Re: Bug in builtin function abspath (again)

[Boris Kolpackov]

Eli Zaretskii <address@hidden> writes:

> > > The realpath function will resolve both absolute and relative paths
> > > and return the absolute pathname corresponding to pathname. All but
> > > the last component of pathname must exist when realpath is called.

I just checked the page for realpath in SUS and I don't see anything
that implies this. My understanding that all components of the path
must exist.


> > It's not immediately clear to me what "all but the last component of
> > pathname" means; presumably it means that the directory containing the
> > last filename in pathname must exist, but that the filename itself does
> > not have to exist.
>
> Yes, that seems to be the meaning.  But on platforms where there's no
> realpath, we currently use abspath that doesn't care whether that
> directory exists.  Since Joe Random Hacker might not know whether her
> Make was built with or without realpath (and the docs don't even tell
> that realpath falls back on abspath), we should try to emulate
> realpath as close as we can, I think.
>
> I also thought about writing an emulation for realpath by using
> readlink.  Unless I'm missing something, that shouldn't be too hard.

Here is the documentation for realpath and abspath from GNU make manual:

`$(realpath NAMES...)'
     For each file name in NAMES return the canonical absolute name.  A
     canonical name does not contain any `.' or `..' components, nor
     any repeated path separators (`/') or symlinks.  In case of a
     failure the empty string is returned.  Consult the `realpath(3)'
     documentation for a list of possible failure causes.

`$(abspath NAMES...)'
     For each file name in NAMES return an absolute name that does not
     contain any `.' or `..' components, nor any repeated path
     separators (`/').  Note that, in contrast to `realpath' function,
     `abspath' does not resolve symlinks and does not require the file
     names to refer to an existing file or directory.  Use the
     `wildcard' function to test for existence.


I guess for platforms without realpath, we can emulate it as
func_wildcard (func_abspath (...)) rather than just func_abspath (...).


hth,
-boris