From 56f3b63beab96eb4dfd6591f6dff00aa76035e6b Mon Sep 17 00:00:00 2001
From: Michael Kerrisk <mtk.manpages@gmail.com>
Date: Sun, 8 Oct 2017 10:49:36 +0200
Subject: [PATCH] sigaction.2: Rework discussion of SA_SIGINFO handler
 arguments

Expand and rework the text a little, in particular adding
a reference to sigreturn(2) as a source of further
information about the ucontext argument.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
---
 man2/sigaction.2 | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/man2/sigaction.2 b/man2/sigaction.2
index 513a94038..62c158e18 100644
--- a/man2/sigaction.2
+++ b/man2/sigaction.2
@@ -145,17 +145,7 @@ then
 .IR sa_handler )
 specifies the signal-handling function for
 .IR signum .
-This function receives the signal number as its first argument, a
-pointer to a
-.I siginfo_t
-as its second argument and a pointer to a
-.I ucontext_t
-(cast to \fIvoid\ *\fP) as its third argument.
-(Commonly, the handler function doesn't make any use of the third argument.
-See
-.BR getcontext (3)
-for further information about
-.IR ucontext_t .)
+This function receives three arguments, as described below.
 .PP
 .I sa_mask
 specifies a mask of signals which should be blocked
@@ -282,6 +272,31 @@ handler(int sig, siginfo_t *info, void *ucontext)
 .EE
 .in
 .PP
+These three arguments are as follows
+.TP
+.I sig
+The number of the signal that caused invocation of the handler.
+.TP
+.I info
+A pointer to a
+.IR siginfo_t ,
+which is a structure containing further information about the signal,
+as described below.
+.TP
+.I ucontext
+This is a pointer to a
+.I ucontext_t
+structure, cast to \fIvoid\ *\fP.
+The structure pointed to by this field contains
+signal context information that was saved
+on the user-space stack by the kernel; for details, see
+.BR sigreturn (2).
+Further information about the
+.IR ucontext_t
+structure can be found in
+.BR getcontext (3).
+Commonly, the handler function doesn't make any use of the third argument.
+.PP
 The
 .I siginfo_t
 data type is a structure with the following fields: