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

NAME

       uselib - load shared library

SYNOPSIS

       #include <unistd.h>

       int uselib(const char *library);

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

DESCRIPTION

       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

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

ERRORS

       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 path_resolution(7).)

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

       ENOEXEC
	      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

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

NOTES

       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/ld.so" 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

       ar(1), gcc(1), ld(1), ldd(1), mmap(2), open(2), dlopen(3), capabilities(7), ld.so(8)

COLOPHON

       This  page is part of release 4.15 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 https://www.kernel.org/doc/man-pages/.

Linux								    2017-09-15								 USELIB(2)