[libbacktrace] Unify function name preference handling

Both read_function_entry and read_referenced_name implement a priority scheme
for names.  The priorities are:
- 1st: DW_AT_linkage_name
- 2nd: Name from DW_AT_abstract_origin or DW_AT_specification
- 3rd: DW_AT_name.

Ensure both functions fully adhere to it.

2019-01-16  Tom de Vries  <tdevries@suse.de>

	* dwarf.c (read_referenced_name): Don't allow DW_AT_name to override any
	name.
	(read_function_entry): Same.  Don't allow name found via
	DW_AT_abstract_origin or case DW_AT_specification to override linkage
	name.

From-SVN: r267963

diff --git a/libbacktrace/ChangeLog b/libbacktrace/ChangeLog
index cd6aba044a5174dfa2b036799ab3de4d9a8ada55..a64537d4dd3ad315c3cf702145be462a9f13d16f 100644 (file)
--- a/libbacktrace/ChangeLog
+++ b/libbacktrace/ChangeLog
@@ -1,3 +1,11 @@
+2019-01-16  Tom de Vries  <tdevries@suse.de>
+
+       * dwarf.c (read_referenced_name): Don't allow DW_AT_name to override any
+       name.
+       (read_function_entry): Same.  Don't allow name found via
+       DW_AT_abstract_origin or case DW_AT_specification to override linkage
+       name.
+
 2019-01-09  Sandra Loosemore  <sandra@codesourcery.com>
 
        PR other/16615

diff --git a/libbacktrace/dwarf.c b/libbacktrace/dwarf.c
index c9ce38342ec6d815237ff5c0a71111191a289ace..af864d68b00ce152ef2317da5a65568a176adefe 100644 (file)
--- a/libbacktrace/dwarf.c
+++ b/libbacktrace/dwarf.c
@@ -2151,18 +2151,25 @@ read_referenced_name (struct dwarf_data *ddata, struct unit *u,
       switch (abbrev->attrs[i].name)
        {
        case DW_AT_name:
-         /* We prefer the linkage name if get one.  */
+         /* Third name preference: don't override.  A name we found in some
+            other way, will normally be more useful -- e.g., this name is
+            normally not mangled.  */
+         if (ret != NULL)
+           break;
          if (val.encoding == ATTR_VAL_STRING)
            ret = val.u.string;
          break;
 
        case DW_AT_linkage_name:
        case DW_AT_MIPS_linkage_name:
+         /* First name preference: override all.  */
          if (val.encoding == ATTR_VAL_STRING)
            return val.u.string;
          break;
 
        case DW_AT_specification:
+         /* Second name preference: override DW_AT_name, don't override
+            DW_AT_linkage_name.  */
          if (abbrev->attrs[i].form == DW_FORM_ref_addr
              || abbrev->attrs[i].form == DW_FORM_ref_sig8)
            {
@@ -2315,6 +2322,7 @@ read_function_entry (struct backtrace_state *state, struct dwarf_data *ddata,
       int highpc_is_relative;
       uint64_t ranges;
       int have_ranges;
+      int have_linkage_name;
 
       code = read_uleb128 (unit_buf);
       if (code == 0)
@@ -2351,6 +2359,7 @@ read_function_entry (struct backtrace_state *state, struct dwarf_data *ddata,
       highpc_is_relative = 0;
       ranges = 0;
       have_ranges = 0;
+      have_linkage_name = 0;
       for (i = 0; i < abbrev->num_attrs; ++i)
        {
          struct attr_val val;
@@ -2399,6 +2408,10 @@ read_function_entry (struct backtrace_state *state, struct dwarf_data *ddata,
 
                case DW_AT_abstract_origin:
                case DW_AT_specification:
+                 /* Second name preference: override DW_AT_name, don't override
+                    DW_AT_linkage_name.  */
+                 if (have_linkage_name)
+                   break;
                  if (abbrev->attrs[i].form == DW_FORM_ref_addr
                      || abbrev->attrs[i].form == DW_FORM_ref_sig8)
                    {
@@ -2420,21 +2433,21 @@ read_function_entry (struct backtrace_state *state, struct dwarf_data *ddata,
                  break;
 
                case DW_AT_name:
+                 /* Third name preference: don't override.  */
+                 if (function->name != NULL)
+                   break;
                  if (val.encoding == ATTR_VAL_STRING)
-                   {
-                     /* Don't override a name we found in some other
-                        way, as it will normally be more
-                        useful--e.g., this name is normally not
-                        mangled.  */
-                     if (function->name == NULL)
-                       function->name = val.u.string;
-                   }
+                   function->name = val.u.string;
                  break;
 
                case DW_AT_linkage_name:
                case DW_AT_MIPS_linkage_name:
+                 /* First name preference: override all.  */
                  if (val.encoding == ATTR_VAL_STRING)
-                   function->name = val.u.string;
+                   {
+                     function->name = val.u.string;
+                     have_linkage_name = 1;
+                   }
                  break;
 
                case DW_AT_low_pc: