uselib(2) — Linux manual page


USELIB(2)                 Linux Programmer's Manual                USELIB(2)

NAME         top

       uselib - load shared library

SYNOPSIS         top

       #include <unistd.h>

       int uselib(const char *library);

       Note: No declaration of this system call is provided in glibc
       headers; see NOTES.

DESCRIPTION         top

       The system call uselib() serves to load a shared library to be used
       by the calling process.  It is given a pathname.  The address where
       to load is found in the library itself.  The library can have any
       recognized binary format.

RETURN VALUE         top

       On success, zero is returned.  On error, -1 is returned, and errno is
       set appropriately.

ERRORS         top

       In addition to all of the error codes returned by open(2) and
       mmap(2), the following may also be returned:

       EACCES The library specified by library does not have read or execute
              permission, or the caller does not have search permission for
              one of the directories in the path prefix.  (See also

       ENFILE The system-wide limit on the total number of open files has
              been reached.

              The file specified by library is not an executable of a known
              type; for example, it does not have the correct magic numbers.

CONFORMING TO         top

       uselib() is Linux-specific, and should not be used in programs
       intended to be portable.

NOTES         top

       This obsolete system call is not supported by glibc.  No declaration
       is provided in glibc headers, but, through a quirk of history, glibc
       versions before 2.23 did export an ABI for this system call.
       Therefore, in order to employ this system call, it was sufficient to
       manually declare the interface in your code; alternatively, you could
       invoke the system call using syscall(2).

       In ancient libc versions, uselib() was used to load the shared
       libraries with names found in an array of names in the binary.

       Since libc 4.3.2, startup code tries to prefix these names with
       "/usr/lib", "/lib" and "" before giving up.  In libc 4.3.4 and later
       these names are looked for in the directories found in
       LD_LIBRARY_PATH, and if not found there, prefixes "/usr/lib", "/lib"
       and "/" are tried.

       From libc 4.4.4 on only the library "/lib/" is loaded, so that
       this dynamic library can load the remaining libraries needed (again
       using this call).  This is also the state of affairs in libc5.

       glibc2 does not use this call.

       Since Linux 3.15, this system call is available only when the kernel
       is configured with the CONFIG_USELIB option.

SEE ALSO         top

       ar(1), gcc(1), ld(1), ldd(1), mmap(2), open(2), dlopen(3),

COLOPHON         top

       This page is part of release 5.09 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                            2017-09-15                        USELIB(2)

Pages that refer to this page: fanotify_mark(2)syscalls(2)