Date: Sun, 5 Feb 2017 17:04:43 -0600 From: "A. Wilcox" <awilfox@...lielinux.org> To: musl@...ts.openwall.com Subject: The Great Big POSIX Conformance Thread [phase 1] Hello fellow muslers, I have been reading through the source tree of musl for two reasons. One is to familiarise myself with the codebase more so that I can be of better use if/when patches need to be written. The other is doing a cursory audit of POSIX conformance per XSH 2008 (2016 ed.); we at Adélie are in the beginning stages of acquiring a license to the VSX-PCTS2016 test suite (which would be phase 2) and I thought it'd be prudent to find any obvious errors before obtaining it. I have found some non-conformant functions through my audit. Four are (hopefully) easy to fix; two require more thought; and one will likely need to be discussed. Easy fixes ========== catopen ------- This function is not implemented, and always fails. This is [barely] legal in POSIX, but the failure must set errno. None of the errors are very appropriate (unfortunately ENOSYS is invalid); maybe ENOMEM will work. getservbyport ------------- Non-conformance of this function was discussed on IRC. Rich Felker had said he would apply the patch I wrote, but it has not been applied yet. If there is an issue with said patch, please let me know so that I may fix it. : https://code.foxkit.us/adelie/patches/raw/master/sys-libs/musl/musl-1.1.15-posix-getservbyport.patch if_nameindex ------------ This function always sets errno to ENOBUFS, even when the function completes succesfully. A full test case is available, and a suggested patch is also available. : https://code.foxkit.us/adelie/musl-posix/tree/master/if_nameindex : https://code.foxkit.us/adelie/patches/raw/master/sys-libs/musl/musl-1.1.15-if_nameindex-errno.patch pathconf -------- This function does not provide a reference for timestamp resolution. See the POSIX reference for more information. This should be easy to fix. : http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/unistd.h.html#tag_13_77_03_03 Further thought required ======================== confstr ------- musl returns the empty string ("") for options where it does not have any values. The POSIX standard states that if an option is recognised but does not have a value, errno should not be set and NULL should be returned. : http://pubs.opengroup.org/onlinepubs/9699919799/functions/confstr.html getlogin -------- musl simply returns getenv("LOGNAME"). getlogin(3) is used to determine the login name of the controlling terminal for the process. In addition to getenv("LOGNAME") being improper behaviour (since getlogin(3) could be used within a su or sudo-run shell), it also causes both coreutils and busybox logname(1) to break conformance: ``` awilcox on ciall ~ $ su Password: ciall ~ # LOGNAME=helloworld logname helloworld ``` The correct behaviour is shown here on glibc: ``` awilcox on ciall [pts/16 Sun 5 16:51] ~: su Password: ciall awilcox # LOGNAME=helloworld logname awilcox ``` The POSIX standard states that implementations generally check the terminal of fds 0/1/2, then fall back to /dev/tty. : http://pubs.opengroup.org/onlinepubs/9699919799/functions/getlogin.html Discussion required =================== getdate ------- The musl implementation of getdate(3) sets getdate_err to 7 for any of the reasons that it should set to 5 (I/O error while reading template file - i.e., fgets fails), 7 (there is no line in the template that matches the input), or 8 (invalid input specification). While I realise musl will probably never implement all conditions that could provide error condition 8, I feel that error condition 5 should at least be implemented. Something as simple as if (ferror(f)) getdate_err = 5; else getdate_err = 7; could suffice, IMO. However, it would be nice to see better, more robust error handling for condition 8 as well. : http://git.musl-libc.org/cgit/musl/tree/src/time/getdate.c#n32 : http://pubs.opengroup.org/onlinepubs/9699919799/functions/getdate.html Best regards, --arw -- A. Wilcox (awilfox) Project Lead, Adélie Linux http://adelielinux.org Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)
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