xref: /titanic_51/usr/src/lib/libexacct/common/exacct_ops.c (revision 89b43686db1fe9681d80a7cf5662730cb9378cae)
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 /*
23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <sys/systeminfo.h>
30 
31 #include <exacct.h>
32 #include <exacct_impl.h>
33 #include <sys/exacct_impl.h>
34 #include <fcntl.h>
35 #include <unistd.h>
36 #include <strings.h>
37 #include <stdlib.h>
38 #include <stdio.h>
39 #include <errno.h>
40 #include <thread.h>
41 #include <pthread.h>
42 
43 #define	EXACCT_HDR_STR	"exacct"
44 #define	EXACCT_HDR_LEN	7
45 
46 #define	DEFAULT_ENTRIES	4
47 #define	SYSINFO_BUFSIZE	256
48 
49 static thread_key_t	errkey = THR_ONCE_KEY;
50 static int		exacct_errval = 0;
51 
52 /*
53  * extended accounting file access routines
54  *
55  *   exacct_ops.c implements the library-specific routines of libexacct:  the
56  *   operations associated with file access and record traversal.  (The
57  *   complementary routines which permit hierarchy building and record packing
58  *   are provided in exacct_core.c, which is used by both libexacct and the
59  *   kernel.) At its heart are the unpack, get, and next routines, which
60  *   navigate the packed records produced by ea_pack_object.
61  */
62 
63 /*
64  * Group stack manipulation code.  As groups can be nested, we need a mechanism
65  * for saving and restoring the current position within the outer groups.  This
66  * state stack is stored within the ea_file_impl_t structure, in the ef_depth,
67  * ef_ndeep and ef_mxdeep members.  On error all these functions set
68  * exacct_error and return -1.
69  */
70 
71 /*
72  * If the stack is NULL, create and initialise it.
73  * If is is not NULL, check it still has space - if not, double its size.
74  */
75 static int stack_check(ea_file_impl_t *f)
76 {
77 	if (f->ef_depth == NULL) {
78 		if ((f->ef_depth =
79 		    ea_alloc(DEFAULT_ENTRIES * sizeof (ea_file_depth_t)))
80 		    == NULL) {
81 			/* exacct_errno set above. */
82 			return (-1);
83 		}
84 		bzero(f->ef_depth, DEFAULT_ENTRIES * sizeof (ea_file_depth_t));
85 		f->ef_mxdeep = DEFAULT_ENTRIES;
86 		f->ef_ndeep = -1;
87 	} else if (f->ef_ndeep + 1 >= f->ef_mxdeep) {
88 		ea_file_depth_t *newstack;
89 
90 		if ((newstack =
91 		    ea_alloc(f->ef_mxdeep * 2 * sizeof (ea_file_depth_t)))
92 		    == NULL) {
93 			/* exacct_errno set above. */
94 			return (-1);
95 		}
96 		bcopy(f->ef_depth, newstack,
97 		    f->ef_mxdeep * sizeof (ea_file_depth_t));
98 		bzero(newstack + f->ef_mxdeep,
99 		    f->ef_mxdeep * sizeof (ea_file_depth_t));
100 		ea_free(f->ef_depth, f->ef_mxdeep * sizeof (ea_file_depth_t));
101 		f->ef_mxdeep *= 2;
102 		f->ef_depth = newstack;
103 	}
104 	return (0);
105 }
106 
107 /*
108  * Free a stack.
109  */
110 static void stack_free(ea_file_impl_t *f)
111 {
112 	if (f->ef_depth != NULL) {
113 		ea_free(f->ef_depth, f->ef_mxdeep * sizeof (ea_file_depth_t));
114 		f->ef_depth = NULL;
115 	}
116 	f->ef_mxdeep = 0;
117 	f->ef_ndeep = -1;
118 }
119 
120 /*
121  * Add a new group onto the stack, pushing down one frame.  nobj is the number
122  * of items in the group.  We have to read this many objects before popping
123  * back up to an enclosing group - see next_object() and previous_object()
124  * below.
125  */
126 static int stack_new_group(ea_file_impl_t *f, int nobjs)
127 {
128 	if (stack_check(f) != 0) {
129 		stack_free(f);
130 		/* exacct_errno set above. */
131 		return (-1);
132 	}
133 	f->ef_ndeep++;
134 	f->ef_depth[f->ef_ndeep].efd_obj = 0;
135 	f->ef_depth[f->ef_ndeep].efd_nobjs = nobjs;
136 	return (0);
137 }
138 
139 /*
140  * Step forwards along the objects within the current group.  If we are still
141  * within a group, return 1.  If we have reached the end of the current group,
142  * unwind the stack back up to the nearest enclosing group that still has
143  * unprocessed objects and return 0.  On EOF or error, set exacct_error
144  * accordingly and return -1.  xread() is required so that this function can
145  * work either on files or memory buffers.
146  */
147 static int
148 stack_next_object(
149     ea_file_impl_t *f,
150     size_t (*xread)(ea_file_impl_t *, void *, size_t))
151 {
152 	uint32_t scratch32;
153 
154 	/*
155 	 * If the stack is empty we are not in a group, so there will be no
156 	 * stack manipulation to do and no large backskips to step over.
157 	 */
158 	if (f->ef_ndeep < 0) {
159 		return (0);
160 	}
161 
162 	/*
163 	 * Otherwise we must be in a group.  If there are objects left in the
164 	 * group, move onto the next one in the group and return.
165 	 */
166 	if (++f->ef_depth[f->ef_ndeep].efd_obj <
167 	    f->ef_depth[f->ef_ndeep].efd_nobjs) {
168 		return (1);
169 
170 	/*
171 	 * If we are at the end of a group we need to move backwards up the
172 	 * stack, consuming the large backskips as we go, until we find a group
173 	 * that still contains unprocessed items, or until we have unwound back
174 	 * off the bottom of the stack (i.e. out of all the groups).
175 	 */
176 	} else {
177 		while (f->ef_ndeep >= 0 &&
178 		    ++f->ef_depth[f->ef_ndeep].efd_obj >=
179 		    f->ef_depth[f->ef_ndeep].efd_nobjs) {
180 			/* Read the large backskip. */
181 			f->ef_ndeep--;
182 			if (xread(f, &scratch32, sizeof (scratch32)) !=
183 			    sizeof (scratch32)) {
184 				EXACCT_SET_ERR(EXR_CORRUPT_FILE);
185 				return (-1);
186 			}
187 		}
188 		return (0);
189 	}
190 }
191 
192 /*
193  * Step backwards along the objects within the current group.  If we are still
194  * within a group, return 1.  If we have reached the end of the current group,
195  * unwind the stack back up to the enclosing group and return 0.
196  */
197 static int stack_previous_object(ea_file_impl_t *f)
198 {
199 	/*
200 	 * If the stack is empty we are not in a group, so there will be no
201 	 * stack manipulation to do.
202 	 */
203 	if (f->ef_ndeep < 0) {
204 		return (0);
205 	}
206 
207 	/*
208 	 * Otherwise we must be in a group.  If there are objects left in the
209 	 * group, move onto the previous one in the group and return.
210 	 */
211 	if (--f->ef_depth[f->ef_ndeep].efd_obj >= 0) {
212 		return (1);
213 
214 	/* Otherwise, step one level back up the group stack. */
215 	} else {
216 		f->ef_ndeep--;
217 		return (0);
218 	}
219 }
220 
221 /*
222  * read/seek/pos virtualisation wrappers.  Because objects can come either from
223  * a file or memory, the read/seek/pos functions need to be wrapped to allow
224  * them to be used on either a file handle or a memory buffer.
225  */
226 
227 static size_t
228 fread_wrapper(ea_file_impl_t *f, void *buf, size_t sz)
229 {
230 	size_t retval;
231 
232 	retval = fread(buf, 1, sz, f->ef_fp);
233 	if (retval == 0 && ferror(f->ef_fp)) {
234 		retval = (size_t)-1;
235 	}
236 	return (retval);
237 }
238 
239 static size_t
240 bufread_wrapper(ea_file_impl_t *f, void *buf, size_t sz)
241 {
242 	if (f->ef_bufsize == 0 && sz != 0)
243 		return ((size_t)0);
244 
245 	if (f->ef_bufsize < sz)
246 		sz = f->ef_bufsize;
247 
248 	bcopy(f->ef_buf, buf, sz);
249 	f->ef_buf += sz;
250 	f->ef_bufsize -= sz;
251 
252 	return (sz);
253 }
254 
255 static off_t
256 fseek_wrapper(ea_file_impl_t *f, off_t adv)
257 {
258 	return (fseeko(f->ef_fp, adv, SEEK_CUR));
259 }
260 
261 static off_t
262 bufseek_wrapper(ea_file_impl_t *f, off_t adv)
263 {
264 	if (f->ef_bufsize == 0 && adv != 0)
265 		return (-1);
266 
267 	if (f->ef_bufsize < adv)
268 		adv = f->ef_bufsize;
269 
270 	f->ef_buf += adv;
271 	f->ef_bufsize -= adv;
272 
273 	return (0);
274 }
275 
276 /*ARGSUSED*/
277 static void *
278 fpos_wrapper(ea_file_impl_t *f)
279 {
280 	return (NULL);
281 }
282 
283 static void *
284 bufpos_wrapper(ea_file_impl_t *f)
285 {
286 	return (f->ef_buf);
287 }
288 
289 /*
290  * Public API
291  */
292 
293 void
294 exacct_seterr(int errval)
295 {
296 	if (thr_main()) {
297 		exacct_errval = errval;
298 		return;
299 	}
300 	(void) thr_keycreate_once(&errkey, 0);
301 	(void) thr_setspecific(errkey, (void *)(intptr_t)errval);
302 }
303 
304 int
305 ea_error(void)
306 {
307 	if (thr_main())
308 		return (exacct_errval);
309 	if (errkey == THR_ONCE_KEY)
310 		return (EXR_OK);
311 	return ((int)(uintptr_t)pthread_getspecific(errkey));
312 }
313 
314 /*
315  * ea_next_object(), ea_previous_object(), and ea_get_object() are written such
316  * that the file cursor is always located on an object boundary.
317  */
318 ea_object_type_t
319 ea_next_object(ea_file_t *ef, ea_object_t *obj)
320 {
321 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
322 	ea_size_t len;
323 	off_t backup;
324 	size_t ret;
325 
326 	/*
327 	 * If ef_advance is zero, then we are executing after a get or previous
328 	 * operation and do not move to the next or previous object.  Otherwise,
329 	 * advance to the next available item.  Note that ef_advance does NOT
330 	 * include the large backskip at the end of a object, this being dealt
331 	 * with by the depth stack handling in stack_next_object.
332 	 */
333 	if (f->ef_advance != 0) {
334 		if (fseeko(f->ef_fp, (off_t)f->ef_advance, SEEK_CUR) == -1) {
335 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
336 			return (EO_ERROR);
337 		}
338 		if (stack_next_object(f, fread_wrapper) == -1) {
339 			/* exacct_error set above. */
340 			return (EO_ERROR);
341 		}
342 	}
343 	f->ef_advance = 0;
344 
345 	/* Read the catalog tag */
346 	ret = fread(&obj->eo_catalog, 1, sizeof (ea_catalog_t), f->ef_fp);
347 	if (ret == 0) {
348 		EXACCT_SET_ERR(EXR_EOF);
349 		return (EO_ERROR);
350 	} else if (ret < sizeof (ea_catalog_t)) {
351 		EXACCT_SET_ERR(EXR_CORRUPT_FILE);
352 		return (EO_ERROR);
353 	}
354 	exacct_order32(&obj->eo_catalog);
355 
356 	backup = sizeof (ea_catalog_t);
357 	obj->eo_type = EO_ITEM;
358 
359 	/* Figure out the offset to just before the large backskip. */
360 	switch (obj->eo_catalog & EXT_TYPE_MASK) {
361 	case EXT_GROUP:
362 		obj->eo_type = EO_GROUP;
363 		f->ef_advance = sizeof (uint32_t);
364 	/* FALLTHROUGH */
365 	case EXT_STRING:
366 	case EXT_EXACCT_OBJECT:
367 	case EXT_RAW:
368 		if (fread(&len, 1, sizeof (ea_size_t), f->ef_fp)
369 		    < sizeof (ea_size_t)) {
370 			obj->eo_type = EO_NONE;
371 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
372 			return (EO_ERROR);
373 		}
374 		exacct_order64(&len);
375 		/* Note: len already includes the size of the backskip. */
376 		f->ef_advance += sizeof (ea_catalog_t) +
377 		    sizeof (ea_size_t) + len;
378 		backup += sizeof (ea_size_t);
379 		break;
380 	case EXT_UINT8:
381 		f->ef_advance = sizeof (ea_catalog_t) + sizeof (uint8_t) +
382 		    sizeof (uint32_t);
383 		break;
384 	case EXT_UINT16:
385 		f->ef_advance = sizeof (ea_catalog_t) + sizeof (uint16_t) +
386 		    sizeof (uint32_t);
387 		break;
388 	case EXT_UINT32:
389 		f->ef_advance = sizeof (ea_catalog_t) + sizeof (uint32_t) +
390 		    sizeof (uint32_t);
391 		break;
392 	case EXT_UINT64:
393 		f->ef_advance = sizeof (ea_catalog_t) + sizeof (uint64_t) +
394 		    sizeof (uint32_t);
395 		break;
396 	case EXT_DOUBLE:
397 		f->ef_advance = sizeof (ea_catalog_t) + sizeof (double) +
398 		    sizeof (uint32_t);
399 		break;
400 	default:
401 		obj->eo_type = EO_NONE;
402 		EXACCT_SET_ERR(EXR_CORRUPT_FILE);
403 		return (EO_ERROR);
404 	}
405 
406 	/* Reposition to the start of this object. */
407 	if (fseeko(f->ef_fp, -backup, SEEK_CUR) == -1) {
408 		obj->eo_type = EO_NONE;
409 		f->ef_advance = 0;
410 		EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
411 		return (EO_ERROR);
412 	}
413 
414 	EXACCT_SET_ERR(EXR_OK);
415 	return (obj->eo_type);
416 }
417 
418 ea_object_type_t
419 ea_previous_object(ea_file_t *ef, ea_object_t *obj)
420 {
421 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
422 	uint32_t bkskip;
423 	int r;
424 
425 	if (fseeko(f->ef_fp, -((off_t)sizeof (uint32_t)), SEEK_CUR) == -1) {
426 		if (errno == EINVAL) {
427 			EXACCT_SET_ERR(EXR_EOF);
428 		} else {
429 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
430 		}
431 		return (EO_ERROR);
432 	}
433 
434 	if ((r = fread(&bkskip, 1, sizeof (uint32_t), f->ef_fp)) !=
435 	    sizeof (uint32_t)) {
436 		if (r == 0) {
437 			EXACCT_SET_ERR(EXR_EOF);
438 		} else {
439 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
440 		}
441 		return (EO_ERROR);
442 	}
443 	exacct_order32(&bkskip);
444 
445 	/*
446 	 * A backskip of 0 means that the current record can't be skipped over.
447 	 * This will be true for the header record, and for records longer than
448 	 * 2^32.
449 	 */
450 	if (bkskip == 0) {
451 		EXACCT_SET_ERR(EXR_EOF);
452 		return (EO_ERROR);
453 	}
454 	(void) stack_previous_object(f);
455 
456 	if (fseeko(f->ef_fp, -((off_t)bkskip), SEEK_CUR) == -1) {
457 		if (errno == EINVAL) {
458 			/*
459 			 * If we attempted to seek past BOF, then the file was
460 			 * corrupt, as we can only trust the backskip we read.
461 			 */
462 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
463 		} else {
464 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
465 		}
466 		return (EO_ERROR);
467 	}
468 
469 	f->ef_advance = 0;
470 	return (ea_next_object(ef, obj));
471 }
472 
473 /*
474  * xget_object() contains the logic for extracting an individual object from a
475  * packed buffer, which it consumes using xread() and xseek() operations
476  * provided by the caller.  flags may be set to either EUP_ALLOC, in which case
477  * new memory is allocated for the variable length items unpacked, or
478  * EUP_NOALLOC, in which case item data pointer indicate locations within the
479  * buffer, using the provided xpos() function.  EUP_NOALLOC is generally not
480  * useful for callers representing interaction with actual file streams, and
481  * should not be specified thereby.
482  */
483 static ea_object_type_t
484 xget_object(
485     ea_file_impl_t *f,
486     ea_object_t *obj,
487     size_t (*xread)(ea_file_impl_t *, void *, size_t),
488     off_t (*xseek)(ea_file_impl_t *, off_t),
489     void *(*xpos)(ea_file_impl_t *),
490     int flags)
491 {
492 	ea_size_t sz;
493 	uint32_t gp_backskip, scratch32;
494 	void *buf;
495 	size_t r;
496 
497 	/* Read the catalog tag. */
498 	if ((r = xread(f, &obj->eo_catalog, sizeof (ea_catalog_t))) == 0) {
499 		EXACCT_SET_ERR(EXR_EOF);
500 		return (EO_ERROR);
501 	} else if (r != sizeof (ea_catalog_t)) {
502 		EXACCT_SET_ERR(EXR_CORRUPT_FILE);
503 		return (EO_ERROR);
504 	}
505 	exacct_order32(&obj->eo_catalog);
506 
507 	/*
508 	 * If this is a record group, we treat it separately:  only record
509 	 * groups cause us to allocate new depth frames.
510 	 */
511 	if ((obj->eo_catalog & EXT_TYPE_MASK) == EXT_GROUP) {
512 		obj->eo_type = EO_GROUP;
513 
514 		/* Read size field, and number of objects. */
515 		if (xread(f, &sz, sizeof (ea_size_t)) != sizeof (ea_size_t)) {
516 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
517 			return (EO_ERROR);
518 		}
519 		exacct_order64(&sz);
520 		if (xread(f, &obj->eo_group.eg_nobjs, sizeof (uint32_t)) !=
521 		    sizeof (uint32_t)) {
522 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
523 			return (EO_ERROR);
524 		}
525 		exacct_order32(&obj->eo_group.eg_nobjs);
526 
527 		/* Now read the group's small backskip. */
528 		if (xread(f, &gp_backskip, sizeof (uint32_t)) !=
529 		    sizeof (uint32_t)) {
530 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
531 			return (EO_ERROR);
532 		}
533 
534 		/* Push a new depth stack frame. */
535 		if (stack_new_group(f, obj->eo_group.eg_nobjs) != 0) {
536 			/* exacct_error set above */
537 			return (EO_ERROR);
538 		}
539 
540 		/*
541 		 * If the group has no items, we now need to position to the
542 		 * end of the group, because there will be no subsequent calls
543 		 * to process the group, it being empty.
544 		 */
545 		if (obj->eo_group.eg_nobjs == 0) {
546 			if (stack_next_object(f, xread) == -1) {
547 				/* exacct_error set above. */
548 				return (EO_ERROR);
549 			}
550 		}
551 
552 		f->ef_advance = 0;
553 		EXACCT_SET_ERR(EXR_OK);
554 		return (obj->eo_type);
555 	}
556 
557 	/*
558 	 * Otherwise we are reading an item.
559 	 */
560 	obj->eo_type = EO_ITEM;
561 	switch (obj->eo_catalog & EXT_TYPE_MASK) {
562 	case EXT_STRING:
563 	case EXT_EXACCT_OBJECT:
564 	case EXT_RAW:
565 		if (xread(f, &sz, sizeof (ea_size_t)) != sizeof (ea_size_t)) {
566 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
567 			return (EO_ERROR);
568 		}
569 		exacct_order64(&sz);
570 		/*
571 		 * Subtract backskip value from size.
572 		 */
573 		sz -= sizeof (uint32_t);
574 		if ((flags & EUP_ALLOC_MASK) == EUP_NOALLOC) {
575 			buf = xpos(f);
576 			if (xseek(f, sz) == -1) {
577 				EXACCT_SET_ERR(EXR_CORRUPT_FILE);
578 				return (EO_ERROR);
579 			}
580 		} else {
581 			if ((buf = ea_alloc(sz)) == NULL)
582 				/* exacct_error set above. */
583 				return (EO_ERROR);
584 			if (xread(f, buf, sz) != sz) {
585 				ea_free(buf, sz);
586 				EXACCT_SET_ERR(EXR_CORRUPT_FILE);
587 				return (EO_ERROR);
588 			}
589 		}
590 		obj->eo_item.ei_string = buf;
591 		/*
592 		 * Maintain our consistent convention that string lengths
593 		 * include the terminating NULL character.
594 		 */
595 		obj->eo_item.ei_size = sz;
596 		break;
597 	case EXT_UINT8:
598 		if (xread(f, &obj->eo_item.ei_uint8, sizeof (uint8_t)) !=
599 		    sizeof (uint8_t)) {
600 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
601 			return (EO_ERROR);
602 		}
603 		obj->eo_item.ei_size = sizeof (uint8_t);
604 		break;
605 	case EXT_UINT16:
606 		if (xread(f, &obj->eo_item.ei_uint16, sizeof (uint16_t)) !=
607 		    sizeof (uint16_t)) {
608 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
609 			return (EO_ERROR);
610 		}
611 		exacct_order16(&obj->eo_item.ei_uint16);
612 		obj->eo_item.ei_size = sizeof (uint16_t);
613 		break;
614 	case EXT_UINT32:
615 		if (xread(f, &obj->eo_item.ei_uint32, sizeof (uint32_t)) !=
616 		    sizeof (uint32_t)) {
617 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
618 			return (EO_ERROR);
619 		}
620 		exacct_order32(&obj->eo_item.ei_uint32);
621 		obj->eo_item.ei_size = sizeof (uint32_t);
622 		break;
623 	case EXT_UINT64:
624 		if (xread(f, &obj->eo_item.ei_uint64, sizeof (uint64_t)) !=
625 		    sizeof (uint64_t)) {
626 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
627 			return (EO_ERROR);
628 		}
629 		exacct_order64(&obj->eo_item.ei_uint64);
630 		obj->eo_item.ei_size = sizeof (uint64_t);
631 		break;
632 	case EXT_DOUBLE:
633 		if (xread(f, &obj->eo_item.ei_double, sizeof (double)) !=
634 		    sizeof (double)) {
635 			EXACCT_SET_ERR(EXR_CORRUPT_FILE);
636 			return (EO_ERROR);
637 		}
638 		exacct_order64((uint64_t *)&obj->eo_item.ei_double);
639 		obj->eo_item.ei_size = sizeof (double);
640 		break;
641 	default:
642 		/*
643 		 * We've encountered an unknown type value.  Flag the error and
644 		 * exit.
645 		 */
646 		EXACCT_SET_ERR(EXR_CORRUPT_FILE);
647 		return (EO_ERROR);
648 	}
649 
650 	/*
651 	 * Advance over current large backskip value,
652 	 * and position at the start of the next object.
653 	 */
654 	if (xread(f, &scratch32, sizeof (scratch32)) != sizeof (scratch32)) {
655 		EXACCT_SET_ERR(EXR_CORRUPT_FILE);
656 		return (EO_ERROR);
657 	}
658 	if (stack_next_object(f, xread) == -1) {
659 		/* exacct_error set above. */
660 		return (EO_ERROR);
661 	}
662 
663 	f->ef_advance = 0;
664 	EXACCT_SET_ERR(EXR_OK);
665 	return (obj->eo_type);
666 }
667 
668 ea_object_type_t
669 ea_get_object(ea_file_t *ef, ea_object_t *obj)
670 {
671 	obj->eo_next = NULL;
672 	return (xget_object((ea_file_impl_t *)ef, obj, fread_wrapper,
673 		    fseek_wrapper, fpos_wrapper, EUP_ALLOC));
674 }
675 
676 /*
677  * unpack_group() recursively unpacks record groups from the buffer tucked
678  * within the passed ea_file, and attaches them to grp.
679  */
680 static int
681 unpack_group(ea_file_impl_t *f, ea_object_t *grp, int flag)
682 {
683 	ea_object_t *obj;
684 	uint_t nobjs = grp->eo_group.eg_nobjs;
685 	int i;
686 
687 	/*
688 	 * Set the group's object count to zero, as we will rebuild it via the
689 	 * individual object attachments.
690 	 */
691 	grp->eo_group.eg_nobjs = 0;
692 	grp->eo_group.eg_objs = NULL;
693 
694 	for (i = 0; i < nobjs; i++) {
695 		if ((obj = ea_alloc(sizeof (ea_object_t))) == NULL) {
696 			/* exacct_errno set above. */
697 			return (-1);
698 		}
699 		obj->eo_next = NULL;
700 		if (xget_object(f, obj, bufread_wrapper, bufseek_wrapper,
701 			    bufpos_wrapper, flag) == -1) {
702 			ea_free(obj, sizeof (ea_object_t));
703 			/* exacct_errno set above. */
704 			return (-1);
705 		}
706 
707 		(void) ea_attach_to_group(grp, obj);
708 
709 		if (obj->eo_type == EO_GROUP &&
710 		    unpack_group(f, obj, flag) == -1) {
711 			/* exacct_errno set above. */
712 			return (-1);
713 		}
714 	}
715 
716 	if (nobjs != grp->eo_group.eg_nobjs) {
717 		EXACCT_SET_ERR(EXR_CORRUPT_FILE);
718 		return (-1);
719 	}
720 	EXACCT_SET_ERR(EXR_OK);
721 	return (0);
722 }
723 
724 /*
725  * ea_unpack_object() can be considered as a finite series of get operations on
726  * a given buffer, that rebuilds the hierarchy of objects compacted by a pack
727  * operation.  Because there is complex state associated with the group depth,
728  * ea_unpack_object() must complete as one operation on a given buffer.
729  */
730 ea_object_type_t
731 ea_unpack_object(ea_object_t **objp, int flag, void *buf, size_t bufsize)
732 {
733 	ea_file_impl_t fake;
734 	ea_object_t *obj;
735 	ea_object_type_t first_obj_type;
736 
737 	*objp = NULL;
738 	if (buf == NULL) {
739 		EXACCT_SET_ERR(EXR_INVALID_BUF);
740 		return (EO_ERROR);
741 	}
742 
743 	/* Set up the structures needed for unpacking */
744 	bzero(&fake, sizeof (ea_file_impl_t));
745 	if (stack_check(&fake) == -1) {
746 		/* exacct_errno set above. */
747 		return (EO_ERROR);
748 	}
749 	fake.ef_buf = buf;
750 	fake.ef_bufsize = bufsize;
751 
752 	/* Unpack the first object in the buffer - this should succeed. */
753 	if ((obj = ea_alloc(sizeof (ea_object_t))) == NULL) {
754 		stack_free(&fake);
755 		/* exacct_errno set above. */
756 		return (EO_ERROR);
757 	}
758 	obj->eo_next = NULL;
759 	if ((first_obj_type = xget_object(&fake, obj, bufread_wrapper,
760 	    bufseek_wrapper, bufpos_wrapper, flag)) == -1) {
761 		stack_free(&fake);
762 		ea_free(obj, sizeof (ea_object_t));
763 		/* exacct_errno set above. */
764 		return (EO_ERROR);
765 	}
766 
767 	if (obj->eo_type == EO_GROUP && unpack_group(&fake, obj, flag) == -1) {
768 		stack_free(&fake);
769 		ea_free_object(obj, flag);
770 		/* exacct_errno set above. */
771 		return (EO_ERROR);
772 	}
773 	*objp = obj;
774 
775 	/*
776 	 * There may be other objects in the buffer - if so, chain them onto
777 	 * the end of the list.  We have reached the end of the list when
778 	 * xget_object() returns -1 with exacct_error set to EXR_EOF.
779 	 */
780 	for (;;) {
781 		if ((obj = ea_alloc(sizeof (ea_object_t))) == NULL) {
782 			stack_free(&fake);
783 			ea_free_object(*objp, flag);
784 			*objp = NULL;
785 			/* exacct_errno set above. */
786 			return (EO_ERROR);
787 		}
788 		obj->eo_next = NULL;
789 		if (xget_object(&fake, obj, bufread_wrapper, bufseek_wrapper,
790 			    bufpos_wrapper, flag) == -1) {
791 			stack_free(&fake);
792 			ea_free(obj, sizeof (ea_object_t));
793 			if (ea_error() == EXR_EOF) {
794 				EXACCT_SET_ERR(EXR_OK);
795 				return (first_obj_type);
796 			} else {
797 				ea_free_object(*objp, flag);
798 				*objp = NULL;
799 				/* exacct_error set above. */
800 				return (EO_ERROR);
801 			}
802 		}
803 
804 		(void) ea_attach_to_object(*objp, obj);
805 
806 		if (obj->eo_type == EO_GROUP &&
807 		    unpack_group(&fake, obj, flag) == -1) {
808 			stack_free(&fake);
809 			ea_free(obj, sizeof (ea_object_t));
810 			ea_free_object(*objp, flag);
811 			*objp = NULL;
812 			/* exacct_errno set above. */
813 			return (EO_ERROR);
814 		}
815 	}
816 }
817 
818 int
819 ea_write_object(ea_file_t *ef, ea_object_t *obj)
820 {
821 	ea_size_t sz;
822 	void *buf;
823 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
824 
825 	/*
826 	 * If we weren't opened for writing, this call fails.
827 	 */
828 	if ((f->ef_oflags & O_RDWR) == 0 &&
829 	    (f->ef_oflags & O_WRONLY) == 0) {
830 		EXACCT_SET_ERR(EXR_NOTSUPP);
831 		return (-1);
832 	}
833 
834 	/* Pack with a null buffer to get the size. */
835 	sz = ea_pack_object(obj, NULL, 0);
836 	if (sz == -1 || (buf = ea_alloc(sz)) == NULL) {
837 		/* exacct_error set above. */
838 		return (-1);
839 	}
840 	if (ea_pack_object(obj, buf, sz) == (size_t)-1) {
841 		ea_free(buf, sz);
842 		/* exacct_error set above. */
843 		return (-1);
844 	}
845 	if (fwrite(buf, sizeof (char), sz, f->ef_fp) != sz) {
846 		ea_free(buf, sz);
847 		EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
848 		return (-1);
849 	}
850 	ea_free(buf, sz);
851 	EXACCT_SET_ERR(EXR_OK);
852 	return (0);
853 }
854 
855 /*
856  * validate_header() must be kept in sync with write_header(), given below, and
857  * exacct_create_header(), in uts/common/os/exacct.c.
858  */
859 static int
860 validate_header(ea_file_t *ef, const char *creator)
861 {
862 	ea_object_t hdr_grp;
863 	ea_object_t scratch_obj;
864 	int error = EXR_OK;
865 	int saw_creator = 0;
866 	int saw_version = 0;
867 	int saw_type = 0;
868 	int saw_hostname = 0;
869 	int n;
870 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
871 
872 	bzero(&hdr_grp, sizeof (ea_object_t));
873 
874 	if (ea_get_object(ef, &hdr_grp) != EO_GROUP) {
875 		error = ea_error();
876 		goto error_case;
877 	}
878 
879 	if (hdr_grp.eo_catalog !=
880 	    (EXT_GROUP | EXC_DEFAULT | EXD_GROUP_HEADER)) {
881 		error = EXR_CORRUPT_FILE;
882 		goto error_case;
883 	}
884 
885 	for (n = 0; n < hdr_grp.eo_group.eg_nobjs; n++) {
886 		bzero(&scratch_obj, sizeof (ea_object_t));
887 		if (ea_get_object(ef, &scratch_obj) == -1) {
888 			error = ea_error();
889 			goto error_case;
890 		}
891 
892 		switch (scratch_obj.eo_catalog) {
893 		case EXT_UINT32 | EXC_DEFAULT | EXD_VERSION:
894 			if (scratch_obj.eo_item.ei_uint32 != EXACCT_VERSION) {
895 				error = EXR_UNKN_VERSION;
896 				goto error_case;
897 			}
898 			saw_version++;
899 			break;
900 		case EXT_STRING | EXC_DEFAULT | EXD_FILETYPE:
901 			if (strcmp(scratch_obj.eo_item.ei_string,
902 			    EXACCT_HDR_STR) != 0) {
903 				error = EXR_CORRUPT_FILE;
904 				goto error_case;
905 			}
906 			saw_type++;
907 			break;
908 		case EXT_STRING | EXC_DEFAULT | EXD_CREATOR:
909 			f->ef_creator =
910 			    ea_strdup(scratch_obj.eo_item.ei_string);
911 			if (f->ef_creator == NULL) {
912 				error = ea_error();
913 				goto error_case;
914 			}
915 			saw_creator++;
916 			break;
917 		/* The hostname is an optional field. */
918 		case EXT_STRING | EXC_DEFAULT | EXD_HOSTNAME:
919 			f->ef_hostname =
920 			    ea_strdup(scratch_obj.eo_item.ei_string);
921 			if (f->ef_hostname == NULL) {
922 				error = ea_error();
923 				goto error_case;
924 			}
925 			saw_hostname++;
926 			break;
927 		default:
928 			/* ignore unrecognized header members */
929 			break;
930 		}
931 		(void) ea_free_item(&scratch_obj, EUP_ALLOC);
932 	}
933 
934 	if (saw_version && saw_type && saw_creator) {
935 		if (creator && strcmp(f->ef_creator, creator) != 0) {
936 			error = EXR_NO_CREATOR;
937 			goto error_case;
938 		}
939 		EXACCT_SET_ERR(EXR_OK);
940 		return (0);
941 	}
942 
943 error_case:
944 	(void) ea_free_item(&scratch_obj, EUP_ALLOC);
945 	if (saw_hostname)
946 		ea_strfree(f->ef_hostname);
947 	if (saw_creator)
948 		ea_strfree(f->ef_creator);
949 	EXACCT_SET_ERR(error);
950 	return (-1);
951 }
952 
953 static int
954 write_header(ea_file_t *ef)
955 {
956 	ea_object_t hdr_grp;
957 	ea_object_t vers_obj;
958 	ea_object_t creator_obj;
959 	ea_object_t filetype_obj;
960 	ea_object_t hostname_obj;
961 	uint32_t bskip;
962 	const uint32_t version = EXACCT_VERSION;
963 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
964 	void *buf;
965 	size_t bufsize;
966 	char hostbuf[SYSINFO_BUFSIZE];
967 	int error = EXR_OK;
968 
969 	bzero(&hdr_grp, sizeof (ea_object_t));
970 	bzero(&vers_obj, sizeof (ea_object_t));
971 	bzero(&creator_obj, sizeof (ea_object_t));
972 	bzero(&filetype_obj, sizeof (ea_object_t));
973 	bzero(&hostname_obj, sizeof (ea_object_t));
974 	bzero(hostbuf, SYSINFO_BUFSIZE);
975 
976 	(void) sysinfo(SI_HOSTNAME, hostbuf, SYSINFO_BUFSIZE);
977 
978 	if (ea_set_item(&vers_obj, EXT_UINT32 | EXC_DEFAULT | EXD_VERSION,
979 		    (void *)&version, 0) == -1 ||
980 	    ea_set_item(&creator_obj, EXT_STRING | EXC_DEFAULT | EXD_CREATOR,
981 		    f->ef_creator, strlen(f->ef_creator)) == -1 ||
982 	    ea_set_item(&filetype_obj, EXT_STRING | EXC_DEFAULT | EXD_FILETYPE,
983 		    EXACCT_HDR_STR, strlen(EXACCT_HDR_STR)) == -1 ||
984 	    ea_set_item(&hostname_obj, EXT_STRING | EXC_DEFAULT | EXD_HOSTNAME,
985 		    hostbuf, strlen(hostbuf)) == -1) {
986 		error = ea_error();
987 		goto cleanup1;
988 	}
989 
990 	(void) ea_set_group(&hdr_grp,
991 	    EXT_GROUP | EXC_DEFAULT | EXD_GROUP_HEADER);
992 	(void) ea_attach_to_group(&hdr_grp, &vers_obj);
993 	(void) ea_attach_to_group(&hdr_grp, &creator_obj);
994 	(void) ea_attach_to_group(&hdr_grp, &filetype_obj);
995 	(void) ea_attach_to_group(&hdr_grp, &hostname_obj);
996 
997 	/* Get the required size by passing a null buffer. */
998 	bufsize = ea_pack_object(&hdr_grp, NULL, 0);
999 	if ((buf = ea_alloc(bufsize)) == NULL) {
1000 		error = ea_error();
1001 		goto cleanup1;
1002 	}
1003 
1004 	if (ea_pack_object(&hdr_grp, buf, bufsize) == (size_t)-1) {
1005 		error = ea_error();
1006 		goto cleanup2;
1007 	}
1008 
1009 	/*
1010 	 * To prevent reading the header when reading the file backwards,
1011 	 * set the large backskip of the header group to 0 (last 4 bytes).
1012 	 */
1013 	bskip = 0;
1014 	exacct_order32(&bskip);
1015 	bcopy(&bskip, (char *)buf + bufsize - sizeof (bskip),
1016 	    sizeof (bskip));
1017 
1018 	if (fwrite(buf, sizeof (char), bufsize, f->ef_fp) != bufsize ||
1019 	    fflush(f->ef_fp) == EOF) {
1020 		error = EXR_SYSCALL_FAIL;
1021 		goto cleanup2;
1022 	}
1023 
1024 cleanup2:
1025 	ea_free(buf, bufsize);
1026 cleanup1:
1027 	(void) ea_free_item(&vers_obj, EUP_ALLOC);
1028 	(void) ea_free_item(&creator_obj, EUP_ALLOC);
1029 	(void) ea_free_item(&filetype_obj, EUP_ALLOC);
1030 	(void) ea_free_item(&hostname_obj, EUP_ALLOC);
1031 	EXACCT_SET_ERR(error);
1032 	return (error == EXR_OK ? 0 : -1);
1033 }
1034 
1035 const char *
1036 ea_get_creator(ea_file_t *ef)
1037 {
1038 	return ((const char *)((ea_file_impl_t *)ef)->ef_creator);
1039 }
1040 
1041 const char *
1042 ea_get_hostname(ea_file_t *ef)
1043 {
1044 	return ((const char *)((ea_file_impl_t *)ef)->ef_hostname);
1045 }
1046 
1047 int
1048 ea_fdopen(ea_file_t *ef, int fd, const char *creator, int aflags, int oflags)
1049 {
1050 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
1051 
1052 	bzero(f, sizeof (*f));
1053 	f->ef_oflags = oflags;
1054 	f->ef_fd = fd;
1055 
1056 	/* Initialize depth stack. */
1057 	if (stack_check(f) == -1) {
1058 		/* exacct_error set above. */
1059 		goto error1;
1060 	}
1061 
1062 	/*
1063 	 * 1.  If we are O_CREAT, then we will need to write a header
1064 	 * after opening name.
1065 	 */
1066 	if (oflags & O_CREAT) {
1067 		if (creator == NULL) {
1068 			EXACCT_SET_ERR(EXR_NO_CREATOR);
1069 			goto error2;
1070 		}
1071 		if ((f->ef_creator = ea_strdup(creator)) == NULL) {
1072 			/* exacct_error set above. */
1073 			goto error2;
1074 		}
1075 		if ((f->ef_fp = fdopen(f->ef_fd, "w")) == NULL) {
1076 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1077 			goto error3;
1078 		}
1079 		if (write_header(ef) == -1) {
1080 			/* exacct_error set above. */
1081 			goto error3;
1082 		}
1083 
1084 	/*
1085 	 * 2.  If we are not O_CREAT, but are RDWR or WRONLY, we need to
1086 	 * seek to EOF so that appends will succeed.
1087 	 */
1088 	} else if (oflags & O_RDWR || oflags & O_WRONLY) {
1089 		if ((f->ef_fp = fdopen(f->ef_fd, "r+")) == NULL) {
1090 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1091 			goto error2;
1092 		}
1093 
1094 		if ((aflags & EO_VALIDATE_MSK) == EO_VALID_HDR) {
1095 			if (validate_header(ef, creator) < 0) {
1096 				/* exacct_error set above. */
1097 				goto error2;
1098 			}
1099 		}
1100 
1101 		if (fseeko(f->ef_fp, 0, SEEK_END) == -1) {
1102 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1103 			goto error2;
1104 		}
1105 
1106 	/*
1107 	 * 3. This is an undefined manner for opening an exacct file.
1108 	 */
1109 	} else if (oflags != O_RDONLY) {
1110 		EXACCT_SET_ERR(EXR_NOTSUPP);
1111 		goto error2;
1112 
1113 	/*
1114 	 * 4a.  If we are RDONLY, then we are in a position such that
1115 	 * either a ea_get_object or an ea_next_object will succeed.  If
1116 	 * aflags was set to EO_TAIL, seek to the end of the file.
1117 	 */
1118 	} else {
1119 		if ((f->ef_fp = fdopen(f->ef_fd, "r")) == NULL) {
1120 			EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1121 			goto error2;
1122 		}
1123 
1124 		if ((aflags & EO_VALIDATE_MSK) == EO_VALID_HDR) {
1125 			if (validate_header(ef, creator) == -1) {
1126 				/* exacct_error set above. */
1127 				goto error2;
1128 			}
1129 		}
1130 
1131 		/*
1132 		 * 4b.  Handle the "open at end" option, for consumers who want
1133 		 * to go backwards through the file (i.e. lastcomm).
1134 		 */
1135 		if ((aflags & EO_POSN_MSK) == EO_TAIL) {
1136 			if (fseeko(f->ef_fp, 0, SEEK_END) < 0) {
1137 				EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1138 				goto error2;
1139 			}
1140 		}
1141 	}
1142 
1143 	EXACCT_SET_ERR(EXR_OK);
1144 	return (0);
1145 
1146 	/* Error cleanup code */
1147 error3:
1148 	ea_strfree(f->ef_creator);
1149 error2:
1150 	stack_free(f);
1151 error1:
1152 	bzero(f, sizeof (*f));
1153 	return (-1);
1154 }
1155 
1156 int
1157 ea_open(ea_file_t *ef, const char *name, const char *creator,
1158     int aflags, int oflags, mode_t mode)
1159 {
1160 	int fd;
1161 
1162 	/*
1163 	 * If overwriting an existing file, make sure to truncate it
1164 	 * to prevent the file being created corrupt.
1165 	 */
1166 	if (oflags & O_CREAT)
1167 		oflags |= O_TRUNC;
1168 
1169 	if ((fd = open(name, oflags, mode)) == -1) {
1170 		EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1171 		return (-1);
1172 	}
1173 
1174 	if (ea_fdopen(ef, fd, creator, aflags, oflags) == -1) {
1175 		(void) close(fd);
1176 		return (-1);
1177 	}
1178 
1179 	return (0);
1180 }
1181 
1182 /*
1183  * ea_close() performs all appropriate close operations on the open exacct file,
1184  * including releasing any memory allocated while parsing the file.
1185  */
1186 int
1187 ea_close(ea_file_t *ef)
1188 {
1189 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
1190 
1191 	if (f->ef_creator != NULL)
1192 		ea_strfree(f->ef_creator);
1193 	if (f->ef_hostname != NULL)
1194 		ea_strfree(f->ef_hostname);
1195 
1196 	ea_free(f->ef_depth, f->ef_mxdeep * sizeof (ea_file_depth_t));
1197 
1198 	if (fclose(f->ef_fp)) {
1199 		EXACCT_SET_ERR(EXR_SYSCALL_FAIL);
1200 		return (-1);
1201 	}
1202 
1203 	EXACCT_SET_ERR(EXR_OK);
1204 	return (0);
1205 }
1206 
1207 /*
1208  * Empty the input buffer and clear any underlying EOF or error bits set on the
1209  * underlying FILE.  This can be used by any library clients who wish to handle
1210  * files that are in motion or who wish to seek the underlying file descriptor.
1211  */
1212 void
1213 ea_clear(ea_file_t *ef)
1214 {
1215 	ea_file_impl_t *f = (ea_file_impl_t *)ef;
1216 
1217 	(void) fflush(f->ef_fp);
1218 	clearerr(f->ef_fp);
1219 }
1220 
1221 /*
1222  * Copy an ea_object_t.  Note that in the case of a group, just the group
1223  * object will be copied, and not its list of members.  To recursively copy
1224  * a group or a list of items use ea_copy_tree().
1225  */
1226 ea_object_t *
1227 ea_copy_object(const ea_object_t *src)
1228 {
1229 	ea_object_t *dst;
1230 
1231 	/* Allocate a new object and copy to it. */
1232 	if ((dst = ea_alloc(sizeof (ea_object_t))) == NULL) {
1233 		return (NULL);
1234 	}
1235 	bcopy(src, dst, sizeof (ea_object_t));
1236 	dst->eo_next = NULL;
1237 
1238 	switch (src->eo_type) {
1239 	case EO_GROUP:
1240 		dst->eo_group.eg_nobjs = 0;
1241 		dst->eo_group.eg_objs = NULL;
1242 		break;
1243 	case EO_ITEM:
1244 		/* Items containing pointers need special treatment. */
1245 		switch (src->eo_catalog & EXT_TYPE_MASK) {
1246 		case EXT_STRING:
1247 			if (src->eo_item.ei_string != NULL) {
1248 				dst->eo_item.ei_string =
1249 				    ea_strdup(src->eo_item.ei_string);
1250 				if (dst->eo_item.ei_string == NULL) {
1251 					ea_free_object(dst, EUP_ALLOC);
1252 					return (NULL);
1253 				}
1254 			}
1255 			break;
1256 		case EXT_RAW:
1257 			if (src->eo_item.ei_raw != NULL) {
1258 				dst->eo_item.ei_raw =
1259 				    ea_alloc(src->eo_item.ei_size);
1260 				if (dst->eo_item.ei_raw == NULL) {
1261 					ea_free_object(dst, EUP_ALLOC);
1262 					return (NULL);
1263 				}
1264 				bcopy(src->eo_item.ei_raw, dst->eo_item.ei_raw,
1265 				    (size_t)src->eo_item.ei_size);
1266 			}
1267 			break;
1268 		case EXT_EXACCT_OBJECT:
1269 			if (src->eo_item.ei_object != NULL) {
1270 				dst->eo_item.ei_object =
1271 				    ea_alloc(src->eo_item.ei_size);
1272 				if (dst->eo_item.ei_object == NULL) {
1273 					ea_free_object(dst, EUP_ALLOC);
1274 					return (NULL);
1275 				}
1276 				bcopy(src->eo_item.ei_raw, dst->eo_item.ei_raw,
1277 				    (size_t)src->eo_item.ei_size);
1278 			}
1279 			break;
1280 		default:
1281 			/* Other item types require no special handling. */
1282 			break;
1283 		}
1284 		break;
1285 	default:
1286 		ea_free_object(dst, EUP_ALLOC);
1287 		EXACCT_SET_ERR(EXR_INVALID_OBJ);
1288 		return (NULL);
1289 	}
1290 	EXACCT_SET_ERR(EXR_OK);
1291 	return (dst);
1292 }
1293 
1294 /*
1295  * Recursively copy a list of ea_object_t.  All the elements in the eo_next
1296  * list will be copied, and any group objects will be recursively copied.
1297  */
1298 ea_object_t *
1299 ea_copy_object_tree(const ea_object_t *src)
1300 {
1301 	ea_object_t *ret_obj, *dst, *last;
1302 
1303 	for (ret_obj = last = NULL; src != NULL;
1304 	    last = dst, src = src->eo_next) {
1305 
1306 		/* Allocate a new object and copy to it. */
1307 		if ((dst = ea_copy_object(src)) == NULL) {
1308 			ea_free_object(ret_obj, EUP_ALLOC);
1309 			return (NULL);
1310 		}
1311 
1312 		/* Groups need the object list copying. */
1313 		if (src->eo_type == EO_GROUP) {
1314 			dst->eo_group.eg_objs =
1315 			    ea_copy_object_tree(src->eo_group.eg_objs);
1316 			if (dst->eo_group.eg_objs == NULL) {
1317 				ea_free_object(ret_obj, EUP_ALLOC);
1318 				return (NULL);
1319 			}
1320 			dst->eo_group.eg_nobjs = src->eo_group.eg_nobjs;
1321 		}
1322 
1323 		/* Remember the list head the first time round. */
1324 		if (ret_obj == NULL) {
1325 			ret_obj = dst;
1326 		}
1327 
1328 		/* Link together if not at the list head. */
1329 		if (last != NULL) {
1330 			last->eo_next = dst;
1331 		}
1332 	}
1333 	EXACCT_SET_ERR(EXR_OK);
1334 	return (ret_obj);
1335 }
1336 
1337 /*
1338  * Read in the specified number of objects, returning the same data
1339  * structure that would have originally been passed to ea_write().
1340  */
1341 ea_object_t *
1342 ea_get_object_tree(ea_file_t *ef, uint32_t nobj)
1343 {
1344 	ea_object_t *first_obj, *prev_obj, *obj;
1345 
1346 	first_obj = prev_obj = NULL;
1347 	while (nobj--) {
1348 		/* Allocate space for the new object. */
1349 		obj = ea_alloc(sizeof (ea_object_t));
1350 		bzero(obj, sizeof (*obj));
1351 
1352 		/* Read it in. */
1353 		if (ea_get_object(ef, obj) == -1) {
1354 			ea_free(obj, sizeof (ea_object_t));
1355 			if (first_obj != NULL) {
1356 				ea_free_object(first_obj, EUP_ALLOC);
1357 			}
1358 			return (NULL);
1359 		}
1360 
1361 		/* Link it into the list. */
1362 		if (first_obj == NULL) {
1363 			first_obj = obj;
1364 		}
1365 		if (prev_obj != NULL) {
1366 			prev_obj->eo_next = obj;
1367 		}
1368 		prev_obj = obj;
1369 
1370 		/* Recurse if the object is a group with contents. */
1371 		if (obj->eo_type == EO_GROUP && obj->eo_group.eg_nobjs > 0) {
1372 			if ((obj->eo_group.eg_objs = ea_get_object_tree(ef,
1373 			    obj->eo_group.eg_nobjs)) == NULL) {
1374 				/* exacct_error set above. */
1375 				ea_free_object(first_obj, EUP_ALLOC);
1376 				return (NULL);
1377 			}
1378 		}
1379 	}
1380 	EXACCT_SET_ERR(EXR_OK);
1381 	return (first_obj);
1382 }
1383