[PATCH] libdw: Handle DW_FORM_[ref|strp]_sup[48] as DW_FORM_GNU_[ref|strp]_alt.

[Mark Wielaard <mark@klomp.org>]

Although we don't yet handle DWARF5 supplemental files, they are like
mostly like GNU alt files.  This way using any of the supplemental files
will at least generate an appropriate error message.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 libdw/ChangeLog           |  9 +++++++++
 libdw/dwarf_formref.c     |  2 ++
 libdw/dwarf_formref_die.c | 15 +++++++++++----
 libdw/dwarf_formstring.c  |  6 ++++--
 src/ChangeLog             |  5 +++++
 src/readelf.c             |  2 ++
 6 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index cc7eae9..5e2c0d8 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,12 @@
+2018-05-08  Mark Wielaard  <mark@klomp.org>
+
+	* dwarf_formref.c (__libdw_formref): Explicitly don't handle
+	DW_FORM_ref_sup4 and DW_FORM_ref_sup8.
+	* dwarf_formref_die.c (dwarf_formref_die): Handle DW_FORM_ref_sup4
+	and DW_FORM_ref_sup8.
+	* dwarf_formstring.c (dwarf_formstring): Handle DW_FORM_strp_sup
+	as DW_FORM_GNU_strp_alt.
+
 2018-05-05  Mark Wielaard  <mark@klomp.org>
 
 	* dwarf.h: Add DWARF line content descriptions.
diff --git a/libdw/dwarf_formref.c b/libdw/dwarf_formref.c
index 2240a25..2bae2a4 100644
--- a/libdw/dwarf_formref.c
+++ b/libdw/dwarf_formref.c
@@ -86,6 +86,8 @@ __libdw_formref (Dwarf_Attribute *attr, Dwarf_Off *return_offset)
     case DW_FORM_ref_addr:
     case DW_FORM_ref_sig8:
     case DW_FORM_GNU_ref_alt:
+    case DW_FORM_ref_sup4:
+    case DW_FORM_ref_sup8:
       /* These aren't handled by dwarf_formref, only by dwarf_formref_die.  */
       __libdw_seterrno (DWARF_E_INVALID_REFERENCE);
       return -1;
diff --git a/libdw/dwarf_formref_die.c b/libdw/dwarf_formref_die.c
index d47fb2f..f196331 100644
--- a/libdw/dwarf_formref_die.c
+++ b/libdw/dwarf_formref_die.c
@@ -44,13 +44,20 @@ dwarf_formref_die (Dwarf_Attribute *attr, Dwarf_Die *result)
   struct Dwarf_CU *cu = attr->cu;
 
   Dwarf_Off offset;
-  if (attr->form == DW_FORM_ref_addr || attr->form == DW_FORM_GNU_ref_alt)
+  if (attr->form == DW_FORM_ref_addr || attr->form == DW_FORM_GNU_ref_alt
+      || attr->form == DW_FORM_ref_sup4 || attr->form == DW_FORM_ref_sup8)
     {
       /* This has an absolute offset.  */
 
-      uint8_t ref_size = (cu->version == 2 && attr->form == DW_FORM_ref_addr
-			  ? cu->address_size
-			  : cu->offset_size);
+      uint8_t ref_size;
+      if (cu->version == 2 && attr->form == DW_FORM_ref_addr)
+	ref_size = cu->address_size;
+      else if (attr->form == DW_FORM_ref_sup4)
+	ref_size = 4;
+      else if (attr->form == DW_FORM_ref_sup8)
+	ref_size = 8;
+      else
+	ref_size = cu->offset_size;
 
       Dwarf *dbg_ret = (attr->form == DW_FORM_GNU_ref_alt
 			? INTUSE(dwarf_getalt) (cu->dbg) : cu->dbg);
diff --git a/libdw/dwarf_formstring.c b/libdw/dwarf_formstring.c
index e7396a7..c55c7f0 100644
--- a/libdw/dwarf_formstring.c
+++ b/libdw/dwarf_formstring.c
@@ -48,7 +48,8 @@ dwarf_formstring (Dwarf_Attribute *attrp)
 
   Dwarf_CU *cu = attrp->cu;
   Dwarf *dbg = cu->dbg;
-  Dwarf *dbg_ret = (attrp->form == DW_FORM_GNU_strp_alt
+  Dwarf *dbg_ret = ((attrp->form == DW_FORM_GNU_strp_alt
+		     || attrp->form == DW_FORM_strp_sup)
 		    ? INTUSE(dwarf_getalt) (dbg) : dbg);
 
   if (unlikely (dbg_ret == NULL))
@@ -70,7 +71,8 @@ dwarf_formstring (Dwarf_Attribute *attrp)
 
   uint64_t off;
   if (attrp->form == DW_FORM_strp
-      || attrp->form == DW_FORM_GNU_strp_alt)
+      || attrp->form == DW_FORM_GNU_strp_alt
+      || attrp->form == DW_FORM_strp_sup)
     {
       if (__libdw_read_offset (dbg, dbg_ret, cu_sec_idx (cu),
 			       attrp->valp, cu->offset_size, &off,
diff --git a/src/ChangeLog b/src/ChangeLog
index 4b55bbc..b1041a8 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-05  Mark Wielaard  <mark@klomp.org>
+
+	* readelf.c (attr_callback): Handle DW_FORM_ref_sup4 and
+	DW_FORM_ref_sup8 as references.
+
 2018-04-24  Mark Wielaard  <mark@klomp.org>
 
 	* readelf.c (print_debug_str_section): Take raw section data. Don't
diff --git a/src/readelf.c b/src/readelf.c
index c2fcfff..c69910a 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -6130,6 +6130,8 @@ attr_callback (Dwarf_Attribute *attrp, void *arg)
     case DW_FORM_ref2:
     case DW_FORM_ref1:
     case DW_FORM_GNU_ref_alt:
+    case DW_FORM_ref_sup4:
+    case DW_FORM_ref_sup8:
       if (cbargs->silent)
 	break;
       Dwarf_Die ref;
-- 
1.8.3.1