IRC, freenode, #hurd, June 2010

<pochu> is there a way (POSIX or Hurdish) to get the corresponding file
  name for a fd or a hurd port?
<marcusb> there is a way
<pochu> marcusb: which one would that be?
<marcusb> I forgot
<marcusb> there is an implementation in libc
<marcusb> realpath has a similar job
<marcusb> but that's not what I mean
<marcusb> pochu: maybe I am misremembering.  But it was something where you
  keep looking up .. and list that directory, looking for the node with the
  ID of the node you had .. for
<marcusb> maybe it works only for directories
<marcusb> yeah
<marcusb> pochu: check the getcwd() implementation of libc
<marcusb> sysdeps/mach/hurd/getcwd.c
<marcusb> _hurd_canonicalize_directory_name_internal 
* pochu looks
<pochu> marcusb: interesting
<pochu> though that is for dirs, and doesn't seem to be extensible to
  files, as you cannot lookup for ".." under a file
<marcusb> right
<pochu> oh you already said that :)
<marcusb> actually, I am not sure that's correct
<marcusb> it's probably correct, but there is no reason why looking .. up
  on a file couldn't return the directory it's contianed in
<pochu> I don't know the interfaces or the Hurd internals very well yet,
  but it would look strange to me if you could do that
<marcusb> the hurd is strange
<pochu> it sounds like if you could `ls getcwd.c/..` to get
  sysdeps/mach/hurd/ :-)
<marcusb> yep
<pochu> ok. interesting
<marcusb> you wouldn't find "ls foo.zip/.." very strange, wouldn't you?
<pochu> I guess not if `ls foo.zip` listed the contents of foo.zip
<marcusb> there you go
<marcusb> or the other way round: would you be surprised if "cat somedir"
  would work?
<pochu> I think so. if it did, what would it do?
<marcusb> originally, cat dir would list the directory content!
<marcusb> in the old unix times
<pochu> I was surprised the first time I typed `vi somedir` by accident
<marcusb> and some early BSDs 
* pochu feels young :-)
<marcusb> he don't worry, I didn't see those times either
<marcusb> technically, files and directories are implemented in the same
  way in the hurd, they both are objects implementing the fs.defs interface
<marcusb> which combines file and directory operations
<marcusb> of course, files and directories implement those functions
  differently
<antrik> marcusb: do you know why this behavior (cat on directories) was
  changed?

IRC, freenode, #hurd, 2013-03-07

* pinotree ponders about sending as RFC his patch for /proc/$pid/maps
<tschwinge> Including a scheme for providing the names of mapped files?
  ;-D
<braunr> that would be really great indeed
<tschwinge> I have not yet researched how Linux does this.  Perhaps store
  the filename used for first opening a file as a string somewhere?
<pinotree> tschwinge: eh, indeed that's lacking in my patch
<braunr> i'm not sure we should aim at doing it the same way
<youpi> I was wondering about having interfaces for naming tasks, threads,
  objects
<youpi> that'd be useful for debugging in general
<braunr> yes
<braunr> i don't think we need to take namespaces into account
<braunr> a simple name or path should be quite enough
<tschwinge> Agreed.  "Just something!"
<tschwinge> So, a Java toString() method for ports.
<tschwinge> ;-)
<braunr> yes
<tschwinge> Oh, and could this also work recursively?  The ext2fs instance
  on /home asks its parent fs about its own path -- can it do that?  (And
  then cache that, most likely?)  Would one get rooted filesnames that way?
<braunr> i really don't think we should link it to the VFS
<braunr> it should merely be a name for debugging
<youpi> yep, same for me
<youpi> I'd say it's the linker's task of just setting a sane name
<braunr> first, keeping it isolated prevents increasing complexity
<braunr> next, it doesn't reduce performance
<tschwinge> youpi: Linker?
<tschwinge> braunr: Ack.
<braunr> yes, ld is the one creating the mappings
<youpi> tschwinge: the one that loads libraries
<tschwinge> Ah, for /proc/*/maps, right.  I've been thinking more globally.

IRC, freenode, #hurd, 2011-07-13

A related issue:

<braunr> rbraun@nordrassil:~$ vminfo $$ | wc -l
<braunr> 1039
<braunr> any idea why a shell would consume more than 1039 map entries ?
<braunr> (well, not more actually)
<braunr> even the kernel and ext2fs have around 100
<braunr> (the kernel has actually only 23, which is very good and expected)
<tschwinge> braunr: I agree that having some sort of debugging information
  for memory objects et al. would be quite hand.  To see where they're
  coming from, etc.
<braunr> tschwinge: this would require naming objects at the mach level
<braunr> e.g. when creating an object
<braunr> giving it the path of a file for example
<tschwinge> braunr: I have recently seen something (due to youpi fixing a
  bug) that bash is doing its own memory management.  Perhaps all these are
  such regions?
<tschwinge> braunr: For example, yes.
<braunr> what ?
<braunr> ?!
<tschwinge> braunr:
  http://lists.gnu.org/archive/html/bug-bash/2011-04/msg00097.html
<braunr> i see

Also see email thread starting at id:"20110714082216.GA8335@sceen.net".