open gmsh file in binary mode (!353) · Merge requests · Core Modules / dune-grid · GitLab

Liam Keegan requested to merge liam.keegan/dune-grid:gmsh_reader_fix into master Sep 16, 2019

otherwise on windows it is opened in text mode
- ftell/fseek on windows only work correctly on binary files
- see e.g. https://stackoverflow.com/questions/47256223/why-does-fseek-0-seek-cur-fail-on-windows
- this makes no difference on posix systems

also: use ftello/fseeko with type off_t instead of ftell/fseek with type long

https://www.gnu.org/software/libc/manual/html_node/File-Positioning.html
"using ftello is preferable whenever it is available"