2 .\" Copyright (c) 2003 Alexey Zelkin <phantom@FreeBSD.org>
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26 .\" $FreeBSD: src/lib/libc/gen/dlinfo.3,v 1.3.2.1 2003/02/20 20:42:45 kan Exp $
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 a
57 function call or special handle
59 If handle is the value returned from
61 call, the information returned by the
63 function is pertains the specified object.
64 If handle is the special handle
66 the information returned pertains to the caller itself.
68 The following are possible values for
70 argument to be passed into
74 Retrieve the Link_map (or
79 On successful return the
81 argument is filled with pointer to Link_map structure
83 describing shared object specified by
87 stuctures are maintained as double-linked list by
100 structure is defined in <link.h> and have following members:
103 caddr_t l_addr; /* Base Address of library */
104 const char *l_name; /* Absolute Path to Library */
105 const void *l_ld; /* Pointer to .dynamic in memory */
106 struct link_map *l_next, /* linked list of of mapped libs */
111 The base address of the object loaded into memory.
113 The full name of loaded shared object.
115 The address of dynamic linking information segment
119 The next Link_map structure on the link-map list.
121 The previous Link_map structure on the link-map list.
124 Retrieve the library search paths associated with given
129 argument should point to
132 .Fa ( Dl_serinfo *p ) .
134 structure must be initialized first with a
135 .Dv RTLD_DI_SERINFOSIZE
146 field points to the search path.
149 field contains one of more flags indicating the origin of the path (see the
151 flags defined in <link.h> header file.)
154 (Example 2) for usage example.
155 .It RTLD_DI_SERINFOSIZE
158 structure for use in a
165 fields are returned to indicate the number of search paths applicable
166 to the handle, and the total size of a
168 buffer required to hold
171 entries and the associated search path strings.
174 (Example 2) for usage example.
176 Retrieve the origin of the dynamic object associated with the handle.
179 argument is filled with
187 to retrieve Link_map structure.
189 The following example shows how dynamic library can detect the list
190 of shared libraries loaded after caller's one.
191 For simplicity, error checking has been omitted.
195 dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map);
197 while (map != NULL) {
198 printf("%p: %s\n", map->l_addr, map->l_name);
205 to retrieve the library search paths.
207 The following example shows how a dynamic object can inspect the library
208 search paths that would be used to locate a simple filename with
210 For simplicity, error checking has been omitted.
212 Dl_serinfo _info, *info = &_info;
216 /* determine search path count and required buffer size */
217 dlinfo(RTLD_SELF, RTLD_DI_SERINFOSIZE, (void *)info);
219 /* allocate new buffer and initialize */
220 info = malloc(_info.dls_size);
221 info->dls_size = _info.dls_size;
222 info->dls_cnt = _info.dls_cnt;
224 /* obtain sarch path information */
225 dlinfo(RTLD_SELF, RTLD_DI_SERINFO, (void *)info);
227 path = &info->dls_serpath[0];
229 for (cnt = 1; cnt <= info->dls_cnt; cnt++, path++) {
230 (void) printf("%2d: %s\n", cnt, path->dls_name);
235 returns 0 on success, or -1 if error occured.
236 Whenever an error has been detected, a message detailing it can
237 be retrieved via a call to
247 function first appeared in the Solaris operating system.
257 function was originally written by
259 .Aq phantom@FreeBSD.org
260 and later extended and improved by
262 .Aq kan@FreeBSD.org .
264 The manual page for this function was written by
266 .Aq phantom@FreeBSD.org .