Hi Michael, On 2020-09-07 11:21, Michael Kerrisk (man-pages) wrote:
Or is it that those functions return an error code that corresponds to a valid `errno` error number? In that case it could be documented better IMHO.Yes, probably you are right. The thing is, when you use pthreads you have to know they are different from the conventional APIs. The pthreads(7) page hints at this: Most pthreads functions return 0 on success, and an error number on failure. Note that the pthreads functions do not set errno.If that is the case, do those functions set `errno` and also return that same `errno` value redundantly?No, they don't use errno at all. So, I exp[anded the text in pthreads(7), to make the point more explicit: Most pthreads functions return 0 on success, and an error number on failure. The error numbers that can be returned have the same meaning as the error numbers returned in errno by conventional system calls and C library functions. Note that the pthreads functions do not set errno. Note that the various pthreads manual pages (should) all refer to pthreads(7) in SEE ALSO. I'm reluctant to add a note like this to every pthreads page, since it seems verbose, but I have also added this note to errno(3): Note that the POSIX threads APIs do not set errno on error. Instead, on failure they return an error number as the function result. These error numbers have the same meanings as the error numbers returned in errno by other APIs. Perhaps that suffices for you?
Yes, that is much clearer now. Thanks, Alex
