Add finger demo to redbean and fix regression

This change fixes a regression in unix.connect() caused by the recent
addition of UNIX domain sockets. The BSD finger command has been added
to third_party for fun and profit. A new demo has been added to redbean
showing how a protocol as simple as finger can be implemented.

third_party/finger/display.c

@@ -0,0 +1,165 @@
+/*
+ * Copyright (c) 1989 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Tony Nardo of the Johns Hopkins University/Applied Physics Lab.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#include "libc/calls/ioctl.h"
+#include "libc/calls/struct/termios.h"
+#include "libc/calls/struct/winsize.h"
+#include "libc/calls/termios.h"
+#include "libc/fmt/fmt.h"
+#include "libc/stdio/stdio.h"
+#include "libc/sysv/consts/fileno.h"
+#include "libc/sysv/consts/termios.h"
+#include "third_party/finger/finger.h"
+// clang-format off
+
+int
+getscreenwidth(void)
+{
+	struct winsize ws;
+	if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0 || ws.ws_col==0) {
+		return 80;
+	}
+	return ws.ws_col;
+}
+
+int
+is8bit(void)
+{
+	static int cache=-1;
+	struct termios tios;
+	if (cache>=0) return cache;
+
+	if (tcgetattr(STDIN_FILENO, &tios)<0) {
+		/* assume 8-bit; it's 1999 now, not 1972 */
+		cache = 1;
+	}
+	else {
+		cache = (tios.c_cflag & CSIZE)==CS8;
+	}
+	return cache;
+}
+
+/************/
+
+static int send_crs=0;
+
+void
+set_crmode(void)
+{
+	send_crs = 1;
+}
+
+static
+void
+fxputc(FILE *f, int ch)
+{
+	/* drop any sign */
+	ch = ch&0xff;
+
+	/* on 7-bit terminals, strip high bit */
+	if (!is8bit()) ch &= 0x7f; 
+
+	/* 
+	 * Assume anything that isn't a control character is printable.
+	 * We can't count on locale stuff to tell us what's printable 
+	 * because we might be looking at someone who uses different
+	 * locale settings or is on the other side of the planet. So,
+	 * strip 0-31, 127, 128-159, and 255. Note that not stripping
+	 * 128-159 is asking for trouble, as 155 (M-esc) is interpreted
+	 * as esc-[ by most terminals. Hopefully this won't break anyone's
+	 * charset.
+	 * 
+	 * It would be nice if we could set the terminal to display in the
+	 * right charset, but we have no way to know what it is. feh.
+	 */
+	
+	if (((ch&0x7f) >= 32 && (ch&0x7f) != 0x7f) || ch=='\t') {
+		putc(ch, f);
+		return;
+	}
+
+	if (ch=='\n') {
+		if (send_crs) putc('\r', f);
+		putc('\n', f);
+		return;
+	}
+
+	if (ch&0x80) {
+		putc('M', f);
+		putc('-', f);
+		ch &= 0x7f;
+	}
+
+	putc('^', f);
+	if (ch==0x7f) putc('?', f);
+	else putc(ch+'@', f);
+}
+
+void
+xputc(int ch)
+{
+	fxputc(stdout, ch);
+}
+
+static void fxputs(FILE *f, const char *buf) {
+	int i;
+	for (i=0; buf[i]; i++) fxputc(f, buf[i]);
+}
+
+int xprintf(const char *fmt, ...) {
+	char buf[1024];
+	va_list ap;
+	
+	va_start(ap, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+	
+	fxputs(stdout, buf);
+	
+	return strlen(buf);
+}
+
+int eprintf(const char *fmt, ...) {
+	char buf[1024];
+	va_list ap;
+	
+	va_start(ap, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+
+	fxputs(stderr, buf);
+	
+	return strlen(buf);
+}