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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

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