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/*
* libexplain - Explain errno values returned by libc functions
* Copyright (C) 2008-2010, 2013 Peter Miller
* Written by Peter Miller <pmiller@opensource.org.au>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 3 of the License, 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libexplain/ac/errno.h>
#include <libexplain/ac/string.h>
#include <libexplain/ac/unistd.h>
#include <libexplain/buffer/enfile.h>
#include <libexplain/buffer/gettext.h>
#include <libexplain/option.h>
#include <libexplain/sizeof.h>
#include <libexplain/string_buffer.h>
#ifdef __linux__
#include <sys/syscall.h>
#include <linux/sysctl.h>
#endif
static long
get_maxfile(void)
{
if (explain_option_dialect_specific())
{
#if defined(__linux__) && defined(SYS__sysctl)
/*
* In the linux kernel, if get_empty_filp() returns NULL, the open
* system call (and others) will return ENFILE.
*/
struct __sysctl_args args;
int32_t maxfile;
size_t maxfile_size = sizeof(maxfile);
int name[] = { CTL_FS, FS_MAXFILE };
/*
* The Linux sysctl(2) man page has this to say:
*
* Glibc does not provide a wrapper for this system call; call it
* using syscall(2).
*
* Or rather... don't call it: use of this system call has long
* been discouraged, and it is so unloved that it is likely
* to disappear in a future kernel version. Remove it from your
* programs now; use the /proc/sys interface instead.
*
* The object names vary between kernel versions, making this system
* call worthless for applications.
*
* Catch 22: you have to open a file to discover the limit of
* open files AFTER you have hit the limit of open files. Sigh.
*/
memset(&args, 0, sizeof(struct __sysctl_args));
args.name = name;
args.nlen = SIZEOF(name);
args.oldval = &maxfile;
args.oldlenp = &maxfile_size;
if (syscall(SYS__sysctl, &args) >= 0)
return maxfile;
#endif
}
return -1;
}
void
explain_buffer_enfile(explain_string_buffer_t *sb)
{
long maxfile;
/*
* FIXME: say the limit -- except that there doesn't seem to be
* a sysconf() name for this. The _SC_OPEN_MAX name is for the
* EMFILE error, which is different.
*/
explain_buffer_gettext
(
sb,
/*
* xgettext: This message is used when explaining an ENFILE error.
*
* Note that it could be followed by the actual limit in
* preentheses (if it can be determined) so it helps of the last
* phrase in the message can sensably be followed by it.
*/
i18n("the system limit on the total number of open files "
"has been reached")
);
/*
* Some systems provide a way to discover the actual limit.
*/
maxfile = get_maxfile();
if (maxfile > 0)
explain_string_buffer_printf(sb, " (%ld)", maxfile);
}
/* vim: set ts=8 sw=4 et : */
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