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curl_global_init(3)                 libcurl                curl_global_init(3)

NAME
       curl_global_init - Global libcurl initialization

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
       multiple calls have the same effect as one call.

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

       This function is thread-safe since libcurl 7.84.0 if
       curl_version_info(3) has the CURL_VERSION_THREADSAFE feature bit set
       (most platforms).

       If this is not thread-safe, you must not call this function when any
       other thread in the program (i.e. a thread sharing the same memory) is
       running.  This does not 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
       initialize 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
              (This flag's presence or absence serves no meaning since 7.57.0.
              The description below is for older libcurl versions.)

              Initialize SSL.

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

              Doing TLS based transfers without having the TLS layer
              initialized 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
              initialization 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
              Initialize 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
              This bit has no point since 7.69.0 but its behavior is instead
              the default.

              Before 7.69.0: 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)

EXAMPLE
        curl_global_init(CURL_GLOBAL_DEFAULT);

        /* use libcurl, then before exiting... */

        curl_global_cleanup();

AVAILABILITY
       Added in 7.8

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_global_sslset(3),  curl_easy_init(3)  libcurl(3)

libcurl 8.1.2                   April 26, 2023             curl_global_init(3)