsegv_handler_t handler);
/*
* Deinstalls the global SIGSEGV handler.
* This goes back to the state where no SIGSEGV handler is installed.
*/
extern void sigsegv_deinstall_handler (void);
/*
* Prepares leaving a SIGSEGV handler (through longjmp or similar means).
* Control is transferred by calling CONTINUATION with CONT_ARG1, CONT_ARG2,
* CONT_ARG3 as arguments.
* CONTINUATION must not return.
* The sigsegv_leave_handler function may return if called from a SIGSEGV
* handler; its return value should be used as the handler's return value.
* The sigsegv_leave_handler function does not return if called from a
* stack overflow handler.
*/
extern int sigsegv_leave_handler (void (*continuation) (void*, void*, void*), void* cont_arg1, void* cont_arg2, void* cont_arg3);
#endif /* HAVE_SIGSEGV_RECOVERY */
#if 1 /* really only HAVE_STACK_OVERFLOW_RECOVERY */
/*
* The type of a context passed to a stack overflow handler.
* This type is system dependent; on some platforms it is an 'ucontext_t *',
* on some platforms it is a 'struct sigcontext *', on others merely an
* opaque 'void *'.
*/
# if defined __linux__ || defined __ANDROID__ \
|| (defined __FreeBSD__ && (defined __arm__ || defined __armhf__ || defined __arm64__)) \
|| defined __NetBSD__ \
|| (defined __APPLE__ && defined __MACH__) \
|| defined _AIX || defined __sun \
|| defined __CYGWIN__ || defined __HAIKU__
typedef ucontext_t *stackoverflow_context_t;
# elif defined __GNU__ \
|| defined __FreeBSD_kernel__ || (defined __FreeBSD__ && !(defined __sparc__ || defined __sparc64__)) || defined __DragonFly__ \
|| defined __OpenBSD__ || defined __sgi
typedef struct sigcontext *stackoverflow_context_t;
# else
typedef void *stackoverflow_context_t;
# endif
/*
* The type of a stack overflow handler.
* Such a handler should perform a longjmp call in order to reduce the amount
* of stack needed. It must not return.
* The emergency argument is 0 when the stack could be repared, or 1 if the
* application should better save its state and exit now.
*
* The handler is run at a moment when nothing about the global state of the
* program is known. Therefore it cannot use facilities that manipulate global
* variables or locks. In particular, it cannot use malloc(); use mmap()
* instead. It cannot use fopen(); use open() instead. Etc. All global
* variables that are accessed by the handler should be marked 'volatile'.
*/
typedef void (*stackoverflow_handler_t) (int emergency, stackoverflow_context_t scp);
/*
* Installs a stack overflow handler.
* The extra_stack argument is a pointer to a pre-allocated area used as a
* stack for executing the handler. It typically comes from a static variable
* or from heap-allocated memoty; placing it on the main stack may fail on
* some operating systems.
* Its size, passed in extra_stack_size, should be sufficiently large. The
* following code determines an appropriate size:
* #include <signal.h>
* #ifndef SIGSTKSZ / * glibc defines SIGSTKSZ for this purpose * /
* # define SIGSTKSZ 16384 / * on most platforms, 16 KB are sufficient * /
* #endif
* Returns 0 on success, or -1 if the system doesn't support catching stack
* overflow.
*/
extern int stackoverflow_install_handler (stackoverflow_handler_t handler,
void* extra_stack, size_t extra_stack_size);
/*
* Deinstalls the stack overflow handler.
*/
extern void stackoverflow_deinstall_handler (void);
#endif /* HAVE_STACK_OVERFLOW_RECOVERY */
/* -------------------------------------------------------------------------- */
#ifdef __cplusplus
}
#endif
#endif /* _SIGSEGV_H */
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