tmpfile() on MS Windows

create temporary files with Microsoft specific fopen() flags "TD"
and (propably redundant) remove them with an atexit() handler

see bug report #3535348
  "sp*.tmp file created, but not deleted when Windows UAC is en"
  https://sourceforge.net/tracker/?func=detail&atid=423915&aid=3535348&group_id=38962

src/main.c

@@ -45,7 +45,11 @@
 #include "misc/misc_time.h"
 
 #if defined(HAS_WINDOWS) || defined(_MSC_VER) || defined(__MINGW32__)
+# include <stdio.h>
 # include "misc/mktemp.h"
+static char *tpf; /* temporary file by name */
+static FILE *tempfile; /* temporary file */
+static void delete_tpf(void);
 #endif
 
 #if defined(HAVE_GETOPT_LONG) && defined(HAVE_GETOPT_H)
@@ -1167,23 +1171,28 @@ main(int argc, char **argv)
                current algorithm is uniform at the expense of a little
                startup time.  */
 
-            FILE *tempfile = tmpfile();
 
 #if defined(HAS_WINDOWS) || defined(_MSC_VER) || defined(__MINGW32__)
-            char *tpf = NULL;     /* temporary file */
             char *dname = NULL;   /* input file*/
+            tpf = NULL;     /* temporary file */
+            tempfile = tmpfile();
 
             /* tmpfile() returns NULL, if in MS Windows as non admin user
-               then we add a tempfile in the local directory */
+               in directory C:\something (no write permission to root C:).
+               Then we add a tempfile in the local directory.
+               File will be removed again at exit() using atexit() */
 
             if (tempfile == NULL) {
+                atexit(delete_tpf);
                 tpf = smktemp("sp");
-                tempfile = fopen(tpf, "w+b");
+                tempfile = fopen(tpf, "w+bTD");
                 if (tempfile == NULL) {
                     fprintf(stderr, "Could not open a temporary file to save and use optional arguments.");
                     sp_shutdown(EXIT_BAD);
                 }
             }
+#else
+            FILE *tempfile = tmpfile();
 #endif
 
             if(!tempfile) {
@@ -1245,11 +1254,6 @@ main(int argc, char **argv)
                 gotone = TRUE;
             }
 
-#if defined(HAS_WINDOWS) || defined(_MSC_VER) || defined(__MINGW32__)
-            if (tpf && (unlink(tpf)==-1))
-                perror("Could not delete temp file");
-#endif
-
             if (ft_batchmode && err)
                 sp_shutdown(EXIT_BAD);
 
@@ -1345,3 +1349,23 @@ main(int argc, char **argv)
     sp_shutdown(EXIT_NORMAL);
     return 0;
 }
+
+
+#if defined(HAS_WINDOWS) || defined(_MSC_VER) || defined(__MINGW32__)
+
+/* For using with atexit */
+void delete_tpf(void)
+{
+    if(tempfile) {
+        fclose(tempfile);
+        tempfile = NULL;
+    }
+
+    if (tpf) {
+        if (unlink(tpf) == -1)
+            perror("Could not delete temp file\n");
+        tpf = NULL;
+    }
+}
+
+#endif