12364 mdb trips assertion related to autowrap

*** 23,33 ****
   * Use is subject to license terms.
   */
  
  /*
   * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
!  * Copyright 2015 Joyent, Inc.
   * Copyright (c) 2014 Nexenta Systems, Inc. All rights reserved.
   */
  
  #include <mdb/mdb_modapi.h>
  #include <mdb/mdb_target.h>
--- 23,33 ----
   * Use is subject to license terms.
   */
  
  /*
   * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
!  * Copyright 2020 Joyent, Inc.
   * Copyright (c) 2014 Nexenta Systems, Inc. All rights reserved.
   */
  
  #include <mdb/mdb_modapi.h>
  #include <mdb/mdb_target.h>
*** 929,938 ****
--- 929,962 ----
  
          return (0);
  }
  
  /*
+  * We want to print an escaped char as e.g. '\0'. We don't use mdb_fmt_print()
+  * as it won't get auto-wrap right here (although even now, we don't include any
+  * trailing comma).
+  */
+ static int
+ print_char_val(mdb_tgt_addr_t addr, printarg_t *pap)
+ {
+         char cval;
+         char *s;
+ 
+         if (mdb_tgt_aread(pap->pa_tgt, pap->pa_as, &cval, 1, addr) != 1)
+                 return (1);
+ 
+         if (mdb.m_flags & MDB_FL_ADB)
+                 s = strchr2adb(&cval, 1);
+         else
+                 s = strchr2esc(&cval, 1);
+ 
+         mdb_printf("'%s'", s);
+         strfree(s);
+         return (0);
+ }
+ 
+ /*
   * Print out a character or integer value.  We use some simple heuristics,
   * described below, to determine the appropriate radix to use for output.
   */
  static int
  print_int_val(const char *type, ctf_encoding_t *ep, ulong_t off,
*** 969,986 ****
           */
          size = ep->cte_bits / NBBY;
          if (size > 8 || (ep->cte_bits % NBBY) != 0 || (size & (size - 1)) != 0)
                  return (print_bitfield(off, pap, ep));
  
!         if (IS_CHAR(*ep)) {
!                 mdb_printf("'");
!                 if (mdb_fmt_print(pap->pa_tgt, pap->pa_as,
!                     addr, 1, 'C') == addr)
!                         return (1);
!                 mdb_printf("'");
!                 return (0);
!         }
  
          if (mdb_tgt_aread(pap->pa_tgt, pap->pa_as, &u.i8, size, addr) != size) {
                  mdb_warn("failed to read %lu bytes at %llx",
                      (ulong_t)size, addr);
                  return (1);
--- 993,1004 ----
           */
          size = ep->cte_bits / NBBY;
          if (size > 8 || (ep->cte_bits % NBBY) != 0 || (size & (size - 1)) != 0)
                  return (print_bitfield(off, pap, ep));
  
!         if (IS_CHAR(*ep))
!                 return (print_char_val(addr, pap));
  
          if (mdb_tgt_aread(pap->pa_tgt, pap->pa_as, &u.i8, size, addr) != size) {
                  mdb_warn("failed to read %lu bytes at %llx",
                      (ulong_t)size, addr);
                  return (1);