| .\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992 |
| .\" |
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| .\" Since the Linux kernel and libraries are constantly changing, this |
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| .\" Modified by Michael Haardt <michael@moria.de> |
| .\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu> |
| .\" Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com> |
| .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com> |
| .\" Modified 2005-01-09 by aeb |
| .\" |
| .TH USELIB 2 2017-09-15 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| uselib \- load shared library |
| .SH SYNOPSIS |
| .B #include <unistd.h> |
| .PP |
| .BI "int uselib(const char *" library ); |
| .PP |
| .IR Note : |
| No declaration of this system call is provided in glibc headers; see NOTES. |
| .SH DESCRIPTION |
| The system call |
| .BR 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. |
| .SH RETURN VALUE |
| On success, zero is returned. |
| On error, \-1 is returned, and |
| .I errno |
| is set appropriately. |
| .SH ERRORS |
| In addition to all of the error codes returned by |
| .BR open (2) |
| and |
| .BR mmap (2), |
| the following may also be returned: |
| .TP |
| .B EACCES |
| The library specified by |
| .I 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 |
| .BR path_resolution (7).) |
| .TP |
| .B ENFILE |
| The system-wide limit on the total number of open files has been reached. |
| .TP |
| .B ENOEXEC |
| The file specified by |
| .I library |
| is not an executable of a known type; |
| for example, it does not have the correct magic numbers. |
| .SH CONFORMING TO |
| .BR uselib () |
| is Linux-specific, and should not be used in programs |
| intended to be portable. |
| .SH 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 |
| .BR syscall (2). |
| .PP |
| In ancient libc versions, |
| .BR uselib () |
| was used to load |
| the shared libraries with names found in an array of names |
| in the binary. |
| .PP |
| .\" libc 4.3.1f - changelog 1993-03-02 |
| Since libc 4.3.2, startup code tries to prefix these names |
| with "/usr/lib", "/lib" and "" before giving up. |
| .\" libc 4.3.4 - changelog 1993-04-21 |
| In libc 4.3.4 and later these names are looked for in the directories |
| found in |
| .BR LD_LIBRARY_PATH , |
| and if not found there, |
| prefixes "/usr/lib", "/lib" and "/" are tried. |
| .PP |
| 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. |
| .PP |
| glibc2 does not use this call. |
| .PP |
| Since Linux 3.15, |
| .\" commit 69369a7003735d0d8ef22097e27a55a8bad9557a |
| this system call is available only when the kernel is configured with the |
| .B CONFIG_USELIB |
| option. |
| .SH SEE ALSO |
| .BR ar (1), |
| .BR gcc (1), |
| .BR ld (1), |
| .BR ldd (1), |
| .BR mmap (2), |
| .BR open (2), |
| .BR dlopen (3), |
| .BR capabilities (7), |
| .BR ld.so (8) |