SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
NAME
sigvec - software signal facilities
SYNOPSIS
#include <sys/signal.h>
sigvec(sig, vec, ovec)
int sig;
struct sigvec *vec, *ovec;
DESCRIPTION
The sigvec facility assigns a handler for a specific signal
sig, using the following structure, defined in
<sys/signal.h>:
struct sigvec {
int (*sv_handler)();
int sv_mask;
int sv_flags;
};
If vec is non-zero, it specifies a handler routine
sv_handler() and mask sv_mask to be used when delivering
sig. Further, if sv_flags is 1, the system delivers the
signal to the process on a signal stack, specified with
sigstack(2). If sv_flags is 2, the system is not restarted
on signal return. If ovec is non-zero, the previous
handling information for the signal is returned to the user.
The system defines a set of signals that may be delivered to
a process. Signal delivery resembles the occurrence of a
hardware interrupt: the signal is blocked from further
occurrence, the current process context is saved, and a new
one is built. A process may specify a handler to which a
signal is delivered, may reinstate the default action for a
signal, or may specify that a signal is to be ignored. A
process may also specify that a default action is to be
taken by the system when a signal occurs. Normally, signal
handlers execute on the current stack of the process; this
may be changed, on a per-handler basis, so that signals are
taken on a special signal stack.
All signals have the same priority. Signal routines execute
with the signal that caused their invocation blocked, but
other signals may yet occur. A global signal mask defines
the set of signals currently blocked from delivery to a
process. The signal mask for a process is initialized from
that of its parent (normally 0); it may be changed with a
sigblock(2) or sigsetmask(2) call, or when a signal is
delivered to the process.
Printed 4/6/89 1
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
When a signal condition arises for a process, the signal is
added to a set of signals pending for the process. If the
signal is not currently blocked by the process then it is
delivered to the process. When a signal is delivered, the
current state of the process is saved, a new signal mask is
calculated (as described later), and the signal handler is
invoked. The call to the handler is arranged so that if the
signal handling routine returns normally the process resumes
execution in the context from before the signal's delivery.
If the process wishes to resume in a different context, then
it must arrange to restore the previous context itself.
When a signal is delivered to a process a new signal mask is
installed for the duration of the process' signal handler
(or until a sigblock or sigsetmask call is made). This new
mask is formed by taking the current signal mask, adding the
signal to be delivered, and or'ing in the signal mask
associated with the handler to be invoked.
The following is a list of all signals with names as in the
include file <sys/signal.h>:
SIGHUP 1 hangup
SIGINT 2 interrupt
SIGQUIT 3* quit
SIGILL 4* illegal instruction (not reset when caught)
SIGTRAP 5* trace trap (not reset when caught)
SIGIOT 6* FLAG instruction when F condition set
SIGDISPLAY 7* event/timer
SIGFPE 8* floating point exception
SIGKILL 9 kill (cannot be caught or ignored)
SIGBUS 10* bus error
SIGSEGV 11* segmentation violation
SIGSYS 12* bad argument to system call
SIGPIPE 13 write on a pipe with no one to read it
SIGALRM 14 alarm clock
SIGTERM 15 software termination signal from kill
SIGURG 16• urgent condition present on socket,
exception condition present on a device
SIGSTOP 17† stop (cannot be caught or ignored)
SIGTSTP 18† stop signal generated from keyboard
SIGCONT 19• continue after stop (cannot be blocked)
SIGCHLD 20• to parent on child stop or exit
SIGCLD 20• synonym for SIGCHLD (for System V compatibility)
SIGTTIN 21† background read attempted from control terminal
SIGTTOU 22† background write attempted to control terminal
SIGIO 23• I/O is possible on a descriptor (see fcntl(2))
SIGXCPU 24 cpu time limit exceeded (see setrlimit(2))
SIGXFSZ 25 file size limit exceeded (see setrlimit(2))
SIGVTALRM 26 virtual time alarm (see setitimer(2))
SIGPROF 27 profiling timer alarm (see setitimer(2))
SIGUSR1 28 user-defined signal 1
Printed 4/6/89 2
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
SIGUSR2 29 user-defined signal 2
SIGWINCH 30• window size changed
SIGPWR 31 power fail
SIGLOST 32 resource lost (e.g., record-lock lost)
The starred signals in the list cause a core image if not
caught or ignored.
Once a signal handler is installed, it remains installed
until another sigvec call is made, or an execve(2) is
performed. The default action for a signal may be
reinstated by setting sv_handler to SIG_DFL; this default is
termination (with a core image for starred signals) except
for signals marked with • or †. Signals marked with • are
discarded if the action is SIG_DFL; signals marked with †
stop the process. If sv_handler is SIG_IGN the signal is
subsequently ignored, and pending instances of the signal
are discarded.
If a caught signal occurs during certain system calls,
terminating the call prematurely, the call is automatically
restarted. In particular, this can occur during a read(2)
or write(2) on a slow device (such as a terminal but not a
file) and during a wait(2).
After a fork(2) the child inherits all signals, the signal
mask, and the signal stack.
The system call execve(2) resets all caught signals to
default action; ignored signals remain ignored; the signal
mask remains the same; the signal stack state is reset.
The mask specified in vec is not allowed to block SIGKILL,
SIGSTOP, or SIGCONT; this is done silently by the system.
The handler routine can be declared:
handler(sig, code, scp)
int sig, code;
struct sigcontext *scp;
Here sig is the signal number, into which the hardware
faults and traps are mapped as defined here; code is a
parameter, a constant, as explained here; scp is a pointer
to the sigcontext structure (defined in <sys/signal.h>),
used to restore the context from before the signal.
The following defines the mapping of hardware traps to
signals and codes. All symbols are defined in detail in
<sys/signal.h>:
Hardware Condition Signal Code
Arithmetic traps:
Printed 4/6/89 3
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
Integer division by zero SIGFPE FPE_INTDIV_TRAP
Floating overflow SIGFPE FPE_FLTOVF_TRAP
Floating division by zero SIGFPE FPE_FLTDIV_TRAP
Floating underflow SIGFPE FPE_FLTUND_TRAP
Floating inexact result SIGFPE FPE_INEXCT_TRAP
Branch/set on unordered condition SIGFPE FPE_BRCOND_TRAP
Not a number SIGFPE FPE_NAN_TRAP
Operand error SIGFPE FPE_OPRND_TRAP
Write to read-only memory SIGBUS
Read/write unmapped memory SIGSEGV
Undefined instruction trap SIGILL ILL_UNDEF_TRAP
Privileged instruction trap SIGILL ILL_PRIVIN_TRAP
A-line instruction trap SIGILL ILL_ALINE_TRAP
F-line instruction trap SIGILL ILL_FLINE_TRAP
Format error trap SIGILL ILL_FORMAT_TRAP
Trace pending SIGTRAP TRAP_TRC
Breakpoint (TRAP #12) instruction SIGTRAP TRAP_BPT
CHK or CHK2 instruction SIGIOT IOT_CHK_TRAP
Trap instructions:
ccTRAPcc/TRAPcc/TRAPV/FTRAPcc SIGIOT IOT_TRAPV_TRAP
TRAP #0 SIGIOT IOT_TRAP0_TRAP
TRAP #1 SIGIOT IOT_TRAP1_TRAP
TRAP #2 SIGIOT IOT_TRAP2_TRAP
TRAP #3 SIGIOT IOT_TRAP3_TRAP
TRAP #4 SIGIOT IOT_TRAP4_TRAP
TRAP #5 SIGIOT IOT_TRAP5_TRAP
TRAP #6 SIGIOT IOT_TRAP6_TRAP
TRAP #7 SIGIOT IOT_TRAP7_TRAP
All entries for SIGFPE are dependent upon the 68881
exception register (see setfp(3m).
The programmer familiar with the Motorola 68020 exception
vectors may be more comfortable with the following table,
organized by exception vector offset, which describes how
each exception is handled by the kernel. For each exception
causing a signal delivery to the process, the signal and
code are given. UPPER_CASE_CONSTANTs for signals and codes
are defined in <sys/signal.h>.
(Note that numeric values of the codes assigned to
exceptions which result in SIGIOT are the offset of the
exception vector; for example, the code for exception vector
0x18, CHK instruction, is IOT_CHK_TRAP which is equated to
0x18.)
0x08 bus error
Directed to page fault handler, this is normally
transparent to the user program unless a segmentation
violation has occurred.
0x0C address error
Printed 4/6/89 4
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
signal=SIGBUS, code=0
0x10 illegal instruction
signal=SIGILL, code=ILL_UNDEF_TRAP
0x14 zero divide
signal=SIGFPE, code=FPE_INTDIV_TRAP
0x18 CHK, CHK2
signal=SIGIOT, code=IOT_CHK_TRAP (0x18)
0x1C cpTRAPcc, TRAPcc, TRAPV (and FTRAPcc)
signal=SIGIOT, code=IOT_TRAPV_TRAP (0x1C)
0x20 privilege violation
signal=SIGILL, code=ILL_PRIVIN_TRAP
0x24 trace
(user process T bit cleared) signal=SIGTRAP code=TRAP_TRC
0x28 line 1010 emulator
signal=SIGILL code=ILL_ALINE_TRAP
0x2C line 1111 emulator
signal=SIGILL code=ILL_FLINE_TRAP
0x30 (unassigned, reserved)
prints stray interrupt message on console
0x34 coprocessor protocol violation
prints stray interrupt message on console
0x38 format error
signal=SIGILL code=ILL_FORMAT_TRAP
0x3C uninitialized interrupt
prints stray interrupt message on console
0x40-0x5C (unassigned, reserved)
prints stray interrupt message on console
0x60 spurious interrupt
prints stray interrupt message on console
0x64-0x7C interrupt vectors
handled by device drivers
0x80 TRAP #0
signal=SIGIOT code=IOT_TRAP0_TRAP (0x80)
0x84 TRAP #1
signal=SIGIOT code=IOT_TRAP1_TRAP (0x84)
Printed 4/6/89 5
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
0x88 TRAP #2
signal=SIGIOT code=IOT_TRAP2_TRAP (0x88)
0x8C TRAP #3
signal=SIGIOT code=IOT_TRAP3_TRAP (0x8C)
0x90 TRAP #4
signal=SIGIOT code=IOT_TRAP4_TRAP (0x90)
0x94 TRAP #5
signal=SIGIOT code=IOT_TRAP5_TRAP (0x94)
0x98 TRAP #6
signal=SIGIOT code=IOT_TRAP6_TRAP (0x98)
0x9C TRAP #7
signal=SIGIOT code=IOT_TRAP7_TRAP (0x9C)
0xA0 TRAP #8
used by kernel (for vector complete)
0xA4 TRAP #9
used by kernel (for vcall)
0xA8 TRAP #10 (decimal)
used by kernel (for return from signal handler)
0xAC TRAP #11 (decimal)
used by kernel (for normal system call)
0xB0 TRAP #12 (decimal)
(used as breakpoint instruction; user process T bit
cleared)
signal=SIGTRAP code=TRAP_BPT
0xB4 TRAP #13 (decimal)
signal=SIGIOT code=IOT_TRAP13_TRAP (0xB4)
2P This trap is used by the 4300 series UTek workstation
display subsystem. Programs intended to run on a 4300
series workstation must avoid use of this trap.
0xB8 TRAP #14 (decimal)
signal=SIGIOT code=IOT_TRAP14_TRAP (0xB8)
2P This trap is used by the 4300 series UTek workstation ROM
and the PDB kernel debugger. Programs intended to run on
a 4300 series UTek workstation must avoid use of this
trap.
0xBC TRAP #15 (decimal)
Printed 4/6/89 6
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
signal=SIGIOT code=IOT_TRAP15_TRAP (0xBC)
2P This trap is used by the 4300 series UTek workstation
kernel to emulate system calls to the UniFLEXr operating
system. Programs intended to run on a 4300 series UTek
workstation must avoid use of this trap.
0xC0 FPCP branch or set on unordered condition
signal=SIGFPE code=FPE_BRCOND_TRAP
0xC4 FPCP inexact result
signal=SIGFPE code=FPE_INEXCT_TRAP
0xC8 FPCP divide by zero
signal=SIGFPE code=FPE_FLTDIV_TRAP
0xCC FPCP underflow
signal=SIGFPE code=FPE_FLTUND_TRAP
0xD0 FPCP operand error
signal=SIGFPE code=FPE_OPRND_TRAP
0xD4 FPCP overflow
signal=SIGFPE code=FPE_FLTOVF_TRAP
0xD8 FPCP signaling NAN
signal=SIGFPE code=FPE_NAN_TRAP
0xDC (unassigned, reserved)
prints stray interrupt message on console
0xE0 PMMU configuration
prints stray interrupt message on console
0xE4 PMMU illegal operation
prints stray interrupt message on console
0xE8 PMMU access level violation
prints stray interrupt message on console
0xEC-0xFC (unassigned, reserved)
prints stray interrupt message on console
0x100-0x3F0 (user defined vectors)
prints stray interrupt message on console
0x3F4 (user defined vector)
used for internal kernel use
0x3F8 (user defined vector)
used for internal kernel use
Printed 4/6/89 7
SIGVEC(2) COMMAND REFERENCE SIGVEC(2)
0x3FC (user defined vector)
used for internal kernel use
DIAGNOSTICS
The sigvec facility fails and no new signal handler is
installed if one of the following occurs:
[EFAULT] Either vec or ovec points to memory which is
not a valid part of the process address space.
[EINVAL] Sig is not a valid signal number.
[EINVAL] An attempt is made to ignore or supply a
handler for SIGKILL or SIGSTOP.
[EINVAL] An attempt is made to ignore SIGCONT (by
default SIGCONT is ignored).
RETURN VALUE
If ovec is non-zero, upon successful completion the previous
handling information is returned in ovec. If ovec is NULL,
upon successful completion a 0 is returned. If an error
occurs, a value of -1 is returned and errno is set to
indicate the error.
SEE ALSO
kill(1), kill(2), ptrace(2), sigblock(2), sigpause(2),
sigsetmask(2), sigstack(2), sigvec(2), setjmp(3c),
setjmp(3f), and tty(4).
Printed 4/6/89 8
%%index%%
na:288,87;
sy:375,914;
de:1289,2414;4063,2952;7375,2782;10517,2775;13652,1342;15354,1496;17210,1474;19044,71;
di:19115,709;
rv:19824,434;
se:20258,411;
%%index%%000000000185