Sending file to crow backend

[mihdim777]

Hello!

I am trying to send a file (any extension) to a backend crow server.

I am using this piece of code and somehow files don't have the same SHA hash.
In Visual Studio I have set to C++17 and Character Set to Use Multi-Byte Character Set.

CROW_ROUTE(app, "/file").methods("POST"_method) ([](const crow::request& req){
		crow::multipart::message msg(req);
		
		auto filepath = msg.parts[0].body;
		auto file = msg.parts[1].body;

		auto file_handler = std::ofstream(filepath);
		file_handler << file;

		file_handler.close();

		return crow::response(200, "Ok");
		});

What am I doing wrong?

Thank you!

[The-EDev]

I ran your code on my machine (Linux), everything worked fine..

I'm using GCC 11.1.0

[The-EDev]

Do you mind telling me how you got Crow and which version you're using? Thanks.

[epajarre]

Does the resulting file have the same size?

I sort of suspect Windows binary/non binary file issue. You could test opening your output file with binary mode flag.

[The-EDev]

Sorry for the late response, I was spinning up a windows VM to test, there is definitely something weird going on, Crow seems to be duplicating newlines in the written file.. I'll look into it further

Well it seems to only happen on windows, same data with Linux produces fine results

[The-EDev]

@epajarre I don't have much experience with windows, the example shows a text file and @mihdim777 is saying the SHA checksum isn't matching..

[The-EDev]

Okay I ran VS debugger, it's not Crow's fault, windows uses CRLF (carriage return, line feed) for a newline, somehow when you're doing file_handler << file; it's duplicating every CR character

Notice how every 0d in this sequence is being repeated,
0d = CR
0a = LF

[epajarre]

So using something like this:

auto file_handler = std::ofstream(filepath,std::ofstream::binary);

should fix the issue.

[mihdim777]

Hello!

Sorry for late response and thank you guys for helping!

@The-EDev Thank you very much for investigation. Indeed it was from Windows machine with that CRLF.

@epajarre yes, by specifying binary ofstream did the trick and now they have the same SHA and files are reopened perfectly.

I'm using the code version from this repo.

Do you think it is a good idea to implement in crow a function to handle file opening, writing and closing? Should I create a PR?

[mihdim777]

Hello!

Also I found this after redownloading this the latest version:

Here is exception threw on this code:

`
#define CROW_MAIN
#include "crow.h"

int main()
{
crow::SimpleApp app;

  CROW_ROUTE(app, "/")([](){
      return "Hello world";
  });

  app.port(8080).multithreaded().run();

}
`

And here is the call stack from routing.h

[mihdim777]

@The-EDev , @epajarre

By adding check for blueprints, route is working again, I am getting response from the server.

[The-EDev]

Also I found this after redownloading this the latest version

Thanks for taking note of this problem, it's been fixed in #208 which I just merged

[The-EDev]

Do you think it is a good idea to implement in crow a function to handle file opening, writing and closing?

I'm not sure, std::ofstream is already simple enough in my opinion, doesn't make much sense to wrap it

[The-EDev]

Thanks for your help @epajarre, I had completely forgotten about std::ofstream::binary.

I'll close this issue since the problem is fixed.