[PATCH] libdw: Explicitly check we could decode diridx in dwarf_getsrclines.

[Mark Wielaard <mark@klomp.org>]

It is highly unlikely dwarf_formudata fails because we setup the attribute
ourselves, but better to explicitly mark diridx as bad if it does.

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

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 661fa9d..21adeb7 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,5 +1,10 @@
 2018-06-05  Mark Wielaard  <mark@klomp.org>
 
+	* dwarf_getsrclines.c (read_srclines): Explicitly set diridx to -1
+	in case dwarf_formudata fails.
+
+2018-06-05  Mark Wielaard  <mark@klomp.org>
+
 	* dwarf_getaranges (dwarf_getaranges): Free new_arange if
 	__libdw_findcu fails.
 
diff --git a/libdw/dwarf_getsrclines.c b/libdw/dwarf_getsrclines.c
index 0c2efaa..07baebc 100644
--- a/libdw/dwarf_getsrclines.c
+++ b/libdw/dwarf_getsrclines.c
@@ -566,7 +566,7 @@ read_srclines (Dwarf *dbg,
       for (unsigned int n = 0; n < nfiles; n++)
 	{
 	  const char *fname = NULL;
-	  Dwarf_Word diridx = -1;
+	  Dwarf_Word diridx = (Dwarf_Word) -1;
 	  for (unsigned char m = 0; m < nforms; m++)
 	    {
 	      if (m == form_path)
@@ -581,7 +581,8 @@ read_srclines (Dwarf *dbg,
 		  attr.code = DW_AT_decl_file; /* Close enough.  */
 		  attr.form = forms[m];
 		  attr.valp = (void *) linep;
-		  dwarf_formudata (&attr, &diridx);
+		  if (dwarf_formudata (&attr, &diridx) != 0)
+		    diridx = (Dwarf_Word) -1;
 		}
 
 	      size_t len = __libdw_form_val_len (&fake_cu, forms[m], linep);
-- 
1.8.3.1