uselib - load shared library
int uselib(const char *library);
: No declaration of this system call is provided in glibc headers;
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
On success, zero is returned. On error, -1 is returned, and errno
In addition to all of the error codes returned by open
(2), the following may also be returned:
- 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).)
- The system-wide limit on the total number of open files has been
- The file specified by library is not an executable of a known type;
for example, it does not have the correct magic numbers.
() 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
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
, 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