mes/lib/gnu/io-read.c
Jan Nieuwenhuizen 6d3b9b687d
hurd: Add _read.
* include/gnu/hurd.h (fd_read): Declare.
* include/gnu/syscall.h (SYS__io_read): New value.
* lib/gnu/_read.c: New file.
* lib/gnu/fd-read.c: New file.
* lib/gnu/io-read.c: New file.
* build-aux/configure-lib.sh (libc_SOURCES): Add _read sources.
2019-12-13 21:52:30 +01:00

61 lines
1.8 KiB
C

/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
*
* This file is part of GNU Mes.
*
* GNU Mes 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 3 of the License, or (at
* your option) any later version.
*
* GNU Mes 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 GNU Mes. If not, see <http://www.gnu.org/licenses/>.
*/
#include <gnu/syscall.h>
struct mach_msg_int_pointer
{
mach_msg_header_t header;
mach_msg_type_t type_one; int one;
mach_msg_type_long_t type_two; union {char *two; char pointer[2048];};
};
kern_return_t
__io_read (io_t io, data_t *data, mach_msg_type_number_t *read, loff_t offset, vm_size_t size)
{
union message
{
struct mach_msg_loff_int request;
struct mach_msg_int_pointer reply;
};
union message message = {0};
message.request.header.msgh_size = sizeof (message.request);
message.request.type_one = mach_msg_type_int64;
message.request.one = offset;
message.request.type_two = mach_msg_type_int32;
message.request.two = size;
kern_return_t result = __syscall_put (io, SYS__io_read,
&message.request.header,
sizeof (message.reply));
if (result == KERN_SUCCESS)
{
*read = message.reply.type_two.msgtl_number;
*data = message.reply.pointer;
}
else
{
*read = 0;
*data = 0;
}
return result;
}