projects / apple / libc.git / blame
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1 | .\" Copyright (c) 2002 Apple Computer, Inc. All rights reserved. |
| 2 | .\" | |
| 3 | .\" @APPLE_LICENSE_HEADER_START@ | |
| 4 | .\" | |
| 5 | .\" The contents of this file constitute Original Code as defined in and | |
| 6 | .\" are subject to the Apple Public Source License Version 1.1 (the | |
| 7 | .\" "License"). You may not use this file except in compliance with the | |
| 8 | .\" License. Please obtain a copy of the License at | |
| 9 | .\" http://www.apple.com/publicsource and read it before using this file. | |
| 10 | .\" | |
| 11 | .\" This Original Code and all software distributed under the License are | |
| 12 | .\" distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER | |
| 13 | .\" EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, | |
| 14 | .\" INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 15 | .\" FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the | |
| 16 | .\" License for the specific language governing rights and limitations | |
| 17 | .\" under the License. | |
| 18 | .\" | |
| 19 | .\" @APPLE_LICENSE_HEADER_END@ | |
| 20 | .\" | |
| 21 | .Dd December 20, 2003 | |
| 22 | .Dt BSD_SIGNAL 3 | |
| 23 | .Os | |
| 24 | .Sh NAME | |
| 25 | .Nm bsd_signal | |
| 26 | .Nd simplified signal facilities | |
| 27 | .Sh SYNOPSIS | |
| 28 | .In signal.h | |
| 29 | .\" The following is Quite Ugly, but syntactically correct. Don't try to | |
| 30 | .\" fix it. | |
| 31 | .Ft void \*(lp* | |
| 32 | .Fn bsd_signal "int sig" "void \*(lp*func\*(rp\*(lpint\*(rp\*(rp\*(rp\*(lpint" | |
| 33 | .Pp | |
| 34 | or in an equivalent but easier to read typedef'd version: | |
| 35 | .Ft typedef "void \*(lp*sig_t\*(rp \*(lpint\*(rp" ; | |
| 36 | .Ft sig_t | |
| 37 | .Fn bsd_signal "int sig" "sig_t func" | |
| 38 | .Sh DESCRIPTION | |
| 39 | The | |
| 40 | .Fn bsd_signal | |
| 41 | function provides a partially compatible interface for programs written | |
| 42 | to historical system interfaces (see USAGE below). | |
| 43 | .Pp | |
| 44 | The function call | |
| 45 | .Fn bsd_signal sig func | |
| 46 | has the effect as if implemented as: | |
| 47 | .Bd -literal -offset indent | |
| 48 | void (*bsd_signal(int sig, void (*func)(int)))(int) | |
| 49 | { | |
| 50 | struct sigaction act, oact; | |
| 51 | ||
| 52 | act.sa_handler = func; | |
| 53 | act.sa_flags = SA_RESTART; | |
| 54 | sigemptyset(&act.sa_mask); | |
| 55 | sigaddset(&act.sa_mask, sig); | |
| 56 | if (sigaction(sig, &act, &oact) == -1) | |
| 57 | return(SIG_ERR); | |
| 58 | return(oact.sa_handler); | |
| 59 | } | |
| 60 | .Ed | |
| 61 | .Pp | |
| 62 | The handler function should be declared: | |
| 63 | .Pp | |
| 64 | .D1 Fn "void func" "int sig" | |
| 65 | .Pp | |
| 66 | where | |
| 67 | .Fa sig | |
| 68 | is the signal number. | |
| 69 | The behavior is undefined if | |
| 70 | .Fn func | |
| 71 | is a function that takes more than one argument, or an argument of a | |
| 72 | different type. | |
| 73 | .Sh RETURN VALUES | |
| 74 | Upon successful completion, | |
| 75 | .Fn bsd_signal | |
| 76 | returns the previous action for | |
| 77 | .Fa sig . | |
| 78 | Otherwise, | |
| 79 | .Er SIG_ERR | |
| 80 | is returned and | |
| 81 | .Va errno | |
| 82 | is set to indicate the error. | |
| 83 | .Sh ERRORS | |
| 84 | Refer to | |
| 85 | .Xr sigaction 2 . | |
| 86 | .Sh USAGE | |
| 87 | This function is a direct replacement for the | |
| 88 | .Bx | |
| 89 | .Xr signal(3) | |
| 90 | function for simple applications that are installing a single-argument signal | |
| 91 | handler function. | |
| 92 | If a | |
| 93 | .Bx | |
| 94 | signal handler function is being installed that expects more than one | |
| 95 | argument, the application has to be modified to use | |
| 96 | .Xr sigaction 2 . | |
| 97 | The | |
| 98 | .Fn bsd_signal | |
| 99 | function differs from | |
| 100 | .Xr signal 3 | |
| 101 | in that the | |
| 102 | .Dv SA_RESTART | |
| 103 | flag is set and the | |
| 104 | .Dv SA_RESETHAND | |
| 105 | will be clear when | |
| 106 | .Fn bsd_signal | |
| 107 | is used. | |
| 108 | The state of these flags is not specified for | |
| 109 | .Xr signal 3 . | |
| 110 | .Sh SEE ALSO | |
| 111 | .Xr sigaction 2 , | |
| 112 | .Xr sigaddset 3 , | |
| 113 | .Xr sigemptyset 3 , | |
| 114 | .Xr signal 3 | |
| 115 | .Sh STANDARDS | |
| 116 | The | |
| 117 | .Fn bsd_signal | |
| 118 | function conforms to | |
| 119 | .St -p1003.1-2001 . |