Open Source Software

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 4.09 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
   https://www.kernel.org/doc/man-pages/.



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