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#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)
{
// check if the vnode represetns a chardev
if (file->vn_dev.chardev == NULL)
{
return -ENXIO;
}
// Unlock the file and call read
vunlock(file);
ssize_t ret = file->vn_dev.chardev->cd_ops->read(file->vn_dev.chardev, pos, buf, count);
vlock(file);
return ret;
}
/*
* 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)
{
// check if the vnode represents a chardev
if (file->vn_dev.chardev == NULL)
{
return -ENXIO;
}
// Unlock the file and call write
vunlock(file);
long ret = file->vn_dev.chardev->cd_ops->write(file->vn_dev.chardev, pos, buf, count);
vlock(file);
return ret;
}
/*
* 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)
{
// check if the vnode represents a chardev
chardev_t *dev = file->vn_dev.chardev;
if (dev == NULL)
{
return -ENXIO;
}
// call the chardev's mmap operation
return dev->cd_ops->mmap(file, ret);
}
static long chardev_file_fill_pframe(vnode_t *file, pframe_t *pf)
{
// check if the vnode represents a chardev
chardev_t *dev = file->vn_dev.chardev;
if (dev == NULL)
{
return -ENXIO;
}
// call the chardev's fill_pframe operation
return dev->cd_ops->fill_pframe(file, pf);
}
static long chardev_file_flush_pframe(vnode_t *file, pframe_t *pf)
{
// check if the vnode represents a chardev
chardev_t *dev = file->vn_dev.chardev;
if (dev == NULL)
{
return -ENXIO;
}
// call the chardev's flush_pframe operation
return dev->cd_ops->flush_pframe(file, pf);
}
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;
}
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