Sync us up to OpenBSD's cat.1 v1.18 and cat.c v1.9.

This gets rid of a bogus cast of NULL in setbuf().
Lets us know the buffer malloc failed.

Reworks the manpage a bit to make it more mdoc(7) compliant, adds
examples.

2 files changed, 84 insertions, 14 deletions

diff --git a/bin/cat/cat.1 b/bin/cat/cat.1
index a762fb1..740734a 100644
--- a/bin/cat/cat.1
+++ b/bin/cat/cat.1
@@ -37,14 +37,13 @@
 .\"
 .Dd May 2, 1995
 .Dt CAT 1
-.Os BSD 3
+.Os
 .Sh NAME
 .Nm cat
 .Nd concatenate and print files
 .Sh SYNOPSIS
 .Nm cat
 .Op Fl benstuv
-.Op Fl
 .Op Ar
 .Sh DESCRIPTION
 The
@@ -52,8 +51,14 @@ The
 utility reads files sequentially, writing them to the standard output.
 The
 .Ar file
-operands are processed in command line order.
-A single dash represents the standard input.
+operands are processed in command-line order.
+If
+.Ar file
+is a single dash
+.Pq Sq \&-
+or absent,
+.Nm
+reads from the standard input.
 .Pp
 The options are as follows:
 .Bl -tag -width indent
@@ -94,29 +99,94 @@ characters (with the high bit set) are printed as
 .Sh DIAGNOSTICS
 The
 .Nm
-utility exits 0 on success, and >0 if an error occurs.
-.Sh BUGS
-Because of the shell language mechanism used to perform output
-redirection, the command
-.Dq Li cat file1 file2 > file1
-will cause the original data in file1 to be destroyed!
+utility exits 0 on success or >0 if an error occurred.
+.Sh EXAMPLES
+The command:
+.Bd -literal -offset indent
+.Ic cat file1
+.Ed
+.Pp
+will print the contents of
+.Ar file1
+to the standard output.
+.Pp
+The command:
+.Bd -literal -offset indent
+.Ic cat file1 file2 > file3
+.Ed
+.Pp
+will sequentially print the contents of
+.Ar file1
+and
+.Ar file2
+to the file
+.Ar file3 ,
+truncating
+.Ar file3
+if it already exists.
+See the manual page for your shell (i.e.,
+.Xr sh 1 )
+for more information on redirection.
+.Pp
+The command:
+.Bd -literal -offset indent
+.Ic cat file1 - file2 - file3
+.Ed
+.Pp
+will print the contents of
+.Ar file1 ,
+print data it receives from the standard input until it receives an
+.Dv EOF
+.Pq Sq ^D
+character, print the contents of
+.Ar file2 ,
+read and output contents of the standard input again, then finally output
+the contents of
+.Ar file3 .
+Note that if the standard input referred to a file, the second dash
+on the command-line would have no effect, since the entire contents of the file
+would have already been read and printed by
+.Nm
+when it encountered the first
+.Ql \&-
+operand.
 .Sh SEE ALSO
 .Xr head 1 ,
 .Xr more 1 ,
 .Xr pr 1 ,
+.Xr sh 1 ,
 .Xr tail 1 ,
-.Xr vis 1
+.Xr vis 1 ,
+.Xr setbuf 3
 .Rs
 .%A Rob Pike
 .%T "UNIX Style, or cat -v Considered Harmful"
 .%J "USENIX Summer Conference Proceedings"
 .%D 1983
 .Re
+.Sh STANDARDS
+The
+.Nm
+utility is compliant with the
+.St -p1003.2-92
+specification.
+.Pp
+The flags
+.Op Fl benstv
+are extensions to the specification.
 .Sh HISTORY
 A
 .Nm
-command appeared in Version 1 AT&T UNIX.
+utility appeared in
+.At v1 .
 .An Dennis Ritchie
 designed and wrote the first man page.
 It appears to have been
 .Xr cat 1 .
+.Sh BUGS
+Because of the shell language mechanism used to perform output
+redirection, the command
+.Ic cat file1 file2 > file1
+will cause the original data in
+.Ar file1
+to be destroyed!
diff --git a/bin/cat/cat.c b/bin/cat/cat.c
index f88c125..c2f11dd 100644
--- a/bin/cat/cat.c
+++ b/bin/cat/cat.c
@@ -96,7 +96,7 @@ main(argc, argv)
 			tflag = vflag = 1;	/* -t implies -v */
 			break;
 		case 'u':
-			setbuf(stdout, (char *)NULL);
+			setbuf(stdout, NULL);
 			break;
 		case 'v':
 			vflag = 1;
@@ -249,7 +249,7 @@ raw_cat(rfd)
 			err(1, "%s", filename);
 		bsize = MAX(sbuf.st_blksize, 1024);
 		if ((buf = malloc(bsize)) == NULL)
-			err(1, NULL);
+			err(1, "buffer");
 	}
 	while ((nr = read(rfd, buf, bsize)) > 0)
 		for (off = 0; nr; nr -= nw, off += nw)