bsd_signal(3p)

1BSD_SIGNAL(3P)             POSIX Programmer's Manual            BSD_SIGNAL(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       bsd_signal - simplified signal facilities
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SYNOPSIS

15       #include <signal.h>
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17       void (*bsd_signal(int sig, void (*func)(int)))(int);
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DESCRIPTION

21       The bsd_signal() function provides a partially compatible interface for
22       programs  written  to  historical  system  interfaces  (see APPLICATION
23       USAGE).
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25       The function call bsd_signal(sig, func) shall be equivalent to the fol‐
26       lowing:
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29              void (*bsd_signal(int sig, void (*func)(int)))(int)
30              {
31                  struct sigaction act, oact;
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34                  act.sa_handler = func;
35                  act.sa_flags = SA_RESTART;
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37                  sigemptyset(&act.sa_mask);
38                  sigaddset(&act.sa_mask, sig);
39                  if (sigaction(sig, &act, &oact) == -1)
40                      return(SIG_ERR);
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42                  return(oact.sa_handler);
43              }
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45       The handler function should be declared:
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48              void handler(int sig);
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50       where  sig is the signal number. The behavior is undefined if func is a
51       function that takes more than one argument, or an argument of a differ‐
52       ent type.
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RETURN VALUE

55       Upon  successful  completion,  bsd_signal()  shall  return the previous
56       action for sig. Otherwise, SIG_ERR shall be returned and errno shall be
57       set to indicate the error.
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ERRORS

60       Refer to sigaction().
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62       The following sections are informative.
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EXAMPLES

65       None.
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APPLICATION USAGE

68       This function is a direct replacement for the BSD signal() function for
69       simple applications that are installing a single-argument  signal  han‐
70       dler function. If a BSD signal handler function is being installed that
71       expects more than one argument, the application has to be  modified  to
72       use  sigaction().  The  bsd_signal()  function differs from signal() in
73       that the SA_RESTART flag is set and  the  SA_RESETHAND  is  clear  when
74       bsd_signal()  is  used.  The  state of these flags is not specified for
75       signal().
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77       It is recommended that new applications use the sigaction() function.
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RATIONALE

80       None.
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FUTURE DIRECTIONS

83       None.
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COPYRIGHT

90       Portions  of  this text are reprinted and reproduced in electronic form
91       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
92       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
93       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
94       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
95       event of any discrepancy between this version and the original IEEE and
96       The  Open Group Standard, the original IEEE and The Open Group Standard
97       is the referee document. The original Standard can be  obtained  online
98       at http://www.opengroup.org/unix/online.html .
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102IEEE/The Open Group                  2003                       BSD_SIGNAL(3P)