Add sample 'cp' program

Don't rely on this for anything, it's just a test case / demo.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

test/io_uring-cp.c

@@ -0,0 +1,227 @@
+/*
+ * gcc -Wall -O2 -D_GNU_SOURCE -o io_uring-cp io_uring-cp.c -luring
+ */
+#include <stdio.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "../src/liburing.h"
+
+#define QD	64
+#define BS	4096
+
+struct ring {
+	struct io_uring uring;
+	int fd;
+};
+
+static struct ring in_ring;
+static struct ring out_ring;
+static void *bufs[QD];
+
+static int setup_context(unsigned entries, struct ring *r, int offload)
+{
+	struct io_uring_params p;
+	int ring_fd;
+
+	memset(&p, 0, sizeof(p));
+	if (offload)
+		p.flags = IORING_SETUP_SQWQ;
+
+	ring_fd = io_uring_queue_init(entries, &p, NULL, &r->uring);
+	if (ring_fd < 0) {
+		fprintf(stderr, "queue_init: %s\n", strerror(-ring_fd));
+		return -1;
+	}
+
+	r->fd = ring_fd;
+	return 0;
+}
+
+static int get_file_size(int fd, off_t *size)
+{
+	struct stat st;
+
+	if (fstat(fd, &st) < 0)
+		return -1;
+	if (S_ISREG(st.st_mode)) {
+		*size = st.st_size;
+		return 0;
+	}
+
+	return -1;
+}
+
+static unsigned iocb_index(struct io_uring_iocb *iocb)
+{
+	return iocb - in_ring.uring.sq.iocbs;
+}
+
+static int queue_read(int fd, off_t size, off_t offset)
+{
+	struct io_uring_iocb *iocb;
+
+	iocb = io_uring_get_iocb(&in_ring.uring);
+	if (!iocb)
+		return 1;
+
+	iocb->opcode = IORING_OP_READ;
+	iocb->flags = 0;
+	iocb->ioprio = 0;
+	iocb->fd = fd;
+	iocb->off = offset;
+	iocb->addr = bufs[iocb_index(iocb)];
+	iocb->len = size;
+	return 0;
+}
+
+static int complete_writes(unsigned *writes)
+{
+	int ret, nr;
+
+	ret = io_uring_submit(out_ring.fd, &out_ring.uring);
+	if (ret < 0) {
+		fprintf(stderr, "io_uring_submit: %s\n", strerror(-ret));
+		return 1;
+	}
+
+	nr = ret;
+	while (nr) {
+		struct io_uring_event *ev = NULL;
+
+		ret = io_uring_wait_completion(out_ring.fd, &out_ring.uring, &ev);
+		if (ret < 0) {
+			fprintf(stderr, "io_uring_wait_completion: %s\n",
+						strerror(-ret));
+			return 1;
+		}
+		if (ev->res < 0) {
+			fprintf(stderr, "ev failed: %s\n", strerror(-ev->res));
+			return 1;
+		}
+		(*writes)--;
+		nr--;
+	}
+
+	return 0;
+}
+
+static void queue_write(int fd, off_t size, off_t offset, unsigned index)
+{
+	struct io_uring_iocb *iocb;
+
+	iocb = io_uring_get_iocb(&out_ring.uring);
+	iocb->opcode = IORING_OP_WRITE;
+	iocb->flags = 0;
+	iocb->ioprio = 0;
+	iocb->fd = fd;
+	iocb->off = offset;
+	iocb->addr = bufs[index];
+	iocb->len = size;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring_event *ev;
+	off_t read_left, write_left, offset;
+	int i, infd, outfd, ret;
+	unsigned reads, writes;
+
+	if (argc < 3) {
+		printf("%s: infile outfile\n", argv[0]);
+		return 1;
+	}
+
+	infd = open(argv[1], O_RDONLY);
+	if (infd < 0) {
+		perror("open infile");
+		return 1;
+	}
+	outfd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	if (outfd < 0) {
+		perror("open outfile");
+		return 1;
+	}
+
+	for (i = 0; i < QD; i++)
+		if (posix_memalign(&bufs[i], BS, BS))
+			return 1;
+
+	if (setup_context(QD, &in_ring, 1))
+		return 1;
+	if (setup_context(QD, &out_ring, 0))
+		return 1;
+	if (get_file_size(infd, &read_left))
+		return 1;
+
+	offset = 0;
+	writes = reads = 0;
+	write_left = read_left;
+	while (read_left || write_left) {
+		off_t this_size = read_left;
+		struct io_uring_iocb *iocb;
+
+		if (this_size > BS)
+			this_size = BS;
+		else if (!this_size)
+			goto skip_read;
+	
+		/*
+		 * Queue up as many reads as we can
+		 */
+		while (read_left && !queue_read(infd, this_size, offset)) {
+			read_left -= this_size;
+			offset += this_size;
+			reads++;
+		}
+
+skip_read:
+		ret = io_uring_submit(in_ring.fd, &in_ring.uring);
+		if (ret < 0) {
+			fprintf(stderr, "io_uring_submit: %s\n", strerror(-ret));
+			break;
+		}
+
+		/*
+		 * read queue full, get at least one completion and queue up
+		 * a write
+		 */
+		while (reads || write_left) {
+			if (reads)
+				ret = io_uring_wait_completion(in_ring.fd,
+						&in_ring.uring, &ev);
+			else
+				ret = io_uring_get_completion(in_ring.fd,
+						&in_ring.uring, &ev);
+			if (ret < 0) {
+				fprintf(stderr, "io_uring_get_completion: %s\n",
+							strerror(-ret));
+				return 1;
+			}
+			if (!ev)
+				break;
+			reads--;
+			if (ev->res < 0) {
+				fprintf(stderr, "ev failed: %s\n",
+						strerror(-ev->res));
+				return 1;
+			}
+			iocb = io_uring_iocb_from_ev(&in_ring.uring, ev);
+			queue_write(outfd, ev->res, iocb->off, ev->index);
+			write_left -= ev->res;
+			writes++;
+		};
+		if (complete_writes(&writes))
+			break;
+	};
+
+	close(infd);
+	close(outfd);
+	io_uring_queue_exit(in_ring.fd, &in_ring.uring);
+	io_uring_queue_exit(out_ring.fd, &out_ring.uring);
+	return 0;
+}