Change the API for getting the bootstrapped defs.

The symtab that contains them is now hidden, and
you can look them up by name but there is no access
to the symtab itself, so there is no risk of
mutating it (by extending it, adding other defs
to it, etc).

11 files changed, 100 insertions, 116 deletions

diff --git a/Makefile b/Makefile
index f2bd34e..6801f63 100644
--- a/Makefile
+++ b/Makefile
@@ -179,22 +179,28 @@ tests/test.proto.pb: tests/test.proto
 	@# TODO: replace with upbc
 	protoc tests/test.proto -otests/test.proto.pb
 
-TESTS= \
+SIMPLE_TESTS= \
   tests/test_string \
-  tests/test_table \
   tests/test_def \
   tests/test_stream \
+  tests/tests
+#    tests/test_decoder \
+
+SIMPLE_CXX_TESTS= \
+  tests/test_table
+
+VARIADIC_TESTS= \
   tests/t.test_vs_proto2.googlemessage1 \
   tests/t.test_vs_proto2.googlemessage2 \
-  tests/test.proto.pb \
-  tests/tests
 
-#    tests/test_decoder \
+TESTS=$(SIMPLE_TESTS) $(SIMPLE_CXX_TESTS) $(VARIADIC_TESTS)
+
 
 tests: $(TESTS)
 $(TESTS): $(LIBUPB)
+tests/tests: tests/test.proto.pb
 
-% : %.c
+$(SIMPLE_TESTS): % : %.c
 	$(E) CC $<
 	$(Q) $(CC) $(CFLAGS) $(CPPFLAGS) -c -o $@ $<
 
@@ -237,9 +243,6 @@ tests/test_table: tests/test_table.cc
 
 tests/tests: src/libupb.a
 
-# Tools
-tools: src/upbc
-src/upbc: $(LIBUPB)
 
 # Benchmarks. ##################################################################
 
diff --git a/benchmarks/parsestream.upb_table.c b/benchmarks/parsestream.upb_table.c
index a646999..85c9ff9 100644
--- a/benchmarks/parsestream.upb_table.c
+++ b/benchmarks/parsestream.upb_table.c
@@ -17,12 +17,6 @@ static bool initialize()
   // Initialize upb state, decode descriptor.
   upb_status status = UPB_STATUS_INIT;
   upb_symtab *s = upb_symtab_new();
-  upb_symtab_add_descriptorproto(s);
-  upb_def *fds_def = upb_symtab_lookup(
-      s, UPB_STRLIT("google.protobuf.FileDescriptorSet"));
-  if (!fds_def) {
-    fprintf(stderr, "Couldn't load FileDescriptorSet def");
-  }
 
   upb_string *fds_str = upb_strreadfile(MESSAGE_DESCRIPTOR_FILE);
   if(fds_str == NULL) {
diff --git a/benchmarks/parsetostruct.upb_table.c b/benchmarks/parsetostruct.upb_table.c
index 592f86e..dfdd5b2 100644
--- a/benchmarks/parsetostruct.upb_table.c
+++ b/benchmarks/parsetostruct.upb_table.c
@@ -20,7 +20,6 @@ static bool initialize()
   // Initialize upb state, decode descriptor.
   upb_status status = UPB_STATUS_INIT;
   upb_symtab *s = upb_symtab_new();
-  upb_symtab_add_descriptorproto(s);
 
   upb_string *fds_str = upb_strreadfile(MESSAGE_DESCRIPTOR_FILE);
   if(fds_str == NULL) {
diff --git a/src/descriptor_const.h b/src/descriptor_const.h
index 44598dc..f02eb75 100644
--- a/src/descriptor_const.h
+++ b/src/descriptor_const.h
@@ -11,8 +11,8 @@ extern "C" {
 
 typedef enum google_protobuf_FieldOptions_CType {
   GOOGLE_PROTOBUF_FIELDOPTIONS_STRING = 0,
-  GOOGLE_PROTOBUF_FIELDOPTIONS_CORD = 1,
-  GOOGLE_PROTOBUF_FIELDOPTIONS_STRING_PIECE = 2
+  GOOGLE_PROTOBUF_FIELDOPTIONS_STRING_PIECE = 2,
+  GOOGLE_PROTOBUF_FIELDOPTIONS_CORD = 1
 } google_protobuf_FieldOptions_CType;
 
 typedef enum google_protobuf_FieldDescriptorProto_Type {
@@ -50,10 +50,8 @@ typedef enum google_protobuf_FileOptions_OptimizeMode {
 
 /* Constants for field names and numbers. */
 
-#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_NAME_PART_FIELDNUM 1
-#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_NAME_PART_FIELDNAME "name_part"
-#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_IS_EXTENSION_FIELDNUM 2
-#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_IS_EXTENSION_FIELDNAME "is_extension"
+#define GOOGLE_PROTOBUF_FILEDESCRIPTORSET_FILE_FIELDNUM 1
+#define GOOGLE_PROTOBUF_FILEDESCRIPTORSET_FILE_FIELDNAME "file"
 #define GOOGLE_PROTOBUF_DESCRIPTORPROTO_NAME_FIELDNUM 1
 #define GOOGLE_PROTOBUF_DESCRIPTORPROTO_NAME_FIELDNAME "name"
 #define GOOGLE_PROTOBUF_DESCRIPTORPROTO_FIELD_FIELDNUM 2
@@ -132,8 +130,10 @@ typedef enum google_protobuf_FileOptions_OptimizeMode {
 #define GOOGLE_PROTOBUF_SERVICEDESCRIPTORPROTO_METHOD_FIELDNAME "method"
 #define GOOGLE_PROTOBUF_SERVICEDESCRIPTORPROTO_OPTIONS_FIELDNUM 3
 #define GOOGLE_PROTOBUF_SERVICEDESCRIPTORPROTO_OPTIONS_FIELDNAME "options"
-#define GOOGLE_PROTOBUF_FILEDESCRIPTORSET_FILE_FIELDNUM 1
-#define GOOGLE_PROTOBUF_FILEDESCRIPTORSET_FILE_FIELDNAME "file"
+#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_NAME_PART_FIELDNUM 1
+#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_NAME_PART_FIELDNAME "name_part"
+#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_IS_EXTENSION_FIELDNUM 2
+#define GOOGLE_PROTOBUF_UNINTERPRETEDOPTION_NAMEPART_IS_EXTENSION_FIELDNAME "is_extension"
 #define GOOGLE_PROTOBUF_SOURCECODEINFO_LOCATION_FIELDNUM 1
 #define GOOGLE_PROTOBUF_SOURCECODEINFO_LOCATION_FIELDNAME "location"
 #define GOOGLE_PROTOBUF_DESCRIPTORPROTO_EXTENSIONRANGE_START_FIELDNUM 1
@@ -146,14 +146,12 @@ typedef enum google_protobuf_FileOptions_OptimizeMode {
 #define GOOGLE_PROTOBUF_FIELDOPTIONS_PACKED_FIELDNAME "packed"
 #define GOOGLE_PROTOBUF_FIELDOPTIONS_DEPRECATED_FIELDNUM 3
 #define GOOGLE_PROTOBUF_FIELDOPTIONS_DEPRECATED_FIELDNAME "deprecated"
-#define GOOGLE_PROTOBUF_FIELDOPTIONS_UNINTERPRETED_OPTION_FIELDNUM 999
-#define GOOGLE_PROTOBUF_FIELDOPTIONS_UNINTERPRETED_OPTION_FIELDNAME "uninterpreted_option"
 #define GOOGLE_PROTOBUF_FIELDOPTIONS_EXPERIMENTAL_MAP_KEY_FIELDNUM 9
 #define GOOGLE_PROTOBUF_FIELDOPTIONS_EXPERIMENTAL_MAP_KEY_FIELDNAME "experimental_map_key"
+#define GOOGLE_PROTOBUF_FIELDOPTIONS_UNINTERPRETED_OPTION_FIELDNUM 999
+#define GOOGLE_PROTOBUF_FIELDOPTIONS_UNINTERPRETED_OPTION_FIELDNAME "uninterpreted_option"
 #define GOOGLE_PROTOBUF_FILEOPTIONS_JAVA_PACKAGE_FIELDNUM 1
 #define GOOGLE_PROTOBUF_FILEOPTIONS_JAVA_PACKAGE_FIELDNAME "java_package"
-#define GOOGLE_PROTOBUF_FILEOPTIONS_UNINTERPRETED_OPTION_FIELDNUM 999
-#define GOOGLE_PROTOBUF_FILEOPTIONS_UNINTERPRETED_OPTION_FIELDNAME "uninterpreted_option"
 #define GOOGLE_PROTOBUF_FILEOPTIONS_JAVA_OUTER_CLASSNAME_FIELDNUM 8
 #define GOOGLE_PROTOBUF_FILEOPTIONS_JAVA_OUTER_CLASSNAME_FIELDNAME "java_outer_classname"
 #define GOOGLE_PROTOBUF_FILEOPTIONS_OPTIMIZE_FOR_FIELDNUM 9
@@ -168,6 +166,8 @@ typedef enum google_protobuf_FileOptions_OptimizeMode {
 #define GOOGLE_PROTOBUF_FILEOPTIONS_PY_GENERIC_SERVICES_FIELDNAME "py_generic_services"
 #define GOOGLE_PROTOBUF_FILEOPTIONS_JAVA_GENERATE_EQUALS_AND_HASH_FIELDNUM 20
 #define GOOGLE_PROTOBUF_FILEOPTIONS_JAVA_GENERATE_EQUALS_AND_HASH_FIELDNAME "java_generate_equals_and_hash"
+#define GOOGLE_PROTOBUF_FILEOPTIONS_UNINTERPRETED_OPTION_FIELDNUM 999
+#define GOOGLE_PROTOBUF_FILEOPTIONS_UNINTERPRETED_OPTION_FIELDNAME "uninterpreted_option"
 #define GOOGLE_PROTOBUF_MESSAGEOPTIONS_MESSAGE_SET_WIRE_FORMAT_FIELDNUM 1
 #define GOOGLE_PROTOBUF_MESSAGEOPTIONS_MESSAGE_SET_WIRE_FORMAT_FIELDNAME "message_set_wire_format"
 #define GOOGLE_PROTOBUF_MESSAGEOPTIONS_NO_STANDARD_DESCRIPTOR_ACCESSOR_FIELDNUM 2
diff --git a/src/upb_decoder.c b/src/upb_decoder.c
index 47e67b6..40ab790 100644
--- a/src/upb_decoder.c
+++ b/src/upb_decoder.c
@@ -346,8 +346,8 @@ void upb_decoder_run(upb_src *src, upb_status *status) {
     //const char *ptr = d->ptr;
     // Decodes as many fields as possible, updating d->ptr appropriately,
     // before falling through to the slow(er) path.
-    const char *end = UPB_MIN(d->end, d->submsg_end);
 #ifdef USE_ASSEMBLY_FASTPATH
+    const char *end = UPB_MIN(d->end, d->submsg_end);
     fastdecode_ret ret = upb_fastdecode(d->ptr, end,
                                         d->dispatcher.top->handlers.set->value,
                                         d->dispatcher.top->handlers.closure,
diff --git a/src/upb_def.c b/src/upb_def.c
index 6a1e543..0382610 100644
--- a/src/upb_def.c
+++ b/src/upb_def.c
@@ -859,6 +859,7 @@ static upb_symtab_ent *upb_resolve(upb_strtable *t,
     // TODO: This branch is totally broken, but currently not used.
     upb_string *sym_str = upb_string_new();
     int baselen = upb_string_len(base);
+    upb_symtab_ent *ret = NULL;
     while(1) {
       // sym_str = base[0...base_len] + UPB_SYMBOL_SEPARATOR + sym
       upb_strlen_t len = baselen + upb_string_len(sym) + 1;
@@ -868,11 +869,18 @@ static upb_symtab_ent *upb_resolve(upb_strtable *t,
       memcpy(buf + baselen + 1, upb_string_getrobuf(sym), upb_string_len(sym));
 
       upb_symtab_ent *e = upb_strtable_lookup(t, sym_str);
-      if (e) return e;
-      else if(baselen == 0) return NULL;  // No more scopes to try.
-
+      if (e) {
+        ret = e;
+        break;
+      } else if(baselen == 0) {
+        // No more scopes to try.
+        ret = NULL;
+        break;
+      }
       baselen = my_memrchr(buf, UPB_SYMBOL_SEPARATOR, baselen);
     }
+    upb_string_unref(sym_str);
+    return ret;
   }
 }
 
@@ -1307,38 +1315,51 @@ static upb_src *upb_baredecoder_src(upb_baredecoder *d) {
   return &d->src;
 }
 
-void upb_symtab_add_descriptorproto(upb_symtab *symtab) {
-  // For the moment we silently decline to perform the operation if the symbols
-  // already exist in the symtab.  Revisit this when we have a better story
-  // about whether syms in a table can be replaced.
-  if(symtab->fds_msgdef) return;
-
-  static upb_string descriptor_str =
-      UPB_STATIC_STRING_ARRAY(descriptor_pb);
-  upb_baredecoder *decoder = upb_baredecoder_new(&descriptor_str);
-  upb_status status = UPB_STATUS_INIT;
-  upb_symtab_addfds(symtab, upb_baredecoder_src(decoder), &status);
-  upb_baredecoder_free(decoder);
-
-  if(!upb_ok(&status)) {
-    // upb itself is corrupt.
-    upb_printerr(&status);
-    upb_clearerr(&status);
-    upb_symtab_unref(symtab);
-    abort();
+static upb_symtab *descriptor_symtab = NULL;
+
+static void upb_free_descriptor_symtab() {
+  if (descriptor_symtab) {
+    // There should be no way for anyone to acquire a ref on this symtab.
+    assert(upb_atomic_only(&descriptor_symtab->refcount));
+    _upb_symtab_free(descriptor_symtab);
+    descriptor_symtab = NULL;
   }
-  upb_def *def = upb_symtab_lookup(
-      symtab, UPB_STRLIT("google.protobuf.FileDescriptorSet"));
-  if (!def || (symtab->fds_msgdef = upb_dyncast_msgdef(def)) == NULL) {
-    // upb itself is corrupt.
-    abort();
+}
+
+upb_def *upb_getdescriptordef(upb_string *str) {
+  // TODO: add locking.
+  if (descriptor_symtab == NULL) {
+    descriptor_symtab = upb_symtab_new();
+
+    static upb_string descriptor_str =
+        UPB_STATIC_STRING_ARRAY(descriptor_pb);
+    upb_baredecoder *decoder = upb_baredecoder_new(&descriptor_str);
+    upb_status status = UPB_STATUS_INIT;
+    upb_symtab_addfds(descriptor_symtab, upb_baredecoder_src(decoder), &status);
+    upb_baredecoder_free(decoder);
+
+    if(!upb_ok(&status)) {
+      // upb itself is corrupt.
+      upb_printerr(&status);
+      upb_clearerr(&status);
+      abort();
+    }
+    upb_status_uninit(&status);
+
+    // As a sanity check, make sure that FileDescriptorSet was loaded.
+    upb_msgdef *def = upb_getfdsdef();
+    if (!def) {
+      // upb itself is corrupt.
+      abort();
+    }
+    upb_def_unref(UPB_UPCAST(def));  // The symtab already holds a ref on it.
+    atexit(upb_free_descriptor_symtab);
   }
-  upb_def_unref(def);  // The symtab already holds a ref on it.
-  upb_status_uninit(&status);
+  return upb_symtab_resolve(
+      descriptor_symtab, UPB_STRLIT("google.protobuf"), str);
 }
 
-upb_msgdef *upb_symtab_fds_def(upb_symtab *s) {
-  assert(s->fds_msgdef != NULL);
-  upb_def_ref(UPB_UPCAST(s->fds_msgdef));
-  return s->fds_msgdef;
+upb_msgdef *upb_getfdsdef() {
+  return upb_downcast_msgdef(
+      upb_getdescriptordef(UPB_STRLIT("FileDescriptorSet")));
 }
diff --git a/src/upb_def.h b/src/upb_def.h
index db33fbb..121d5bc 100644
--- a/src/upb_def.h
+++ b/src/upb_def.h
@@ -276,7 +276,7 @@ void _upb_symtab_free(upb_symtab *s);  // Must not be called directly!
 
 INLINE void upb_symtab_ref(upb_symtab *s) { upb_atomic_ref(&s->refcount); }
 INLINE void upb_symtab_unref(upb_symtab *s) {
-  if(upb_atomic_unref(&s->refcount)) _upb_symtab_free(s);
+  if(s && upb_atomic_unref(&s->refcount)) _upb_symtab_free(s);
 }
 
 // Resolves the given symbol using the rules described in descriptor.proto,
@@ -314,17 +314,20 @@ upb_def **upb_symtab_getdefs(upb_symtab *s, int *count, upb_deftype_t type);
 // more useful?  Maybe it should be an option.
 void upb_symtab_addfds(upb_symtab *s, upb_src *desc, upb_status *status);
 
-// Adds defs for google.protobuf.FileDescriptorSet and friends to this symtab.
-// This is necessary for bootstrapping, since these are the upb_defs that
-// specify other defs and allow them to be loaded.
-void upb_symtab_add_descriptorproto(upb_symtab *s);
-
-// Returns the upb_msgdef for google.protobuf.FileDescriptorSet, which the
-// caller owns a ref on.  This is a convenience method that is equivalent to
-// looking up the symbol called "google.protobuf.FileDescriptorSet" yourself,
-// except that it only will return a def that was added by
-// upb_symtab_add_descriptorproto().
-upb_msgdef *upb_symtab_fds_def(upb_symtab *s);
+// Returns a def corresponding to the given name, from descriptor.proto.
+// upb internally bootstraps the defs in descriptor.proto, since they are
+// necessary for loading other descriptors.  The caller owns a ref on the
+// returned def (which is NULL if no such def exists in descriptor.proto).
+//
+// The name should *not* be qualified by the package, to promote
+// interoperability between the internal and external releases of Protocol
+// Buffers (inside Google, these are in the "proto2" package, externally they
+// are in "google.protobuf".
+upb_def *upb_getdescriptordef(upb_string *str);
+
+// A convenience method for getting the upb_def for FileDescriptorProto.
+// Return should never be NULL.
+upb_msgdef *upb_getfdsdef();
 
 
 /* upb_def casts **************************************************************/
diff --git a/src/upb_glue.c b/src/upb_glue.c
index 536adc0..a3d4e7d 100644
--- a/src/upb_glue.c
+++ b/src/upb_glue.c
@@ -38,13 +38,12 @@ void upb_strtomsg(upb_string *str, upb_msg *msg, upb_msgdef *md,
 }
 
 void upb_parsedesc(upb_symtab *symtab, upb_string *str, upb_status *status) {
-  upb_symtab_add_descriptorproto(symtab);
   upb_stringsrc strsrc;
   upb_stringsrc_init(&strsrc);
   upb_stringsrc_reset(&strsrc, str);
 
   upb_decoder d;
-  upb_msgdef *fds_msgdef = upb_symtab_fds_def(symtab);
+  upb_msgdef *fds_msgdef = upb_getfdsdef();
   upb_decoder_init(&d, fds_msgdef);
   upb_decoder_reset(&d, upb_stringsrc_bytesrc(&strsrc));
 
diff --git a/src/upbc.c b/src/upbc.c
index 4cfa6e6..428ec41 100644
--- a/src/upbc.c
+++ b/src/upbc.c
@@ -191,29 +191,12 @@ int main(int argc, char *argv[])
   // TODO: make upb_parsedesc use a separate symtab, so we can use it here when
   // importing descriptor.proto.
   upb_symtab *s = upb_symtab_new();
-  upb_symtab_add_descriptorproto(s);
-  upb_symtab *s2 = upb_symtab_new();
   upb_status status = UPB_STATUS_INIT;
-
-  upb_stringsrc strsrc;
-  upb_stringsrc_init(&strsrc);
-  upb_stringsrc_reset(&strsrc, descriptor);
-
-  upb_decoder d;
-  upb_msgdef *fds_msgdef = upb_symtab_fds_def(s);
-  upb_decoder_init(&d, fds_msgdef);
-  upb_decoder_reset(&d, upb_stringsrc_bytesrc(&strsrc));
-
-  upb_symtab_addfds(s2, upb_decoder_src(&d), &status);
-  upb_stringsrc_uninit(&strsrc);
-  upb_decoder_uninit(&d);
-  upb_def_unref(UPB_UPCAST(fds_msgdef));
-
+  upb_parsedesc(s, descriptor, &status);
   if(!upb_ok(&status)) {
     upb_printerr(&status);
     error("Failed to parse input file descriptor\n");
   }
-
   upb_status_uninit(&status);
 
   /* Emit output files. */
@@ -232,7 +215,6 @@ int main(int argc, char *argv[])
   free(defs);
   upb_string_unref(descriptor);
   upb_symtab_unref(s);
-  upb_symtab_unref(s2);
   fclose(h_const_file);
 
   return 0;
diff --git a/tests/test_def.c b/tests/test_def.c
index 2d2658f..287cc32 100644
--- a/tests/test_def.c
+++ b/tests/test_def.c
@@ -5,8 +5,8 @@
 
 int main() {
   upb_symtab *s = upb_symtab_new();
-  upb_symtab_add_descriptorproto(s);
 
+  // Will be empty atm since we haven't added anything to the symtab.
   int count;
   upb_def **defs = upb_symtab_getdefs(s, &count, UPB_DEF_ANY);
   for (int i = 0; i < count; i++) {
@@ -14,12 +14,9 @@ int main() {
   }
   free(defs);
 
-  upb_string *str = upb_strdupc("google.protobuf.FileDescriptorSet");
-  upb_def *fds = upb_symtab_lookup(s, str);
+  upb_msgdef *fds = upb_getfdsdef();
   assert(fds != NULL);
-  assert(upb_dyncast_msgdef(fds) != NULL);
-  upb_def_unref(fds);
-  upb_string_unref(str);
+  upb_def_unref(UPB_UPCAST(fds));
   upb_symtab_unref(s);
   return 0;
 }
diff --git a/tests/test_vs_proto2.cc b/tests/test_vs_proto2.cc
index 749eedf..1839123 100644
--- a/tests/test_vs_proto2.cc
+++ b/tests/test_vs_proto2.cc
@@ -213,26 +213,13 @@ int main(int argc, char *argv[])
     fprintf(stderr, "Couldn't read " MESSAGE_DESCRIPTOR_FILE ".\n");
     return 1;
   }
-  upb_symtab_add_descriptorproto(symtab);
-  upb_def *fds_msgdef = upb_symtab_lookup(
-      symtab, UPB_STRLIT("google.protobuf.FileDescriptorSet"));
-  assert(fds_msgdef);
-
-  upb_stringsrc ssrc;
-  upb_stringsrc_init(&ssrc);
-  upb_stringsrc_reset(&ssrc, fds);
-  upb_decoder decoder;
-  upb_decoder_init(&decoder, upb_downcast_msgdef(fds_msgdef));
-  upb_decoder_reset(&decoder, upb_stringsrc_bytesrc(&ssrc));
-  upb_symtab_addfds(symtab, upb_decoder_src(&decoder), &status);
+  upb_parsedesc(symtab, fds, &status);
   if(!upb_ok(&status)) {
     fprintf(stderr, "Error importing " MESSAGE_DESCRIPTOR_FILE ": ");
     upb_printerr(&status);
     return 1;
   }
   upb_string_unref(fds);
-  upb_decoder_uninit(&decoder);
-  upb_stringsrc_uninit(&ssrc);
 
   upb_string *proto_name = upb_strdupc(MESSAGE_NAME);
   upb_def *def = upb_symtab_lookup(symtab, proto_name);
@@ -260,7 +247,6 @@ int main(int argc, char *argv[])
 
   upb_msg_unref(upb_msg, msgdef);
   upb_def_unref(UPB_UPCAST(msgdef));
-  upb_def_unref(fds_msgdef);
   upb_string_unref(str);
   upb_symtab_unref(symtab);
   upb_status_uninit(&status);