Re: [PATCH] Fix crash in AIX when current working directory is NULL

[Ulrich Weigand <Ulrich.Weigand@de.ibm.com>]

Aditya Vidyadhar Kamath wrote:  

>diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c  
>index 84b1480dbcb..7962acc784d 100644  
>--- a/gdb/dwarf2/read.c  
>+++ b/gdb/dwarf2/read.c  
>@@ -859,7 +859,7 @@ dwarf2_per_bfd::dwarf2_per_bfd (bfd *obfd, const
>dwarf2_debug_sections *names,  
>  bool can_copy_) 
>   : obfd (obfd),  
>     can_copy (can_copy_),  
>-    captured_cwd (current_directory),  
>+    captured_cwd (current_directory == NULL ? "" :
current_directory),  
>     captured_debug_dir (debug_file_directory)  

The captured_cwd logic was introduced by Tom Tromey in
commit 3fbf1a34f10aa6a67d9f96c437e8f9dc57832d22.  Previously,
in the case where current_directory == NULL, that NULL pointer
was passed directly to openp, which passes it on to gdb_abspath.

That latter routine does in fact has extra code handling a NULL
cwd input (basically treating any input path as absolute).
This is different from how an empty string as cwd input is
handled (for an empty string, it looks like an extra '/'
is prepended).

So even with this proposed patch, we'd still have a change in
behavior (though no longer a crash) as compared to the version
before Tom's commit above.

Tom, any thoughts on how this should be handled?  Should we
add another check when passing captured_cwd to openp?
Change captured_cwd to something like std::optional<std::string>?

Bye,
Ulrich