Use UTF-8 backend by default on Windows.

lib/CMakeLists.txt

diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 524f23d..a7ffa99 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -121,7 +121,6 @@
   zip_source_crc.c
   zip_source_deflate.c
   zip_source_error.c
-  zip_source_file.c
   zip_source_filep.c
   zip_source_free.c
   zip_source_function.c
@@ -139,10 +138,6 @@
   zip_source_supports.c
   zip_source_tell.c
   zip_source_tell_write.c
-  zip_source_win32a.c
-  zip_source_win32file.c
-  zip_source_win32utf8.c
-  zip_source_win32w.c
   zip_source_window.c
   zip_source_write.c
   zip_source_zip.c
@@ -159,6 +154,19 @@
   zip_utf-8.c
 )
 
+IF(WIN32)
+  SET(LIBZIP_OPSYS_FILES
+    zip_source_win32a.c
+    zip_source_win32file.c
+    zip_source_win32utf8.c
+    zip_source_win32w.c
+  )
+ELSE(WIN32)
+  SET(LIBZIP_OPSYS_FILES
+    zip_source_file.c
+  )
+ENDIF(WIN32)
+
 INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR}
   ${CMAKE_CURRENT_BINARY_DIR}/..)
 
@@ -175,7 +183,7 @@
   SET(LIBZIP_EXTRA_FILES mkstemp.c)
 ENDIF(NOT HAVE_MKSTEMP)
 
-ADD_LIBRARY(zip SHARED ${LIBZIP_SOURCES} ${LIBZIP_EXTRA_FILES})
+ADD_LIBRARY(zip SHARED ${LIBZIP_SOURCES} ${LIBZIP_EXTRA_FILES} ${LIBZIP_OPSYS_FILES})
 SET_TARGET_PROPERTIES(zip PROPERTIES VERSION 3.0 SOVERSION 3 )
 TARGET_LINK_LIBRARIES(zip ${ZLIB_LIBRARY})
 INSTALL(TARGETS zip

lib/zip_source_win32utf8.c

diff --git a/lib/zip_source_win32utf8.c b/lib/zip_source_win32utf8.c
index 55988fe..f57c4ef 100644
--- a/lib/zip_source_win32utf8.c
+++ b/lib/zip_source_win32utf8.c
@@ -40,7 +40,7 @@
 
 
 ZIP_EXTERN zip_source_t *
-zip_source_win32utf8(zip_t *za, const char *fname, zip_uint64_t start, zip_int64_t len)
+zip_source_file(zip_t *za, const char *fname, zip_uint64_t start, zip_int64_t len)
 {
     if (za == NULL)
 	return NULL;
@@ -50,7 +50,7 @@
 
 
 ZIP_EXTERN zip_source_t *
-zip_source_win32utf8_create(const char *fname, zip_uint64_t start, zip_int64_t length, zip_error_t *error)
+zip_source_file_create(const char *fname, zip_uint64_t start, zip_int64_t length, zip_error_t *error)
 {
     int size;
     wchar_t *wfname;

lib/zip_source_win32w.c

diff --git a/lib/zip_source_win32w.c b/lib/zip_source_win32w.c
index b659edc..62f204e 100644
--- a/lib/zip_source_win32w.c
+++ b/lib/zip_source_win32w.c
@@ -1,5 +1,5 @@
 /*
-zip_source_win32w.c -- create data source from Windows file (Unicode)
+zip_source_win32w.c -- create data source from Windows file (UTF-16)
 Copyright (C) 1999-2014 Dieter Baron and Thomas Klausner
 
 This file is part of libzip, a library to manipulate ZIP archives.