MDEV-11127 : Fix innochecksum to work with large files on Windows.

- don't use stat() for file size, it doesn not handle large size
  use GetFileSizeEx() instead

- don't use lseek(), it can't handle large files, use _lseeki64() instead.

- Also, switch off OS file buffering for innochecksum on Windows,
to avoid thrashing file cache.

extra/innochecksum.cc

@@ -243,10 +243,9 @@ int main(int argc, char **argv)
   time_t lastt;                  /* last time */
   ulint oldcsum, oldcsumfield, csum, csumfield, crc32, logseq, logseqfield;
                                  /* ulints for checksum storage */
-  struct stat st;                /* for stat, if you couldn't guess */
   unsigned long long int size;   /* size of file (has to be 64 bits) */
   ulint pages;                   /* number of pages in file */
-  off_t offset= 0;
+  unsigned long long offset= 0;
   int fd;
 
   printf("InnoDB offline file checksum utility.\n");
@@ -269,6 +268,47 @@ int main(int argc, char **argv)
     goto error;
   }
 
+#ifdef _WIN32
+  /* Switch off OS file buffering for the file. */
+
+  HANDLE h = CreateFile(filename, GENERIC_READ,
+   FILE_SHARE_READ|FILE_SHARE_WRITE, 0,
+   OPEN_EXISTING, FILE_FLAG_NO_BUFFERING, 0);
+
+  if (!h)
+  {
+    fprintf(stderr, "Error; cant open file\n");
+    goto error;
+  }
+
+  if (!GetFileSizeEx(h, (LARGE_INTEGER *)&size))
+  {
+    fprintf(stderr, "Error; GetFileSize() failed\n");
+    goto error;
+  }
+
+  fd = _open_osfhandle ((intptr_t) h, _O_RDONLY);
+  if (fd < 0)
+  {
+    fprintf(stderr, "Error; _open_osfhandle() failed\n");
+    goto error;
+  }
+
+  f = _fdopen(fd, "rb");
+  if (!f)
+  {
+    fprintf(stderr, "Error; fdopen() failed\n");
+    goto error;
+  }
+
+  /*
+    Disable stdio buffering (FILE_FLAG_NO_BUFFERING requires properly IO buffers
+    which stdio does not guarantee.
+  */
+  setvbuf(f, NULL, _IONBF, 0);
+
+#else
+  struct stat st;
   /* stat the file to get size and page count */
   if (stat(filename, &st))
   {
@@ -279,6 +319,8 @@ int main(int argc, char **argv)
 
   /* Open the file for reading */
   f= fopen(filename, "rb");
+#endif
+
   if (f == NULL)
   {
     fprintf(stderr, "Error; %s cannot be opened", filename);
@@ -323,7 +365,7 @@ int main(int argc, char **argv)
   }
   else if (verbose)
   {
-    printf("file %s = %llu bytes (%lu pages)...\n", filename, size, pages);
+    printf("file %s = %llu bytes (%lu pages)...\n", filename, size, (ulong)pages);
     if (do_one_page)
       printf("InnoChecksum; checking page %lu\n", do_page);
     else
@@ -348,9 +390,12 @@ int main(int argc, char **argv)
       goto error;
     }
 
-    offset= (off_t)start_page * (off_t)physical_page_size;
-
+    offset= (ulonglong)start_page * (ulonglong)physical_page_size;
+#ifdef _WIN32
+    if (_lseeki64(fd, offset, SEEK_SET) != offset)
+#else
     if (lseek(fd, offset, SEEK_SET) != offset)
+#endif
     {
       perror("Error; Unable to seek to necessary offset");
       goto error;