| Title |
Capturing SIGSEGV's in code in QNX4 |
| Ref. No. |
QNX.000010013 |
| Category(ies) |
Development |
| Issue |
When an application crashes it generates a SIGSEGV, is there a way to capture this signal so the application doesn't crash?
|
| Solution |
Yes, the following code example shows how this can be done.
#include <signal.h>
#include <sys/sigcontext.h> /* follows if you don't have it in your system */
void catch(int signo, SIGCONTEXT *scp)
{
printf("death by signal %u at 0x%lxn", signo, scp->sc_ip);
exit(1);
}
//The fields:
ulong_t sc_info; /* fault specific info */
ushort_t sc_errc; /* error code pushed by processor */
uchar_t sc_fault; /* actual fault # */
uchar_t sc_flags; /* signal handler flags: */
//are only available in QNX 4.24 and above, as is the sigaltstack() et al...
#ifndef sigcont_h
#define sigcont_h 1
#ifndef __TYPES_H_INCLUDED
#include <sys/types.h>
#endif
typedef struct _sigcontext SIGCONTEXT;
struct _sigcontext {
ulong_t sc_mask;
ulong_t sc_gs:16,:16; /* register set at fault time */
ulong_t sc_fs:16,:16;
ulong_t sc_es:16,:16;
ulong_t sc_ds:16,:16;
ulong_t sc_di;
ulong_t sc_si;
ulong_t sc_bp;
ulong_t :32; /* hole from pushad */
ulong_t sc_bx;
ulong_t sc_dx;
ulong_t sc_cx;
ulong_t sc_ax;
ulong_t sc_ip;
ulong_t sc_cs:16, :16;
ulong_t sc_fl;
ulong_t sc_sp;
ulong_t sc_ss:16, :16;
ulong_t sc_info; /* fault specific info */
ushort_t sc_errc; /* error code pushed by processor */
uchar_t sc_fault; /* actual fault # */
uchar_t sc_flags; /* signal handler flags: */
#define SC_ONSTACK 1
};
enum {
TRAP_ZDIV = 0, /* SIGFPE: divide by zero */
TRAP_DEBUG = 1, /* SIGTRAP: debug fault */
TRAP_NMI = 2, /* SGIBUS: nmi fault */
TRAP_BRKPT = 3, /* SIGTRAP: cpu breakpoint */
TRAP_OFLOW = 4, /* SIGFPE: integer overflow*/
TRAP_BOUNDS = 5, /* SIGFPE: bound instn failed*/
TRAP_BADOP = 6, /* SIGILL: invalid opcode */
TRAP_NONDP = 7, /* SIGFPE: NDP not present or available */
TRAP_DFAULT = 8, /* never: double fault (system error) */
TRAP_NDPSEGV = 9, /* SIGSEGV: NDP invalid address */
TRAP_BADTSS = 10, /* never: invalid tss (system error) */
TRAP_NOTPRESENT=11, /* SIGSEGV: referenced segment not preset */
TRAP_NOSTACK = 12, /* SIGSEGV: esp|ebp bad address */
TRAP_GPF = 13, /* SIGSEGV: other */
TRAP_PAGE = 14, /* SIGSEGV: page fault */
TRAP_FPERROR = 16, /* SIGFPE: floating point error */
};
#define __ERRC_VALID (1<<TRAP_DFAULT | 1<<TRAP_BADTSS |
1<<TRAP_NOTPRESENT | 1<<TRAP_NOSTACK | 1<<TRAP_GPF | 1<<TRAP_PAGE )
#define __INFO_VALID (1<<TRAP_PAGE)
#endif |
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