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 5/12/88 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 5/12/88 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 5/12/88 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 5/12/88 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 5/12/88 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 5/12/88 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 5/12/88 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 5/12/88 8
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