[PATCH] Cygwin: ldd: Also look for not found DLLs when exit status is non-zero

[PATCH] Cygwin: ldd: Also look for not found DLLs when exit status is non-zero

[Jon Turney]

If the process exited with e.g. STATUS_DLL_NOT_FOUND, also process the
file to look for not found DLLs.

(We currently only do this when a STATUS_DLL_NOT_FOUND exception occurs,
which I haven't managed to observe)

This still isn't 100% correct, as it only examines the specified file
for missing DLLs, not recursively on the DLLs it depends upon.
---
 winsup/utils/ldd.cc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/winsup/utils/ldd.cc b/winsup/utils/ldd.cc
index e1af99e12..1e1863c1c 100644
--- a/winsup/utils/ldd.cc
+++ b/winsup/utils/ldd.cc
@@ -407,6 +407,8 @@ report (const char *in_fn, bool multiple)
 	  }
 	  break;
 	case EXIT_PROCESS_DEBUG_EVENT:
+	  if (ev.u.ExitProcess.dwExitCode != 0)
+	    process_fn = fn_win;
 print_and_exit:
 	  print_dlls (&dll_list, isdll ? fn_win : NULL, process_fn);
 	  exitnow = true;
-- 
2.28.0

Re: [PATCH] Cygwin: ldd: Also look for not found DLLs when exit status is non-zero

[Corinna Vinschen]

On Sep 10 13:27, Jon Turney wrote:
> If the process exited with e.g. STATUS_DLL_NOT_FOUND, also process the
> file to look for not found DLLs.
> 
> (We currently only do this when a STATUS_DLL_NOT_FOUND exception occurs,
> which I haven't managed to observe)
> 
> This still isn't 100% correct, as it only examines the specified file
> for missing DLLs, not recursively on the DLLs it depends upon.

Better than nothing?  Please push.


Thanks,
Corinna

Re: [PATCH] Cygwin: ldd: Also look for not found DLLs when exit status is non-zero

[Jon Turney]

On 10/09/2020 15:04, Corinna Vinschen wrote:
> On Sep 10 13:27, Jon Turney wrote:
>> If the process exited with e.g. STATUS_DLL_NOT_FOUND, also process the
>> file to look for not found DLLs.
>>
>> (We currently only do this when a STATUS_DLL_NOT_FOUND exception occurs,
>> which I haven't managed to observe)
>>
>> This still isn't 100% correct, as it only examines the specified file
>> for missing DLLs, not recursively on the DLLs it depends upon.
> 
> Better than nothing?

Well, except when people are misled when investigating problems because 
they assume the output is accurate. (e.g. [1])

[1] https://cygwin.com/pipermail/cygwin/2020-September/246164.html

I guess what's maybe needed is some indication that an error occurred 
and the output may be incomplete if the inferior process exited with a 
non-zero status.  But not sure how we can do that while keeping the 
output compatible with linux ldd.

Re: [PATCH] Cygwin: ldd: Also look for not found DLLs when exit status is non-zero

[Corinna Vinschen]

On Sep 11 13:33, Jon Turney wrote:
> On 10/09/2020 15:04, Corinna Vinschen wrote:
> > On Sep 10 13:27, Jon Turney wrote:
> > > If the process exited with e.g. STATUS_DLL_NOT_FOUND, also process the
> > > file to look for not found DLLs.
> > > 
> > > (We currently only do this when a STATUS_DLL_NOT_FOUND exception occurs,
> > > which I haven't managed to observe)
> > > 
> > > This still isn't 100% correct, as it only examines the specified file
> > > for missing DLLs, not recursively on the DLLs it depends upon.
> > 
> > Better than nothing?
> 
> Well, except when people are misled when investigating problems because they
> assume the output is accurate. (e.g. [1])
> 
> [1] https://cygwin.com/pipermail/cygwin/2020-September/246164.html
> 
> I guess what's maybe needed is some indication that an error occurred and
> the output may be incomplete if the inferior process exited with a non-zero
> status.  But not sure how we can do that while keeping the output compatible
> with linux ldd.

I assume there *may* occur an error in ldd as well, so it might be
intersting to check the Linux ldd sources to see how it generates
error output.


Corinna