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/*
Copyright (C) 1994 Free Software Foundation
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "priv.h"
/* Implement io_read as described in <hurd/io.defs>. */
error_t
diskfs_S_io_read (struct protid *cred,
char **data,
unsigned int *datalen,
off_t offset,
int maxread)
{
struct node *np;
int err;
int off = offset;
char *buf;
int ourbuf = 0;
if (!cred)
return EOPNOTSUPP;
np = cred->po->np;
if (!(cred->po->openstat & O_READ))
return EBADF;
if (maxread < 0)
return EINVAL;
mutex_lock (&np->i_toplock);
if (err = ioserver_get_conch (&np->i_conch))
{
mutex_unlock (&np->i_toplock);
return err;
}
if (off == -1)
off = cred->po->filepointer;
if (!(err = catch_exception ()))
{
if (off + maxread > np->di->di_size)
maxread = np->di->di_size - off;
end_catch_exception ();
}
if (!err)
{
if (maxread > *datalen)
{
ourbuf = 1;
vm_allocate (mach_task_self (), (u_int *) &buf, maxread, 1);
*data = buf;
}
else
buf = *data;
*datalen = maxread;
if (maxread)
err = io_rdwr (np, buf, off, maxread, 0);
else
err = 0;
if (offset == -1 && !err)
cred->po->filepointer += *datalen;
if (err && ourbuf)
vm_deallocate (mach_task_self (), (u_int) buf, maxread);
}
mutex_unlock (&np->i_toplock);
return err;
}
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