ares_library_init(3) [centos man page]

ARES_LIBRARY_INIT(3)					     Library Functions Manual					      ARES_LIBRARY_INIT(3)

NAME

       ares_library_init - c-ares library initialization

SYNOPSIS

       #include <ares.h>

       int ares_library_init(int flags)

       cc file.c -lcares

DESCRIPTION

       The  ares_library_init  function  performs  initializations internally required by the c-ares library that must take place before any other
       function provided by c-ares can be used in a program.

       This function must be called at least once within the life of a program, before the program actually  executes  any  other  c-ares  library
       function.  Initializations done by this function remain effective until a number of calls to ares_library_cleanup(3) equal to the number of
       calls to this function are performed.

       Successive calls to this function do nothing further, only the first call done when c-ares is in an uninitialized state is actually  effec-
       tive.

       The  flags  parameter  is a bit pattern that tells c-ares exactly which features should be initialized, as described below. Set the desired
       bits by ORing the values together. In normal operation you should specify ARES_LIB_INIT_ALL. Don't use  any  other  value  unless  you  are
       familiar with it and trying to control some internal c-ares feature.

       This  function  is not thread safe.  You have to call it once the program has started, but this call must be done before the program starts
       any other thread. This is required to avoid  potential  race  conditions  in  library  initialization,  and  also  due  to  the	fact  that
       ares_library_init(3)  might  call  functions  from other libraries that are thread unsafe, and could conflict with any other thread that is
       already using these other libraries.

       Win32/64 application DLLs shall not call ares_library_init(3) from the DllMain function. Doing so will produce deadlocks  and  other  prob-
       lems.

FLAGS

       ARES_LIB_INIT_ALL
	    Initialize everything possible. This sets all known bits.

       ARES_LIB_INIT_WIN32
	    Initialize Win32/64 specific libraries.

       ARES_LIB_INIT_NONE
	    Initialize nothing extra. This sets no bit.

RETURN VALUE

       Upon  successful completion, ares_library_init() will return 0.	Otherwise, a non-zero error number will be returned to indicate the error.
       Except for ares_strerror(3), you shall not call any other c-ares function upon ares_library_init(3) failure.

AVAILABILITY

       This function was first introduced in c-ares version 1.7.0 along with the definition of preprocessor symbol CARES_HAVE_ARES_LIBRARY_INIT as
       an   indication	of  the  availability  of  this  function.  Its  recursive  behavior,  which  requires	a  matching  number  of  calls	to
       ares_library_cleanup() in order to deinitialize the library, is present since c-ares version 1.10.0. Earlier  versions  would  deinitialize
       the library on the first call to ares_library_cleanup().

       Since the introduction of this function it is absolutely mandatory to call it for any Win32/64 program using c-ares.

       Non-Win32/64  systems can still use c-ares version 1.7.0 without calling ares_library_init(3) due to the fact that currently it is nearly a
       do-nothing function on non-Win32/64 platforms at this point.

SEE ALSO

       ares_library_cleanup(3), ares_strerror(3)

AUTHOR

       Yang Tse

       Copyright 1998 by the Massachusetts Institute of Technology.
       Copyright (C) 2004-2009 by Daniel Stenberg.

								    19 May 2009 					      ARES_LIBRARY_INIT(3)