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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_base; /* 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 */
113 caddr_t l_addr; /* Load Offset of library */
114 const char *l_refname; /* Object this one filters for */
116 .Bl -tag -width ".Va l_addr"
118 The base address of the object loaded into memory.
120 The full name of the loaded shared object.
122 The address of the dynamic linking information segment
128 structure on the link-map list.
132 structure on the link-map list.
134 The load offset of the object, that is, the difference between
135 the actual load address and the base virtual address the object
138 A name of the object this object filters for, if any.
139 If there are more then one filtee, a name from the first
141 dynamic entry is supplied.
143 .It Dv RTLD_DI_SERINFO
144 Retrieve the library search paths associated with the given
149 argument should point to
152 .Pq Fa "Dl_serinfo *p" .
155 structure must be initialized first with the
156 .Dv RTLD_DI_SERINFOSIZE
167 field points to the search path.
170 field contains one of more flags indicating the origin of the path (see the
177 example 2, for a usage example.
178 .It Dv RTLD_DI_SERINFOSIZE
181 structure for use in a
188 fields are returned to indicate the number of search paths applicable
189 to the handle, and the total size of a
191 buffer required to hold
194 entries and the associated search path strings.
197 example 2, for a usage example.
198 .It Va RTLD_DI_ORIGIN
199 Retrieve the origin of the dynamic object associated with the handle.
200 On successful return,
202 argument is filled with the
210 function returns 0 on success, or \-1 if an error occurred.
211 Whenever an error has been detected, a message detailing it can
212 be retrieved via a call to
221 The following example shows how dynamic library can detect the list
222 of shared libraries loaded after caller's one.
223 For simplicity, error checking has been omitted.
224 .Bd -literal -offset indent
227 dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map);
229 while (map != NULL) {
230 printf("%p: %s\\n", map->l_addr, map->l_name);
237 to retrieve the library search paths.
239 The following example shows how a dynamic object can inspect the library
240 search paths that would be used to locate a simple filename with
242 For simplicity, error checking has been omitted.
243 .Bd -literal -offset indent
244 Dl_serinfo _info, *info = &_info;
248 /* determine search path count and required buffer size */
249 dlinfo(RTLD_SELF, RTLD_DI_SERINFOSIZE, (void *)info);
251 /* allocate new buffer and initialize */
252 info = malloc(_info.dls_size);
253 info->dls_size = _info.dls_size;
254 info->dls_cnt = _info.dls_cnt;
256 /* obtain sarch path information */
257 dlinfo(RTLD_SELF, RTLD_DI_SERINFO, (void *)info);
259 path = &info->dls_serpath[0];
261 for (cnt = 1; cnt <= info->dls_cnt; cnt++, path++) {
262 (void) printf("%2d: %s\\n", cnt, path->dls_name);
273 function first appeared in the Solaris operating system.
282 implementation of the
284 function was originally written by
285 .An Alexey Zelkin Aq Mt phantom@FreeBSD.org
286 and later extended and improved by
287 .An Alexander Kabaev Aq Mt kan@FreeBSD.org .
289 The manual page for this function was written by
290 .An Alexey Zelkin Aq Mt phantom@FreeBSD.org .