Re: [PATCH] readelf: Print DIE offset in attribute reading error messages.

[Mark Wielaard <mark@klomp.org>]

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On Thu, 2017-11-16 at 15:31 +0100, Mark Wielaard wrote:
> On Tue, 2017-10-03 at 16:59 +0200, Mark Wielaard wrote:
> > When processing large files it is useful to know the DIE offset if
> > printing of attributes fails (especially when redirecting the output).
> > With this change the error message looks like:
> > 
> >   eu-readelf: DIE [2aeb8ef1] cannot get attribute value: invalid DWARF
> 
> Got another report about a large debug file where this improved error
> message would have been really handy. So I pushed it to master now.

This has been really useful to debug some DWARF format issues, but it
could be even more useful. Since we know the attribute name and form
(or we would have generated an error earlier) add those to the error
message too.

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From ce0469a04bf3b8e438647bb66f468c16ac52a4af Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Tue, 21 Nov 2017 11:13:00 +0100
Subject: [PATCH] readelf: Print attribute name and form in error message.

Now an error getting the attribute value will not only print the DIE offset
and the reason, but also the attribute name and form. e.g.

  DIE [b] cannot get attribute 'ranges' (sec_offset) value: .debug_ranges
  section missing

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 src/ChangeLog | 5 +++++
 src/readelf.c | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/ChangeLog b/src/ChangeLog
index d112cd2..d2b25de 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2017-11-21  Mark Wielaard  <mark@klomp.org>
+
+	* readelf.c (attr_callback): Print attribute name and form in error
+	message.
+
 2017-10-03  Mark Wielaard  <mark@klomp.org>
 
 	* readelf.c (attr_callback): Print DIE offset in error messages.
diff --git a/src/readelf.c b/src/readelf.c
index e364583..229c036 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -5968,8 +5968,12 @@ attr_callback (Dwarf_Attribute *attrp, void *arg)
 	    attrval_out:
 	      if (!cbargs->silent)
 		error (0, 0, gettext ("DIE [%" PRIx64 "] "
-				      "cannot get attribute value: %s"),
-		       dwarf_dieoffset (die), dwarf_errmsg (-1));
+				      "cannot get attribute '%s' (%s) value: "
+				      "%s"),
+		       dwarf_dieoffset (die),
+		       dwarf_attr_name (attr),
+		       dwarf_form_name (form),
+		       dwarf_errmsg (-1));
 	      return DWARF_CB_ABORT;
 	    }
 	  char *a = format_dwarf_addr (cbargs->dwflmod, cbargs->addrsize,
-- 
1.8.3.1