Renamed cuses example and added test program

An earlier version of the fioclient.c example was intended to be
used together with cusexmp.c. The former has since evolved into
ioctl_client.c and no longer has the function necessary to test
CUSE. Therefore, we've added a new cuse_client.c that is clearly
associated with the cuse.c example file system.

1 files changed, 322 insertions, 0 deletions

diff --git a/example/cuse.c b/example/cuse.c
new file mode 100644
index 0000000..443d308
--- /dev/null
+++ b/example/cuse.c
@@ -0,0 +1,322 @@
+/*
+  CUSE example: Character device in Userspace
+  Copyright (C) 2008-2009  SUSE Linux Products GmbH
+  Copyright (C) 2008-2009  Tejun Heo <tj@kernel.org>
+
+  This program can be distributed under the terms of the GNU GPL.
+  See the file COPYING.
+
+*/
+
+/** @file
+ * @tableofcontents
+ *
+ * This example demonstrates how to implement a character device in
+ * userspace ("CUSE"). This is only allowed for root. The character
+ * device should appear in /dev under the specified name. It can be
+ * tested with the cuse_client.c program.
+ *
+ * Mount the file system with:
+ *
+ *     cuse -f --name=mydevice
+ *
+ * You should now have a new /dev/mydevice character device. To "unmount" it,
+ * kill the "cuse" process.
+ *
+ * \section section_compile compiling this example
+ *
+ *     gcc -Wall cuse.c `pkg-config fuse3 --cflags --libs` -o cuse
+ *
+ * \section section_source the complete source
+ * \include cuse.c
+ */
+
+
+#define FUSE_USE_VERSION 30
+
+#include <config.h>
+
+#include <cuse_lowlevel.h>
+#include <fuse_opt.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include "ioctl.h"
+
+static void *cusexmp_buf;
+static size_t cusexmp_size;
+
+static const char *usage =
+"usage: cusexmp [options]\n"
+"\n"
+"options:\n"
+"    --help|-h             print this help message\n"
+"    --maj=MAJ|-M MAJ      device major number\n"
+"    --min=MIN|-m MIN      device minor number\n"
+"    --name=NAME|-n NAME   device name (mandatory)\n"
+"    -d   -o debug         enable debug output (implies -f)\n"
+"    -f                    foreground operation\n"
+"    -s                    disable multi-threaded operation\n"
+"\n";
+
+static int cusexmp_resize(size_t new_size)
+{
+	void *new_buf;
+
+	if (new_size == cusexmp_size)
+		return 0;
+
+	new_buf = realloc(cusexmp_buf, new_size);
+	if (!new_buf && new_size)
+		return -ENOMEM;
+
+	if (new_size > cusexmp_size)
+		memset(new_buf + cusexmp_size, 0, new_size - cusexmp_size);
+
+	cusexmp_buf = new_buf;
+	cusexmp_size = new_size;
+
+	return 0;
+}
+
+static int cusexmp_expand(size_t new_size)
+{
+	if (new_size > cusexmp_size)
+		return cusexmp_resize(new_size);
+	return 0;
+}
+
+static void cusexmp_open(fuse_req_t req, struct fuse_file_info *fi)
+{
+	fuse_reply_open(req, fi);
+}
+
+static void cusexmp_read(fuse_req_t req, size_t size, off_t off,
+			 struct fuse_file_info *fi)
+{
+	(void)fi;
+
+	if (off >= cusexmp_size)
+		off = cusexmp_size;
+	if (size > cusexmp_size - off)
+		size = cusexmp_size - off;
+
+	fuse_reply_buf(req, cusexmp_buf + off, size);
+}
+
+static void cusexmp_write(fuse_req_t req, const char *buf, size_t size,
+			  off_t off, struct fuse_file_info *fi)
+{
+	(void)fi;
+
+	if (cusexmp_expand(off + size)) {
+		fuse_reply_err(req, ENOMEM);
+		return;
+	}
+
+	memcpy(cusexmp_buf + off, buf, size);
+	fuse_reply_write(req, size);
+}
+
+static void fioc_do_rw(fuse_req_t req, void *addr, const void *in_buf,
+		       size_t in_bufsz, size_t out_bufsz, int is_read)
+{
+	const struct fioc_rw_arg *arg;
+	struct iovec in_iov[2], out_iov[3], iov[3];
+	size_t cur_size;
+
+	/* read in arg */
+	in_iov[0].iov_base = addr;
+	in_iov[0].iov_len = sizeof(*arg);
+	if (!in_bufsz) {
+		fuse_reply_ioctl_retry(req, in_iov, 1, NULL, 0);
+		return;
+	}
+	arg = in_buf;
+	in_buf += sizeof(*arg);
+	in_bufsz -= sizeof(*arg);
+
+	/* prepare size outputs */
+	out_iov[0].iov_base =
+		addr + (unsigned long)&(((struct fioc_rw_arg *)0)->prev_size);
+	out_iov[0].iov_len = sizeof(arg->prev_size);
+
+	out_iov[1].iov_base =
+		addr + (unsigned long)&(((struct fioc_rw_arg *)0)->new_size);
+	out_iov[1].iov_len = sizeof(arg->new_size);
+
+	/* prepare client buf */
+	if (is_read) {
+		out_iov[2].iov_base = arg->buf;
+		out_iov[2].iov_len = arg->size;
+		if (!out_bufsz) {
+			fuse_reply_ioctl_retry(req, in_iov, 1, out_iov, 3);
+			return;
+		}
+	} else {
+		in_iov[1].iov_base = arg->buf;
+		in_iov[1].iov_len = arg->size;
+		if (arg->size && !in_bufsz) {
+			fuse_reply_ioctl_retry(req, in_iov, 2, out_iov, 2);
+			return;
+		}
+	}
+
+	/* we're all set */
+	cur_size = cusexmp_size;
+	iov[0].iov_base = &cur_size;
+	iov[0].iov_len = sizeof(cur_size);
+
+	iov[1].iov_base = &cusexmp_size;
+	iov[1].iov_len = sizeof(cusexmp_size);
+
+	if (is_read) {
+		size_t off = arg->offset;
+		size_t size = arg->size;
+
+		if (off >= cusexmp_size)
+			off = cusexmp_size;
+		if (size > cusexmp_size - off)
+			size = cusexmp_size - off;
+
+		iov[2].iov_base = cusexmp_buf + off;
+		iov[2].iov_len = size;
+		fuse_reply_ioctl_iov(req, size, iov, 3);
+	} else {
+		if (cusexmp_expand(arg->offset + in_bufsz)) {
+			fuse_reply_err(req, ENOMEM);
+			return;
+		}
+
+		memcpy(cusexmp_buf + arg->offset, in_buf, in_bufsz);
+		fuse_reply_ioctl_iov(req, in_bufsz, iov, 2);
+	}
+}
+
+static void cusexmp_ioctl(fuse_req_t req, int cmd, void *arg,
+			  struct fuse_file_info *fi, unsigned flags,
+			  const void *in_buf, size_t in_bufsz, size_t out_bufsz)
+{
+	int is_read = 0;
+
+	(void)fi;
+
+	if (flags & FUSE_IOCTL_COMPAT) {
+		fuse_reply_err(req, ENOSYS);
+		return;
+	}
+
+	switch (cmd) {
+	case FIOC_GET_SIZE:
+		if (!out_bufsz) {
+			struct iovec iov = { arg, sizeof(size_t) };
+
+			fuse_reply_ioctl_retry(req, NULL, 0, &iov, 1);
+		} else
+			fuse_reply_ioctl(req, 0, &cusexmp_size,
+					 sizeof(cusexmp_size));
+		break;
+
+	case FIOC_SET_SIZE:
+		if (!in_bufsz) {
+			struct iovec iov = { arg, sizeof(size_t) };
+
+			fuse_reply_ioctl_retry(req, &iov, 1, NULL, 0);
+		} else {
+			cusexmp_resize(*(size_t *)in_buf);
+			fuse_reply_ioctl(req, 0, NULL, 0);
+		}
+		break;
+
+	case FIOC_READ:
+		is_read = 1;
+	case FIOC_WRITE:
+		fioc_do_rw(req, arg, in_buf, in_bufsz, out_bufsz, is_read);
+		break;
+
+	default:
+		fuse_reply_err(req, EINVAL);
+	}
+}
+
+struct cusexmp_param {
+	unsigned		major;
+	unsigned		minor;
+	char			*dev_name;
+	int			is_help;
+};
+
+#define CUSEXMP_OPT(t, p) { t, offsetof(struct cusexmp_param, p), 1 }
+
+static const struct fuse_opt cusexmp_opts[] = {
+	CUSEXMP_OPT("-M %u",		major),
+	CUSEXMP_OPT("--maj=%u",		major),
+	CUSEXMP_OPT("-m %u",		minor),
+	CUSEXMP_OPT("--min=%u",		minor),
+	CUSEXMP_OPT("-n %s",		dev_name),
+	CUSEXMP_OPT("--name=%s",	dev_name),
+	FUSE_OPT_KEY("-h",		0),
+	FUSE_OPT_KEY("--help",		0),
+	FUSE_OPT_END
+};
+
+static int cusexmp_process_arg(void *data, const char *arg, int key,
+			       struct fuse_args *outargs)
+{
+	struct cusexmp_param *param = data;
+
+	(void)outargs;
+	(void)arg;
+
+	switch (key) {
+	case 0:
+		param->is_help = 1;
+		fprintf(stderr, "%s", usage);
+		return fuse_opt_add_arg(outargs, "-ho");
+	default:
+		return 1;
+	}
+}
+
+static const struct cuse_lowlevel_ops cusexmp_clop = {
+	.open		= cusexmp_open,
+	.read		= cusexmp_read,
+	.write		= cusexmp_write,
+	.ioctl		= cusexmp_ioctl,
+};
+
+int main(int argc, char **argv)
+{
+	struct fuse_args args = FUSE_ARGS_INIT(argc, argv);
+	struct cusexmp_param param = { 0, 0, NULL, 0 };
+	char dev_name[128] = "DEVNAME=";
+	const char *dev_info_argv[] = { dev_name };
+	struct cuse_info ci;
+
+	if (fuse_opt_parse(&args, &param, cusexmp_opts, cusexmp_process_arg)) {
+		printf("failed to parse option\n");
+		return 1;
+	}
+
+	if (!param.is_help) {
+		if (!param.dev_name) {
+			fprintf(stderr, "Error: device name missing\n");
+			return 1;
+		}
+		strncat(dev_name, param.dev_name, sizeof(dev_name) - 9);
+	}
+
+	memset(&ci, 0, sizeof(ci));
+	ci.dev_major = param.major;
+	ci.dev_minor = param.minor;
+	ci.dev_info_argc = 1;
+	ci.dev_info_argv = dev_info_argv;
+	ci.flags = CUSE_UNRESTRICTED_IOCTL;
+
+	return cuse_lowlevel_main(args.argc, args.argv, &ci, &cusexmp_clop,
+				  NULL);
+}