Date: Fri, 27 Jul 2018 09:35:41 -0600 From: Ian Lepore <ian@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r336746 - in head/lib: libc/gen libutil Message-ID: <1532705741.61594.53.camel@freebsd.org> In-Reply-To: <20180727150304.GA2489@kib.kiev.ua> References: <201807261834.w6QIYc9i080738@repo.freebsd.org> <20180727150304.GA2489@kib.kiev.ua>
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On Fri, 2018-07-27 at 18:03 +0300, Konstantin Belousov wrote: > On Thu, Jul 26, 2018 at 06:34:38PM +0000, Ian Lepore wrote: > > > > Author: ian > > Date: Thu Jul 26 18:34:38 2018 > > New Revision: 336746 > > URL: https://svnweb.freebsd.org/changeset/base/336746 > > > > Log: > > Make pw_scan(3) more compatible with getpwent(3) et. al. when processing > > data from /etc/passwd rather than /etc/master.passwd. > > > > The libc getpwent(3) and related functions automatically read master.passwd > > when run by root, or passwd when run by a non-root user. When run by non- > > root, getpwent() copes with the missing data by setting the corresponding > > fields in the passwd struct to known values (zeroes for numbers, or a > > pointer to an empty string for literals). When libutil's pw_scan(3) was > > used to parse a line without the root-accessible data, it was leaving > > garbage in the corresponding fields. > > > > These changes rename the static pw_init() function used by getpwent() and > > friends to __pw_initpwd(), and move it into pw_scan.c so that common init > > code can be shared between libc and libutil. pw_scan(3) now calls > > __pw_initpwd() before __pw_scan(), just like the getpwent() family does, so > > that reading an arbitrary passwd file in either format and parsing it with > > pw_scan(3) returns the same results as getpwent(3) would. > > > > This also adds a new pw_initpwd(3) function to libutil, so that code which > > creates passwd structs from scratch in some manner that doesn't involve > > pw_scan() can initialize the struct to the values expected by lots of > > existing code, which doesn't expect to encounter NULL pointers or garbage > > values in some fields. > > > If my reading is right, you just made libutil depend on the internal > libc interfaces. Formal consequence is that libutil.so version must > be bumped each time the used interface is changed (and it is allowed > to change). I think that your change actually requires the bump of > libutil.so.N version already. > > Also, libutil.so.N should be moved from the libutil pkgbase package to > the clibs package, I am not sure about this. > > At the higher level, I very much dislike this change. FBSDprivate_1.0 > namespace is for symbols providing the internal interfaces for the > C runtime implementation in the FreeBSD. This is mostly a knot of > inter-dependencies between rtld, libc and libthr. libutil arguably > should not participate. > > If you want for libc to provide a functionality outside the C runtime, > please make the sustainable interface, which ABI can be maintained, and > export the symbols in the normal namespace, with the usual stability > guarantees. There was already a function, __pw_scan(), in file pw_scan.c, which was called from both libutil and libc implementations. I added a new function __pw_initpwd() into the pw_scan.c file. That function is called from all the same places that __pw_scan() is called from. So as near as I can tell, I haven't changed the structure of anything or created any new linkages between the libraries that didn't exist already. I will admit I don't understand the FBSDprivate_1.0 stuff at all, and there appears to be no documentation or guidance on how to work with it. Since __pw_scan was in the private list, and I was adding a new function that is like it in every way, I reasoned that the new function should be in the list too. It's actually not clear to me that either of the functions should be in that list, but like I said... no published info about it that I could find. I also noticed that chpass(1) and pwd_mkdb(8)_both directly compile in their own copy of the pw_scan.c source using .PATH in their makefiles. I wonder if doing that as the way of sharing the code between libc and libutil would be a better thing to do? (And presumably that would remove the need to have entries in the FBSDprivate_1.0 list?) -- Ian
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