Re: [PATCH 5/5] gdbsupport: add path_join function

[Pedro Alves <pedro@palves.net>]

On 2022-04-18 19:11, Simon Marchi via Gdb-patches wrote:

>> Suggest to add a couple of Windows-specific tests here: one which
>> starts with "d:/" instead of just "/", and another with backslashes.
> 
> Should these tests only be ran on Windows hosts?  In an ideal world,
> this function (and the rest of path handling in GDB) should support
> cross-debugging both ways: GDB on Linux debugging a remote Windows
> program, GDB on Windows debugging a remote Linux program.  That means
> corner cases like GDB on Linux should not recognize C:/foo as an
> absolute path when debugging a native Linux program, but it should
> recognize it as an absolute path when debugging a remote Windows
> program.  And it should recognize foo\bar\ as ending with a directory
> separator when debugging remotely a Windows program, and not when
> debugging natively.  And vice-versa for a Windows GDB / Linux program.
> 
> Existing code isn't written with that in mind though (macros like
> IS_DIR_SEPARATOR are host-specific), and I'm not ready to tackle that
> right now.   So I've written path_join ignoring those cross-debugging
> scenarios.
> 
> So, if I add a test like:
> 
>   s = ::path_join ("foo\\", "bar", nullptr);
>   SELF_CHECK (s == "foo\\bar" || s == "foo/bar");
> 
> it won't pass on Linux, as s will be "foo\\/bar".  So, as long as
> path_join is host-dependent, I think we'll need to accept that some
> tests will be host-dependent.  That's not ideal, but that's how things
> are at the moment.


Note we have:

(gdb) help set target-file-system-kind 
Set assumed file system kind for target reported file names.
If `unix', target file names (e.g., loaded shared library file names)
starting the forward slash (`/') character are considered absolute,
and the directory separator character is the forward slash (`/').  If
`dos-based', target file names starting with a drive letter followed
by a colon (e.g., `c:'), are also considered absolute, and the
backslash (`\') is also considered a directory separator.  Set to
`auto' (which is the default), to let GDB decide, based on its
knowledge of the target operating system.
(gdb) 

This is used in solib.c only currently.  Something like "source-file-system-kind"
might make sense to have too.  (Not suggesting we add it now.)