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171689da | 1 | /* Global list of NSS service modules. |
2b778ceb | 2 | Copyright (c) 2020-2021 Free Software Foundation, Inc. |
171689da FW |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library 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 GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
16 | License along with the GNU C Library; if not, see | |
17 | <https://www.gnu.org/licenses/>. */ | |
18 | ||
19 | #ifndef _NSS_MODULE_H | |
20 | #define _NSS_MODULE_H | |
21 | ||
22 | #include <nss.h> | |
23 | #include <stdbool.h> | |
24 | ||
25 | /* See nss_database.h for a summary of how this relates. */ | |
26 | ||
27 | /* Typed function pointers for all functions that can be defined by a | |
28 | service module. */ | |
29 | struct nss_module_functions | |
30 | { | |
31 | #undef DEFINE_NSS_FUNCTION | |
32 | #define DEFINE_NSS_FUNCTION(f) nss_##f *f; | |
33 | #include "function.def" | |
34 | }; | |
35 | ||
36 | /* Untyped version of struct nss_module_functions, for consistent | |
37 | processing purposes. */ | |
38 | typedef void *nss_module_functions_untyped[sizeof (struct nss_module_functions) | |
39 | / sizeof (void *)]; | |
40 | ||
41 | /* Initialization state of a NSS module. */ | |
42 | enum nss_module_state | |
43 | { | |
44 | nss_module_uninitialized, | |
45 | nss_module_loaded, | |
46 | nss_module_failed, | |
47 | }; | |
48 | ||
49 | /* A NSS service module (potentially unloaded). Client code should | |
50 | use the functions below. */ | |
51 | struct nss_module | |
52 | { | |
53 | /* Actual type is enum nss_module_state. Use int due to atomic | |
54 | access. Used in a double-checked locking idiom. */ | |
55 | int state; | |
56 | ||
57 | /* The function pointers in the module. */ | |
58 | union | |
59 | { | |
60 | struct nss_module_functions typed; | |
61 | nss_module_functions_untyped untyped; | |
62 | } functions; | |
63 | ||
64 | /* Only used for __libc_freeres unloading. */ | |
65 | void *handle; | |
66 | ||
67 | /* The next module in the list. */ | |
68 | struct nss_module *next; | |
69 | ||
70 | /* The name of the module (as it appears in /etc/nsswitch.conf). */ | |
71 | char name[]; | |
72 | }; | |
73 | ||
74 | /* Allocates the NSS module NAME (of NAME_LENGTH bytes) and places it | |
75 | into the global list. If it already exists in the list, return the | |
76 | pre-existing module. This does not actually load the module. | |
77 | Returns NULL on memory allocation failure. */ | |
78 | struct nss_module *__nss_module_allocate (const char *name, | |
79 | size_t name_length) attribute_hidden; | |
80 | ||
81 | /* Ensures that MODULE is in a loaded or failed state. */ | |
82 | bool __nss_module_load (struct nss_module *module) attribute_hidden; | |
83 | ||
84 | /* Ensures that MODULE is loaded and returns a pointer to the function | |
85 | NAME defined in it. Returns NULL if MODULE could not be loaded, or | |
86 | if the function NAME is not defined in the module. */ | |
87 | void *__nss_module_get_function (struct nss_module *module, const char *name) | |
88 | attribute_hidden; | |
89 | ||
90 | /* Called from __libc_freeres. */ | |
91 | void __nss_module_freeres (void) attribute_hidden; | |
92 | ||
93 | #endif /* NSS_MODULE_H */ |