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33 .Nd information about dynamically loaded object
40 .Fn dlinfo "void * restrict handle" "int request" "void * restrict p"
44 function provides information about dynamically loaded object.
47 and exact meaning and type of
49 argument depend on value of the
51 argument provided by caller.
55 argument is either the value returned from the
57 function call or special handle
61 is the value returned from
63 the information returned by the
65 function pertains to the specified object.
66 If handle is the special handle
68 the information returned pertains to the caller itself.
70 Possible values for the
73 .Bl -tag -width indent
74 .It Dv RTLD_DI_LINKMAP
77 .Pq Vt "struct link_map"
78 structure pointer for the specified
80 On successful return, the
82 argument is filled with the pointer to the
86 describing a shared object specified by the
91 structures are maintained as a doubly linked list by
104 structure is defined in
106 and has the following members:
107 .Bd -literal -offset indent
108 caddr_t l_addr; /* Base Address of library */
109 const char *l_name; /* Absolute Path to Library */
110 const void *l_ld; /* Pointer to .dynamic in memory */
111 struct link_map *l_next, /* linked list of mapped libs */
114 .Bl -tag -width ".Va l_addr"
116 The base address of the object loaded into memory.
118 The full name of the loaded shared object.
120 The address of the dynamic linking information segment
126 structure on the link-map list.
130 structure on the link-map list.
132 .It Dv RTLD_DI_SERINFO
133 Retrieve the library search paths associated with the given
138 argument should point to
141 .Pq Fa "Dl_serinfo *p" .
144 structure must be initialized first with the
145 .Dv RTLD_DI_SERINFOSIZE
156 field points to the search path.
159 field contains one of more flags indicating the origin of the path (see the
166 example 2, for a usage example.
167 .It Dv RTLD_DI_SERINFOSIZE
170 structure for use in a
177 fields are returned to indicate the number of search paths applicable
178 to the handle, and the total size of a
180 buffer required to hold
183 entries and the associated search path strings.
186 example 2, for a usage example.
187 .It Va RTLD_DI_ORIGIN
188 Retrieve the origin of the dynamic object associated with the handle.
189 On successful return,
191 argument is filled with the
199 function returns 0 on success, or \-1 if an error occurred.
200 Whenever an error has been detected, a message detailing it can
201 be retrieved via a call to
210 The following example shows how dynamic library can detect the list
211 of shared libraries loaded after caller's one.
212 For simplicity, error checking has been omitted.
213 .Bd -literal -offset indent
216 dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map);
218 while (map != NULL) {
219 printf("%p: %s\\n", map->l_addr, map->l_name);
226 to retrieve the library search paths.
228 The following example shows how a dynamic object can inspect the library
229 search paths that would be used to locate a simple filename with
231 For simplicity, error checking has been omitted.
232 .Bd -literal -offset indent
233 Dl_serinfo _info, *info = &_info;
237 /* determine search path count and required buffer size */
238 dlinfo(RTLD_SELF, RTLD_DI_SERINFOSIZE, (void *)info);
240 /* allocate new buffer and initialize */
241 info = malloc(_info.dls_size);
242 info->dls_size = _info.dls_size;
243 info->dls_cnt = _info.dls_cnt;
245 /* obtain sarch path information */
246 dlinfo(RTLD_SELF, RTLD_DI_SERINFO, (void *)info);
248 path = &info->dls_serpath[0];
250 for (cnt = 1; cnt <= info->dls_cnt; cnt++, path++) {
251 (void) printf("%2d: %s\\n", cnt, path->dls_name);
262 function first appeared in the Solaris operating system.
271 implementation of the
273 function was originally written by
275 .Aq phantom@FreeBSD.org
276 and later extended and improved by
278 .Aq kan@FreeBSD.org .
280 The manual page for this function was written by
282 .Aq phantom@FreeBSD.org .