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dlinfo (3)
  • dlinfo (3) ( Solaris man: Библиотечные вызовы )
  • >> dlinfo (3) ( FreeBSD man: Библиотечные вызовы )

  • BSD mandoc
     

    NAME

    dlinfo
    
     - information about dynamically loaded object
    
     
    

    LIBRARY

    Lb libc
    
     
    

    SYNOPSIS

       #include <link.h>
       #include <dlfcn.h>
    int dlinfo (void * restrict handle int request void * restrict p);
     

    DESCRIPTION

    The dlinfo ();
    function provides information about dynamically loaded object. The action taken by dlinfo ();
    and exact meaning and type of Fa p argument depend on value of the Fa request argument provided by caller.

    The Fa handle argument is either the value returned from the dlopen(3) function call or special handle RTLD_SELF If Fa handle is the value returned from dlopen(3), the information returned by the dlinfo ();
    function pertains to the specified object. If handle is the special handle RTLD_SELF the information returned pertains to the caller itself.

    Possible values for the Fa request argument are:

    RTLD_DI_LINKMAP
    Retrieve the Vt Link_map (Vt struct link_map ) structure pointer for the specified Fa handle . On successful return, the Fa p argument is filled with the pointer to the Vt Link_map structure (Fa Link_map **p ) describing a shared object specified by the Fa handle argument. The Vt Link_map structures are maintained as a doubly linked list by ld.so1, in the same order as dlopen(3) and dlclose(3) are called. See Sx EXAMPLES , example 1.

    The Vt Link_map structure is defined in    #include <link.h>
    and has the following members:

    caddr_t         l_addr;    /* Base Address of library */
    const char      *l_name;   /* Absolute Path to Library */
    const void      *l_ld;     /* Pointer to .dynamic in memory */
    struct link_map *l_next,   /* linked list of mapped libs */
                    *l_prev;
    

    l_addr
    The base address of the object loaded into memory.
    l_name
    The full name of the loaded shared object.
    l_ld
    The address of the dynamic linking information segment (PT_DYNAMIC ) loaded into memory.
    l_next
    The next Vt Link_map structure on the link-map list.
    l_prev
    The previous Vt Link_map structure on the link-map list.

    RTLD_DI_SERINFO
    Retrieve the library search paths associated with the given Fa handle argument. The Fa p argument should point to Vt Dl_serinfo structure buffer (Fa Dl_serinfo *p ) The Vt Dl_serinfo structure must be initialized first with the RTLD_DI_SERINFOSIZE request.

    The returned Vt Dl_serinfo structure contains dls_cnt Vt Dl_serpath entries. Each entry's dlp_name field points to the search path. The corresponding dlp_info field contains one of more flags indicating the origin of the path (see the LA_SER_* flags defined in the    #include <link.h>
    header file). See Sx EXAMPLES , example 2, for a usage example.

    RTLD_DI_SERINFOSIZE
    Initialize a Vt Dl_serinfo structure for use in a RTLD_DI_SERINFO request. Both the dls_cnt and dls_size fields are returned to indicate the number of search paths applicable to the handle, and the total size of a Vt Dl_serinfo buffer required to hold dls_cnt Vt Dl_serpath entries and the associated search path strings. See Sx EXAMPLES , example 2, for a usage example.
    RTLD_DI_ORIGIN
    Retrieve the origin of the dynamic object associated with the handle. On successful return, Fa p argument is filled with the Vt char pointer (Fa char *p )

     

    RETURN VALUES

    The dlinfo ();
    function returns 0 on success, or -1 if an error occurred. Whenever an error has been detected, a message detailing it can be retrieved via a call to dlerror(3).  

    EXAMPLES

    Example 1: Using dlinfo ();
    to retrieve Vt Link_map structure.

    The following example shows how dynamic library can detect the list of shared libraries loaded after caller's one. For simplicity, error checking has been omitted.

    Link_map *map;
    
    dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &map);
    
    while (map != NULL) {
            printf("%p: %s\n", map->l_addr, map->l_name);
            map = map->l_next;
    }
    

    Example 2: Using dlinfo ();
    to retrieve the library search paths.

    The following example shows how a dynamic object can inspect the library search paths that would be used to locate a simple filename with dlopen(3). For simplicity, error checking has been omitted.

    Dl_serinfo       _info, *info = &_info;
    Dl_serpath      *path;
    unsigned int     cnt;
    
    /* determine search path count and required buffer size */
    dlinfo(RTLD_SELF, RTLD_DI_SERINFOSIZE, (void *)info);
    
    /* allocate new buffer and initialize */
    info = malloc(_info.dls_size);
    info->dls_size = _info.dls_size;
    info->dls_cnt = _info.dls_cnt;
    
    /* obtain sarch path information */
    dlinfo(RTLD_SELF, RTLD_DI_SERINFO, (void *)info);
    
    path = &info->dls_serpath[0];
    
    for (cnt = 1; cnt <= info->dls_cnt; cnt++, path++) {
            (void) printf("%2d: %s\n", cnt, path->dls_name);
    }
    
     

    SEE ALSO

    rtld(1), dladdr(3), dlopen(3), dlsym(3)  

    HISTORY

    The dlinfo ();
    function first appeared in the Solaris operating system. In Fx , it first appeared in Fx 4.8 .  

    AUTHORS

    An -nosplit The Fx implementation of the dlinfo ();
    function was originally written by An Alexey Zelkin Aq [email protected] and later extended and improved by An Alexander Kabaev Aq [email protected] .

    The manual page for this function was written by An Alexey Zelkin Aq [email protected] .


     

    Index

    NAME
    LIBRARY
    SYNOPSIS
    DESCRIPTION
    RETURN VALUES
    EXAMPLES
    SEE ALSO
    HISTORY
    AUTHORS


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