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/* Global list of NSS service modules.
Copyright (c) 2020-2022 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_MODULE_H
#define _NSS_MODULE_H
#include <nss.h>
#include <stdbool.h>
/* See nss_database.h for a summary of how this relates. */
/* Typed function pointers for all functions that can be defined by a
service module. */
struct nss_module_functions
{
#undef DEFINE_NSS_FUNCTION
#define DEFINE_NSS_FUNCTION(f) nss_##f *f;
#include "function.def"
};
/* Number of elements of the nss_module_functions_untyped array. */
enum
{
nss_module_functions_count = (sizeof (struct nss_module_functions)
/ sizeof (void *))
};
/* Untyped version of struct nss_module_functions, for consistent
processing purposes. */
typedef void *nss_module_functions_untyped[nss_module_functions_count];
/* Locate the nss_files functions, as if by dlopen/dlsym. */
void __nss_files_functions (nss_module_functions_untyped pointers)
attribute_hidden;
/* Initialization state of a NSS module. */
enum nss_module_state
{
nss_module_uninitialized,
nss_module_loaded,
nss_module_failed,
};
/* A NSS service module (potentially unloaded). Client code should
use the functions below. */
struct nss_module
{
/* Actual type is enum nss_module_state. Use int due to atomic
access. Used in a double-checked locking idiom. */
int state;
/* The function pointers in the module. */
union
{
struct nss_module_functions typed;
nss_module_functions_untyped untyped;
} functions;
/* Only used for __libc_freeres unloading. */
void *handle;
/* The next module in the list. */
struct nss_module *next;
/* The name of the module (as it appears in /etc/nsswitch.conf). */
char name[];
};
/* Allocates the NSS module NAME (of NAME_LENGTH bytes) and places it
into the global list. If it already exists in the list, return the
pre-existing module. This does not actually load the module.
Returns NULL on memory allocation failure. */
struct nss_module *__nss_module_allocate (const char *name,
size_t name_length) attribute_hidden;
/* Ensures that MODULE is in a loaded or failed state. */
bool __nss_module_load (struct nss_module *module) attribute_hidden;
/* Ensures that MODULE is loaded and returns a pointer to the function
NAME defined in it. Returns NULL if MODULE could not be loaded, or
if the function NAME is not defined in the module. */
void *__nss_module_get_function (struct nss_module *module, const char *name)
attribute_hidden;
/* Block attempts to dlopen any module we haven't already opened. */
void __nss_module_disable_loading (void);
/* Called from __libc_freeres. */
void __nss_module_freeres (void) attribute_hidden;
#endif /* NSS_MODULE_H */
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