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Annotation of 43BSDReno/lib/libc/gen/signal.3, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1980 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)signal.3    6.5 (Berkeley) 7/1/90
        !             6: .\"
        !             7: .TH SIGNAL 3C "July 1, 1990"
        !             8: .UC 4
        !             9: .ie t .ds d \(dg
        !            10: .el .ds d \z'|+'
        !            11: .ie t .ds b \(bu
        !            12: .el .ds b @
        !            13: .SH NAME
        !            14: signal \- simplified software signal facilities
        !            15: .SH SYNOPSIS
        !            16: .nf
        !            17: .B #include <signal.h>
        !            18: .PP
        !            19: .B void (*signal(sig, func))()
        !            20: .B void (*func)();
        !            21: .fi
        !            22: .SH DESCRIPTION
        !            23: .I Signal
        !            24: is a simplified interface to the more general
        !            25: .IR sigaction (2)
        !            26: facility.
        !            27: .PP
        !            28: A signal
        !            29: is generated by some abnormal event,
        !            30: initiated by a user at a terminal (quit, interrupt, stop),
        !            31: by a program error (bus error, etc.),
        !            32: by request of another program (kill),
        !            33: or when a process is stopped because it wishes to access
        !            34: its control terminal while in the background (see
        !            35: .IR tty (4)).
        !            36: Signals are optionally generated
        !            37: when a process resumes after being stopped,
        !            38: when the status of child processes changes,
        !            39: or when input is ready at the control terminal.
        !            40: Most signals cause termination of the receiving process if no action
        !            41: is taken; some signals instead cause the process receiving them
        !            42: to be stopped, or are simply discarded if the process has not
        !            43: requested otherwise.
        !            44: Except for the SIGKILL and SIGSTOP
        !            45: signals, the
        !            46: .I signal
        !            47: call allows signals either to be ignored
        !            48: or to cause an interrupt to a specified location.
        !            49: The following is a list of all signals with
        !            50: names as in the include file
        !            51: .RI < signal.h >:
        !            52: .LP
        !            53: .nf
        !            54: .ta \w'SIGVTALRM 'u +\w'15*  'u
        !            55: SIGHUP 1       hangup
        !            56: SIGINT 2       interrupt
        !            57: SIGQUIT        3*      quit
        !            58: SIGILL 4*      illegal instruction
        !            59: SIGTRAP        5*      trace trap
        !            60: SIGABRT        6*      \fIabort\fP() call (formerly SIGIOT)
        !            61: SIGEMT 7*      EMT instruction
        !            62: SIGFPE 8*      floating point exception
        !            63: SIGKILL        9       kill (cannot be caught or ignored)
        !            64: SIGBUS 10*     bus error
        !            65: SIGSEGV        11*     segmentation violation
        !            66: SIGSYS 12*     bad argument to system call
        !            67: SIGPIPE        13      write on a pipe with no one to read it
        !            68: SIGALRM        14      alarm clock
        !            69: SIGTERM        15      software termination signal
        !            70: SIGURG 16\*b   urgent condition present on socket
        !            71: SIGSTOP        17\*d   stop (cannot be caught or ignored)
        !            72: SIGTSTP        18\*d   stop signal generated from keyboard
        !            73: SIGCONT        19\*b   continue after stop
        !            74: SIGCHLD        20\*b   child status has changed
        !            75: SIGTTIN        21\*d   background read attempted from control terminal
        !            76: SIGTTOU        22\*d   background write attempted to control terminal
        !            77: SIGIO  23\*b   i/o is possible on a descriptor (see \fIfcntl\fP(2))
        !            78: SIGXCPU        24      cpu time limit exceeded (see \fIsetrlimit\fP(2))
        !            79: SIGXFSZ        25      file size limit exceeded (see \fIsetrlimit\fP(2))
        !            80: SIGVTALRM      26      virtual time alarm (see \fIsetitimer\fP(2))
        !            81: SIGPROF        27      profiling timer alarm (see \fIsetitimer\fP(2))
        !            82: SIGWINCH       28\*b   Window size change
        !            83: SIGINFO        29\*b   status request from keyboard
        !            84: SIGUSR1        30      User defined signal 1
        !            85: SIGUSR2        31      User defined signal 2
        !            86: .fi
        !            87: .PP
        !            88: The starred signals in the list above cause a core image
        !            89: if not caught or ignored.
        !            90: .PP
        !            91: If
        !            92: .I func
        !            93: is SIG_DFL, the default action
        !            94: for signal
        !            95: .I sig
        !            96: is reinstated; this default is termination
        !            97: (with a core image for starred signals)
        !            98: except for signals marked with \*b or \*d.
        !            99: Signals marked with \*b are discarded if the action
        !           100: is SIG_DFL; signals marked
        !           101: with \*d cause the process to stop.
        !           102: If
        !           103: .I func
        !           104: is SIG_IGN the signal is subsequently ignored
        !           105: and pending instances of the signal are discarded.
        !           106: Otherwise, when the signal occurs
        !           107: further occurrences of the signal are
        !           108: automatically blocked and
        !           109: .I func
        !           110: is called.
        !           111: .PP
        !           112: A return from the function unblocks
        !           113: the handled signal and
        !           114: continues the process at the point it was interrupted.
        !           115: \fBUnlike previous signal facilities, the handler \fIfunc\fP
        !           116: remains installed after a signal has been delivered.\fP
        !           117: .PP
        !           118: If a caught signal occurs
        !           119: during certain system calls, causing
        !           120: the call to terminate prematurely, the call
        !           121: is automatically restarted
        !           122: (the handler is installed using the SA_RESTART flag with
        !           123: .IR sigaction (2)).
        !           124: The affected system calls include
        !           125: .IR read (2),
        !           126: .IR write (2),
        !           127: .IR sendto (2),
        !           128: .IR recvfrom (2),
        !           129: .IR sendmsg (2)
        !           130: and
        !           131: .IR recvmsg (2)
        !           132: on a communications channel or a slow device (such as a terminal,
        !           133: but not a regular file)
        !           134: and during a
        !           135: .IR wait (2)
        !           136: or
        !           137: .IR ioctl (2).
        !           138: However, calls that have already committed are not restarted,
        !           139: but instead return a partial success (for example, a short read count).
        !           140: .PP
        !           141: The value of
        !           142: .I signal
        !           143: is the previous (or initial)
        !           144: value of
        !           145: .I func
        !           146: for the particular signal.
        !           147: .PP
        !           148: After a
        !           149: .IR fork (2)
        !           150: or
        !           151: .IR vfork (2)
        !           152: the child inherits
        !           153: all signals.
        !           154: .IR  Execve (2)
        !           155: resets all caught signals to the default action;
        !           156: ignored signals remain ignored.
        !           157: .SH "RETURN VALUE
        !           158: The previous action is returned on a successful call.
        !           159: Otherwise, \-1 is returned and 
        !           160: .I errno
        !           161: is set to indicate the error.
        !           162: .SH ERRORS
        !           163: .I Signal
        !           164: will fail and no action will take place if one of the
        !           165: following occur:
        !           166: .TP 15
        !           167: [EINVAL]
        !           168: .I Sig
        !           169: is not a valid signal number.
        !           170: .TP 15
        !           171: [EINVAL]
        !           172: An attempt is made to ignore or supply a handler for SIGKILL
        !           173: or SIGSTOP.
        !           174: .SH "SEE ALSO"
        !           175: kill(1), ptrace(2), kill(2),
        !           176: sigaction(2), sigprocmask(2), sigsuspend(2),
        !           177: sigstack(2), setjmp(3), tty(4)
        !           178: .SH "NOTES  (VAX-11)"
        !           179: The handler routine can be declared:
        !           180: .PP
        !           181:     void handler(sig, code, scp)
        !           182: .PP
        !           183: Here
        !           184: .I sig
        !           185: is the signal number, into which the hardware faults and traps are
        !           186: mapped as defined below.  Code is a parameter which is either a constant
        !           187: as given below or, for compatibility mode faults, the code provided by
        !           188: the hardware. 
        !           189: .I Scp
        !           190: is a pointer to the
        !           191: .I "struct sigcontext"
        !           192: used by the system to restore the process context from before
        !           193: the signal.
        !           194: Compatibility mode faults are distinguished from the
        !           195: other SIGILL traps by having PSL_CM set in the psl.
        !           196: .PP
        !           197: The following defines the mapping of hardware traps to signals
        !           198: and codes.  All of these symbols are defined in
        !           199: .RI < signal.h >:
        !           200: .LP
        !           201: .ta \w'     Floating/decimal divide by zero   'u +\w'15*  'u +8n
        !           202: .nf
        !           203:    Hardware condition  Signal  Code
        !           204: 
        !           205: Arithmetic traps:
        !           206:    Integer overflow    SIGFPE  FPE_INTOVF_TRAP
        !           207:    Integer division by zero    SIGFPE  FPE_INTDIV_TRAP
        !           208:    Floating overflow trap      SIGFPE  FPE_FLTOVF_TRAP
        !           209:    Floating/decimal division by zero   SIGFPE  FPE_FLTDIV_TRAP
        !           210:    Floating underflow trap     SIGFPE  FPE_FLTUND_TRAP
        !           211:    Decimal overflow trap       SIGFPE  FPE_DECOVF_TRAP
        !           212:    Subscript-range     SIGFPE  FPE_SUBRNG_TRAP
        !           213:    Floating overflow fault     SIGFPE  FPE_FLTOVF_FAULT
        !           214:    Floating divide by zero fault       SIGFPE  FPE_FLTDIV_FAULT
        !           215:    Floating underflow fault    SIGFPE  FPE_FLTUND_FAULT
        !           216: Length access control  SIGSEGV
        !           217: Protection violation   SIGBUS
        !           218: Reserved instruction   SIGILL  ILL_RESAD_FAULT
        !           219: Customer-reserved instr.       SIGEMT
        !           220: Reserved operand       SIGILL  ILL_PRIVIN_FAULT
        !           221: Reserved addressing    SIGILL  ILL_RESOP_FAULT
        !           222: Trace pending  SIGTRAP
        !           223: Bpt instruction        SIGTRAP
        !           224: Compatibility-mode     SIGILL  hardware supplied code
        !           225: Chme   SIGSEGV
        !           226: Chms   SIGSEGV
        !           227: Chmu   SIGSEGV
        !           228: .fi

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