usr/src/cmd/mdb/common/mdb/mdb_nv.c - illumos-gate - Gitiles

 /*
  * CDDL HEADER START
  *
  * The contents of this file are subject to the terms of the
  * Common Development and Distribution License, Version 1.0 only
  * (the "License").  You may not use this file except in compliance
  * with the License.
  *
  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  * or http://www.opensolaris.org/os/licensing.
  * See the License for the specific language governing permissions
  * and limitations under the License.
  *
  * When distributing Covered Code, include this CDDL HEADER in each
  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  * If applicable, add the following below this CDDL HEADER, with the
  * fields enclosed by brackets "[]" replaced with your own identifying
  * information: Portions Copyright [yyyy] [name of copyright owner]
  *
  * CDDL HEADER END
  */
 /*
  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */
 /*
  * Copyright (c) 2013 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
  */

 #include <mdb/mdb_debug.h>
 #include <mdb/mdb_string.h>
 #include <mdb/mdb_modapi.h>
 #include <mdb/mdb_err.h>
 #include <mdb/mdb_nv.h>
 #include <mdb/mdb.h>

 #define	NV_NAME(v) \
 	(((v)->v_flags & MDB_NV_EXTNAME) ? (v)->v_ename : (v)->v_lname)

 #define	NV_SIZE(v) \
 	(((v)->v_flags & MDB_NV_EXTNAME) ? sizeof (mdb_var_t) : \
 	sizeof (mdb_var_t) + strlen((v)->v_lname))

 #define	NV_HASHSZ	211

 static size_t
 nv_hashstring(const char *key)
 {
 	size_t g, h = 0;
 	const char *p;

 	ASSERT(key != NULL);

 	for (p = key; *p != '\0'; p++) {
 		h = (h << 4) + *p;

 		if ((g = (h & 0xf0000000)) != 0) {
 			h ^= (g >> 24);
 			h ^= g;
 		}
 	}

 	return (h);
 }

 static mdb_var_t *
 nv_var_alloc(const char *name, const mdb_nv_disc_t *disc,
 	uintmax_t value, uint_t flags, uint_t um_flags, mdb_var_t *next)
 {
 	size_t nbytes;
 	mdb_var_t *v;

 	if (flags & MDB_NV_EXTNAME)
 		nbytes = sizeof (mdb_var_t);
 	else
 		nbytes = sizeof (mdb_var_t) + strlen(name);

 	v = mdb_alloc(nbytes, um_flags);

 	if (v == NULL)
 		return (NULL);

 	if (flags & MDB_NV_EXTNAME) {
 		v->v_ename = name;
 		v->v_lname[0] = '\0';
 	} else {
 		/*
 		 * We don't overflow here since the mdb_var_t itself has
 		 * room for the trailing \0.
 		 */
 		(void) strcpy(v->v_lname, name);
 		v->v_ename = NULL;
 	}

 	v->v_uvalue = value;
 	v->v_flags = flags & ~(MDB_NV_SILENT | MDB_NV_INTERPOS);
 	v->v_disc = disc;
 	v->v_next = next;

 	return (v);
 }

 static void
 nv_var_free(mdb_var_t *v, uint_t um_flags)
 {
 	if (um_flags & UM_GC)
 		return;

 	if (v->v_flags & MDB_NV_OVERLOAD) {
 		mdb_var_t *w, *nw;

 		for (w = v->v_ndef; w != NULL; w = nw) {
 			nw = w->v_ndef;
 			mdb_free(w, NV_SIZE(w));
 		}
 	}

 	mdb_free(v, NV_SIZE(v));
 }

 /*
  * Can return NULL only if the nv's memory allocation flags include UM_NOSLEEP
  */
 mdb_nv_t *
 mdb_nv_create(mdb_nv_t *nv, uint_t um_flags)
 {
 	nv->nv_hash = mdb_zalloc(sizeof (mdb_var_t *) * NV_HASHSZ, um_flags);

 	if (nv->nv_hash == NULL)
 		return (NULL);

 	nv->nv_hashsz = NV_HASHSZ;
 	nv->nv_nelems = 0;
 	nv->nv_iter_elt = NULL;
 	nv->nv_iter_bucket = 0;
 	nv->nv_um_flags = um_flags;

 	return (nv);
 }

 void
 mdb_nv_destroy(mdb_nv_t *nv)
 {
 	mdb_var_t *v, *w;
 	size_t i;

 	if (nv->nv_um_flags & UM_GC)
 		return;

 	for (i = 0; i < nv->nv_hashsz; i++) {
 		for (v = nv->nv_hash[i]; v != NULL; v = w) {
 			w = v->v_next;
 			nv_var_free(v, nv->nv_um_flags);
 		}
 	}

 	mdb_free(nv->nv_hash, sizeof (mdb_var_t *) * NV_HASHSZ);
 }

 mdb_var_t *
 mdb_nv_lookup(mdb_nv_t *nv, const char *name)
 {
 	size_t i = nv_hashstring(name) % nv->nv_hashsz;
 	mdb_var_t *v;

 	for (v = nv->nv_hash[i]; v != NULL; v = v->v_next) {
 		if (strcmp(NV_NAME(v), name) == 0)
 			return (v);
 	}

 	return (NULL);
 }

 /*
  * Interpose W in place of V.  We replace V with W in nv_hash, and then
  * set W's v_ndef overload chain to point at V.
  */
 static mdb_var_t *
 nv_var_interpos(mdb_nv_t *nv, size_t i, mdb_var_t *v, mdb_var_t *w)
 {
 	mdb_var_t **pvp = &nv->nv_hash[i];

 	while (*pvp != v) {
 		mdb_var_t *vp = *pvp;
 		ASSERT(vp != NULL);
 		pvp = &vp->v_next;
 	}

 	*pvp = w;
 	w->v_next = v->v_next;
 	w->v_ndef = v;
 	v->v_next = NULL;

 	return (w);
 }

 /*
  * Add W to the end of V's overload chain.  We simply follow v_ndef to the
  * end, and then append W.  We don't expect these chains to grow very long.
  */
 static mdb_var_t *
 nv_var_overload(mdb_var_t *v, mdb_var_t *w)
 {
 	while (v->v_ndef != NULL)
 		v = v->v_ndef;

 	v->v_ndef = w;
 	return (w);
 }

 /*
  * Can return NULL only if the nv's memory allocation flags include UM_NOSLEEP
  */
 mdb_var_t *
 mdb_nv_insert(mdb_nv_t *nv, const char *name, const mdb_nv_disc_t *disc,
     uintmax_t value, uint_t flags)
 {
 	size_t i = nv_hashstring(name) % nv->nv_hashsz;
 	mdb_var_t *v;

 	ASSERT(!(flags & MDB_NV_EXTNAME) || !(flags & MDB_NV_OVERLOAD));
 	ASSERT(!(flags & MDB_NV_RDONLY) || !(flags & MDB_NV_OVERLOAD));

 	/*
 	 * If the specified name is already hashed,
 	 * and MDB_NV_OVERLOAD is set:	insert new var into overload chain
 	 * and MDB_NV_RDONLY is set:	leave var unchanged, issue warning
 	 * otherwise:			update var with new value
 	 */
 	for (v = nv->nv_hash[i]; v != NULL; v = v->v_next) {
 		if (strcmp(NV_NAME(v), name) == 0) {
 			if (v->v_flags & MDB_NV_OVERLOAD) {
 				mdb_var_t *w = nv_var_alloc(NV_NAME(v), disc,
 				    value, flags, nv->nv_um_flags, NULL);

 				if (w == NULL) {
 					ASSERT(nv->nv_um_flags & UM_NOSLEEP);
 					return (NULL);
 				}

 				if (flags & MDB_NV_INTERPOS)
 					v = nv_var_interpos(nv, i, v, w);
 				else
 					v = nv_var_overload(v, w);

 			} else if (v->v_flags & MDB_NV_RDONLY) {
 				if (!(flags & MDB_NV_SILENT)) {
 					warn("cannot modify read-only "
 					    "variable '%s'\n", NV_NAME(v));
 				}
 			} else
 				v->v_uvalue = value;

 			ASSERT(v != NULL);
 			return (v);
 		}
 	}

 	/*
 	 * If the specified name was not found, initialize a new element
 	 * and add it to the hash table at the beginning of this chain:
 	 */
 	v = nv_var_alloc(name, disc, value, flags, nv->nv_um_flags,
 	    nv->nv_hash[i]);

 	if (v == NULL) {
 		ASSERT(nv->nv_um_flags & UM_NOSLEEP);
 		return (NULL);
 	}

 	nv->nv_hash[i] = v;
 	nv->nv_nelems++;

 	return (v);
 }

 static void
 nv_var_defn_remove(mdb_var_t *v, mdb_var_t *corpse, uint_t um_flags)
 {
 	mdb_var_t *w = v;

 	while (v->v_ndef != NULL && v->v_ndef != corpse)
 		v = v->v_ndef;

 	if (v == NULL) {
 		fail("var %p ('%s') not found on defn chain of %p\n",
 		    (void *)corpse, NV_NAME(corpse), (void *)w);
 	}

 	v->v_ndef = corpse->v_ndef;
 	corpse->v_ndef = NULL;
 	nv_var_free(corpse, um_flags);
 }

 void
 mdb_nv_remove(mdb_nv_t *nv, mdb_var_t *corpse)
 {
 	const char *cname = NV_NAME(corpse);
 	size_t i = nv_hashstring(cname) % nv->nv_hashsz;
 	mdb_var_t *v = nv->nv_hash[i];
 	mdb_var_t **pvp;

 	if (corpse->v_flags & MDB_NV_PERSIST) {
 		warn("cannot remove persistent variable '%s'\n", cname);
 		return;
 	}

 	if (v != corpse) {
 		do {
 			if (strcmp(NV_NAME(v), cname) == 0) {
 				if (corpse->v_flags & MDB_NV_OVERLOAD) {
 					nv_var_defn_remove(v, corpse,
 					    nv->nv_um_flags);
 					return; /* No v_next changes needed */
 				} else
 					goto notfound;
 			}

 			if (v->v_next == corpse)
 				break; /* Corpse is next on the chain */

 		} while ((v = v->v_next) != NULL);

 		if (v == NULL)
 			goto notfound;

 		pvp = &v->v_next;
 	} else
 		pvp = &nv->nv_hash[i];

 	if ((corpse->v_flags & MDB_NV_OVERLOAD) && corpse->v_ndef != NULL) {
 		corpse->v_ndef->v_next = corpse->v_next;
 		*pvp = corpse->v_ndef;
 		corpse->v_ndef = NULL;
 	} else {
 		*pvp = corpse->v_next;
 		nv->nv_nelems--;
 	}

 	nv_var_free(corpse, nv->nv_um_flags);
 	return;

 notfound:
 	fail("var %p ('%s') not found on hash chain: nv=%p [%lu]\n",
 	    (void *)corpse, cname, (void *)nv, (ulong_t)i);
 }

 void
 mdb_nv_rewind(mdb_nv_t *nv)
 {
 	size_t i;

 	for (i = 0; i < nv->nv_hashsz; i++) {
 		if (nv->nv_hash[i] != NULL)
 			break;
 	}

 	nv->nv_iter_elt = i < nv->nv_hashsz ? nv->nv_hash[i] : NULL;
 	nv->nv_iter_bucket = i;
 }

 mdb_var_t *
 mdb_nv_advance(mdb_nv_t *nv)
 {
 	mdb_var_t *v = nv->nv_iter_elt;
 	size_t i;

 	if (v == NULL)
 		return (NULL);

 	if (v->v_next != NULL) {
 		nv->nv_iter_elt = v->v_next;
 		return (v);
 	}

 	for (i = nv->nv_iter_bucket + 1; i < nv->nv_hashsz; i++) {
 		if (nv->nv_hash[i] != NULL)
 			break;
 	}

 	nv->nv_iter_elt = i < nv->nv_hashsz ? nv->nv_hash[i] : NULL;
 	nv->nv_iter_bucket = i;

 	return (v);
 }

 mdb_var_t *
 mdb_nv_peek(mdb_nv_t *nv)
 {
 	return (nv->nv_iter_elt);
 }

 size_t
 mdb_nv_size(mdb_nv_t *nv)
 {
 	return (nv->nv_nelems);
 }

 static int
 nv_compare(const mdb_var_t **lp, const mdb_var_t **rp)
 {
 	return (strcmp(mdb_nv_get_name(*lp), mdb_nv_get_name(*rp)));
 }

 void
 mdb_nv_sort_iter(mdb_nv_t *nv, int (*func)(mdb_var_t *, void *),
     void *private, uint_t um_flags)
 {
 	mdb_var_t **vps =
 	    mdb_alloc(nv->nv_nelems * sizeof (mdb_var_t *), um_flags);

 	if (nv->nv_nelems != 0 && vps != NULL) {
 		mdb_var_t *v, **vpp = vps;
 		size_t i;

 		for (mdb_nv_rewind(nv); (v = mdb_nv_advance(nv)) != NULL; )
 			*vpp++ = v;

 		qsort(vps, nv->nv_nelems, sizeof (mdb_var_t *),
 		    (int (*)(const void *, const void *))nv_compare);

 		for (vpp = vps, i = 0; i < nv->nv_nelems; i++) {
 			if (func(*vpp++, private) == -1)
 				break;
 		}

 		if (!(um_flags & UM_GC))
 			mdb_free(vps, nv->nv_nelems * sizeof (mdb_var_t *));
 	}
 }

 void
 mdb_nv_defn_iter(mdb_var_t *v, int (*func)(mdb_var_t *, void *), void *private)
 {
 	if (func(v, private) == -1 || !(v->v_flags & MDB_NV_OVERLOAD))
 		return;

 	for (v = v->v_ndef; v != NULL; v = v->v_ndef) {
 		if (func(v, private) == -1)
 			break;
 	}
 }

 uintmax_t
 mdb_nv_get_value(const mdb_var_t *v)
 {
 	if (v->v_disc)
 		return (v->v_disc->disc_get(v));

 	return (v->v_uvalue);
 }

 void
 mdb_nv_set_value(mdb_var_t *v, uintmax_t l)
 {
 	if (v->v_flags & MDB_NV_RDONLY) {
 		warn("cannot modify read-only variable '%s'\n", NV_NAME(v));
 		return;
 	}

 	if (v->v_disc)
 		v->v_disc->disc_set(v, l);
 	else
 		v->v_uvalue = l;
 }

 void *
 mdb_nv_get_cookie(const mdb_var_t *v)
 {
 	if (v->v_disc)
 		return ((void *)(uintptr_t)v->v_disc->disc_get(v));

 	return (MDB_NV_COOKIE(v));
 }

 void
 mdb_nv_set_cookie(mdb_var_t *v, void *cookie)
 {
 	mdb_nv_set_value(v, (uintmax_t)(uintptr_t)cookie);
 }

 const char *
 mdb_nv_get_name(const mdb_var_t *v)
 {
 	return (NV_NAME(v));
 }

 mdb_var_t *
 mdb_nv_get_ndef(const mdb_var_t *v)
 {
 	if (v->v_flags & MDB_NV_OVERLOAD)
 		return (v->v_ndef);

 	return (NULL);
 }
	/*
	* CDDL HEADER START
	*
	* The contents of this file are subject to the terms of the
	* Common Development and Distribution License, Version 1.0 only
	* (the "License"). You may not use this file except in compliance
	* with the License.
	*
	* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
	* or http://www.opensolaris.org/os/licensing.
	* See the License for the specific language governing permissions
	* and limitations under the License.
	*
	* When distributing Covered Code, include this CDDL HEADER in each
	* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
	* If applicable, add the following below this CDDL HEADER, with the
	* fields enclosed by brackets "[]" replaced with your own identifying
	* information: Portions Copyright [yyyy] [name of copyright owner]
	*
	* CDDL HEADER END
	*/
	/*
	* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
	* Use is subject to license terms.
	*/
	/*
	* Copyright (c) 2013 Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
	*/

	#include <mdb/mdb_debug.h>
	#include <mdb/mdb_string.h>
	#include <mdb/mdb_modapi.h>
	#include <mdb/mdb_err.h>
	#include <mdb/mdb_nv.h>
	#include <mdb/mdb.h>

	#define NV_NAME(v) \
	(((v)->v_flags & MDB_NV_EXTNAME) ? (v)->v_ename : (v)->v_lname)

	#define NV_SIZE(v) \
	(((v)->v_flags & MDB_NV_EXTNAME) ? sizeof (mdb_var_t) : \
	sizeof (mdb_var_t) + strlen((v)->v_lname))

	#define NV_HASHSZ 211

	static size_t
	nv_hashstring(const char *key)
	{
	size_t g, h = 0;
	const char *p;

	ASSERT(key != NULL);

	for (p = key; *p != '\0'; p++) {
	h = (h << 4) + *p;

	if ((g = (h & 0xf0000000)) != 0) {
	h ^= (g >> 24);
	h ^= g;
	}
	}

	return (h);
	}

	static mdb_var_t *
	nv_var_alloc(const char name, const mdb_nv_disc_t disc,
	uintmax_t value, uint_t flags, uint_t um_flags, mdb_var_t *next)
	{
	size_t nbytes;
	mdb_var_t *v;

	if (flags & MDB_NV_EXTNAME)
	nbytes = sizeof (mdb_var_t);
	else
	nbytes = sizeof (mdb_var_t) + strlen(name);

	v = mdb_alloc(nbytes, um_flags);

	if (v == NULL)
	return (NULL);

	if (flags & MDB_NV_EXTNAME) {
	v->v_ename = name;
	v->v_lname[0] = '\0';
	} else {
	/*
	* We don't overflow here since the mdb_var_t itself has
	* room for the trailing \0.
	*/
	(void) strcpy(v->v_lname, name);
	v->v_ename = NULL;
	}

	v->v_uvalue = value;
	v->v_flags = flags & ~(MDB_NV_SILENT \| MDB_NV_INTERPOS);
	v->v_disc = disc;
	v->v_next = next;

	return (v);
	}

	static void
	nv_var_free(mdb_var_t *v, uint_t um_flags)
	{
	if (um_flags & UM_GC)
	return;

	if (v->v_flags & MDB_NV_OVERLOAD) {
	mdb_var_t w, nw;

	for (w = v->v_ndef; w != NULL; w = nw) {
	nw = w->v_ndef;
	mdb_free(w, NV_SIZE(w));
	}
	}

	mdb_free(v, NV_SIZE(v));
	}

	/*
	* Can return NULL only if the nv's memory allocation flags include UM_NOSLEEP
	*/
	mdb_nv_t *
	mdb_nv_create(mdb_nv_t *nv, uint_t um_flags)
	{
	nv->nv_hash = mdb_zalloc(sizeof (mdb_var_t ) NV_HASHSZ, um_flags);

	if (nv->nv_hash == NULL)
	return (NULL);

	nv->nv_hashsz = NV_HASHSZ;
	nv->nv_nelems = 0;
	nv->nv_iter_elt = NULL;
	nv->nv_iter_bucket = 0;
	nv->nv_um_flags = um_flags;

	return (nv);
	}

	void
	mdb_nv_destroy(mdb_nv_t *nv)
	{
	mdb_var_t v, w;
	size_t i;

	if (nv->nv_um_flags & UM_GC)
	return;

	for (i = 0; i < nv->nv_hashsz; i++) {
	for (v = nv->nv_hash[i]; v != NULL; v = w) {
	w = v->v_next;
	nv_var_free(v, nv->nv_um_flags);
	}
	}

	mdb_free(nv->nv_hash, sizeof (mdb_var_t ) NV_HASHSZ);
	}

	mdb_var_t *
	mdb_nv_lookup(mdb_nv_t nv, const char name)
	{
	size_t i = nv_hashstring(name) % nv->nv_hashsz;
	mdb_var_t *v;

	for (v = nv->nv_hash[i]; v != NULL; v = v->v_next) {
	if (strcmp(NV_NAME(v), name) == 0)
	return (v);
	}

	return (NULL);
	}

	/*
	* Interpose W in place of V. We replace V with W in nv_hash, and then
	* set W's v_ndef overload chain to point at V.
	*/
	static mdb_var_t *
	nv_var_interpos(mdb_nv_t nv, size_t i, mdb_var_t v, mdb_var_t *w)
	{
	mdb_var_t **pvp = &nv->nv_hash[i];

	while (*pvp != v) {
	mdb_var_t vp = pvp;
	ASSERT(vp != NULL);
	pvp = &vp->v_next;
	}

	*pvp = w;
	w->v_next = v->v_next;
	w->v_ndef = v;
	v->v_next = NULL;

	return (w);
	}

	/*
	* Add W to the end of V's overload chain. We simply follow v_ndef to the
	* end, and then append W. We don't expect these chains to grow very long.
	*/
	static mdb_var_t *
	nv_var_overload(mdb_var_t v, mdb_var_t w)
	{
	while (v->v_ndef != NULL)
	v = v->v_ndef;

	v->v_ndef = w;
	return (w);
	}

	/*
	* Can return NULL only if the nv's memory allocation flags include UM_NOSLEEP
	*/
	mdb_var_t *
	mdb_nv_insert(mdb_nv_t nv, const char name, const mdb_nv_disc_t *disc,
	uintmax_t value, uint_t flags)
	{
	size_t i = nv_hashstring(name) % nv->nv_hashsz;
	mdb_var_t *v;

	ASSERT(!(flags & MDB_NV_EXTNAME) \|\| !(flags & MDB_NV_OVERLOAD));
	ASSERT(!(flags & MDB_NV_RDONLY) \|\| !(flags & MDB_NV_OVERLOAD));

	/*
	* If the specified name is already hashed,
	* and MDB_NV_OVERLOAD is set: insert new var into overload chain
	* and MDB_NV_RDONLY is set: leave var unchanged, issue warning
	* otherwise: update var with new value
	*/
	for (v = nv->nv_hash[i]; v != NULL; v = v->v_next) {
	if (strcmp(NV_NAME(v), name) == 0) {
	if (v->v_flags & MDB_NV_OVERLOAD) {
	mdb_var_t *w = nv_var_alloc(NV_NAME(v), disc,
	value, flags, nv->nv_um_flags, NULL);

	if (w == NULL) {
	ASSERT(nv->nv_um_flags & UM_NOSLEEP);
	return (NULL);
	}

	if (flags & MDB_NV_INTERPOS)
	v = nv_var_interpos(nv, i, v, w);
	else
	v = nv_var_overload(v, w);

	} else if (v->v_flags & MDB_NV_RDONLY) {
	if (!(flags & MDB_NV_SILENT)) {
	warn("cannot modify read-only "
	"variable '%s'\n", NV_NAME(v));
	}
	} else
	v->v_uvalue = value;

	ASSERT(v != NULL);
	return (v);
	}
	}

	/*
	* If the specified name was not found, initialize a new element
	* and add it to the hash table at the beginning of this chain:
	*/
	v = nv_var_alloc(name, disc, value, flags, nv->nv_um_flags,
	nv->nv_hash[i]);

	if (v == NULL) {
	ASSERT(nv->nv_um_flags & UM_NOSLEEP);
	return (NULL);
	}

	nv->nv_hash[i] = v;
	nv->nv_nelems++;

	return (v);
	}

	static void
	nv_var_defn_remove(mdb_var_t v, mdb_var_t corpse, uint_t um_flags)
	{
	mdb_var_t *w = v;

	while (v->v_ndef != NULL && v->v_ndef != corpse)
	v = v->v_ndef;

	if (v == NULL) {
	fail("var %p ('%s') not found on defn chain of %p\n",
	(void )corpse, NV_NAME(corpse), (void )w);
	}

	v->v_ndef = corpse->v_ndef;
	corpse->v_ndef = NULL;
	nv_var_free(corpse, um_flags);
	}

	void
	mdb_nv_remove(mdb_nv_t nv, mdb_var_t corpse)
	{
	const char *cname = NV_NAME(corpse);
	size_t i = nv_hashstring(cname) % nv->nv_hashsz;
	mdb_var_t *v = nv->nv_hash[i];
	mdb_var_t **pvp;

	if (corpse->v_flags & MDB_NV_PERSIST) {
	warn("cannot remove persistent variable '%s'\n", cname);
	return;
	}

	if (v != corpse) {
	do {
	if (strcmp(NV_NAME(v), cname) == 0) {
	if (corpse->v_flags & MDB_NV_OVERLOAD) {
	nv_var_defn_remove(v, corpse,
	nv->nv_um_flags);
	return; /* No v_next changes needed */
	} else
	goto notfound;
	}

	if (v->v_next == corpse)
	break; /* Corpse is next on the chain */

	} while ((v = v->v_next) != NULL);

	if (v == NULL)
	goto notfound;

	pvp = &v->v_next;
	} else
	pvp = &nv->nv_hash[i];

	if ((corpse->v_flags & MDB_NV_OVERLOAD) && corpse->v_ndef != NULL) {
	corpse->v_ndef->v_next = corpse->v_next;
	*pvp = corpse->v_ndef;
	corpse->v_ndef = NULL;
	} else {
	*pvp = corpse->v_next;
	nv->nv_nelems--;
	}

	nv_var_free(corpse, nv->nv_um_flags);
	return;

	notfound:
	fail("var %p ('%s') not found on hash chain: nv=%p [%lu]\n",
	(void )corpse, cname, (void )nv, (ulong_t)i);
	}

	void
	mdb_nv_rewind(mdb_nv_t *nv)
	{
	size_t i;

	for (i = 0; i < nv->nv_hashsz; i++) {
	if (nv->nv_hash[i] != NULL)
	break;
	}

	nv->nv_iter_elt = i < nv->nv_hashsz ? nv->nv_hash[i] : NULL;
	nv->nv_iter_bucket = i;
	}

	mdb_var_t *
	mdb_nv_advance(mdb_nv_t *nv)
	{
	mdb_var_t *v = nv->nv_iter_elt;
	size_t i;

	if (v == NULL)
	return (NULL);

	if (v->v_next != NULL) {
	nv->nv_iter_elt = v->v_next;
	return (v);
	}

	for (i = nv->nv_iter_bucket + 1; i < nv->nv_hashsz; i++) {
	if (nv->nv_hash[i] != NULL)
	break;
	}

	nv->nv_iter_elt = i < nv->nv_hashsz ? nv->nv_hash[i] : NULL;
	nv->nv_iter_bucket = i;

	return (v);
	}

	mdb_var_t *
	mdb_nv_peek(mdb_nv_t *nv)
	{
	return (nv->nv_iter_elt);
	}

	size_t
	mdb_nv_size(mdb_nv_t *nv)
	{
	return (nv->nv_nelems);
	}

	static int
	nv_compare(const mdb_var_t lp, const mdb_var_t rp)
	{
	return (strcmp(mdb_nv_get_name(lp), mdb_nv_get_name(rp)));
	}

	void
	mdb_nv_sort_iter(mdb_nv_t nv, int (func)(mdb_var_t , void ),
	void *private, uint_t um_flags)
	{
	mdb_var_t **vps =
	mdb_alloc(nv->nv_nelems * sizeof (mdb_var_t *), um_flags);

	if (nv->nv_nelems != 0 && vps != NULL) {
	mdb_var_t v, *vpp = vps;
	size_t i;

	for (mdb_nv_rewind(nv); (v = mdb_nv_advance(nv)) != NULL; )
	*vpp++ = v;

	qsort(vps, nv->nv_nelems, sizeof (mdb_var_t *),
	(int ()(const void , const void *))nv_compare);

	for (vpp = vps, i = 0; i < nv->nv_nelems; i++) {
	if (func(*vpp++, private) == -1)
	break;
	}

	if (!(um_flags & UM_GC))
	mdb_free(vps, nv->nv_nelems * sizeof (mdb_var_t *));
	}
	}

	void
	mdb_nv_defn_iter(mdb_var_t v, int (func)(mdb_var_t , void ), void *private)
	{
	if (func(v, private) == -1 \|\| !(v->v_flags & MDB_NV_OVERLOAD))
	return;

	for (v = v->v_ndef; v != NULL; v = v->v_ndef) {
	if (func(v, private) == -1)
	break;
	}
	}

	uintmax_t
	mdb_nv_get_value(const mdb_var_t *v)
	{
	if (v->v_disc)
	return (v->v_disc->disc_get(v));

	return (v->v_uvalue);
	}

	void
	mdb_nv_set_value(mdb_var_t *v, uintmax_t l)
	{
	if (v->v_flags & MDB_NV_RDONLY) {
	warn("cannot modify read-only variable '%s'\n", NV_NAME(v));
	return;
	}

	if (v->v_disc)
	v->v_disc->disc_set(v, l);
	else
	v->v_uvalue = l;
	}

	void *
	mdb_nv_get_cookie(const mdb_var_t *v)
	{
	if (v->v_disc)
	return ((void *)(uintptr_t)v->v_disc->disc_get(v));

	return (MDB_NV_COOKIE(v));
	}

	void
	mdb_nv_set_cookie(mdb_var_t v, void cookie)
	{
	mdb_nv_set_value(v, (uintmax_t)(uintptr_t)cookie);
	}

	const char *
	mdb_nv_get_name(const mdb_var_t *v)
	{
	return (NV_NAME(v));
	}

	mdb_var_t *
	mdb_nv_get_ndef(const mdb_var_t *v)
	{
	if (v->v_flags & MDB_NV_OVERLOAD)
	return (v->v_ndef);

	return (NULL);
	}