[COMMITTED] debuginfod_find_section: Always update rc with most recent error code

[COMMITTED] debuginfod_find_section: Always update rc with most recent error code

[Aaron Merey]

debuginfod_find_section may attempt to download both the debuginfo
and executable matching the given build-id.  If neither of these
files can be found, update rc to ensure that we always return an
accurate error code in this case.

Signed-off-by: Aaron Merey <amerey@redhat.com>
---
 debuginfod/ChangeLog           | 5 +++++
 debuginfod/debuginfod-client.c | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/debuginfod/ChangeLog b/debuginfod/ChangeLog
index 4d576cae..5678002a 100644
--- a/debuginfod/ChangeLog
+++ b/debuginfod/ChangeLog
@@ -1,3 +1,8 @@
+2022-11-04  Aaron Merey  <amerey@redhat.com>
+
+	* debuginfod-client.c (debuginfod_find_section): Ensure rc
+	is always updated with the most recent error code.
+
 2022-11-03  Frank Ch. Eigler <fche@redhat.com>
 
 	* debuginfod.cxx (handle_buildid): Correctly manage lifetime
diff --git a/debuginfod/debuginfod-client.c b/debuginfod/debuginfod-client.c
index f48e32cc..99da05ef 100644
--- a/debuginfod/debuginfod-client.c
+++ b/debuginfod/debuginfod-client.c
@@ -1944,7 +1944,8 @@ debuginfod_find_section (debuginfod_client *client,
 
   if (rc == -EEXIST)
     {
-      /* The section should be found in the executable.  */
+      /* Either the debuginfo couldn't be found or the section should
+	 be in the executable.  */
       fd = debuginfod_find_executable (client, build_id,
 				       build_id_len, &tmp_path);
       if (fd > 0)
@@ -1952,6 +1953,9 @@ debuginfod_find_section (debuginfod_client *client,
 	  rc = extract_section (fd, section, tmp_path, path);
 	  close (fd);
 	}
+      else
+	/* Update rc so that we return the most recent error code.  */
+	rc = fd;
     }
 
   free (tmp_path);
-- 
2.37.3

Re: [COMMITTED] debuginfod_find_section: Always update rc with most recent error code

[Mark Wielaard]

Hi Aaron,

On Fri, 2022-11-04 at 17:40 -0400, Aaron Merey via Elfutils-devel
wrote:
> debuginfod_find_section may attempt to download both the debuginfo
> and executable matching the given build-id.  If neither of these
> files can be found, update rc to ensure that we always return an
> accurate error code in this case.

Nicely spotted, otherwise we might have returned -EEXIST.

> diff --git a/debuginfod/debuginfod-client.c b/debuginfod/debuginfod-
> client.c
> index f48e32cc..99da05ef 100644
> --- a/debuginfod/debuginfod-client.c
> +++ b/debuginfod/debuginfod-client.c
> @@ -1944,7 +1944,8 @@ debuginfod_find_section (debuginfod_client *client,
>  
>    if (rc == -EEXIST)
>      {
> -      /* The section should be found in the executable.  */
> +      /* Either the debuginfo couldn't be found or the section should
> +	 be in the executable.  */
>        fd = debuginfod_find_executable (client, build_id,
>  				       build_id_len, &tmp_path);
>        if (fd > 0)

I know this is in existing code, so this might have missed in a
previous review. But shouldn't this be fd >= 0 ?

That is what is checked in the rest of the code. Except for the
debuginfod_find_section function which uses fd >0 twice.

It is unlikely, but I think fd can be zero if it (stdin) was closed by
the program for some reason. Then I think zero can be reused as new
file descriptor?

Cheers,

Mark

Re: [COMMITTED] debuginfod_find_section: Always update rc with most recent error code

[Aaron Merey]

Hi Mark,

On Mon, Nov 7, 2022 at 9:19 AM Mark Wielaard <mark@klomp.org> wrote:
> >    if (rc == -EEXIST)
> >      {
> > -      /* The section should be found in the executable.  */
> > +      /* Either the debuginfo couldn't be found or the section should
> > +      be in the executable.  */
> >        fd = debuginfod_find_executable (client, build_id,
> >                                      build_id_len, &tmp_path);
> >        if (fd > 0)
>
> I know this is in existing code, so this might have missed in a
> previous review. But shouldn't this be fd >= 0 ?
>
> That is what is checked in the rest of the code. Except for the
> debuginfod_find_section function which uses fd >0 twice.
>
> It is unlikely, but I think fd can be zero if it (stdin) was closed by
> the program for some reason. Then I think zero can be reused as new
> file descriptor?

Thanks for catching this typo, will merge a fix.

Aaron