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uselib - load shared library
int uselib(const char *library);
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
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
ENFILE The system limit on the total number of open files has been
The file specified by library is not an executable of known
type, e.g., does not have the correct magic numbers.
uselib() is Linux-specific, and should not be used in programs intended
to be portable.
uselib() was used by early libc startup code 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.
ar(1), gcc(1), ld(1), ldd(1), mmap(2), open(2), dlopen(3),
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