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/*
Copyright (C) 1994, 1995, 1996, 1997 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"
#include "io_S.h"
#include <fcntl.h>
/* Implement io_read as described in <hurd/io.defs>. */
kern_return_t
diskfs_S_io_read (struct protid *cred,
char **data,
mach_msg_type_number_t *datalen,
off_t offset,
mach_msg_type_number_t 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;
mutex_lock (&np->lock);
iohelp_get_conch (&np->conch);
if (off == -1)
off = cred->po->filepointer;
if (off < 0)
{
mutex_unlock (&np->lock);
return EINVAL;
}
if (off > np->dn_stat.st_size)
maxread = 0;
else if (off + (off_t) maxread > np->dn_stat.st_size)
maxread = np->dn_stat.st_size - off;
if (maxread > *datalen)
{
ourbuf = 1;
vm_allocate (mach_task_self (), (u_int *) &buf, maxread, 1);
*data = buf;
}
else
buf = *data;
*datalen = maxread;
if (maxread == 0)
err = 0;
else if (S_ISLNK (np->dn_stat.st_mode))
/* Read from a symlink. */
if (! diskfs_read_symlink_hook)
err = EINVAL;
else
{
if (off == 0 && maxread == np->dn_stat.st_size)
err = (*diskfs_read_symlink_hook)(np, buf);
else
{
char *whole_link = alloca (np->dn_stat.st_size);
err = (*diskfs_read_symlink_hook)(np, whole_link);
if (! err)
memcpy (buf, whole_link + off, maxread);
}
}
else
err = EINVAL; /* Use read below. */
if (err == EINVAL)
err = _diskfs_rdwr_internal (np, buf, off, datalen, 0,
cred->po->openstat & O_NOATIME);
if (diskfs_synchronous)
diskfs_node_update (np, 1); /* atime! */
if (offset == -1 && !err)
cred->po->filepointer += *datalen;
if (err && ourbuf)
vm_deallocate (mach_task_self (), (u_int) buf, maxread);
mutex_unlock (&np->lock);
return err;
}
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