MinGW program

I'm porting a small app from linux to windows and I need a replacement for truncate() function

will this:

FILE *file;
char *path="/tmp/aaa.txt";
long outpos;
file = fopen(path);
/* some code changing file */
chsize(file->_file, outpos);
fclose(file);

work as in the same way as truncate()?

file = fopen(path);
FAIL.
FILE * fopen(const char * restrict path, const char * restrict mode);

truncate(path);
FAIL.
int truncate(const char *path, off_t length);

also, if you have the file open for writing you can just use ftruncate() on the file descriptor (file) instead of using truncate() on the path.
ftruncate() is in mingw's unistd.h.