signal.2: ffix

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/signal.2

@@ -38,9 +38,9 @@
 signal \- ANSI C signal handling
 .SH SYNOPSIS
 .B #include <signal.h>
-.sp
+.PP
 .B typedef void (*sighandler_t)(int);
-.sp
+.PP
 .BI "sighandler_t signal(int " signum ", sighandler_t " handler );
 .SH DESCRIPTION
 The behavior of
@@ -51,7 +51,7 @@ and has also varied historically across different versions of Linux.
 .BR sigaction (2)
 instead.
 See \fIPortability\fP below.
-
+.PP
 .BR signal ()
 sets the disposition of the signal
 .I signum
@@ -61,7 +61,7 @@ which is either
 .BR SIG_IGN ,
 .BR SIG_DFL ,
 or the address of a programmer-defined function (a "signal handler").
-
+.PP
 If the signal
 .I signum
 is delivered to the process, then one of the following happens:
@@ -163,9 +163,9 @@ is defined.
 Without use of such a type, the declaration of
 .BR signal ()
 is the somewhat harder to read:
+.PP
 .in +4n
 .nf
-
 .BI "void ( *" signal "(int " signum ", void (*" handler ")(int)) ) (int);"
 .fi
 .in
@@ -181,13 +181,13 @@ The semantics when using
 to establish a signal handler vary across systems
 (and POSIX.1 explicitly permits this variation);
 .B do not use it for this purpose.
-
+.PP
 POSIX.1 solved the portability mess by specifying
 .BR sigaction (2),
 which provides explicit control of the semantics when a
 signal handler is invoked; use that interface instead of
 .BR signal ().
-
+.PP
 In the original UNIX systems, when a handler that was established using
 .BR signal ()
 was invoked by the delivery of a signal,
@@ -197,16 +197,18 @@ and the system did not block delivery of further instances of the signal.
 This is equivalent to calling
 .BR sigaction (2)
 with the following flags:
-
+.PP
+.EX
     sa.sa_flags = SA_RESETHAND | SA_NODEFER;
-
+.EE
+.PP
 System\ V also provides these semantics for
 .BR signal ().
 This was bad because the signal might be delivered again
 before the handler had a chance to reestablish itself.
 Furthermore, rapid deliveries of the same signal could
 result in recursive invocations of the handler.
-
+.PP
 BSD improved on this situation, but unfortunately also
 changed the semantics of the existing
 .BR signal ()
@@ -221,9 +223,11 @@ restarted if interrupted by a signal handler (see
 The BSD semantics are equivalent to calling
 .BR sigaction (2)
 with the following flags:
-
+.PP
+.EX
     sa.sa_flags = SA_RESTART;
-
+.EE
+.PP
 The situation on Linux is as follows:
 .IP * 2
 The kernel's