Rewrite abbrev_table_load to handle sequences of zeroes more intelligently.

diff --git a/src/dwarflint.c b/src/dwarflint.c
index ccf5ad759b0126708fabb7e73a5b76745ef01433..eb791ef6a91a588376c9087bf7a8f3ca9f78dcac 100644 (file)
--- a/src/dwarflint.c
+++ b/src/dwarflint.c
@@ -630,45 +630,45 @@ abbrev_table_load (struct read_ctx *ctx)
   struct abbrev_table *section_chain = NULL;
   struct abbrev_table *section = NULL;
 
-  /* Disallow null abbrev at the beginning of the section.  */
-  bool last_was_nul = true;
-  bool expect_section_end = false;
+#define SECTION_ENDS (ctx->ptr >= ctx->end)
 
-  while (ctx->ptr < ctx->end)
+  while (!SECTION_ENDS)
     {
-      uint64_t abbr_off = read_ctx_get_offset (ctx);
-      uint64_t abbr_code, abbr_tag;
-
-      /* Abbreviation code.  */
-      if (!CHECKED_READ_ULEB128 (ctx, &abbr_code,
-                                PRI_ABBR, "abbrev code", abbr_off))
-       goto free_and_out;
+      uint64_t abbr_off, prev_abbr_off = (uint64_t)-1;
+      uint64_t abbr_code, prev_abbr_code = (uint64_t)-1;
+      uint64_t abbr_tag;
+      uint64_t zero_seq_off = (uint64_t)-1;
 
-      if (abbr_code == 0)
-       {
-         /* It is legal to use one or more null abbrevs at the end of
-            the last section, e.g. for padding purposes.  However
-            mid-section, allow at most one delimiting abbrev.  */
-         if (last_was_nul)
-           expect_section_end = true;
-
-         section = NULL;
-         last_was_nul = true;
-         continue;
-       }
-      else
+      while (!SECTION_ENDS)
        {
-         if (expect_section_end)
-           /* XXX That would technically be an empty section, make it
-              a warning?  */
-           ERROR (PRI_ABBR
-                  ": abbrev with non-zero code follows several abbrevs with zero code.\n",
-                  abbr_off);
-
-         last_was_nul = expect_section_end = false;
+         abbr_off = read_ctx_get_offset (ctx);
+
+         /* Abbreviation code.  */
+         if (!CHECKED_READ_ULEB128 (ctx, &abbr_code,
+                                    PRI_ABBR, "abbrev code", abbr_off))
+           goto free_and_out;
+
+         if (abbr_code == 0 && prev_abbr_code == 0
+             && zero_seq_off == (uint64_t)-1)
+           zero_seq_off = prev_abbr_off;
+
+         if (abbr_code != 0)
+           break;
+         else
+           section = NULL;
+
+         prev_abbr_code = abbr_code;
+         prev_abbr_off = abbr_off;
        }
 
-      /* Make a room for new abbreviation.  */
+      if (zero_seq_off != (uint64_t)-1)
+       WARNING (PRI_ABBR": unnecessary zero padding.\n", zero_seq_off);
+
+      if (SECTION_ENDS)
+       break;
+
+#undef SECTION_ENDS
+
       if (section == NULL)
        {
          section = xcalloc (1, sizeof (*section));
@@ -676,7 +676,6 @@ abbrev_table_load (struct read_ctx *ctx)
          section->next = section_chain;
          section_chain = section;
        }
-
       REALLOC (section, abbr);
 
       struct abbrev *cur = section->abbr + section->size++;
@@ -775,10 +774,10 @@ abbrev_table_load (struct read_ctx *ctx)
                  assert (attr_off > 0);
                  sibling_attr = attr_off;
 
-                 if (!cur->has_children && be_strict)
-                   ERROR (PRI_ABBR_ATTR
-                          ": Excessive DW_AT_sibling attribute at childless abbrev.\n",
-                          abbr_off, attr_off);
+                 if (!cur->has_children)
+                   WARNING (PRI_ABBR_ATTR
+                            ": Excessive DW_AT_sibling attribute at childless abbrev.\n",
+                            abbr_off, attr_off);
                }
 
              switch (check_sibling_form (attrib_form))
@@ -803,17 +802,6 @@ abbrev_table_load (struct read_ctx *ctx)
       while (!null_attrib);
     }
 
-  if (expect_section_end)
-    {
-      /* More than one abbrev with zero code should only be necessary
-        for alignment purposes.  */
-      /* XXX Check zero abbrevs are not excessive, i.e. if it's not
-        possible to achieve that alignment with fewer zero abbrevs.  */
-      if (((uintptr_t)ctx->ptr & -ctx->data->d_align) != 0)
-       WARNING ("Abbreviation section unnecessarily terminated with sequence "
-                "of abbrevs with code 0.\n");
-    }
-
   return section_chain;
 
  free_and_out: