1 files changed, 57 insertions, 0 deletions
diff --git a/winch.c b/winch.c
new file mode 100644
index 0000000..be63c52
--- /dev/null
+++ b/winch.c
@@ -0,0 +1,57 @@
+/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <err.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <sysexits.h>
+#include <unistd.h>
+
+static struct {
+    int read;
+    int write;
+} fd;
+
+static void sigwinch() {
+    struct winsize window;
+    int error = ioctl(STDERR_FILENO, TIOCGWINSZ, &window);
+    if (error) err(EX_IOERR, "TIOCGWINSZ");
+
+    ssize_t size = write(fd.write, &window, sizeof(window));
+    if (size < 0) err(EX_IOERR, "write(%d)", fd.write);
+    if ((size_t)size < sizeof(window)) errx(EX_IOERR, "short write(%d)", fd.write);
+}
+
+int winch(void) {
+    int error = pipe((int *)&fd);
+    if (error) err(EX_OSERR, "pipe");
+
+    error = fcntl(fd.read, F_SETFD, FD_CLOEXEC);
+    if (error) err(EX_IOERR, "fcntl");
+
+    error = fcntl(fd.write, F_SETFD, FD_CLOEXEC);
+    if (error) err(EX_IOERR, "fcntl");
+
+    struct sigaction action = {
+        .sa_handler = sigwinch,
+        .sa_flags = SA_RESTART,
+    };
+    error = sigaction(SIGWINCH, &action, NULL);
+    if (error) err(EX_OSERR, "sigaction");
+
+    return fd.read;
+}