libdw: Make __libdw_dieabbrev more robust on failure.

Make sure to always set die->abbrev to DWARF_END_ABBREV on failure.
DWARF_END_ABBREV is also what the function reports on failure. And it
will prevent trying to lookup the abbrev ever again.

Signed-off-by: Mark Wielaard <mark@klomp.org>

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 07a1346..7832165 100644 (file)
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,8 @@
+2018-06-12  Mark Wielaard  <mark@klomp.org>
+
+       * libdw.h (__libdw_dieabbrev): Set die->abbrev to DWARF_END_ABBREV
+       on failure.
+
 2018-06-10  Mark Wielaard  <mark@klomp.org>
 
        * dwarf_attr_integrate.c (dwarf_attr_integrate): Stop after 16 DIE

diff --git a/libdw/libdwP.h b/libdw/libdwP.h
index 3d8e145..eebb7d1 100644 (file)
--- a/libdw/libdwP.h
+++ b/libdw/libdwP.h
@@ -653,8 +653,9 @@ __libdw_dieabbrev (Dwarf_Die *die, const unsigned char **readp)
       /* Get the abbreviation code.  */
       unsigned int code;
       const unsigned char *addr = die->addr;
-      if (die->cu == NULL || addr >= (const unsigned char *) die->cu->endp)
-       return DWARF_END_ABBREV;
+      if (unlikely (die->cu == NULL
+                   || addr >= (const unsigned char *) die->cu->endp))
+       return die->abbrev = DWARF_END_ABBREV;
       get_uleb128 (code, addr, die->cu->endp);
       if (readp != NULL)
        *readp = addr;