Building with Visual C++, prerequisites
=======================================

   This document describes how to compile, build and install curl and libcurl
   from sources using the Visual C++ build tool. To build with VC++, you will
   of course have to first install VC++. The minimum required version of
   VC is 6 (part of Visual Studio 6). However using a more recent version is
   strongly recommended.

   VC++ is also part of the Windows Platform SDK. You do not have to install
   the full Visual Studio or Visual C++ if all you want is to build curl.

   The latest Platform SDK can be downloaded freely from:

    https://msdn.microsoft.com/en-us/windows/bb980924

   If you are building with VC6 then you will also need the February 2003
   Edition of the Platform SDK which can be downloaded from:

    https://www.microsoft.com/en-us/download/details.aspx?id=12261

   If you wish to support zlib, openssl, c-ares, ssh2, you will have to download
   them separately and copy them to the deps directory as shown below:

   somedirectory\
    |_curl-src
    | |_winbuild
    |
    |_deps
      |_ lib
      |_ include
      |_ bin

   It is also possible to create the deps directory in some other random
   places and tell the Makefile its location using the WITH_DEVEL option.

Building straight from git
==========================

 When you check out code git and build it, as opposed from a released source
 code archive, you need to first run the "buildconf.bat" batch file (present
 in the source code root directory) to set things up.

Building with Visual C++
========================

Open a Visual Studio Command prompt or the SDK CMD shell.

    Using the CMD Shell:
     choose the right environment via the setenv command (see setenv /?)
     for the full list of options. setenv /xp /x86 /release for example.

    Using the Visual Studio command prompt Shell:
     Everything is already pre-configured by calling one of the command
     prompt.

Once you are in the console, go to the winbuild directory in the Curl
sources:
    cd curl-src\winbuild

Then you can call nmake /f Makefile.vc with the desired options (see below).
The builds will be in the top src directory, builds\ directory, in
a directory named using the options given to the nmake call.

nmake /f Makefile.vc mode=<static or dll> <options>

where <options> is one or many of:
  VC=<6,7,8,9,10,11,12,14,15>  - VC versions
  WITH_DEVEL=<path>            - Paths for the development files (SSL, zlib, etc.)
                                 Defaults to sibbling directory deps: ../deps
                                 Libraries can be fetched at http://windows.php.net/downloads/php-sdk/deps/
                                 Uncompress them into the deps folder.
  WITH_SSL=<dll or static>     - Enable OpenSSL support, DLL or static
  WITH_NGHTTP2=<dll or static> - Enable HTTP/2 support, DLL or static
  WITH_MBEDTLS=<dll or static> - Enable mbedTLS support, DLL or static
  WITH_CARES=<dll or static>   - Enable c-ares support, DLL or static
  WITH_ZLIB=<dll or static>    - Enable zlib support, DLL or static
  WITH_SSH2=<dll or static>    - Enable libSSH2 support, DLL or static
  ENABLE_SSPI=<yes or no>      - Enable SSPI support, defaults to yes
  ENABLE_IPV6=<yes or no>      - Enable IPv6, defaults to yes
  ENABLE_IDN=<yes or no>       - Enable use of Windows IDN APIs, defaults to yes
                                 Requires Windows Vista or later, or installation from:
                                 https://www.microsoft.com/downloads/details.aspx?FamilyID=AD6158D7-DDBA-416A-9109-07607425A815
  ENABLE_WINSSL=<yes or no>    - Enable native Windows SSL support, defaults to yes
  GEN_PDB=<yes or no>          - Generate Program Database (debug symbols for release build)
  DEBUG=<yes or no>            - Debug builds
  MACHINE=<x86 or x64>         - Target architecture (default is x86)

Static linking of Microsoft's C RunTime (CRT):
==============================================
If you are using mode=static nmake will create and link to the static build of
libcurl but *not* the static CRT. If you must you can force nmake to link in
the static CRT by passing RTLIBCFG=static. Typically you shouldn't use that
option, and nmake will default to the DLL CRT. RTLIBCFG is rarely used and
therefore rarely tested. When passing RTLIBCFG for a configuration that was
already built but not with that option, or if the option was specified
differently, you must destroy the build directory containing the configuration
so that nmake can build it from scratch.

Legacy Windows and SSL
======================
When you build curl using the build files in this directory the default SSL
backend will be WinSSL (Windows SSPI, more specifically Schannel), the native
SSL library that comes with the Windows OS. WinSSL in Windows <= XP is not able
to connect to servers that no longer support the legacy handshakes and
algorithms used by those versions. If you will be using curl in one of those
earlier versions of Windows you should choose another SSL backend like OpenSSL.
