1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #include <mdb/mdb_modapi.h>
27 
28 typedef struct combined_walk {
29 	int (*cw_init)(mdb_walk_state_t *);
30 	int (*cw_step)(mdb_walk_state_t *);
31 	void (*cw_fini)(mdb_walk_state_t *);
32 	struct combined_walk *cw_next;
33 	void *cw_data;
34 	boolean_t cw_initialized;
35 } combined_walk_t;
36 
37 typedef struct combined_walk_data {
38 	uintptr_t cwd_initial_walk_addr;	/* to init each walk */
39 	combined_walk_t *cwd_current_walk;
40 	combined_walk_t *cwd_final_walk;	/* tail pointer */
41 
42 	struct combined_walk_data *cwd_next;
43 	struct combined_walk_data *cwd_prev;
44 	void *cwd_tag;				/* used to find this data */
45 } combined_walk_data_t;
46 
47 /*
48  * Initialize a combined walk to
49  * A) present a single concatenated series of elements from different
50  *    structures, or
51  * B) select from several possible walks at runtime.
52  * Multiple walks are done in the same order passed to combined_walk_add(). Each
53  * walk is initialized with the same wsp->walk_addr.
54  */
55 void
combined_walk_init(mdb_walk_state_t * wsp)56 combined_walk_init(mdb_walk_state_t *wsp)
57 {
58 	combined_walk_data_t *cwd;
59 
60 	cwd = mdb_alloc(sizeof (combined_walk_data_t), UM_SLEEP);
61 
62 	cwd->cwd_initial_walk_addr = wsp->walk_addr;
63 	cwd->cwd_current_walk = cwd->cwd_final_walk = NULL;
64 	cwd->cwd_next = cwd->cwd_prev = NULL;
65 	cwd->cwd_tag = NULL;
66 	wsp->walk_data = cwd;
67 }
68 
69 /*
70  * If a sub-walker's walk_step() is interrupted (by Ctrl-C or entering 'q' when
71  * prompted for the next screenful of data), there won't be an opportunity to
72  * switch wsp->walk_data from the sub-walker's data back to the combined walk
73  * data, since control will not return from walk_step(). Since mdb is
74  * single-threaded, we can save the combined walk data for combined_walk_fini()
75  * to use in case it was reached from an interrupted walk_step(). To allow for
76  * the possibility of nested combined walks, we'll save them on a list tagged by
77  * the sub-walker's data.
78  */
79 static combined_walk_data_t *cwd_saved;
80 
81 static void
combined_walk_data_save(combined_walk_data_t * cwd,void * tag)82 combined_walk_data_save(combined_walk_data_t *cwd, void *tag)
83 {
84 	cwd->cwd_next = cwd_saved;
85 	cwd->cwd_prev = NULL;
86 	if (cwd_saved != NULL) {
87 		cwd_saved->cwd_prev = cwd;
88 	}
89 	cwd_saved = cwd;
90 	cwd->cwd_tag = tag;
91 }
92 
93 static void
combined_walk_data_drop(combined_walk_data_t * cwd)94 combined_walk_data_drop(combined_walk_data_t *cwd)
95 {
96 	if (cwd->cwd_prev == NULL) {
97 		cwd_saved = cwd->cwd_next;
98 	} else {
99 		cwd->cwd_prev->cwd_next = cwd->cwd_next;
100 	}
101 	if (cwd->cwd_next != NULL) {
102 		cwd->cwd_next->cwd_prev = cwd->cwd_prev;
103 	}
104 	cwd->cwd_next = cwd->cwd_prev = NULL;
105 	cwd->cwd_tag = NULL;
106 }
107 
108 static combined_walk_data_t *
combined_walk_data_find(void * tag)109 combined_walk_data_find(void *tag)
110 {
111 	combined_walk_data_t *cwd;
112 
113 	if (tag == NULL) {
114 		return (NULL);
115 	}
116 
117 	for (cwd = cwd_saved; cwd != NULL; cwd = cwd->cwd_next) {
118 		if (cwd->cwd_tag == tag) {
119 			return (cwd);
120 		}
121 	}
122 
123 	return (NULL);
124 }
125 
126 static void
combined_walk_append(combined_walk_data_t * cwd,combined_walk_t * cw)127 combined_walk_append(combined_walk_data_t *cwd, combined_walk_t *cw)
128 {
129 	if (cwd->cwd_final_walk == NULL) {
130 		cwd->cwd_current_walk = cwd->cwd_final_walk = cw;
131 	} else {
132 		cwd->cwd_final_walk->cw_next = cw;
133 		cwd->cwd_final_walk = cw;
134 	}
135 }
136 
137 static combined_walk_t *
combined_walk_remove_current(combined_walk_data_t * cwd)138 combined_walk_remove_current(combined_walk_data_t *cwd)
139 {
140 	combined_walk_t *cw = cwd->cwd_current_walk;
141 	if (cw == NULL) {
142 		return (NULL);
143 	}
144 	if (cw == cwd->cwd_final_walk) {
145 		cwd->cwd_final_walk = cw->cw_next;
146 	}
147 	cwd->cwd_current_walk = cw->cw_next;
148 	cw->cw_next = NULL;
149 	return (cw);
150 }
151 
152 void
combined_walk_add(mdb_walk_state_t * wsp,int (* walk_init)(mdb_walk_state_t *),int (* walk_step)(mdb_walk_state_t *),void (* walk_fini)(mdb_walk_state_t *))153 combined_walk_add(mdb_walk_state_t *wsp,
154 	int (*walk_init)(mdb_walk_state_t *),
155 	int (*walk_step)(mdb_walk_state_t *),
156 	void (*walk_fini)(mdb_walk_state_t *))
157 {
158 	combined_walk_data_t *cwd = wsp->walk_data;
159 	combined_walk_t *cw;
160 
161 	cw = mdb_alloc(sizeof (combined_walk_t), UM_SLEEP);
162 
163 	cw->cw_init = walk_init;
164 	cw->cw_step = walk_step;
165 	cw->cw_fini = walk_fini;
166 	cw->cw_next = NULL;
167 	cw->cw_data = NULL;
168 	cw->cw_initialized = B_FALSE;
169 
170 	combined_walk_append(cwd, cw);
171 }
172 
173 int
combined_walk_step(mdb_walk_state_t * wsp)174 combined_walk_step(mdb_walk_state_t *wsp)
175 {
176 	combined_walk_data_t *cwd = wsp->walk_data;
177 	combined_walk_t *cw = cwd->cwd_current_walk;
178 	int status;
179 
180 	if (cw == NULL) {
181 		return (WALK_DONE);
182 	}
183 
184 	if (cw->cw_initialized) {
185 		wsp->walk_data = cw->cw_data;
186 	} else {
187 		wsp->walk_addr = cwd->cwd_initial_walk_addr;
188 		status = cw->cw_init(wsp);
189 		cw->cw_data = wsp->walk_data;
190 		if (status != WALK_NEXT)
191 			goto done;
192 		cw->cw_initialized = B_TRUE;
193 	}
194 
195 	/* save cwd for fini() in case step() is interrupted */
196 	combined_walk_data_save(cwd, cw->cw_data);
197 	status = cw->cw_step(wsp);
198 	/* control may never reach here */
199 	combined_walk_data_drop(cwd);
200 
201 	if (status == WALK_DONE)
202 		goto done;
203 	wsp->walk_data = cwd;
204 	return (status);
205 
206 done:
207 	(void) combined_walk_remove_current(cwd);
208 	if (cw->cw_initialized)
209 		cw->cw_fini(wsp);
210 	mdb_free(cw, sizeof (combined_walk_t));
211 	wsp->walk_data = cwd;
212 	if (status == WALK_DONE)
213 		return (combined_walk_step(wsp));
214 	return (status);
215 }
216 
217 void
combined_walk_fini(mdb_walk_state_t * wsp)218 combined_walk_fini(mdb_walk_state_t *wsp)
219 {
220 	combined_walk_data_t *cwd;
221 	combined_walk_t *cw;
222 
223 	/*
224 	 * If walk_step() was interrupted, wsp->walk_data will be the
225 	 * sub-walker's data, not the combined walker's data, so first check to
226 	 * see if there is saved combined walk data tagged by the presumed
227 	 * sub-walker's walk data.
228 	 */
229 	cwd = combined_walk_data_find(wsp->walk_data);
230 	if (cwd == NULL) {
231 		/*
232 		 * walk_step() was not interrupted, so wsp->walk_data is
233 		 * actually the combined walk data.
234 		 */
235 		cwd = wsp->walk_data;
236 	} else {
237 		combined_walk_data_drop(cwd);
238 	}
239 
240 	while ((cw = combined_walk_remove_current(cwd)) != NULL) {
241 		if (cw->cw_initialized) {
242 			wsp->walk_data = cw->cw_data;
243 			cw->cw_fini(wsp);
244 		}
245 		mdb_free(cw, sizeof (combined_walk_t));
246 	}
247 
248 	mdb_free(cwd, sizeof (combined_walk_data_t));
249 }
250