mes/lib/linux/lseek.c
Jan Nieuwenhuizen 3abd3e0bcc
mescc: Mes C Library: lseek: Be careful clearing read buffer.
* lib/linux/lseek.c (_lseek): New function.
* lib/linux/lseek.c (lseek): Use it to check if we should reset read
buffer.
* lib/mes/__buffered_read.c (__read_buffer_max): New variable.
(__buffered_read_init): Add environment override: MES_READ_BUFFER.
(__buffered_read): Use it.
2020-01-20 22:47:52 +01:00

47 lines
1.5 KiB
C

/* -*-comment-start: "//";comment-end:""-*-
* GNU Mes --- Maxwell Equations of Software
* Copyright © 2016,2017,2018,2019 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 <mes/lib.h>
#include <linux/syscall.h>
#include <syscall.h>
#include <stdio.h>
#include <sys/types.h>
#if !__MESC__ /* FIXME: We want bin/mes-mescc's x86-linux sha256sum to stay the same. */
off_t
_lseek (int filedes, off_t offset, int whence)
{
return _sys_call3 (SYS_lseek, (int) filedes, (long) offset, (int) whence);
}
#endif
off_t
lseek (int filedes, off_t offset, int whence)
{
#if !__MESC__ /* FIXME: We want bin/mes-mescc's x86-linux sha256sum to stay the same. */
if (_lseek (filedes, 0, SEEK_CUR) == -1)
return -1;
#endif
size_t skip = __buffered_read_clear (filedes);
if (whence == SEEK_CUR)
offset -= skip;
return _sys_call3 (SYS_lseek, (int) filedes, (long) offset, (int) whence);
}