11584 ::xcall would be useful
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>

*** 22,32 ****
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  /*
   * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
!  * Copyright (c) 2015, Joyent, Inc.  All rights reserved.
   */
  
  #include <mdb/mdb_ctf.h>
  #include <mdb/mdb_ctf_impl.h>
  #include <mdb/mdb_err.h>
--- 22,32 ----
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   */
  /*
   * Copyright (c) 2013, 2016 by Delphix. All rights reserved.
!  * Copyright (c) 2018, Joyent, Inc.
   */
  
  #include <mdb/mdb_ctf.h>
  #include <mdb/mdb_ctf_impl.h>
  #include <mdb/mdb_err.h>
*** 1234,1245 ****
  
          (void) mdb_snprintf(tgtname, sizeof (tgtname),
              "member %s of type %s", name, mp->m_tgtname);
  
          if (mdb_ctf_member_info(mp->m_tgtid, name, &tgtoff, &tgtmid) != 0) {
!                 mdb_ctf_warn(mp->m_flags,
!                     "could not find %s\n", tgtname);
                  return (set_errno(EMDB_CTFNOMEMB));
          }
  
          return (vread_helper(modmid, modbuf + modoff / NBBY,
              tgtmid, tgtbuf + tgtoff / NBBY, tgtname, mp->m_flags));
--- 1234,1246 ----
  
          (void) mdb_snprintf(tgtname, sizeof (tgtname),
              "member %s of type %s", name, mp->m_tgtname);
  
          if (mdb_ctf_member_info(mp->m_tgtid, name, &tgtoff, &tgtmid) != 0) {
!                 if (mp->m_flags & MDB_CTF_VREAD_IGNORE_ABSENT)
!                         return (0);
!                 mdb_ctf_warn(mp->m_flags, "could not find %s\n", tgtname);
                  return (set_errno(EMDB_CTFNOMEMB));
          }
  
          return (vread_helper(modmid, modbuf + modoff / NBBY,
              tgtmid, tgtbuf + tgtoff / NBBY, tgtname, mp->m_flags));
*** 1610,1625 ****
   * Enums will also be translated by name, so the mdb module will receive
   * the enum value it expects even if the target has renumbered the enum.
   * Warning: it will therefore only work with enums are only used to store
   * legitimate enum values (not several values or-ed together).
   *
!  * By default, if mdb_ctf_vread() can not find any members or enum values,
!  * it will print a descriptive message (with mdb_warn()) and fail.
!  * Passing MDB_CTF_VREAD_QUIET in 'flags' will suppress the warning message.
!  * Additional flags can be used to ignore specific types of translation
!  * failure, but should be used with caution, because they will silently leave
!  * the caller's buffer uninitialized.
   */
  int
  mdb_ctf_vread(void *modbuf, const char *target_typename,
      const char *mdb_typename, uintptr_t addr, uint_t flags)
  {
--- 1611,1625 ----
   * Enums will also be translated by name, so the mdb module will receive
   * the enum value it expects even if the target has renumbered the enum.
   * Warning: it will therefore only work with enums are only used to store
   * legitimate enum values (not several values or-ed together).
   *
!  * Flags values:
!  *
!  * MDB_CTF_VREAD_QUIET: keep quiet about failures
!  * MDB_CTF_VREAD_IGNORE_ABSENT: ignore any member that couldn't be found in the
!  * target struct; be careful not to use an uninitialized result.
   */
  int
  mdb_ctf_vread(void *modbuf, const char *target_typename,
      const char *mdb_typename, uintptr_t addr, uint_t flags)
  {
*** 1628,1637 ****
--- 1628,1638 ----
          void *tgtbuf;
          size_t size;
          mdb_ctf_id_t tgtid;
          mdb_ctf_id_t modid;
          mdb_module_t *mod;
+         int ret;
  
          if ((mod = mdb_get_module()) == NULL || (mfp = mod->mod_ctfp) == NULL) {
                  mdb_ctf_warn(flags, "no ctf data found for mdb module %s\n",
                      mod->mod_name);
                  return (set_errno(EMDB_NOCTF));
*** 1660,1678 ****
                  mdb_ctf_warn(flags, "couldn't determine size of type %s\n",
                      target_typename);
                  return (-1); /* errno is set for us */
          }
  
!         tgtbuf = mdb_alloc(size, UM_SLEEP | UM_GC);
  
          if (mdb_vread(tgtbuf, size, addr) < 0) {
                  mdb_ctf_warn(flags, "couldn't read %s from %p\n",
                      target_typename, addr);
                  return (-1); /* errno is set for us */
          }
  
!         return (vread_helper(modid, modbuf, tgtid, tgtbuf, NULL, flags));
  }
  
  /*
   * Note: mdb_ctf_readsym() doesn't take separate parameters for the name
   * of the target's type vs the mdb module's type.  Use with complicated
--- 1661,1684 ----
                  mdb_ctf_warn(flags, "couldn't determine size of type %s\n",
                      target_typename);
                  return (-1); /* errno is set for us */
          }
  
!         tgtbuf = mdb_alloc(size, UM_SLEEP);
  
          if (mdb_vread(tgtbuf, size, addr) < 0) {
                  mdb_ctf_warn(flags, "couldn't read %s from %p\n",
                      target_typename, addr);
+                 mdb_free(tgtbuf, size);
                  return (-1); /* errno is set for us */
          }
  
!         ret = vread_helper(modid, modbuf, tgtid, tgtbuf, NULL, flags);
! 
!         mdb_free(tgtbuf, size);
! 
!         return (ret);
  }
  
  /*
   * Note: mdb_ctf_readsym() doesn't take separate parameters for the name
   * of the target's type vs the mdb module's type.  Use with complicated