Add /dev/full device

kernel/src/device/full.rs

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::{
+    events::IoEvents,
+    fs::{
+        device::{Device, DeviceId, DeviceType},
+        inode_handle::FileIo,
+    },
+    prelude::*,
+    process::signal::{PollHandle, Pollable},
+};
+
+pub struct Full;
+
+impl Device for Full {
+    fn type_(&self) -> DeviceType {
+        DeviceType::Char
+    }
+
+    fn id(&self) -> DeviceId {
+        // Same value with Linux
+        DeviceId::new(1, 7)
+    }
+
+    fn open(&self) -> Result<Option<Arc<dyn FileIo>>> {
+        Ok(Some(Arc::new(Full)))
+    }
+}
+
+impl Pollable for Full {
+    fn poll(&self, mask: IoEvents, _poller: Option<&mut PollHandle>) -> IoEvents {
+        let events = IoEvents::IN | IoEvents::OUT;
+        events & mask
+    }
+}
+
+impl FileIo for Full {
+    fn read(&self, writer: &mut VmWriter) -> Result<usize> {
+        let len = writer.avail();
+        writer.fill_zeros(len)?;
+        Ok(len)
+    }
+
+    fn write(&self, _reader: &mut VmReader) -> Result<usize> {
+        return_errno_with_message!(Errno::ENOSPC, "no space left on /dev/full")
+    }
+}

kernel/src/device/mod.rs

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: MPL-2.0
 
+mod full;
 mod null;
 mod pty;
 mod random;
@@ -56,6 +57,9 @@ pub fn init_in_first_process(ctx: &Context) -> Result<()> {
     let urandom = Arc::new(urandom::Urandom);
     add_node(urandom, "urandom", &fs_resolver)?;
 
+    let full = Arc::new(full::Full);
+    add_node(full, "full", &fs_resolver)?;
+
     pty::init_in_first_process(&fs_resolver)?;
 
     shm::init_in_first_process(&fs_resolver)?;

test/src/apps/Makefile

@@ -17,6 +17,7 @@ TEST_APPS := \
 	capability \
 	clone3 \
 	cpu_affinity \
+	devfs \
 	epoll \
 	eventfd2 \
 	execve \

test/src/apps/devfs/Makefile

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: MPL-2.0
+
+include ../test_common.mk
+
+EXTRA_C_FLAGS :=

test/src/apps/devfs/full.c

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: MPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <sys/poll.h>
+#include "../test.h"
+
+#define DEVICE_PATH "/dev/full"
+#define READ_SIZE 100
+
+int fd;
+char buffer[READ_SIZE];
+
+FN_SETUP(open)
+{
+	fd = CHECK(open(DEVICE_PATH, O_RDWR));
+}
+END_SETUP()
+
+FN_TEST(fstat)
+{
+	struct stat stat;
+	TEST_RES(fstat(fd, &stat),
+		 S_ISCHR(stat.st_mode) && stat.st_rdev == makedev(0x1, 0x7));
+}
+END_TEST()
+
+FN_TEST(read)
+{
+	memset(buffer, 1, sizeof(buffer));
+	char all_zeros[READ_SIZE] = { 0 };
+
+	TEST_RES(read(fd, buffer, READ_SIZE),
+		 _ret == READ_SIZE &&
+			 memcmp(buffer, all_zeros, READ_SIZE) == 0);
+	TEST_RES(read(fd, buffer, 0), _ret == 0);
+	TEST_ERRNO(read(fd, NULL, 1), EFAULT);
+	TEST_RES(read(fd, NULL, 0), _ret == 0);
+}
+END_TEST()
+
+FN_TEST(write)
+{
+	TEST_ERRNO(write(fd, buffer, 1), ENOSPC);
+	TEST_ERRNO(write(fd, buffer, 0), ENOSPC);
+	TEST_ERRNO(write(fd, NULL, 1), ENOSPC);
+	TEST_ERRNO(write(fd, NULL, 0), ENOSPC);
+}
+END_TEST()
+
+FN_TEST(poll)
+{
+	struct pollfd pfd = { .fd = fd, .events = POLLIN | POLLOUT };
+	TEST_RES(poll(&pfd, 1, 0), pfd.revents == POLLIN | POLLOUT);
+}
+END_TEST()
+
+FN_SETUP(close)
+{
+	CHECK(close(fd));
+}
+END_SETUP()

test/src/apps/scripts/fs.sh

@@ -66,3 +66,4 @@ pipe/short_rw
 epoll/epoll_err
 epoll/poll_err
 file_io/iovec_err
+devfs/full