From fcd154280c21746db7d994ed1be77f20f91c90c0 Mon Sep 17 00:00:00 2001
From: David Härdeman <david@hardeman.nu>
Date: Mon, 22 Jun 2020 15:17:36 +0200
Subject: Add basic splice support to server-proxy (untested)

---
 uring.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

(limited to 'uring.c')

diff --git a/uring.c b/uring.c
index 31dfe26..3437d7e 100644
--- a/uring.c
+++ b/uring.c
@@ -1,9 +1,11 @@
+#define _GNU_SOURCE
 #include <liburing.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <string.h>
+#include <unistd.h>
 
 #include "main.h"
 #include "uring.h"
@@ -12,6 +14,10 @@ struct uring_ev {
 	struct io_uring uring;
 	struct io_uring_params uring_params;
 	struct uring_task task;
+
+	/* for testing if the kernel supports splice */
+	int pipe[2];
+	int tfd;
 };
 
 enum cqe_type {
@@ -518,6 +524,22 @@ uring_accept(struct uring_task *task, struct saddr *saddr, utask_cb_t cb)
 	io_uring_sqe_set_data(sqe, task);
 }
 
+void
+uring_splice(struct uring_task *task, int fd_in, int fd_out, utask_cb_t cb)
+{
+	struct io_uring_sqe *sqe;
+	
+	assert_return(task && fd_in >= 0 && fd_out >= 0 && cb);
+
+	debug(DBG_UR, "task %s (%p), fd_in %i, fd_out %i, refcount %u",
+	      task->name, task, fd_in, fd_out, task->refcount);
+
+	sqe = get_sqe(task);
+	task->cb = cb;
+	io_uring_prep_splice(sqe, fd_in, -1, fd_out, -1, 4096, SPLICE_F_MOVE);
+	io_uring_sqe_set_data(sqe, task);
+}
+
 void
 uring_poll(struct uring_task *task, short poll_mask, utask_cb_t cb)
 {
@@ -592,6 +614,30 @@ uring_delete()
 	uring_task_put(task);
 }
 
+static void
+uring_splice_test_cb(struct uring_task *task, int res)
+{
+	struct uring_ev *uring = container_of(task, struct uring_ev, task);
+
+	assert_die(task && uring == cfg->uring, "splice test failed");
+
+	uring_close(task, uring->tfd);
+	uring_close(task, uring->pipe[PIPE_RD]);
+	uring_close(task, uring->pipe[PIPE_WR]);
+
+	uring->tfd = -1;
+	uring->pipe[PIPE_RD] = -1;
+	uring->pipe[PIPE_WR] = -1;
+
+	if (res >= 0) {
+		cfg->splice_supported = true;
+		debug(DBG_UR, "splice supported");
+	} else if (res == -EINVAL)
+		debug(DBG_UR, "splice not supported");
+	else 
+		error("splice check failed: %i\n", res);
+}
+
 void
 uring_init()
 {
@@ -611,6 +657,15 @@ uring_init()
 
 	uring_task_init(&uring->task, "io_uring", &cfg->task, uring_free);
 	cfg->uring = uring;
+
+	/* splice check, a bit convoluted, but seems to be no simpler way */
+	cfg->splice_supported = false;
+	if (pipe2(uring->pipe, O_CLOEXEC) < 0)
+		die("pipe2: %m");
+	uring->tfd = open("/dev/null", O_RDONLY | O_CLOEXEC | O_NOCTTY);
+	if (uring->tfd < 0)
+		die("open(\"/dev/null\"): %m");
+	uring_splice(&uring->task, uring->tfd, uring->pipe[PIPE_WR], uring_splice_test_cb);
 }
 
 static inline void
-- 
cgit v1.2.3