ARES_LIBRARY_INIT(3)   FreeBSD 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)

       int ares_library_init_mem(int flags,
                                 void *(*amalloc)(size_t),)(size_t),
                                 void (*afree)(void *ptr),)(void *ptr),
                                 void (*arealloc)(void *ptr, size_t size)))(void *ptr, size_t size))

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 _library_cleanup&section=3">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
       effective.

       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.

       The ares_library_init_mem function allows the caller to provide memory
       management functions that the c-ares library will be use instead of
       malloc(3), free(3) and realloc(3).

       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
       _library_init&section=3">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.

       On Windows platforms, the library user should ensure that WSAStartup()
       is called before the c-ares library is initialized and used.

       Win32/64 application DLLs shall not call _library_init&section=3">ares_library_init(3) from the
       DllMain function. Doing so will produce deadlocks and other problems.

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 _strerror&section=3">ares_strerror(3), you shall not call any other c-ares
       function upon _library_init&section=3">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
       _library_init&section=3">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)