glibc (2.38)
1 /* User functions for run-time dynamic loading.
2 Copyright (C) 1995-2023 Free Software Foundation, Inc.
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 _DLFCN_H
20 #define _DLFCN_H 1
21
22 #include <features.h>
23 #define __need_size_t
24 #include <stddef.h>
25
26 /* Collect various system dependent definitions and declarations. */
27 #include <bits/dlfcn.h>
28
29
30 #ifdef __USE_GNU
31 #include <bits/dl_find_object.h>
32
33 /* Type for namespace indices. */
34 typedef long int Lmid_t;
35
36 /* Special namespace ID values. */
37 # define LM_ID_BASE 0 /* Initial namespace. */
38 # define LM_ID_NEWLM -1 /* For dlmopen: request new namespace. */
39 #endif
40
41 /* If the first argument of `dlsym' or `dlvsym' is set to RTLD_NEXT
42 the run-time address of the symbol called NAME in the next shared
43 object is returned. The "next" relation is defined by the order
44 the shared objects were loaded. */
45 #define RTLD_NEXT ((void *) -1l)
46
47 /* If the first argument to `dlsym' or `dlvsym' is set to RTLD_DEFAULT
48 the run-time address of the symbol called NAME in the global scope
49 is returned. */
50 #define RTLD_DEFAULT ((void *) 0)
51
52 __BEGIN_DECLS
53
54 /* Open the shared object FILE and map it in; return a handle that can be
55 passed to `dlsym' to get symbol values from it. */
56 extern void *dlopen (const char *__file, int __mode) __THROWNL;
57
58 /* Unmap and close a shared object opened by `dlopen'.
59 The handle cannot be used again after calling `dlclose'. */
60 extern int dlclose (void *__handle) __THROWNL __nonnull ((1));
61
62 /* Find the run-time address in the shared object HANDLE refers to
63 of the symbol called NAME. */
64 extern void *dlsym (void *__restrict __handle,
65 const char *__restrict __name) __THROW __nonnull ((2));
66
67 #ifdef __USE_GNU
68 /* Like `dlopen', but request object to be allocated in a new namespace. */
69 extern void *dlmopen (Lmid_t __nsid, const char *__file, int __mode) __THROWNL;
70
71 /* Find the run-time address in the shared object HANDLE refers to
72 of the symbol called NAME with VERSION. */
73 extern void *dlvsym (void *__restrict __handle,
74 const char *__restrict __name,
75 const char *__restrict __version)
76 __THROW __nonnull ((2, 3));
77 #endif
78
79 /* When any of the above functions fails, call this function
80 to return a string describing the error. Each call resets
81 the error string so that a following call returns null. */
82 extern char *dlerror (void) __THROW;
83
84
85 #ifdef __USE_GNU
86 /* Structure containing information about object searched using
87 `dladdr'. */
88 typedef struct
89 {
90 const char *dli_fname; /* File name of defining object. */
91 void *dli_fbase; /* Load address of that object. */
92 const char *dli_sname; /* Name of nearest symbol. */
93 void *dli_saddr; /* Exact value of nearest symbol. */
94 } Dl_info;
95
96 /* Fill in *INFO with the following information about ADDRESS.
97 Returns 0 iff no shared object's segments contain that address. */
98 extern int dladdr (const void *__address, Dl_info *__info)
99 __THROW __nonnull ((2));
100
101 /* Same as `dladdr', but additionally sets *EXTRA_INFO according to FLAGS. */
102 extern int dladdr1 (const void *__address, Dl_info *__info,
103 void **__extra_info, int __flags) __THROW __nonnull ((2));
104
105 /* These are the possible values for the FLAGS argument to `dladdr1'.
106 This indicates what extra information is stored at *EXTRA_INFO.
107 It may also be zero, in which case the EXTRA_INFO argument is not used. */
108 enum
109 {
110 /* Matching symbol table entry (const ElfNN_Sym *). */
111 RTLD_DL_SYMENT = 1,
112
113 /* The object containing the address (struct link_map *). */
114 RTLD_DL_LINKMAP = 2
115 };
116
117
118 /* Get information about the shared object HANDLE refers to.
119 REQUEST is from among the values below, and determines the use of ARG.
120
121 On success, returns zero. On failure, returns -1 and records an error
122 message to be fetched with `dlerror'. */
123 extern int dlinfo (void *__restrict __handle,
124 int __request, void *__restrict __arg)
125 __THROW __nonnull ((1, 3));
126
127 /* These are the possible values for the REQUEST argument to `dlinfo'. */
128 enum
129 {
130 /* Treat ARG as `lmid_t *'; store namespace ID for HANDLE there. */
131 RTLD_DI_LMID = 1,
132
133 /* Treat ARG as `struct link_map **';
134 store the `struct link_map *' for HANDLE there. */
135 RTLD_DI_LINKMAP = 2,
136
137 RTLD_DI_CONFIGADDR = 3, /* Unsupported, defined by Solaris. */
138
139 /* Treat ARG as `Dl_serinfo *' (see below), and fill in to describe the
140 directories that will be searched for dependencies of this object.
141 RTLD_DI_SERINFOSIZE fills in just the `dls_cnt' and `dls_size'
142 entries to indicate the size of the buffer that must be passed to
143 RTLD_DI_SERINFO to fill in the full information. */
144 RTLD_DI_SERINFO = 4,
145 RTLD_DI_SERINFOSIZE = 5,
146
147 /* Treat ARG as `char *', and store there the directory name used to
148 expand $ORIGIN in this shared object's dependency file names. */
149 RTLD_DI_ORIGIN = 6,
150
151 RTLD_DI_PROFILENAME = 7, /* Unsupported, defined by Solaris. */
152 RTLD_DI_PROFILEOUT = 8, /* Unsupported, defined by Solaris. */
153
154 /* Treat ARG as `size_t *', and store there the TLS module ID
155 of this object's PT_TLS segment, as used in TLS relocations;
156 store zero if this object does not define a PT_TLS segment. */
157 RTLD_DI_TLS_MODID = 9,
158
159 /* Treat ARG as `void **', and store there a pointer to the calling
160 thread's TLS block corresponding to this object's PT_TLS segment.
161 Store a null pointer if this object does not define a PT_TLS
162 segment, or if the calling thread has not allocated a block for it. */
163 RTLD_DI_TLS_DATA = 10,
164
165 /* Treat ARG as const ElfW(Phdr) **, and store the address of the
166 program header array at that location. The dlinfo call returns
167 the number of program headers in the array. */
168 RTLD_DI_PHDR = 11,
169
170 RTLD_DI_MAX = 11
171 };
172
173
174 /* This is the type of elements in `Dl_serinfo', below.
175 The `dls_name' member points to space in the buffer passed to `dlinfo'. */
176 typedef struct
177 {
178 char *dls_name; /* Name of library search path directory. */
179 unsigned int dls_flags; /* Indicates where this directory came from. */
180 } Dl_serpath;
181
182 /* This is the structure that must be passed (by reference) to `dlinfo' for
183 the RTLD_DI_SERINFO and RTLD_DI_SERINFOSIZE requests. */
184 typedef struct
185 {
186 size_t dls_size; /* Size in bytes of the whole buffer. */
187 unsigned int dls_cnt; /* Number of elements in `dls_serpath'. */
188 # if __GNUC_PREREQ (3, 0)
189 /* The zero-length array avoids an unwanted array subscript check by
190 the compiler, while the surrounding anonymous union preserves the
191 historic size of the type. At the time of writing, GNU C does
192 not support structs with flexible array members in unions. */
193 __extension__ union
194 {
195 Dl_serpath dls_serpath[0]; /* Actually longer, dls_cnt elements. */
196 Dl_serpath __dls_serpath_pad[1];
197 };
198 # else
199 Dl_serpath dls_serpath[1]; /* Actually longer, dls_cnt elements. */
200 # endif
201 } Dl_serinfo;
202
203 struct dl_find_object
204 {
205 __extension__ unsigned long long int dlfo_flags;
206 void *dlfo_map_start; /* Beginning of mapping containing address. */
207 void *dlfo_map_end; /* End of mapping. */
208 struct link_map *dlfo_link_map;
209 void *dlfo_eh_frame; /* Exception handling data of the object. */
210 # if DLFO_STRUCT_HAS_EH_DBASE
211 void *dlfo_eh_dbase; /* Base address for DW_EH_PE_datarel. */
212 # if __WORDSIZE == 32
213 unsigned int __dlfo_eh_dbase_pad;
214 # endif
215 # endif
216 # if DLFO_STRUCT_HAS_EH_COUNT
217 int dlfo_eh_count; /* Number of exception handling entries. */
218 unsigned int __dlfo_eh_count_pad;
219 # endif
220 __extension__ unsigned long long int __dflo_reserved[7];
221 };
222
223 /* If ADDRESS is found in an object, fill in *RESULT and return 0.
224 Otherwise, return -1. */
225 int _dl_find_object (void *__address, struct dl_find_object *__result) __THROW;
226
227 #endif /* __USE_GNU */
228
229
230 __END_DECLS
231
232 #endif /* dlfcn.h */
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