From 2944f70ee33de24b023ad1edb04246e4b71eef17 Mon Sep 17 00:00:00 2001
From: Vito Caputo <vcaputo@pengaru.com>
Date: Tue, 22 Sep 2020 18:16:38 -0700
Subject: *: initial commit

wye is an input-oriented tee variant

The name is derived from the plumbing name for a
directional tee, or "Y" intersection.
---
 Makefile.am     |  1 +
 README          | 12 ++++++++
 bootstrap       |  3 ++
 configure.ac    | 16 ++++++++++
 src/Makefile.am |  2 ++
 src/wye.c       | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 127 insertions(+)
 create mode 100644 Makefile.am
 create mode 100644 README
 create mode 100755 bootstrap
 create mode 100644 configure.ac
 create mode 100644 src/Makefile.am
 create mode 100644 src/wye.c

diff --git a/Makefile.am b/Makefile.am
new file mode 100644
index 0000000..af437a6
--- /dev/null
+++ b/Makefile.am
@@ -0,0 +1 @@
+SUBDIRS = src
diff --git a/README b/README
new file mode 100644
index 0000000..e57b6c3
--- /dev/null
+++ b/README
@@ -0,0 +1,12 @@
+`wye` is an input variant of the `tee` utility
+
+Usage is like `tee`: wye [FILE]...
+
+wye always consumes from its stdin, the optional files specified are
+read-multiplexed as alternative inputs to stdin.  All reads are
+performed using PIPE_BUF sized buffers which are the atomic units for
+unix pipes, any read data is immediately written to stdout.
+
+Someone should try get this command added upstream in GNU Coreutils
+upstream, and give me credit for the name.  This implementation is a
+quick and dirty hack and not particularly robust.
diff --git a/bootstrap b/bootstrap
new file mode 100755
index 0000000..c5a7472
--- /dev/null
+++ b/bootstrap
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+autoreconf --install
diff --git a/configure.ac b/configure.ac
new file mode 100644
index 0000000..8cdfc3e
--- /dev/null
+++ b/configure.ac
@@ -0,0 +1,16 @@
+AC_INIT([wye], [1.0], [vcaputo@pengaru.com])
+AM_INIT_AUTOMAKE([-Wall -Werror foreign])
+AC_PROG_CC
+AM_PROG_CC_C_O
+AM_PROG_AR
+AC_PROG_RANLIB
+AM_SILENT_RULES([yes])
+
+CFLAGS="$CFLAGS -Wall"
+
+AC_CONFIG_FILES([
+ Makefile
+ src/Makefile
+])
+
+AC_OUTPUT
diff --git a/src/Makefile.am b/src/Makefile.am
new file mode 100644
index 0000000..8490c6e
--- /dev/null
+++ b/src/Makefile.am
@@ -0,0 +1,2 @@
+bin_PROGRAMS = wye
+wye_SOURCES = wye.c
diff --git a/src/wye.c b/src/wye.c
new file mode 100644
index 0000000..17cbc3b
--- /dev/null
+++ b/src/wye.c
@@ -0,0 +1,93 @@
+/*
+ *  Copyright (C) 2020 - Vito Caputo - <vcaputo@pengaru.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 3 as published
+ *  by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int main(int argc, char *argv[])
+{
+	int		n = argc;
+	struct pollfd	*pfds;
+
+	assert(argc >= 1);
+
+	pfds = calloc(n, sizeof(*pfds));
+	if (!pfds) {
+		fprintf(stderr, "Unable to allocate struct pollfd array: %s\n",
+			strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	for (int i = 0; i < n; i++) {
+		if (i > 0) {
+			const char	*path = argv[i];
+
+			pfds[i].fd = open(path, O_RDONLY);
+			if (pfds[i].fd == -1) {
+				fprintf(stderr, "Unable to open \"%s\": %s\n",
+					path, strerror(errno));
+				return EXIT_FAILURE;
+			}
+		}
+		pfds[i].events = POLLIN;
+	}
+
+	while (poll(pfds, n, -1) > 0) {
+		for (int i = 0; i < n; i++) {
+			char	buf[PIPE_BUF];
+			ssize_t	rr, rw;
+
+			if (pfds[i].revents & POLLHUP) {
+				fprintf(stderr, "fd %i hangup, quitting\n",
+					pfds[i].fd);
+				return EXIT_SUCCESS;
+			}
+
+			if (!(pfds[i].revents & POLLIN))
+				continue;
+
+			rr = read(pfds[i].fd, buf, sizeof(buf));
+			if (rr < 0) {
+				fprintf(stderr, "Error reading fd %i: %s\n",
+					pfds[i].fd, strerror(errno));
+				return EXIT_FAILURE;
+			}
+
+			rw = write(1, buf, rr);
+			if (rw < 0) {
+				fprintf(stderr, "Error writing: %s\n",
+					strerror(errno));
+				return EXIT_FAILURE;
+			}
+
+			if (rw != rr) {
+				fprintf(stderr, "Short write\n");
+				return EXIT_FAILURE;
+			}
+		}
+	}
+
+	return EXIT_FAILURE;
+}
-- 
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