Add instructions for Windows compilation

.gitignore

@@ -82,6 +82,15 @@ test/junk_data
 test/s3proxy-*
 test/write_multiblock
 
+#
+# Windows ports
+#
+*.dll
+*.exe
+fuse.pc
+WinFsp/
+bin/
+
 #
 # Local variables:
 # tab-width: 4

COMPILATION.md

@@ -32,3 +32,58 @@ cd s3fs-fuse
 make
 sudo make install
 ```
+
+## Compilation on Windows (using MSYS2)
+
+On Windows, use [MSYS2](https://www.msys2.org/) to compile for itself.
+
+1. Install [WinFsp](https://github.com/billziss-gh/winfsp) to your machine.
+2. Install dependencies onto MSYS2:
+
+   ```sh
+   pacman -S git autoconf automake gcc make pkg-config libopenssl-devel libcurl-devel libxml2-devel libzstd-devel
+   ```
+
+3. Clone this repository, then change directory into the cloned one.
+4. Copy WinFsp files to the directory:
+
+   ```sh
+   cp -r "/c/Program Files (x86)/WinFsp" "./WinFsp"
+   ```
+
+5. Write `fuse.pc` to resolve the package correctly:
+
+   ```sh
+   cat > ./fuse.pc << 'EOS'
+   arch=x64
+   prefix=${pcfiledir}/WinFsp
+   incdir=${prefix}/inc/fuse
+   implib=${prefix}/bin/winfsp-${arch}.dll
+
+   Name: fuse
+   Description: WinFsp FUSE compatible API
+   Version: 2.8.4
+   URL: http://www.secfs.net/winfsp/
+   Libs: "${implib}"
+   Cflags: -I"${incdir}"
+   EOS
+   ```
+
+6. Compile using the command line:
+
+   ```sh
+   ./autogen.sh
+   PKG_CONFIG_PATH="$PKG_CONFIG_PATH:$(pwd)" ./configure
+   make
+   ```
+
+7. Copy binary files to distribute at one place:
+
+   ```sh
+   mkdir ./bin
+   cp ./src/s3fs.exe ./bin/
+   cp ./WinFsp/bin/winfsp-x64.dll ./bin/
+   cp /usr/bin/msys-*.dll ./bin/
+   ```
+
+8. Distribute these files.