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Re: [Minios-devel] [UNIKRAFT PATCH v2 2/3] lib/devfs: Add /dev/null and /dev/zero support
On 17.12.19 08:43, Costin Lupu wrote:
This is shamelessly copied and adapted from our implementation
for /dev/random device support.
Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
---
lib/devfs/Config.uk | 17 ++++
lib/devfs/Makefile.uk | 2 +
lib/devfs/null.c | 145 ++++++++++++++++++++++++++++++
lib/vfscore/include/vfscore/uio.h | 1 +
4 files changed, 165 insertions(+)
create mode 100644 lib/devfs/null.c
diff --git a/lib/devfs/Config.uk b/lib/devfs/Config.uk
index 6f21c01c..0f459c4e 100644
--- a/lib/devfs/Config.uk
+++ b/lib/devfs/Config.uk
@@ -8,4 +8,21 @@ if LIBDEVFS
bool "Mount /dev during boot"
depends on LIBVFSCORE_AUTOMOUNT_ROOTFS
default n
+
+ # hidden
+ config LIBDEVFS_DEV_NULL_ZERO
+ bool
+ default n
+
+ config LIBDEVFS_DEV_NULL
+ bool "/dev/null"
Calling it "/dev/null" may be misleading when the automount option is
not enabled. I would call it "Register null device" and the other
"Register zero device" - this would be inline with ukswrand.
+ default y if LIBDEVFS_AUTOMOUNT
+ select LIBDEVFS_DEV_NULL_ZERO
+ default n
+
+ config LIBDEVFS_DEV_ZERO
+ bool "/dev/zero"
+ default y if LIBDEVFS_AUTOMOUNT
+ select LIBDEVFS_DEV_NULL_ZERO
+ default n
endif
diff --git a/lib/devfs/Makefile.uk b/lib/devfs/Makefile.uk
index c496fd56..2cffefab 100644
--- a/lib/devfs/Makefile.uk
+++ b/lib/devfs/Makefile.uk
@@ -3,6 +3,8 @@ $(eval $(call addlib_s,libdevfs,$(CONFIG_LIBDEVFS)))
CINCLUDES-y += -I$(LIBDEVFS_BASE)/include
LIBDEVFS_CFLAGS-$(call gcc_version_ge,8,0) += -Wno-cast-function-type
+LIBDEVFS_CFLAGS-y += -Wno-unused-parameter
Can you use the __unused macro in your code instead? In the base repo,
we shouldn't suppress warnings if not necessary (the previous
`-Wno-cast-function-type` is required because of the VFS operations).
Other from these two comments, the patch seems to be fine.
LIBDEVFS_SRCS-y += $(LIBDEVFS_BASE)/device.c
LIBDEVFS_SRCS-y += $(LIBDEVFS_BASE)/devfs_vnops.c
+LIBDEVFS_SRCS-$(CONFIG_LIBDEVFS_DEV_NULL_ZERO) += $(LIBDEVFS_BASE)/null.c
diff --git a/lib/devfs/null.c b/lib/devfs/null.c
new file mode 100644
index 00000000..f08c27d2
--- /dev/null
+++ b/lib/devfs/null.c
@@ -0,0 +1,145 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Authors: Costin Lupu <costin.lupu@xxxxxxxxx>
+ *
+ * Copyright (c) 2019, University Politehnica of Bucharest. All rights
reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holder nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * THIS HEADER MAY NOT BE EXTRACTED OR MODIFIED IN ANY WAY.
+ */
+
+#include <uk/config.h>
+#include <stdlib.h>
+#include <string.h>
+#include <uk/ctors.h>
+#include <uk/print.h>
+#include <vfscore/uio.h>
+#include <devfs/device.h>
+
+
+int dev_null_write(struct device *dev, struct uio *uio, int flags)
+{
+ uio->uio_resid = 0;
+ return 0;
+}
+
+int dev_null_open(struct device *device, int mode)
+{
+ return 0;
+}
+
+
+int dev_null_close(struct device *device)
+{
+ return 0;
+}
+
+#ifdef CONFIG_LIBDEVFS_DEV_NULL
+
+#define DEV_NULL_NAME "null"
+
+int dev_null_read(struct device *dev, struct uio *uio, int flags)
+{
+ uio->uio_resid = uio->uio_iov->iov_len;
+ return 0;
+}
+
+static struct devops null_devops = {
+ .read = dev_null_read,
+ .write = dev_null_write,
+ .open = dev_null_open,
+ .close = dev_null_close,
+};
+
+static struct driver drv_null = {
+ .devops = &null_devops,
+ .devsz = 0,
+ .name = DEV_NULL_NAME
+};
+#endif
+
+#ifdef CONFIG_LIBDEVFS_DEV_ZERO
+
+#define DEV_ZERO_NAME "zero"
+
+int dev_zero_read(struct device *dev, struct uio *uio, int flags)
+{
+ size_t count;
+ char *buf;
+
+ buf = uio->uio_iov->iov_base;
+ count = uio->uio_iov->iov_len;
+
+ memset(buf, 0, count);
+ uio->uio_resid = 0;
+ return 0;
+}
+
+static struct devops zero_devops = {
+ .read = dev_zero_read,
+ .write = dev_null_write,
+ .open = dev_null_open,
+ .close = dev_null_close,
+};
+
+static struct driver drv_zero = {
+ .devops = &zero_devops,
+ .devsz = 0,
+ .name = DEV_ZERO_NAME
+};
+#endif
+
+static int devfs_register_null(void)
+{
+ struct device *dev;
+
+#ifdef CONFIG_LIBDEVFS_DEV_NULL
+ uk_pr_debug("Register '%s' to devfs\n", DEV_NULL_NAME);
+
+ /* register /dev/null */
+ dev = device_create(&drv_null, DEV_NULL_NAME, D_CHR);
+ if (dev == NULL) {
+ uk_pr_err("Failed to register '%s' to devfs\n", DEV_NULL_NAME);
+ return -1;
+ }
+#endif
+
+#ifdef CONFIG_LIBDEVFS_DEV_ZERO
+ uk_pr_debug("Register '%s' to devfs\n", DEV_ZERO_NAME);
+
+ /* register /dev/zero */
+ dev = device_create(&drv_zero, DEV_ZERO_NAME, D_CHR);
+ if (dev == NULL) {
+ uk_pr_err("Failed to register '%s' to devfs\n", DEV_ZERO_NAME);
+ return -1;
+ }
+#endif
+
+ return 0;
+}
+
+devfs_initcall(devfs_register_null);
diff --git a/lib/vfscore/include/vfscore/uio.h
b/lib/vfscore/include/vfscore/uio.h
index 83dd5b9a..b14fdb82 100644
--- a/lib/vfscore/include/vfscore/uio.h
+++ b/lib/vfscore/include/vfscore/uio.h
@@ -36,6 +36,7 @@
#include <sys/types.h>
#include <sys/uio.h>
#include <limits.h>
+#include <uk/assert.h>
enum uio_rw { UIO_READ, UIO_WRITE };
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