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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
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USELIB(2) Linux Programmer's Manual USELIB(2)
uselib - load shared library
#include <unistd.h>
int uselib(const char *library);
Note: No declaration of this system call is provided in glibc
headers; see NOTES.
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.
On success, zero is returned. On error, -1 is returned, and errno is
set appropriately.
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.
uselib() is Linux-specific, and should not be used in programs
intended to be portable.
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.
ar(1), gcc(1), ld(1), ldd(1), mmap(2), open(2), dlopen(3),
capabilities(7), ld.so(8)
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)
Pages that refer to this page: syscalls(2)
Copyright and license for this manual page
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