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libcares/INSTALL.md  view on Meta::CPAN

(This section was graciously brought to us by Jim Duey, with additions by
Dan Fandrich)

Download and unpack the c-ares package.

`cd` to the new directory. (e.g. `cd c-ares-1.7.6`)

Set environment variables to point to the cross-compile toolchain and call
configure with any options you need.  Be sure and specify the `--host` and
`--build` parameters at configuration time.  The following script is an
example of cross-compiling for the IBM 405GP PowerPC processor using the
toolchain from MonteVista for Hardhat Linux.

```sh
#! /bin/sh

export PATH=$PATH:/opt/hardhat/devkit/ppc/405/bin
export CPPFLAGS="-I/opt/hardhat/devkit/ppc/405/target/usr/include"
export AR=ppc_405-ar
export AS=ppc_405-as
export LD=ppc_405-ld
export RANLIB=ppc_405-ranlib
export CC=ppc_405-gcc
export NM=ppc_405-nm

./configure --target=powerpc-hardhat-linux \
     --host=powerpc-hardhat-linux \
     --build=i586-pc-linux-gnu \
     --prefix=/opt/hardhat/devkit/ppc/405/target/usr/local \
     --exec-prefix=/usr/local
```

You may also need to provide a parameter like `--with-random=/dev/urandom`
to configure as it cannot detect the presence of a random number
generating device for a target system.  The `--prefix` parameter
specifies where c-ares will be installed.  If `configure` completes
successfully, do `make` and `make install` as usual.

In some cases, you may be able to simplify the above commands to as
little as:

    ./configure --host=ARCH-OS


### Cygwin (Windows)

Almost identical to the unix installation. Run the configure script in the
c-ares root with `sh configure`. Make sure you have the sh executable in
`/bin/` or you'll see the configure fail toward the end.

Run `make`


### QNX

(This section was graciously brought to us by David Bentham)

As QNX is targeted for resource constrained environments, the QNX headers
set conservative limits. This includes the `FD_SETSIZE` macro, set by default
to 32. Socket descriptors returned within the c-ares library may exceed this,
resulting in memory faults/SIGSEGV crashes when passed into `select(..)`
calls using `fd_set` macros.

A good all-round solution to this is to override the default when building
c-ares, by overriding `CFLAGS` during configure, example:

    # configure CFLAGS='-DFD_SETSIZE=64 -g -O2'


### RISC OS

The library can be cross-compiled using gccsdk as follows:

    CC=riscos-gcc AR=riscos-ar RANLIB='riscos-ar -s' ./configure \
         --host=arm-riscos-aof --without-random --disable-shared
    make

where `riscos-gcc` and `riscos-ar` are links to the gccsdk tools.
You can then link your program with `c-ares/lib/.libs/libcares.a`.


### Android

Method using a configure cross-compile (tested with Android NDK r7b):

  - prepare the toolchain of the Android NDK for standalone use; this can
    be done by invoking the script:

        ./tools/make-standalone-toolchain.sh

    which creates a usual cross-compile toolchain. Lets assume that you put
    this toolchain below `/opt` then invoke configure with something
    like:

    ```
        export PATH=/opt/arm-linux-androideabi-4.4.3/bin:$PATH
       ./configure --host=arm-linux-androideabi [more configure options]
        make
    ```
  - if you want to compile directly from our GIT repo you might run into
    this issue with older automake stuff:

    ```
        checking host system type...
        Invalid configuration `arm-linux-androideabi':
        system `androideabi' not recognized
        configure: error: /bin/sh ./config.sub arm-linux-androideabi failed
    ```
    this issue can be fixed with using more recent versions of `config.sub`
    and `config.guess` which can be obtained here:
    http://git.savannah.gnu.org/gitweb/?p=config.git;a=tree
    you need to replace your system-own versions which usually can be
    found in your automake folder:
    `find /usr -name config.sub`


CMake builds
============

Current releases of c-ares introduce a CMake v3+ build system that has been
tested on most platforms including Windows, Linux, FreeBSD, MacOS, AIX and