[GitHub] [incubator-nuttx-apps] xiaoxiang781216 commented on pull request #226: apps: Change all "set_errno(xxx);" to "errno = xxx;"

[GitBox <gi...@apache.org>]

xiaoxiang781216 commented on pull request #226:
URL: https://github.com/apache/incubator-nuttx-apps/pull/226#issuecomment-622961165


   > Have you tried this in protected and/or kernel build modes. There might be probablys write to the errno in those cases since the errno resides in the TCB which is not accessible. In those modes set_errno() is a function call that goes through a syscall and error is defined to be get_errno() which will only support read access.
   > 
   
   Yes, you are right. userspace can't access TCB directly in protected/kernel build.
   
   > So reading the errno in the modes is okay, but writing must explicitly use set_errno(). That does break the standard but I am open to other technical solutions.
   
   What I can imagine:
   1.Move errno to userspace(e.g. at the begining of thread stack)
   2.Overwrite assignment operatior(but require C++)
   


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