/*
* Writes to a file.
*/
PUBLIC ssize_t sys_write(int fd, const void *buf, size_t n)
{
dev_t dev; /* Device number. */
struct file *f; /* File. */
struct inode *i; /* Inode. */
ssize_t count = 0; /* Bytes actually written. */
/* Invalid file descriptor. */
if ((fd < 0) || (fd >= OPEN_MAX) || ((f = curr_proc->ofiles[fd]) == NULL))
return (-EBADF);
/* File not opened for writing. */
if (ACCMODE(f->oflag) == O_RDONLY)
return (-EBADF);
/* Invalid buffer. */
if (!chkmem(buf, n, MAY_READ))
return (-EINVAL);
i = f->inode;
/* Append mode. */
if (f->oflag & O_APPEND)
f->pos = i->size;
/* Character special file. */
if (S_ISCHR(i->mode))
{
dev = i->blocks[0];
count = cdev_write(dev, buf, n);
return (count);
}
/* Block special file. */
else if (S_ISBLK(i->mode))
{
dev = i->blocks[0];
count = bdev_write(dev, buf, n, f->pos);
}
/* Pipe file. */
else if (S_ISFIFO(i->mode))
{
kprintf("write to pipe");
count = pipe_write(i, buf, n);
}
/* Regular file. */
else if (S_ISREG(i->mode))
count = file_write(i, buf, n, f->pos);
/* Failed to write. */
if (count < 0)
return (curr_proc->errno);
f->pos += count;
return (count);
}
/*
* Reads from a file.
*/
PUBLIC ssize_t sys_read(int fd, void *buf, size_t n)
{
dev_t dev; /* Device number. */
struct file *f; /* File. */
struct inode *i; /* Inode. */
ssize_t count; /* Bytes actually read. */
/* Invalid file descriptor. */
if ((fd < 0) || (fd >= OPEN_MAX) || ((f = curr_proc->ofiles[fd]) == NULL))
return (-EBADF);
/* File not opened for reading. */
if (ACCMODE(f->oflag) == O_WRONLY)
return (-EBADF);
#if (EDUCATIONAL_KERNEL == 0)
/* Invalid buffer. */
if (!chkmem(buf, n, MAY_WRITE))
return (-EINVAL);
#endif
/* Nothing to do. */
if (n == 0)
return (0);
i = f->inode;
/* Character special file. */
if (S_ISCHR(i->mode))
{
dev = i->blocks[0];
count = cdev_read(dev, buf, n);
return (count);
}
/* Block special file. */
else if (S_ISBLK(i->mode))
{
dev = i->blocks[0];
count = bdev_read(dev, buf, n, f->pos);
}
/* Pipe file. */
else if (S_ISFIFO(i->mode))
{
kprintf("read from pipe");
count = pipe_read(i, buf, n);
}
/* Regular file/directory. */
else if ((S_ISDIR(i->mode)) || (S_ISREG(i->mode)))
count = file_read(i, buf, n, f->pos);
/* Unknown file type. */
else
return (-EINVAL);
/* Failed to read. */
if (count < 0)
return (curr_proc->errno);
inode_touch(i);
f->pos += count;
return (count);
}
