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Diffstat (limited to 'lib/sys-limits.h')
-rw-r--r-- | lib/sys-limits.h | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/lib/sys-limits.h b/lib/sys-limits.h new file mode 100644 index 0000000..9b6b490 --- /dev/null +++ b/lib/sys-limits.h @@ -0,0 +1,42 @@ +/* System call limits + + Copyright 2018-2020 Free Software Foundation, Inc. + + 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 3, 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, see <https://www.gnu.org/licenses/>. */ + +#ifndef _GL_SYS_LIMITS_H +#define _GL_SYS_LIMITS_H + +#include <limits.h> + +/* Maximum number of bytes to read or write in a single system call. + This can be useful for system calls like sendfile on GNU/Linux, + which do not handle more than MAX_RW_COUNT bytes correctly. + The Linux kernel MAX_RW_COUNT is at least INT_MAX >> 20 << 20, + where the 20 comes from the Hexagon port with 1 MiB pages; use that + as an approximation, as the exact value may not be available to us. + + Using this also works around a serious Linux bug before 2.6.16; see + <https://bugzilla.redhat.com/show_bug.cgi?id=612839>. + + Using this also works around a Tru64 5.1 bug, where attempting + to read INT_MAX bytes fails with errno == EINVAL. See + <https://lists.gnu.org/r/bug-gnu-utils/2002-04/msg00010.html>. + + Using this is likely to work around similar bugs in other operating + systems. */ + +enum { SYS_BUFSIZE_MAX = INT_MAX >> 20 << 20 }; + +#endif |