gh-85283: Build termios extension with the limited C API

[vstinner]

• Issue: [C API] Convert a few stdlib extensions to the limited C API (PEP 384) #85283

---

📚 Documentation preview 📚: https://cpython-previews--116928.org.readthedocs.build/

[kulikjak]

Hi! After this commit, I am seeing the following errors when building main on Solaris:

/..../cpython/Modules/termios.c:430:20: error: 'errno' undeclared (first use in this function)
  430 |     if (r == -1 && errno == EINVAL) {
      |                    ^~~~~
/..../cpython/Modules/termios.c:56:1: note: 'errno' is defined in header '<errno.h>'; did you forget to '#include <errno.h>'?
   55 | #include "clinic/termios.c.h"
  +++ |+#include <errno.h>

AFAICT, this is because of the newly added #define Py_LIMITED_API 0x030d0000, which "hides" the errno.h include in Python.h (same as the newly added string.h include). When I add the missing include, it compiles again.

Should I create a PR with a fix?

[vstinner]

/..../cpython/Modules/termios.c:430:20: error: 'errno' undeclared (first use in this function)
  430 |     if (r == -1 && errno == EINVAL) {

That's strange. I cannot find this line in the main branch.

Do you have a patch on top of the main branch? If yes, you should consider to propose it upstream?

In main, I have:

    if (r == -1) {
        return PyErr_SetFromErrno(state->TermiosError);  // LINE 430
    }

[kulikjak]

Oh, I am very sorry. This is indeed from an internal patch and not in the termios.c sources...

It's a patch that workarounded an issue with the TIOCGWINSZ ioctl on Solaris, which is already fixed, and which I forgot to remove it (and since it was just a temporary workaround, I didn't upstream it).

[vstinner]

It's a patch that workarounded an issue with the TIOCGWINSZ ioctl on Solaris, which I forgot to remove before (and since it was just a temporary workaround, I didn't upstream it).

Well, either remove it, or propose it upstream. If you keep it, just add <errno.h> include ;-)