/*
* 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);
}
/*===========================================================================*
* rw_block *
*===========================================================================*/
static void rw_block(
register struct buf *bp, /* buffer pointer */
int rw_flag /* READING or WRITING */
)
{
/* Read or write a disk block. This is the only routine in which actual disk
* I/O is invoked. If an error occurs, a message is printed here, but the error
* is not reported to the caller. If the error occurred while purging a block
* from the cache, it is not clear what the caller could do about it anyway.
*/
int r, op_failed = 0;
u64_t pos;
dev_t dev;
if ( (dev = bp->b_dev) != NO_DEV) {
pos = mul64u(bp->b_blocknr, fs_block_size);
if (rw_flag == READING)
r = bdev_read(dev, pos, bp->b_data, fs_block_size,
BDEV_NOFLAGS);
else
r = bdev_write(dev, pos, bp->b_data, fs_block_size,
BDEV_NOFLAGS);
if (r < 0) {
printf("Ext2(%d) I/O error on device %d/%d, block %u\n",
SELF_E, major(dev), minor(dev), bp->b_blocknr);
op_failed = 1;
} else if (r != (ssize_t) fs_block_size) {
r = END_OF_FILE;
op_failed = 1;
}
if (op_failed) {
bp->b_dev = NO_DEV; /* invalidate block */
/* Report read errors to interested parties. */
if (rw_flag == READING) rdwt_err = r;
}
}
bp->b_dirt = CLEAN;
}