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sourceware.org Git - glibc.git/blob - elf/dl-object.c
4dff99ed110201acc69df65b04d02cb43ba7fed4
1 /* Storage management for the chain of loaded shared objects.
2 Copyright (C) 1995-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
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/>. */
28 /* Add the new link_map NEW to the end of the namespace list. */
30 _dl_add_to_namespace_list (struct link_map
*new, Lmid_t nsid
)
32 /* We modify the list of loaded objects. */
33 __rtld_lock_lock_recursive (GL(dl_load_write_lock
));
35 if (GL(dl_ns
)[nsid
]._ns_loaded
!= NULL
)
37 struct link_map
*l
= GL(dl_ns
)[nsid
]._ns_loaded
;
38 while (l
->l_next
!= NULL
)
41 /* new->l_next = NULL; Would be necessary but we use calloc. */
45 GL(dl_ns
)[nsid
]._ns_loaded
= new;
46 ++GL(dl_ns
)[nsid
]._ns_nloaded
;
47 new->l_serial
= GL(dl_load_adds
);
50 __rtld_lock_unlock_recursive (GL(dl_load_write_lock
));
54 /* Allocate a `struct link_map' for a new object being loaded,
55 and enter it into the _dl_loaded list. */
57 _dl_new_object (char *realname
, const char *libname
, int type
,
58 struct link_map
*loader
, int mode
, Lmid_t nsid
)
62 if (__glibc_unlikely ((mode
& __RTLD_OPENEXEC
) != 0))
64 assert (type
== lt_executable
);
65 assert (nsid
== LM_ID_BASE
);
67 /* Ignore the specified libname for the main executable. It is
68 only known with an explicit loader invocation. */
71 /* We create the map for the executable before we know whether
72 we have auditing libraries and if yes, how many. Assume the
77 naudit
= GLRO (dl_naudit
);
80 size_t libname_len
= strlen (libname
) + 1;
82 struct libname_list
*newname
;
84 size_t audit_space
= naudit
* sizeof (new->l_audit
[0]);
86 # define audit_space 0
89 new = (struct link_map
*) calloc (sizeof (*new) + audit_space
90 + sizeof (struct link_map
*)
91 + sizeof (*newname
) + libname_len
, 1);
96 new->l_symbolic_searchlist
.r_list
= (struct link_map
**) ((char *) (new + 1)
99 new->l_libname
= newname
100 = (struct libname_list
*) (new->l_symbolic_searchlist
.r_list
+ 1);
101 newname
->name
= (char *) memcpy (newname
+ 1, libname
, libname_len
);
102 /* newname->next = NULL; We use calloc therefore not necessary. */
103 newname
->dont_free
= 1;
105 /* When we create the executable link map, or a VDSO link map, we start
106 with "" for the l_name. In these cases "" points to ld.so rodata
107 and won't get dumped during core file generation. Therefore to assist
108 gdb and to create more self-contained core files we adjust l_name to
109 point at the newly allocated copy (which will get dumped) instead of
110 the ld.so rodata copy.
112 Furthermore, in case of explicit loader invocation, discard the
113 name of the main executable, to match the regular behavior, where
114 name of the executable is not known. */
116 if (*realname
!= '\0' && (mode
& __RTLD_OPENEXEC
) == 0)
118 if (*realname
!= '\0')
120 new->l_name
= realname
;
122 new->l_name
= (char *) newname
->name
+ libname_len
- 1;
125 /* If we set the bit now since we know it is never used we avoid
126 dirtying the cache line later. */
127 if ((GLRO(dl_debug_mask
) & DL_DEBUG_UNUSED
) == 0)
129 new->l_loader
= loader
;
130 #if NO_TLS_OFFSET != 0
131 new->l_tls_offset
= NO_TLS_OFFSET
;
136 for (unsigned int cnt
= 0; cnt
< naudit
; ++cnt
)
138 new->l_audit
[cnt
].cookie
= (uintptr_t) new;
139 /* new->l_audit[cnt].bindflags = 0; */
143 /* new->l_global = 0; We use calloc therefore not necessary. */
145 /* Use the 'l_scope_mem' array by default for the 'l_scope'
146 information. If we need more entries we will allocate a large
147 array dynamically. */
148 new->l_scope
= new->l_scope_mem
;
149 new->l_scope_max
= sizeof (new->l_scope_mem
) / sizeof (new->l_scope_mem
[0]);
151 /* Counter for the scopes we have to handle. */
154 if (GL(dl_ns
)[nsid
]._ns_loaded
!= NULL
)
155 /* Add the global scope. */
156 new->l_scope
[idx
++] = &GL(dl_ns
)[nsid
]._ns_loaded
->l_searchlist
;
158 /* If we have no loader the new object acts as it. */
162 /* Determine the local scope. */
163 while (loader
->l_loader
!= NULL
)
164 loader
= loader
->l_loader
;
166 /* Insert the scope if it isn't the global scope we already added. */
167 if (idx
== 0 || &loader
->l_searchlist
!= new->l_scope
[0])
169 if ((mode
& RTLD_DEEPBIND
) != 0 && idx
!= 0)
171 new->l_scope
[1] = new->l_scope
[0];
175 new->l_scope
[idx
] = &loader
->l_searchlist
;
178 new->l_local_scope
[0] = &new->l_searchlist
;
180 /* Determine the origin. If allocating the link map for the main
181 executable, the realname is not known and "". In this case, the
182 origin needs to be determined by other means. However, in case
183 of an explicit loader invocation, the pathname of the main
184 executable is known and needs to be processed here: From the
185 point of view of the kernel, the main executable is the
186 dynamic loader, and this would lead to a computation of the wrong
188 if (realname
[0] != '\0')
190 size_t realname_len
= strlen (realname
) + 1;
194 if (realname
[0] == '/')
196 /* It is an absolute path. Use it. But we have to make a
197 copy since we strip out the trailing slash. */
198 cp
= origin
= (char *) malloc (realname_len
);
201 origin
= (char *) -1;
207 size_t len
= realname_len
;
210 /* Get the current directory name. */
217 new_origin
= (char *) realloc (origin
, len
);
218 if (new_origin
== NULL
)
219 /* We exit the loop. Note that result == NULL. */
223 while ((result
= __getcwd (origin
, len
- realname_len
)) == NULL
228 /* We were not able to determine the current directory.
229 Note that free(origin) is OK if origin == NULL. */
231 origin
= (char *) -1;
235 /* Find the end of the path and see whether we have to add a
236 slash. We could use rawmemchr but this need not be
238 cp
= (strchr
) (origin
, '\0');
243 /* Add the real file name. */
244 cp
= __mempcpy (cp
, realname
, realname_len
);
246 /* Now remove the filename and the slash. Leave the slash if
247 the name is something like "/foo". */
253 /* Keep the only slash which is the first character. */
258 new->l_origin
= origin
;
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