Why can't I use fopen?

Question

In the mold of a previous question I asked about the so-called safe library deprecations, I find myself similarly bemused as to why fopen() should be deprecated

Answer 1

Or is it something else?

Some implementations of the FILE structure used by 'fopen' has the file descriptor defined as 'unsigned short'. This leaves you with a maximum of 255 simultaneously open files, minus stdin, stdout, and stderr.

While the value of being able to have 255 open files is debatable, of course, this implementation detail materializes on the Solaris 8 platform when you have more than 252 socket connections! What first appeared as a seemingly random failure to establish an SSL connection using libcurl in my application turned out to be caused by this, but it took deploying debug versions of libcurl and openssl and stepping the customer through debugger script to finally figure it out.

While it's not entirely the fault of 'fopen', one can see the virtues of throwing off the shackles of old interfaces; the choice to deprecate might be based on the pain of maintaining binary compatibility with an antiquated implementation.