start to impliment mscp as a library

this commit starts to refactor file.h|c to path.h|c and
add mscp.c|h. not completed yet.

src/mscp.h

@@ -0,0 +1,43 @@
+#ifndef _MSCP_H_
+#define _MSCP_H_
+
+#include <stdbool.h>
+
+#define MSCP_DIRECT_L2R	1
+#define MSCP_DIRECT_R2L	2
+
+struct mscp_opts {
+	/* mscp options */
+	int	direct;	/* MSCP_DIRECT_ */
+
+	int	nr_threads;
+	int	nr_ahead;
+	size_t	min_chunk_sz;
+	size_t	max_chunk_sz;
+	size_t	buf_sz;
+
+	int	verbose_level;
+	bool	quiet;
+	bool	dryrun;
+
+	/* ssh options */
+	char	ssh_login_name[64];
+	char	ssh_port[32];
+	char	ssh_identity[PATH_MAX];
+	char	ssh_cipher_spec[64];
+	char	ssh_hmac_spec[32];
+	int	ssh_debug_level;
+	int	ssh_compress_level;
+	bool	ssh_no_hostkey_check;
+	bool	ssh_disable_tcp_nodely;
+};
+
+struct mscp;
+
+struct mscp *mscp_init(const char *remote_host, struct mscp_opts *opts);
+int mscp_add_src_path(struct mscp *m, const char *src_path);
+int mscp_set_dst_path(struct mscp *m, const char *dst_path);
+int mscp_prepare(struct mscp *m);
+int mscp_start(struct mscp *m);
+
+#endif /* _MSCP_H_ */