Created student weenix repository

1 files changed, 176 insertions, 0 deletions

diff --git a/kernel/fs/vnode_specials.c b/kernel/fs/vnode_specials.c
new file mode 100644
index 0000000..a6c38a3
--- /dev/null
+++ b/kernel/fs/vnode_specials.c
@@ -0,0 +1,176 @@
+#include <errno.h>
+#include <fs/stat.h>
+#include <fs/vfs.h>
+#include <fs/vnode.h>
+#include <util/debug.h>
+
+static long special_file_stat(vnode_t *file, stat_t *ss);
+
+static ssize_t chardev_file_read(vnode_t *file, size_t pos, void *buf,
+                                 size_t count);
+
+static ssize_t chardev_file_write(vnode_t *file, size_t pos, const void *buf,
+                                  size_t count);
+
+static long chardev_file_mmap(vnode_t *file, mobj_t **ret);
+
+static long chardev_file_fill_pframe(vnode_t *file, pframe_t *pf);
+
+static long chardev_file_flush_pframe(vnode_t *file, pframe_t *pf);
+
+static vnode_ops_t chardev_spec_vops = {
+    .read = chardev_file_read,
+    .write = chardev_file_write,
+    .mmap = chardev_file_mmap,
+    .mknod = NULL,
+    .lookup = NULL,
+    .link = NULL,
+    .unlink = NULL,
+    .mkdir = NULL,
+    .rmdir = NULL,
+    .readdir = NULL,
+    .stat = special_file_stat,
+    .get_pframe = NULL,
+    .fill_pframe = chardev_file_fill_pframe,
+    .flush_pframe = chardev_file_flush_pframe,
+};
+
+static ssize_t blockdev_file_read(vnode_t *file, size_t pos, void *buf,
+                                  size_t count);
+
+static ssize_t blockdev_file_write(vnode_t *file, size_t pos, const void *buf,
+                                   size_t count);
+
+static long blockdev_file_mmap(vnode_t *file, mobj_t **ret);
+
+static long blockdev_file_fill_pframe(vnode_t *file, pframe_t *pf);
+
+static long blockdev_file_flush_pframe(vnode_t *file, pframe_t *pf);
+
+static vnode_ops_t blockdev_spec_vops = {
+    .read = blockdev_file_read,
+    .write = blockdev_file_write,
+    .mmap = blockdev_file_mmap,
+    .mknod = NULL,
+    .lookup = NULL,
+    .link = NULL,
+    .unlink = NULL,
+    .mkdir = NULL,
+    .rmdir = NULL,
+    .readdir = NULL,
+    .stat = special_file_stat,
+    .get_pframe = NULL,
+    .fill_pframe = blockdev_file_fill_pframe,
+    .flush_pframe = blockdev_file_flush_pframe,
+};
+
+void init_special_vnode(vnode_t *vn)
+{
+    if (S_ISCHR(vn->vn_mode))
+    {
+        vn->vn_ops = &chardev_spec_vops;
+        vn->vn_dev.chardev = chardev_lookup(vn->vn_devid);
+    }
+    else
+    {
+        KASSERT(S_ISBLK(vn->vn_mode));
+        vn->vn_ops = &blockdev_spec_vops;
+        vn->vn_dev.blockdev = blockdev_lookup(vn->vn_devid);
+    }
+}
+
+static long special_file_stat(vnode_t *file, stat_t *ss)
+{
+    KASSERT(file->vn_fs->fs_root->vn_ops->stat != NULL);
+    // call the containing file system's stat routine
+    return file->vn_fs->fs_root->vn_ops->stat(file, ss);
+}
+
+/*
+ * Make a read by deferring to the underlying chardev and its read operation.
+ *
+ * Returns what the chardev's read returned.
+ *
+ * Hint: Watch out! chardev_file_read and chardev_file_write are indirectly
+ * called in do_read and do_write, respectively, as the read/write ops for
+ * chardev-type vnodes. This means that the vnode file should be locked
+ * upon entry to this function.
+ *
+ * However, tty_read and tty_write, the read/write ops for the tty chardev,
+ * are potentially blocking. To avoid deadlock, you should unlock the file
+ * before calling the chardev's read, and lock it again after. If you fail
+ * to do this, a shell reading from /dev/tty0 for instance, will block all
+ * access to the /dev/tty0 vnode. This means that if someone runs `ls /dev/`,
+ * while a shell is reading from `/dev/tty0`, the `ls` call will hang.
+ *
+ * Also, if a vnode represents a chardev, you can access the chardev using
+ * vnode->vn_dev.chardev.
+ *
+ */
+static ssize_t chardev_file_read(vnode_t *file, size_t pos, void *buf,
+                                 size_t count)
+{
+    NOT_YET_IMPLEMENTED("VFS: ***none***");
+    return 0;
+}
+
+/*
+ * Make a write by deferring to the underlying chardev and its write operation.
+ *
+ * Return what the chardev's write returned.
+ *
+ * See the comments from chardev_file_read above for hints.
+ *
+ */
+static long chardev_file_write(vnode_t *file, size_t pos, const void *buf,
+                               size_t count)
+{
+    NOT_YET_IMPLEMENTED("VFS: ***none***");
+    return 0;
+}
+
+/*
+ * For this and the following chardev functions, simply defer to the underlying
+ * chardev's corresponding operations.
+ */
+static long chardev_file_mmap(vnode_t *file, mobj_t **ret)
+{
+    NOT_YET_IMPLEMENTED("VM: ***none***");
+    return 0;
+}
+
+static long chardev_file_fill_pframe(vnode_t *file, pframe_t *pf)
+{
+    NOT_YET_IMPLEMENTED("VM: ***none***");
+    return 0;
+}
+
+static long chardev_file_flush_pframe(vnode_t *file, pframe_t *pf)
+{
+    NOT_YET_IMPLEMENTED("VM: ***none***");
+    return 0;
+}
+
+static ssize_t blockdev_file_read(vnode_t *file, size_t pos, void *buf,
+                                  size_t count)
+{
+    return -ENOTSUP;
+}
+
+static long blockdev_file_write(vnode_t *file, size_t pos, const void *buf,
+                                size_t count)
+{
+    return -ENOTSUP;
+}
+
+static long blockdev_file_mmap(vnode_t *file, mobj_t **ret) { return -ENOTSUP; }
+
+static long blockdev_file_fill_pframe(vnode_t *file, pframe_t *pf)
+{
+    return -ENOTSUP;
+}
+
+static long blockdev_file_flush_pframe(vnode_t *file, pframe_t *pf)
+{
+    return -ENOTSUP;
+}