Ported upb to C89, for greater portability.

A large part of this change contains surface-level
porting, like moving variable declarations to the
top of the block.

However there are a few more substantial things too:

- moved internal-only struct definitions to a separate
  file (structdefs.int.h), for greater encapsulation
  and ABI compatibility.

- removed the UPB_UPCAST macro, since it requires access
  to the internal-only struct definitions.  Replaced uses
  with calls to inline, type-safe casting functions.

- removed the UPB_DEFINE_CLASS/UPB_DEFINE_STRUCT macros.
  Class and struct definitions are now more explicit -- you
  get to see the actual class/struct keywords in the source.
  The casting convenience functions have been moved into
  UPB_DECLARE_DERIVED_TYPE() and UPB_DECLARE_DERIVED_TYPE2().

- the new way that we duplicate base methods in derived types
  is also more convenient and requires less duplication.
  It is also less greppable, but hopefully that is not
  too big a problem.

Compiler flags (-std=c89 -pedantic) should help to rigorously
enforce that the code is free of C99-isms.

A few functions are not available in C89 (strtoll).  There
are temporary, hacky solutions in place.

1 files changed, 23 insertions, 16 deletions

diff --git a/upb/pb/glue.c b/upb/pb/glue.c
index 1259dac..76c8356 100644
--- a/upb/pb/glue.c
+++ b/upb/pb/glue.c
@@ -15,28 +15,31 @@
 
 upb_def **upb_load_defs_from_descriptor(const char *str, size_t len, int *n,
                                         void *owner, upb_status *status) {
-  // Create handlers.
+  /* Create handlers. */
+  const upb_pbdecodermethod *decoder_m;
   const upb_handlers *reader_h = upb_descreader_newhandlers(&reader_h);
+  upb_env env;
   upb_pbdecodermethodopts opts;
+  upb_pbdecoder *decoder;
+  upb_descreader *reader;
+  bool ok;
+  upb_def **ret = NULL;
+  upb_def **defs;
+
   upb_pbdecodermethodopts_init(&opts, reader_h);
-  const upb_pbdecodermethod *decoder_m =
-      upb_pbdecodermethod_new(&opts, &decoder_m);
+  decoder_m = upb_pbdecodermethod_new(&opts, &decoder_m);
 
-  upb_env env;
   upb_env_init(&env);
   upb_env_reporterrorsto(&env, status);
 
-  upb_descreader *reader = upb_descreader_create(&env, reader_h);
-  upb_pbdecoder *decoder =
-      upb_pbdecoder_create(&env, decoder_m, upb_descreader_input(reader));
-
-  // Push input data.
-  bool ok = upb_bufsrc_putbuf(str, len, upb_pbdecoder_input(decoder));
+  reader = upb_descreader_create(&env, reader_h);
+  decoder = upb_pbdecoder_create(&env, decoder_m, upb_descreader_input(reader));
 
-  upb_def **ret = NULL;
+  /* Push input data. */
+  ok = upb_bufsrc_putbuf(str, len, upb_pbdecoder_input(decoder));
 
   if (!ok) goto cleanup;
-  upb_def **defs = upb_descreader_getdefs(reader, owner, n);
+  defs = upb_descreader_getdefs(reader, owner, n);
   ret = malloc(sizeof(upb_def*) * (*n));
   memcpy(ret, defs, sizeof(upb_def*) * (*n));
 
@@ -50,21 +53,24 @@ cleanup:
 bool upb_load_descriptor_into_symtab(upb_symtab *s, const char *str, size_t len,
                                      upb_status *status) {
   int n;
+  bool success;
   upb_def **defs = upb_load_defs_from_descriptor(str, len, &n, &defs, status);
   if (!defs) return false;
-  bool success = upb_symtab_add(s, defs, n, &defs, status);
+  success = upb_symtab_add(s, defs, n, &defs, status);
   free(defs);
   return success;
 }
 
 char *upb_readfile(const char *filename, size_t *len) {
+  long size;
+  char *buf;
   FILE *f = fopen(filename, "rb");
   if(!f) return NULL;
   if(fseek(f, 0, SEEK_END) != 0) goto error;
-  long size = ftell(f);
+  size = ftell(f);
   if(size < 0) goto error;
   if(fseek(f, 0, SEEK_SET) != 0) goto error;
-  char *buf = malloc(size + 1);
+  buf = malloc(size + 1);
   if(size && fread(buf, size, 1, f) != 1) goto error;
   fclose(f);
   if (len) *len = size;
@@ -78,12 +84,13 @@ error:
 bool upb_load_descriptor_file_into_symtab(upb_symtab *symtab, const char *fname,
                                           upb_status *status) {
   size_t len;
+  bool success;
   char *data = upb_readfile(fname, &len);
   if (!data) {
     if (status) upb_status_seterrf(status, "Couldn't read file: %s", fname);
     return false;
   }
-  bool success = upb_load_descriptor_into_symtab(symtab, data, len, status);
+  success = upb_load_descriptor_into_symtab(symtab, data, len, status);
   free(data);
   return success;
 }