libsysprof: hoist fallback symbol creation

This makes sure that we get that even when not using the Elf symbolizer
but also means we can fallback through the Elf symbolizer into the
debuginfod symbolizer.

src/libsysprof/sysprof-document-symbols.c

@@ -85,6 +85,71 @@ symbolize_free (Symbolize *state)
   g_free (state);
 }
 
+static SysprofSymbol *
+do_symbolize (SysprofSymbolizer     *symbolizer,
+              SysprofStrings        *strings,
+              SysprofProcessInfo    *process_info,
+              SysprofAddressContext  last_context,
+              SysprofAddress         address)
+{
+  SysprofDocumentMmap *map;
+  g_autofree char *name = NULL;
+  SysprofSymbol *ret;
+  const char *nick = NULL;
+  const char *path;
+  guint64 map_begin;
+  guint64 map_end;
+  guint64 relative_address;
+  guint64 begin_address;
+  guint64 end_address;
+  guint64 file_offset;
+
+  if ((ret = _sysprof_symbolizer_symbolize (symbolizer, strings, process_info, last_context, address)))
+    return ret;
+
+  /* Fallback, we failed to locate the symbol within a file we can
+   * access, so tell the user about what file contained the symbol
+   * and where (relative to that file) the IP was.
+   */
+
+  if (!(map = sysprof_address_layout_lookup (process_info->address_layout, address)))
+    return NULL;
+
+  map_begin = sysprof_document_mmap_get_start_address (map);
+  map_end = sysprof_document_mmap_get_end_address (map);
+
+  g_assert (address >= map_begin);
+  g_assert (address < map_end);
+
+  file_offset = sysprof_document_mmap_get_file_offset (map);
+
+  relative_address = address;
+  relative_address -= map_begin;
+  relative_address += file_offset;
+
+  path = sysprof_document_mmap_get_file (map);
+
+  begin_address = CLAMP (begin_address, file_offset, file_offset + (map_end - map_begin));
+  end_address = CLAMP (end_address, file_offset, file_offset + (map_end - map_begin));
+  if (end_address == begin_address)
+    end_address++;
+
+  name = g_strdup_printf ("In File %s+0x%"G_GINT64_MODIFIER"x",
+                          sysprof_document_mmap_get_file (map),
+                          relative_address);
+  begin_address = address;
+  end_address = address + 1;
+
+  ret = _sysprof_symbol_new (sysprof_strings_get (strings, name),
+                             sysprof_strings_get (strings, path),
+                             sysprof_strings_get (strings, nick),
+                             begin_address, end_address,
+                             SYSPROF_SYMBOL_KIND_USER);
+  ret->is_fallback = TRUE;
+
+  return ret;
+}
+
 static void
 add_traceable (SysprofDocumentSymbols   *self,
                SysprofStrings           *strings,
@@ -123,7 +188,7 @@ add_traceable (SysprofDocumentSymbols   *self,
           if (sysprof_symbol_cache_lookup (self->kernel_symbols, address) != NULL)
             continue;
 
-          if ((symbol = _sysprof_symbolizer_symbolize (symbolizer, strings, process_info, last_context, address)))
+          if ((symbol = do_symbolize (symbolizer, strings, process_info, last_context, address)))
             sysprof_symbol_cache_take (self->kernel_symbols, g_steal_pointer (&symbol));
         }
       else
@@ -134,7 +199,7 @@ add_traceable (SysprofDocumentSymbols   *self,
               sysprof_symbol_cache_lookup (process_info->symbol_cache, address) != NULL)
             continue;
 
-          if ((symbol = _sysprof_symbolizer_symbolize (symbolizer, strings, process_info, last_context, address)))
+          if ((symbol = do_symbolize (symbolizer, strings, process_info, last_context, address)))
             sysprof_symbol_cache_take (process_info->symbol_cache, g_steal_pointer (&symbol));
         }
     }

src/libsysprof/sysprof-elf-symbolizer.c

@@ -113,7 +113,7 @@ sysprof_elf_symbolizer_symbolize (SysprofSymbolizer        *symbolizer,
                                        build_id,
                                        file_inode,
                                        NULL)))
-    goto fallback;
+    return NULL;
 
   nick = sysprof_elf_get_nick (elf);
 
@@ -124,7 +124,7 @@ sysprof_elf_symbolizer_symbolize (SysprofSymbolizer        *symbolizer,
                                                   relative_address,
                                                   &begin_address,
                                                   &end_address)))
-    goto fallback;
+    return NULL;
 
   /* Sanitize address ranges if we have to. Sometimes that can happen
    * for us, but it seems to be limited to glibc.
@@ -142,26 +142,6 @@ sysprof_elf_symbolizer_symbolize (SysprofSymbolizer        *symbolizer,
                              SYSPROF_SYMBOL_KIND_USER);
 
   return ret;
-
-fallback:
-  /* Fallback, we failed to locate the symbol within a file we can
-   * access, so tell the user about what file contained the symbol
-   * and where (relative to that file) the IP was.
-   */
-  name = g_strdup_printf ("In File %s+0x%"G_GINT64_MODIFIER"x",
-                          sysprof_document_mmap_get_file (map),
-                          relative_address);
-  begin_address = address;
-  end_address = address + 1;
-
-  ret = _sysprof_symbol_new (sysprof_strings_get (strings, name),
-                             sysprof_strings_get (strings, path),
-                             sysprof_strings_get (strings, nick),
-                             begin_address, end_address,
-                             SYSPROF_SYMBOL_KIND_USER);
-  ret->is_fallback = TRUE;
-
-  return ret;
 }
 
 static void