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/* Mapping NSS services to action lists.
Copyright (C) 2020-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library 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 2.1 of the License, or (at your option) any later version.
The GNU C Library 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 the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _NSS_DATABASE_H
#define _NSS_DATABASE_H
#include <file_change_detection.h>
/* Each "line" in nsswitch.conf maps a supported database (example:
passwd) to one or more name service providers (example: files dns).
Internally, each name service provider (example: dns) is a
dynamically loadable module (i.e. libnss_dns.so), managed by
nss_module.h. The sequence of providers and rules (example: files
[SUCCESS=RETURN] dns) is mapped by nss_action.h to a cached entry
which encodes the sequence of modules and rules. Keeping track of
all supported databases and their corresponding actions is done
here.
The key entry is __nss_database_get, which provides a set of
actions which can be used with nss_lookup_function() and
nss_next(). Callers should assume that these functions are fast,
and should not cache the result longer than needed. */
#include "nss_action.h"
/* The enumeration literal in enum nss_database for the database NAME
(e.g., nss_database_hosts for hosts). */
#define NSS_DATABASE_LITERAL(name) nss_database_##name
enum nss_database
{
#define DEFINE_DATABASE(name) NSS_DATABASE_LITERAL (name),
#include "databases.def"
#undef DEFINE_DATABASE
/* Total number of databases. */
NSS_DATABASE_COUNT
};
/* Looks up the action list for DB and stores it in *ACTIONS. Returns
true on success or false on failure. Success can mean that
*ACTIONS is NULL. */
bool __nss_database_get (enum nss_database db, nss_action_list *actions)
attribute_hidden;
/* Like __nss_database_get, but does not reload /etc/nsswitch.conf
from disk. This assumes that there has been a previous successful
__nss_database_get call (which may not have returned any data). */
nss_action_list __nss_database_get_noreload (enum nss_database db)
attribute_hidden;
/* Called from __libc_freeres. */
void __nss_database_freeres (void) attribute_hidden;
/* Internal type. Exposed only for fork handling purposes. */
struct nss_database_data
{
struct file_change_detection nsswitch_conf;
nss_action_list services[NSS_DATABASE_COUNT];
int reload_disabled; /* Actually bool; int for atomic access. */
bool initialized;
};
/* Called by fork in the parent process, before forking. */
void __nss_database_fork_prepare_parent (struct nss_database_data *data)
attribute_hidden;
/* Called by fork in the new subprocess, after forking. */
void __nss_database_fork_subprocess (struct nss_database_data *data)
attribute_hidden;
#endif /* _NSS_DATABASE_H */
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