in src/main/cpp/zipcompressaction.cpp [55:150]
bool ZipCompressAction::execute(log4cxx::helpers::Pool& p) const
{
	if (!priv->source.exists(p))
	{
		return false;
	}
	apr_pool_t* aprpool = p.getAPRPool();
	apr_procattr_t* attr;
	apr_status_t stat = apr_procattr_create(&attr, aprpool);
	if (stat != APR_SUCCESS)
	{
		throw IOException(stat);
	}
	stat = apr_procattr_io_set(attr, APR_NO_PIPE, APR_NO_PIPE, APR_FULL_BLOCK);
	if (stat != APR_SUCCESS)
	{
		throw IOException(stat);
	}
	stat = apr_procattr_cmdtype_set(attr, APR_PROGRAM_PATH);
	if (stat != APR_SUCCESS)
	{
		throw IOException(stat);
	}
	//
	// redirect the child's error stream to this processes' error stream
	//
	apr_file_t* child_err;
	stat = apr_file_open_stderr(&child_err, aprpool);
	if (stat == APR_SUCCESS)
	{
		stat =  apr_procattr_child_err_set(attr, child_err, NULL);
		if (stat != APR_SUCCESS)
		{
			throw IOException(stat);
		}
	}
	const char** args = (const char**)
		apr_palloc(aprpool, 5 * sizeof(*args));
	int i = 0;
	args[i++] = "zip";
	args[i++] = "-q";
	args[i++] = Transcoder::encode(priv->destination.getPath(), p);
	args[i++] = Transcoder::encode(priv->source.getPath(), p);
	args[i++] = NULL;
	if (priv->destination.exists(p))
	{
		priv->destination.deleteFile(p);
	}
	apr_proc_t pid;
	stat = apr_proc_create(&pid, "zip", args, NULL, attr, aprpool);
	if (stat != APR_SUCCESS && priv->throwIOExceptionOnForkFailure)
	{
		throw IOException(stat);
	}else if(stat != APR_SUCCESS && !priv->throwIOExceptionOnForkFailure)
	{
		/* If we fail here (to create the zip child process),
		 * skip the compression and consider the rotation to be
		 * otherwise successful. The caller has already rotated
		 * the log file (`source` here refers to the
		 * uncompressed, rotated path, and `destination` the
		 * same path with `.zip` appended). Remove the empty
		 * destination file and leave source as-is.
		 */
		LogLog::warn(LOG4CXX_STR("Failed to fork zip during log rotation; leaving log file uncompressed"));
		return true;
	}
	int exitCode;
	apr_proc_wait(&pid, &exitCode, NULL, APR_WAIT);
	if (exitCode != APR_SUCCESS)
	{
		throw IOException(exitCode);
	}
	if (priv->deleteSource)
	{
		priv->source.deleteFile(p);
	}
	return true;
}