Split upb::Arena/upb::Allocator from upb::Environment. (#58)

* Split upb::Arena/upb::Allocator from upb::Environment.

This will allow arenas and allocators to be used
independently of environments, which will be important
for an upcoming change (a message representation).
Overall this design feels cleaner that the previous
Environment/SeededAllocator design.

As part of this change, moved all allocations in upb
to use a global allocator instead of hard-coding
malloc/free.  This will allow injecting OOM faults
for more robust testing.

One place that doesn't use the global allocator is
the tracked ref code.  Instead of its previous approach
of CHECK_OOM() after every malloc() or table insert, it
simply uses an allocator that does this automatically.

I moved Allocator/Arena/Environment into upb.h.
This seems principled since these are the only types
in upb whose size is directly exposed to users, since
they form the basis of memory allocation strategy.

* Cleaned up some header includes and fixed more malloc -> upb_gmalloc().

* Changes from PR review.

* Don't use UINTPTR_MAX or UINT64_MAX.

* Punt on adding line/file for now.

* We actually can't store (uint64_t)-1, update comment and test.

2 files changed, 35 insertions, 25 deletions

diff --git a/upb/descriptor/reader.c b/upb/descriptor/reader.c
index e9d7978..fc1de78 100644
--- a/upb/descriptor/reader.c
+++ b/upb/descriptor/reader.c
@@ -61,7 +61,7 @@ struct upb_descreader {
 };
 
 static char *upb_strndup(const char *buf, size_t n) {
-  char *ret = malloc(n + 1);
+  char *ret = upb_gmalloc(n + 1);
   if (!ret) return NULL;
   memcpy(ret, buf, n);
   ret[n] = '\0';
@@ -75,9 +75,12 @@ static char *upb_strndup(const char *buf, size_t n) {
  * Caller owns a ref on the returned string. */
 static char *upb_join(const char *base, const char *name) {
   if (!base || strlen(base) == 0) {
-    return upb_strdup(name);
+    return upb_gstrdup(name);
   } else {
-    char *ret = malloc(strlen(base) + strlen(name) + 2);
+    char *ret = upb_gmalloc(strlen(base) + strlen(name) + 2);
+    if (!ret) {
+      return NULL;
+    }
     ret[0] = '\0';
     strcat(ret, base);
     strcat(ret, ".");
@@ -87,14 +90,20 @@ static char *upb_join(const char *base, const char *name) {
 }
 
 /* Qualify the defname for all defs starting with offset "start" with "str". */
-static void upb_descreader_qualify(upb_filedef *f, char *str, int32_t start) {
+static bool upb_descreader_qualify(upb_filedef *f, char *str, int32_t start) {
   size_t i;
   for (i = start; i < upb_filedef_defcount(f); i++) {
     upb_def *def = upb_filedef_mutabledef(f, i);
     char *name = upb_join(str, upb_def_fullname(def));
+    if (!name) {
+      /* Need better logic here; at this point we've qualified some names but
+       * not others. */
+      return false;
+    }
     upb_def_setfullname(def, name, NULL);
-    free(name);
+    upb_gfree(name);
   }
+  return true;
 }
 
 
@@ -120,16 +129,19 @@ void upb_descreader_startcontainer(upb_descreader *r) {
   f->name = NULL;
 }
 
-void upb_descreader_endcontainer(upb_descreader *r) {
+bool upb_descreader_endcontainer(upb_descreader *r) {
   upb_descreader_frame *f = &r->stack[--r->stack_len];
-  upb_descreader_qualify(r->file, f->name, f->start);
-  free(f->name);
+  if (!upb_descreader_qualify(r->file, f->name, f->start)) {
+    return false;
+  }
+  upb_gfree(f->name);
   f->name = NULL;
+  return true;
 }
 
 void upb_descreader_setscopename(upb_descreader *r, char *str) {
   upb_descreader_frame *f = &r->stack[r->stack_len-1];
-  free(f->name);
+  upb_gfree(f->name);
   f->name = str;
 }
 
@@ -156,8 +168,7 @@ static bool file_end(void *closure, const void *hd, upb_status *status) {
   upb_descreader *r = closure;
   UPB_UNUSED(hd);
   UPB_UNUSED(status);
-  upb_descreader_endcontainer(r);
-  return true;
+  return upb_descreader_endcontainer(r);
 }
 
 static size_t file_onname(void *closure, const void *hd, const char *buf,
@@ -171,6 +182,7 @@ static size_t file_onname(void *closure, const void *hd, const char *buf,
   name = upb_strndup(buf, n);
   /* XXX: see comment at the top of the file. */
   ok = upb_filedef_setname(r->file, name, NULL);
+  upb_gfree(name);
   UPB_ASSERT_VAR(ok, ok);
   return n;
 }
@@ -254,7 +266,7 @@ static size_t enumval_onname(void *closure, const void *hd, const char *buf,
   UPB_UNUSED(hd);
   UPB_UNUSED(handle);
   /* XXX: see comment at the top of the file. */
-  free(r->name);
+  upb_gfree(r->name);
   r->name = upb_strndup(buf, n);
   r->saw_name = true;
   return n;
@@ -279,7 +291,7 @@ static bool enumval_endmsg(void *closure, const void *hd, upb_status *status) {
   }
   e = upb_downcast_enumdef_mutable(upb_descreader_last(r));
   upb_enumdef_addval(e, r->name, r->number, status);
-  free(r->name);
+  upb_gfree(r->name);
   r->name = NULL;
   return true;
 }
@@ -311,7 +323,7 @@ static size_t enum_onname(void *closure, const void *hd, const char *buf,
   UPB_UNUSED(handle);
   /* XXX: see comment at the top of the file. */
   upb_def_setfullname(upb_descreader_last(r), fullname, NULL);
-  free(fullname);
+  upb_gfree(fullname);
   return n;
 }
 
@@ -321,7 +333,7 @@ static bool field_startmsg(void *closure, const void *hd) {
   upb_descreader *r = closure;
   UPB_UNUSED(hd);
   assert(r->f);
-  free(r->default_string);
+  upb_gfree(r->default_string);
   r->default_string = NULL;
 
   /* fielddefs default to packed, but descriptors default to non-packed. */
@@ -480,7 +492,7 @@ static size_t field_onname(void *closure, const void *hd, const char *buf,
 
   /* XXX: see comment at the top of the file. */
   upb_fielddef_setname(r->f, name, NULL);
-  free(name);
+  upb_gfree(name);
   return n;
 }
 
@@ -493,7 +505,7 @@ static size_t field_ontypename(void *closure, const void *hd, const char *buf,
 
   /* XXX: see comment at the top of the file. */
   upb_fielddef_setsubdefname(r->f, name, NULL);
-  free(name);
+  upb_gfree(name);
   return n;
 }
 
@@ -506,7 +518,7 @@ static size_t field_onextendee(void *closure, const void *hd, const char *buf,
 
   /* XXX: see comment at the top of the file. */
   upb_fielddef_setcontainingtypename(r->f, name, NULL);
-  free(name);
+  upb_gfree(name);
   return n;
 }
 
@@ -519,7 +531,7 @@ static size_t field_ondefaultval(void *closure, const void *hd, const char *buf,
   /* Have to convert from string to the correct type, but we might not know the
    * type yet, so we save it as a string until the end of the field.
    * XXX: see comment at the top of the file. */
-  free(r->default_string);
+  upb_gfree(r->default_string);
   r->default_string = upb_strndup(buf, n);
   return n;
 }
@@ -543,8 +555,7 @@ static bool msg_end(void *closure, const void *hd, upb_status *status) {
     upb_status_seterrmsg(status, "Encountered message with no name.");
     return false;
   }
-  upb_descreader_endcontainer(r);
-  return true;
+  return upb_descreader_endcontainer(r);
 }
 
 static size_t msg_name(void *closure, const void *hd, const char *buf,
@@ -683,12 +694,12 @@ void descreader_cleanup(void *_r) {
     upb_filedef_unref(upb_descreader_file(r, i), &r->files);
   }
 
-  free(r->name);
+  upb_gfree(r->name);
   upb_inttable_uninit(&r->files);
-  free(r->default_string);
+  upb_gfree(r->default_string);
   while (r->stack_len > 0) {
     upb_descreader_frame *f = &r->stack[--r->stack_len];
-    free(f->name);
+    upb_gfree(f->name);
   }
 }
 
diff --git a/upb/descriptor/reader.h b/upb/descriptor/reader.h
index a6fc7f0..e8ede0d 100644
--- a/upb/descriptor/reader.h
+++ b/upb/descriptor/reader.h
@@ -7,7 +7,6 @@
 #ifndef UPB_DESCRIPTOR_H
 #define UPB_DESCRIPTOR_H
 
-#include "upb/env.h"
 #include "upb/sink.h"
 
 #ifdef __cplusplus