errno – Tarik Billa

Which systems define EAGAIN and EWOULDBLOCK as different values?

December 27, 2023 by Tarik

There were some… http://www.gnu.org/s/hello/manual/libc/Error-Codes.html Portability Note: In many older Unix systems, this condition was indicated by EWOULDBLOCK, which was a distinct error code different from EAGAIN. To make your program portable, you should check for both codes and treat them the same. http://lists.parisc-linux.org/hypermail/parisc-linux/9895.html On some SysV systems EAGAIN != EWOULDBLOCK. I think we inherited the … Read more

How to catch Errno::ECONNRESET class in “case when”?

December 12, 2023 by Tarik

This is because of how the === operator works on the class Class The case statement internally calls the === method on the object you are evaluating against. If you want to test for e class, you just test against e, not e.class. That’s because e.class would fall into the when Class case, because, well, … Read more

Cannot assign requested address – possible causes?

November 22, 2023 by Tarik

It turns out that the problem really was that the address was busy – the busyness was caused by some other problems in how we are handling network communications. Your inputs have helped me figure this out. Thank you. EDIT: to be specific, the problems in handling our network communications were that these status updates … Read more

Why return a negative errno? (e.g. return -EIO)

September 20, 2023 by Tarik

First, this isn’t really a C thing. You’re looking at a function that is written in C for some purpose. The same conventions could be used in any language. Back in my old Unix days, there was something of a convention that 0 meant success, a positive number meant minor problems, and a negative number … Read more

Is there a way to use errno safely in a multi-threaded application? [duplicate]

September 11, 2023 by Tarik

If your standard library is multithread aware, then it probably has a #define that changes errno into a function call that returns a thread-local error return value. However, to use this you generally must include <errno.h>, rather than relying on an extern declaration. I found an article Thread-safety and POSIX.1 which addresses this very question.

Unable to run Protractor – ECONNREFUSED connect ECONNREFUSED

July 21, 2023 by Tarik

I solved this with –standalone flag: webdriver-manager start –standalone

How to convert errno in UNIX to corresponding string?

May 30, 2023 by Tarik

strerror() should do it. http://linux.die.net/man/3/strerror FYI, so that you can find these things more easily, yourself: If you type man errno (or whatever function you’re investigating), and look at the very bottom of the man page, you’ll see a list of related functions. If you man each of those (taking a guess about which one(s) … Read more

How to set errno value?

May 16, 2023 by Tarik

For all practical purposes, you can treat errno like a global variable (although it’s usually not). So include errno.h and just use it: errno = ENOENT; You should ask yourself if errno is the best error-reporting mechanism for your purposes. Can the functions be engineered to return the error code themselves ?

Should I set errno?

May 11, 2023 by Tarik

This is a bit old, but errno – manual section 3 says that you can directly assign to it, even though it is a macro, and it will be thread local

Is &errno legal C?

April 25, 2023 by Tarik

So §6.5.3.2p1 specifies The operand of the unary & operator shall be either a function designator, the result of a [] or unary * operator, or an lvalue that designates an object that is not a bit-field and is not declared with the register storage-class specifier. Which I think can be taken to mean that … Read more