libtf: implement basic file i/o with epoll

some scetching of i/o api, and implement basic read and write
functionality. integrate polling to scheduler and an epoll based
polling mechanism.

1 files changed, 131 insertions, 0 deletions

diff --git a/src/io-unix.c b/src/io-unix.c
new file mode 100644
index 0000000..d333122
--- /dev/null
+++ b/src/io-unix.c
@@ -0,0 +1,131 @@
+/* io-unix.c - non-blocking io primitives for unix
+ *
+ * Copyright (C) 2009 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 or later as
+ * published by the Free Software Foundation.
+ *
+ * See http://www.gnu.org/ for details.
+ */
+
+int tf_open(struct tf_fd *fd, const char *pathname, int flags)
+{
+	int kfd, r;
+
+	kfd = open(pathname, flags | O_CLOEXEC | O_NONBLOCK);
+	if (unlikely(kfd < 0))
+		return -errno;
+
+	r = tf_fd_init(fd, kfd, TF_FD_AUTOCLOSE | TF_FD_STREAM_ORIENTED);
+	if (r < 0) {
+		close(kfd);
+		return r;
+	}
+	return 0;
+}
+
+int tf_open_fd(struct tf_fd *fd, int kfd)
+{
+	int mode, flags = 0;
+
+	mode = fcntl(kfd, F_GETFL, 0);
+	if (!(mode & O_NONBLOCK)) {
+		fcntl(fd->fd, F_SETFL, mode | O_NONBLOCK);
+		flags |= TF_FD_RESTORE_BLOCKING;
+	}
+
+	return tf_fd_init(fd, kfd, TF_FD_STREAM_ORIENTED | flags);
+}
+
+int tf_close(struct tf_fd *fd)
+{
+	int r;
+
+	if (fd->flags & TF_FD_RESTORE_BLOCKING) {
+		fcntl(fd->fd, F_SETFL, fcntl(fd->fd, F_GETFL, 0) & ~O_NONBLOCK);
+	}
+	if (fd->flags & TF_FD_AUTOCLOSE) {
+		r = close(fd->fd);
+		if (unlikely(r == -1))
+			return -errno;
+	}
+	return 0;
+}
+
+int tf_read(struct tf_fd *fd, void *buf, size_t count, tf_mtime_diff_t timeout)
+{
+	ssize_t n;
+	int r, mode;
+
+	mode = tf_schedule_timeout(timeout);
+	tf_fd_wait(fd, EPOLLIN);
+	do {
+		n = read(fd->fd, buf, count);
+		if (n == count) {
+			r = 0;
+			break;
+		}
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			if (errno != EAGAIN) {
+				r = errno;
+				break;
+			}
+		} else if (n == 0) {
+			r = EIO;
+			break;
+		} else {
+			buf += n;
+			count -= n;
+			if (!(fd->flags & TF_FD_STREAM_ORIENTED))
+				continue;
+		}
+
+		r = tf_schedule(mode);
+		if (r != TF_WAKEUP_FD)
+			break;
+	} while (1);
+	tf_fd_release(fd);
+
+	return -r;
+}
+
+int tf_write(struct tf_fd *fd, const void *buf, size_t count,
+	     tf_mtime_diff_t timeout)
+{
+	ssize_t n;
+	int r, mode;
+
+	mode = tf_schedule_timeout(timeout);
+	tf_fd_wait(fd, EPOLLOUT);
+	do {
+		n = write(fd->fd, buf, count);
+		if (n == count) {
+			r = 0;
+			break;
+		}
+		if (n < 0) {
+			if (errno == EINTR)
+				continue;
+			if (errno != EAGAIN) {
+				r = errno;
+				break;
+			}
+		} else {
+			buf += n;
+			count -= n;
+			if (!(fd->flags & TF_FD_STREAM_ORIENTED))
+				continue;
+		}
+
+		r = tf_schedule(mode);
+		if (r != TF_WAKEUP_FD)
+			break;
+	} while (1);
+	tf_fd_release(fd);
+
+	return -r;
+}