1  /* System call limits
       2  
       3     Copyright 2018-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  #ifndef _GL_SYS_LIMITS_H
      19  #define _GL_SYS_LIMITS_H
      20  
      21  #include <limits.h>
      22  
      23  /* Maximum number of bytes to read or write in a single system call.
      24     This can be useful for system calls like sendfile on GNU/Linux,
      25     which do not handle more than MAX_RW_COUNT bytes correctly.
      26     The Linux kernel MAX_RW_COUNT is at least INT_MAX >> 20 << 20,
      27     where the 20 comes from the Hexagon port with 1 MiB pages; use that
      28     as an approximation, as the exact value may not be available to us.
      29  
      30     Using this also works around a serious Linux bug before 2.6.16; see
      31     <https://bugzilla.redhat.com/show_bug.cgi?id=612839>.
      32  
      33     Using this also works around a Tru64 5.1 bug, where attempting
      34     to read INT_MAX bytes fails with errno == EINVAL.  See
      35     <https://lists.gnu.org/r/bug-gnu-utils/2002-04/msg00010.html>.
      36  
      37     Using this is likely to work around similar bugs in other operating
      38     systems.  */
      39  
      40  enum { SYS_BUFSIZE_MAX = INT_MAX >> 20 << 20 };
      41  
      42  #endif