curl_global_init(3)             libcurl Manual             curl_global_init(3)

NAME
       curl_global_init - Global libcurl initialisation

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_global_init(long flags);

DESCRIPTION
       This  function  sets  up  the  program  environment that libcurl needs.
       Think of it as an extension of the library loader.

       This function must be called at least once within a program (a  program
       is  all  the  code that shares a memory space) before the program calls
       any other function in libcurl.  The environment it sets up is  constant
       for  the life of the program and is the same for every program, so mul-
       tiple calls have the same effect as one call.

       The flags option is a bit pattern that tells libcurl exactly what  fea-
       tures  to  init,  as described below. Set the desired bits by ORing the
       values   together.    In   normal   operation,   you    must    specify
       CURL_GLOBAL_ALL.   Don't  use  any  other value unless you are familiar
       with it and mean to control internal operations of libcurl.

       This function is not thread safe. You must not call it when  any  other
       thread  in  the program (i.e. a thread sharing the same memory) is run-
       ning.  This doesn't just mean no other thread that  is  using  libcurl.
       Because curl_global_init(3) calls functions of other libraries that are
       similarly thread unsafe, it could conflict with any other  thread  that
       uses these other libraries.

       If  you are initializing libcurl from a Windows DLL you should not ini-
       tialize it from DllMain or a static initializer because  Windows  holds
       the loader lock during that time and it could cause a deadlock.

       See  the  description  in libcurl(3) of global environment requirements
       for details of how to use this function.

FLAGS
       CURL_GLOBAL_ALL
              Initialize everything possible. This sets all known bits  except
              CURL_GLOBAL_ACK_EINTR.

       CURL_GLOBAL_SSL
              Initialize SSL.

              The  implication  here  is that if this bit is not set, the ini-
              tialization of the SSL layer needs to be done by the application
              or  at  least  outside of libcurl. The exact procedure how to do
              SSL initializtion depends on the TLS backend libcurl uses.

              Doing TLS based transfers without having the TLS layer  initial-
              ized may lead to unexpected behaviors.

       CURL_GLOBAL_WIN32
              Initialize the Win32 socket libraries.

              The  implication  here  is that if this bit is not set, the ini-
              tialization of winsock has to be done by the application or  you
              risk  getting  undefined  behaviors. This option exists for when
              the initialization is handled outside of libcurl so  there's  no
              need for libcurl to do it again.

       CURL_GLOBAL_NOTHING
              Initialise nothing extra. This sets no bit.

       CURL_GLOBAL_DEFAULT
              A  sensible default. It will init both SSL and Win32. Right now,
              this equals the functionality of the CURL_GLOBAL_ALL mask.

       CURL_GLOBAL_ACK_EINTR
              When this flag is set, curl  will  acknowledge  EINTR  condition
              when connecting or when waiting for data.  Otherwise, curl waits
              until full timeout elapses. (Added in 7.30.0)

RETURN VALUE
       If this function returns non-zero, something went wrong and you  cannot
       use the other curl functions.

SEE ALSO
       curl_global_init_mem(3),    curl_global_cleanup(3),   curl_easy_init(3)
       libcurl(3)

libcurl 7.54.0                   June 29, 2016             curl_global_init(3)