Replace use of iostream-based classes

[mobin-2008]

Fixes #240

Hi.
We already discussed about some technical points about this new implementation in #240 and here's its PR

My plan

My plan has 4 sections:
low-level header: dinit-iostream.h

• ostream
  ostream is a low-level library and will be used for writing into file descriptors, This class provide a buffer for each output stream (4K buffer size yet) and provide print() function for writing into fds. print() and printerr() are designed to replace cout and cerr. Here's basic usage of them:

dio::print("Hello World\n");
std::string service_name = "boot";
unsigned load_time = 12;
dio::printerr("Dinit loaded", service_name, "in", load_time, "seconds");

• istream
  same as ostream but for reading from file descriptors. ToDo

high-level header: dinit-fstream.h

• ofstream
  ofstream is a high-level library and will be used for writing into files, This class open a file and create a ostream object and will provide some functions such as open(). ToDo
• ifstream
  same as ofstream but for reading from files. ToDo

Also dinitcheck modified to use these new header(s) for catching any regression. I hope it'll be on right track. Regards

Signed-off-by: Mobin "Hojjat" Aydinfar <[email protected]>

[mobin-2008]

We need to have "endl"?

[davmac314]

The endl there looks superfluous. It might be needed elsewhere, if the buffer needs to be flushed.

[mobin-2008]

syncing with stdio is disabled by default, Is it fine?

[davmac314]

is this supposed to be the equivalent of ios_base::sync_with_stdio? The comment doesn't match that. What do you mean by "sync with stdio"?

[davmac314]

Please make your own judgement and we can discuss if necessary when the PR is complete. You did ask to take on this issue so it is your responsibility! If there are questions you really can't resolve, you can ask them in the issue so we have a reasonable record of the decisions there.

I would prefer not to have draft PRs - they are distracting (for me, due to all the notifications) and not a good way to discuss technical details. If you need to show some example of code in a discussion, you can link to one of your own branches for example. I'm going to unsubscribe from this PR, you will need to notify me when it is ready.

[mobin-2008]

I will create a new PR when it mostly done