1: /* System call limits
2:
3: Copyright 2018-2019 Free Software Foundation, Inc.
4:
5: This program is free software; you can redistribute it and/or modify
6: it under the terms of the GNU General Public License as published by
7: the Free Software Foundation; either version 3, or (at your option)
8: any later version.
9:
10: This program 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 General Public License for more details.
14:
15: You should have received a copy of the GNU 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
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