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.Dd December 20, 2003 .Dt BSD_SIGNAL 3 .Os .Sh NAME .Nm bsd_signal .Nd simplified signal facilities .Sh SYNOPSIS n signal.h The following is Quite Ugly, but syntactically correct. Don't try to
fix it.
.Ft void \*(lp* .Fn bsd_signal "int sig" "void \*(lp*func\*(rp\*(lpint\*(rp\*(rp\*(rp\*(lpint"
p or in an equivalent but easier to read typedef'd version: .Ft typedef "void \*(lp*sig_t\*(rp \*(lpint\*(rp" ; .Ft sig_t .Fn bsd_signal "int sig" "sig_t func" .Sh DESCRIPTION The .Fn bsd_signal function provides a partially compatible interface for programs written to historical system interfaces (see USAGE below).
p The function call .Fn bsd_signal sig func has the effect as if implemented as: d -literal -offset indent void (*bsd_signal(int sig, void (*func)(int)))(int) { struct sigaction act, oact; act.sa_handler = func; act.sa_flags = SA_RESTART; sigemptyset(&act.sa_mask); sigaddset(&act.sa_mask, sig); if (sigaction(sig, &act, &oact) == -1) return(SIG_ERR); return(oact.sa_handler); } .Ed
p The handler function should be declared:
p .D1 Fn "void func" "int sig"
p where .Fa sig is the signal number. The behavior is undefined if .Fn func is a function that takes more than one argument, or an argument of a different type. .Sh RETURN VALUES Upon successful completion, .Fn bsd_signal returns the previous action for .Fa sig . Otherwise, .Er SIG_ERR is returned and .Va errno is set to indicate the error. .Sh ERRORS Refer to .Xr sigaction 2 . .Sh USAGE This function is a direct replacement for the x .Xr signal(3) function for simple applications that are installing a single-argument signal handler function. If a x signal handler function is being installed that expects more than one argument, the application has to be modified to use .Xr sigaction 2 . The .Fn bsd_signal function differs from .Xr signal 3 in that the .Dv SA_RESTART flag is set and the .Dv SA_RESETHAND will be clear when .Fn bsd_signal is used. The state of these flags is not specified for .Xr signal 3 . .Sh SEE ALSO .Xr sigaction 2 , .Xr sigaddset 3 , .Xr sigemptyset 3 , .Xr signal 3 .Sh STANDARDS The .Fn bsd_signal function conforms to .St -p1003.1-2001 .