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+'\" t
+.\" Copyright (c) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH bsd_signal 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+bsd_signal \- signal handling with BSD semantics
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <signal.h>
+.P
+.B typedef void (*sighandler_t)(int);
+.P
+.BI "sighandler_t bsd_signal(int " signum ", sighandler_t " handler );
+.fi
+.P
+.RS -4
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.RE
+.P
+.BR bsd_signal ():
+.nf
+    Since glibc 2.26:
+        _XOPEN_SOURCE >= 500
+.\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
+            && ! (_POSIX_C_SOURCE >= 200809L)
+    glibc 2.25 and earlier:
+        _XOPEN_SOURCE
+.fi
+.SH DESCRIPTION
+The
+.BR bsd_signal ()
+function takes the same arguments, and performs the same task, as
+.BR signal (2).
+.P
+The difference between the two is that
+.BR bsd_signal ()
+is guaranteed to provide reliable signal semantics, that is:
+a) the disposition of the signal is not reset to the default
+when the handler is invoked;
+b) delivery of further instances of the signal is blocked while
+the signal handler is executing; and
+c) if the handler interrupts a blocking system call,
+then the system call is automatically restarted.
+A portable application cannot rely on
+.BR signal (2)
+to provide these guarantees.
+.SH RETURN VALUE
+The
+.BR bsd_signal ()
+function returns the previous value of the signal handler, or
+.B SIG_ERR
+on error.
+.SH ERRORS
+As for
+.BR signal (2).
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface	Attribute	Value
+T{
+.na
+.nh
+.BR bsd_signal ()
+T}	Thread safety	MT-Safe
+.TE
+.SH VERSIONS
+Use of
+.BR bsd_signal ()
+should be avoided; use
+.BR sigaction (2)
+instead.
+.P
+On modern Linux systems,
+.BR bsd_signal ()
+and
+.BR signal (2)
+are equivalent.
+But on older systems,
+.BR signal (2)
+provided unreliable signal semantics; see
+.BR signal (2)
+for details.
+.P
+The use of
+.I sighandler_t
+is a GNU extension;
+this type is defined only if the
+.B _GNU_SOURCE
+feature test macro is defined.
+.SH STANDARDS
+None.
+.SH HISTORY
+4.2BSD, POSIX.1-2001.
+Removed in POSIX.1-2008,
+recommending the use of
+.BR sigaction (2)
+instead.
+.SH SEE ALSO
+.BR sigaction (2),
+.BR signal (2),
+.BR sysv_signal (3),
+.BR signal (7)