/*
* Read a portion of a file into an internal buffer.
* Return the location in the buffer and the amount in the buffer.
*/
static int
buf_read_file(struct open_file *f, char **buf_p, size_t *size_p)
{
struct file *fp = (struct file *)f->f_fsdata;
struct m_ext2fs *fs = fp->f_fs;
long off;
indp_t file_block;
indp_t disk_block = 0; /* XXX: gcc */
size_t block_size;
int rc;
off = ext2_blkoff(fs, fp->f_seekp);
file_block = ext2_lblkno(fs, fp->f_seekp);
block_size = fs->e2fs_bsize; /* no fragment */
if (file_block != fp->f_buf_blkno) {
rc = block_map(f, file_block, &disk_block);
if (rc)
return rc;
if (disk_block == 0) {
memset(fp->f_buf, 0, block_size);
fp->f_buf_size = block_size;
} else {
twiddle();
rc = DEV_STRATEGY(f->f_dev)(f->f_devdata, F_READ,
FSBTODB(fs, disk_block),
block_size, fp->f_buf, &fp->f_buf_size);
if (rc)
return rc;
}
fp->f_buf_blkno = file_block;
}
/*
* Return address of byte in buffer corresponding to
* offset, and size of remainder of buffer after that
* byte.
*/
*buf_p = fp->f_buf + off;
*size_p = block_size - off;
/*
* But truncate buffer at end of file.
*/
/* XXX should handle LARGEFILE */
if (*size_p > fp->f_di.e2di_size - fp->f_seekp)
*size_p = fp->f_di.e2di_size - fp->f_seekp;
return 0;
}
/*
* Return buffer with the contents of block "offset" from the beginning of
* directory "ip". If "res" is non-zero, fill it in with a pointer to the
* remaining space in the directory.
*/
int
ext2fs_blkatoff(struct vnode *vp, off_t offset, char **res, struct buf **bpp)
{
struct inode *ip;
struct m_ext2fs *fs;
struct buf *bp;
daddr_t lbn;
int error;
ip = VTOI(vp);
fs = ip->i_e2fs;
lbn = ext2_lblkno(fs, offset);
*bpp = NULL;
if ((error = bread(vp, lbn, fs->e2fs_bsize, 0, &bp)) != 0) {
return (error);
}
if (res)
*res = (char *)bp->b_data + ext2_blkoff(fs, offset);
*bpp = bp;
return (0);
}
