Fix cabd tests on Windows

On Windows, the tests should write to "NUL" instead of "/dev/null".

Resolved an issue where a large unsigned int cast to an off_t resulted
in a negative value, because off_t is 32-bits instead of 64.

libmspack/mspack/cabd.c

@@ -1012,7 +1012,7 @@ static int cabd_extract(struct mscab_decompressor *base,
   struct mscabd_folder_p *fol;
   struct mspack_system *sys;
   struct mspack_file *fh;
-  off_t filelen;
+  unsigned int filelen;
 
   if (!self) return MSPACK_ERR_ARGS;
   if (!file) return self->error = MSPACK_ERR_ARGS;
@@ -1049,7 +1049,7 @@ static int cabd_extract(struct mscab_decompressor *base,
    * In salvage mode, don't assume block sizes, just try decoding
    */
   if (!self->salvage) {
-    off_t maxlen = fol->base.num_blocks * CAB_BLOCKMAX;
+    unsigned int maxlen = fol->base.num_blocks * CAB_BLOCKMAX;
     if ((file->offset + filelen) > maxlen) {
       sys->message(NULL, "ERROR; file \"%s\" cannot be extracted, "
                    "cabinet set is incomplete", file->filename);

libmspack/test/cabd_md5.c

@@ -7,7 +7,7 @@
 #include <string.h>
 #include "mspack.h"
 #include <sys/stat.h>
-#ifdef _WIN32
+#ifdef _MSC_VER
 #include "dirent.h"
 #else
 #include <dirent.h>

libmspack/test/cabd_test.c

@@ -20,6 +20,13 @@ unsigned int test_count = 0;
     if (!(x)) {printf("%s:%d FAILED %s\n",__func__,__LINE__,#x);exit(1);} \
 } while (0)
 
+
+#ifdef _MSC_VER
+# define DEV_NULL "NUL"
+#else
+# define DEV_NULL "/dev/null"
+#endif
+
 /* open where cab file doesn't exist */
 void cabd_open_test_01() {
     struct mscab_decompressor *cabd;
@@ -342,7 +349,7 @@ void cabd_extract_test_01() {
         TEST(cab = cabd->open(cabd, files[i]));
         TEST(cab->files != NULL);
         for (file = cab->files; file; file = file->next) {
-            int err = cabd->extract(cabd, file, "/dev/null");
+            int err = cabd->extract(cabd, file, DEV_NULL);
             TEST(err == MSPACK_ERR_DATAFORMAT || err == MSPACK_ERR_DECRUNCH);
         }
         cabd->close(cabd, cab);
@@ -363,11 +370,11 @@ void cabd_extract_test_02() {
      */
     TEST(cabd = mspack_create_cab_decompressor(NULL));
     TEST(cab = cabd->open(cabd, TESTFILE("cve-2014-9732-folders-segfault.cab")));
-    err = cabd->extract(cabd, cab->files, "/dev/null");
+    err = cabd->extract(cabd, cab->files, DEV_NULL);
     TEST(err == MSPACK_ERR_OK);
-    err = cabd->extract(cabd, cab->files->next, "/dev/null");
+    err = cabd->extract(cabd, cab->files->next, DEV_NULL);
     TEST(err == MSPACK_ERR_DATAFORMAT || err == MSPACK_ERR_DECRUNCH);
-    err = cabd->extract(cabd, cab->files, "/dev/null");
+    err = cabd->extract(cabd, cab->files, DEV_NULL);
     TEST(err == MSPACK_ERR_OK);
     cabd->close(cabd, cab);
     mspack_destroy_cab_decompressor(cabd);