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  * Copyright (c) 2011 by Delphix. All rights reserved.
27  */
28 /*
29  * Copyright (c) 2013, Joyent, Inc.  All rights reserved.
30  */
31 
32 /*
33  * DTrace print() action
34  *
35  * This file contains the post-processing logic for the print() action.  The
36  * print action behaves identically to trace() in that it generates a
37  * DTRACEACT_DIFEXPR action, but the action argument field refers to a CTF type
38  * string stored in the DOF string table (similar to printf formats).  We
39  * take the result of the trace action and post-process it in the fashion of
40  * MDB's ::print dcmd.
41  *
42  * This implementation differs from MDB's in the following ways:
43  *
44  *        - We do not expose any options or flags.  The behavior of print() is
45  *          equivalent to "::print -tn".
46  *
47  *        - MDB will display "holes" in structures (unused padding between
48  *          members).
49  *
50  *        - When printing arrays of structures, MDB will leave a trailing ','
51  *          after the last element.
52  *
53  *        - MDB will print time_t types as date and time.
54  *
55  *        - MDB will detect when an enum is actually the OR of several flags,
56  *          and print it out with the constituent flags separated.
57  *
58  *        - For large arrays, MDB will print the first few members and then
59  *          print a "..." continuation line.
60  *
61  *        - MDB will break and wrap arrays at 80 columns.
62  *
63  *        - MDB prints out floats and doubles by hand, as it must run in kmdb
64  *          context.  We're able to leverage the printf() format strings,
65  *          but the result is a slightly different format.
66  */
67 
68 #include <sys/sysmacros.h>
69 #include <strings.h>
70 #include <stdlib.h>
71 #include <alloca.h>
72 #include <assert.h>
73 #include <ctype.h>
74 #include <errno.h>
75 #include <limits.h>
76 #include <sys/socket.h>
77 #include <netdb.h>
78 #include <netinet/in.h>
79 #include <arpa/inet.h>
80 #include <arpa/nameser.h>
81 
82 #include <dt_module.h>
83 #include <dt_printf.h>
84 #include <dt_string.h>
85 #include <dt_impl.h>
86 
87 /* determines whether the given integer CTF encoding is a character */
88 #define   CTF_IS_CHAR(e) \
89           (((e).cte_format & (CTF_INT_CHAR | CTF_INT_SIGNED)) == \
90           (CTF_INT_CHAR | CTF_INT_SIGNED) && (e).cte_bits == NBBY)
91 /* determines whether the given CTF kind is a struct or union */
92 #define   CTF_IS_STRUCTLIKE(k) \
93           ((k) == CTF_K_STRUCT || (k) == CTF_K_UNION)
94 
95 /*
96  * Print structure passed down recursively through printing algorithm.
97  */
98 typedef struct dt_printarg {
99           dtrace_hdl_t        *pa_dtp;  /* libdtrace handle */
100           caddr_t             pa_addr;  /* base address of trace data */
101           ctf_file_t          *pa_ctfp; /* CTF container */
102           int                 pa_depth; /* member depth */
103           int                 pa_nest;  /* nested array depth */
104           FILE                *pa_file; /* output file */
105 } dt_printarg_t;
106 
107 static int dt_print_member(const char *, ctf_id_t, ulong_t, int, void *);
108 
109 /*
110  * Safe version of ctf_type_name() that will fall back to just "<ctfid>" if it
111  * can't resolve the type.
112  */
113 static void
dt_print_type_name(ctf_file_t * ctfp,ctf_id_t id,char * buf,size_t buflen)114 dt_print_type_name(ctf_file_t *ctfp, ctf_id_t id, char *buf, size_t buflen)
115 {
116           if (ctf_type_name(ctfp, id, buf, buflen) == NULL)
117                     (void) snprintf(buf, buflen, "<%ld>", id);
118 }
119 
120 /*
121  * Print any necessary trailing braces for structures or unions.  We don't get
122  * invoked when a struct or union ends, so we infer the need to print braces
123  * based on the depth the last time we printed something and the new depth.
124  */
125 static void
dt_print_trailing_braces(dt_printarg_t * pap,int depth)126 dt_print_trailing_braces(dt_printarg_t *pap, int depth)
127 {
128           int d;
129 
130           for (d = pap->pa_depth; d > depth; d--) {
131                     (void) fprintf(pap->pa_file, "%*s}%s",
132                         (d + pap->pa_nest - 1) * 4, "",
133                         d == depth + 1 ? "" : "\n");
134           }
135 }
136 
137 /*
138  * Print the appropriate amount of indentation given the current depth and
139  * array nesting.
140  */
141 static void
dt_print_indent(dt_printarg_t * pap)142 dt_print_indent(dt_printarg_t *pap)
143 {
144           (void) fprintf(pap->pa_file, "%*s",
145               (pap->pa_depth + pap->pa_nest) * 4, "");
146 }
147 
148 /*
149  * Print a bitfield.  It's worth noting that the D compiler support for
150  * bitfields is currently broken; printing "D`user_desc_t" (pulled in by the
151  * various D provider files) will produce incorrect results compared to
152  * "genunix`user_desc_t".
153  */
154 static void
print_bitfield(dt_printarg_t * pap,ulong_t off,ctf_encoding_t * ep)155 print_bitfield(dt_printarg_t *pap, ulong_t off, ctf_encoding_t *ep)
156 {
157           FILE *fp = pap->pa_file;
158           caddr_t addr = pap->pa_addr + off / NBBY;
159           uint64_t mask = (1ULL << ep->cte_bits) - 1;
160           uint64_t value = 0;
161           size_t size = (ep->cte_bits + (NBBY - 1)) / NBBY;
162           uint8_t *buf = (uint8_t *)&value;
163           uint8_t shift;
164 
165           /*
166            * On big-endian machines, we need to adjust the buf pointer to refer
167            * to the lowest 'size' bytes in 'value', and we need to shift based on
168            * the offset from the end of the data, not the offset of the start.
169            */
170 #if BYTE_ORDER == _BIG_ENDIAN
171           buf += sizeof (value) - size;
172           off += ep->cte_bits;
173 #endif
174           bcopy(addr, buf, size);
175           shift = off % NBBY;
176 
177           /*
178            * Offsets are counted from opposite ends on little- and
179            * big-endian machines.
180            */
181 #if BYTE_ORDER == _BIG_ENDIAN
182           shift = NBBY - shift;
183 #endif
184 
185           /*
186            * If the bits we want do not begin on a byte boundary, shift the data
187            * right so that the value is in the lowest 'cte_bits' of 'value'.
188            */
189           if (off % NBBY != 0)
190                     value >>= shift;
191           value &= mask;
192 
193           (void) fprintf(fp, "%#llx", (u_longlong_t)value);
194 }
195 
196 /*
197  * Dump the contents of memory as a fixed-size integer in hex.
198  */
199 static void
dt_print_hex(FILE * fp,caddr_t addr,size_t size)200 dt_print_hex(FILE *fp, caddr_t addr, size_t size)
201 {
202           switch (size) {
203           case sizeof (uint8_t):
204                     (void) fprintf(fp, "%#x", *(uint8_t *)addr);
205                     break;
206           case sizeof (uint16_t):
207                     /* LINTED - alignment */
208                     (void) fprintf(fp, "%#x", *(uint16_t *)addr);
209                     break;
210           case sizeof (uint32_t):
211                     /* LINTED - alignment */
212                     (void) fprintf(fp, "%#x", *(uint32_t *)addr);
213                     break;
214           case sizeof (uint64_t):
215                     (void) fprintf(fp, "%#llx",
216                         /* LINTED - alignment */
217                         (unsigned long long)*(uint64_t *)addr);
218                     break;
219           default:
220                     (void) fprintf(fp, "<invalid size %u>", (uint_t)size);
221           }
222 }
223 
224 /*
225  * Print an integer type.  Before dumping the contents via dt_print_hex(), we
226  * first check the encoding to see if it's part of a bitfield or a character.
227  */
228 static void
dt_print_int(ctf_id_t base,ulong_t off,dt_printarg_t * pap)229 dt_print_int(ctf_id_t base, ulong_t off, dt_printarg_t *pap)
230 {
231           FILE *fp = pap->pa_file;
232           ctf_file_t *ctfp = pap->pa_ctfp;
233           ctf_encoding_t e;
234           size_t size;
235           caddr_t addr = pap->pa_addr + off / NBBY;
236 
237           if (ctf_type_encoding(ctfp, base, &e) == CTF_ERR) {
238                     (void) fprintf(fp, "<unknown encoding>");
239                     return;
240           }
241 
242           /*
243            * This comes from MDB - it's not clear under what circumstances this
244            * would be found.
245            */
246           if (e.cte_format & CTF_INT_VARARGS) {
247                     (void) fprintf(fp, "...");
248                     return;
249           }
250 
251           /*
252            * We print this as a bitfield if the bit encoding indicates it's not
253            * an even power of two byte size, or is larger than 8 bytes.
254            */
255           size = e.cte_bits / NBBY;
256           if (size > 8 || (e.cte_bits % NBBY) != 0 || (size & (size - 1)) != 0) {
257                     print_bitfield(pap, off, &e);
258                     return;
259           }
260 
261           /*
262            * If this is a character, print it out as such.
263            */
264           if (CTF_IS_CHAR(e)) {
265                     char c = *(char *)addr;
266                     if (isprint((unsigned char)c))
267                               (void) fprintf(fp, "'%c'", c);
268                     else if (c == 0)
269                               (void) fprintf(fp, "'\\0'");
270                     else
271                               (void) fprintf(fp, "'\\%03o'", c);
272                     return;
273           }
274 
275           dt_print_hex(fp, addr, size);
276 }
277 
278 /*
279  * Print a floating point (float, double, long double) value.
280  */
281 /* ARGSUSED */
282 static void
dt_print_float(ctf_id_t base,ulong_t off,dt_printarg_t * pap)283 dt_print_float(ctf_id_t base, ulong_t off, dt_printarg_t *pap)
284 {
285           FILE *fp = pap->pa_file;
286           ctf_file_t *ctfp = pap->pa_ctfp;
287           ctf_encoding_t e;
288           caddr_t addr = pap->pa_addr + off / NBBY;
289 
290           if (ctf_type_encoding(ctfp, base, &e) == 0) {
291                     if (e.cte_format == CTF_FP_SINGLE &&
292                         e.cte_bits == sizeof (float) * NBBY) {
293                               /* LINTED - alignment */
294                               (void) fprintf(fp, "%+.7e", *((float *)addr));
295                     } else if (e.cte_format == CTF_FP_DOUBLE &&
296                         e.cte_bits == sizeof (double) * NBBY) {
297                               /* LINTED - alignment */
298                               (void) fprintf(fp, "%+.7e", *((double *)addr));
299                     } else if (e.cte_format == CTF_FP_LDOUBLE &&
300                         e.cte_bits == sizeof (long double) * NBBY) {
301                               /* LINTED - alignment */
302                               (void) fprintf(fp, "%+.16LE", *((long double *)addr));
303                     } else {
304                               (void) fprintf(fp, "<unknown encoding>");
305                     }
306           }
307 }
308 
309 /*
310  * A pointer is generally printed as a fixed-size integer.  If we have a
311  * function pointer, we try to look up its name.
312  */
313 static void
dt_print_ptr(ctf_id_t base,ulong_t off,dt_printarg_t * pap)314 dt_print_ptr(ctf_id_t base, ulong_t off, dt_printarg_t *pap)
315 {
316           FILE *fp = pap->pa_file;
317           ctf_file_t *ctfp = pap->pa_ctfp;
318           caddr_t addr = pap->pa_addr + off / NBBY;
319           size_t size = ctf_type_size(ctfp, base);
320           ctf_id_t bid = ctf_type_reference(ctfp, base);
321           uint64_t pc;
322           dtrace_syminfo_t dts;
323           GElf_Sym sym;
324 
325           if (bid == CTF_ERR || ctf_type_kind(ctfp, bid) != CTF_K_FUNCTION) {
326                     dt_print_hex(fp, addr, size);
327           } else {
328                     /* LINTED - alignment */
329                     pc = *((uint64_t *)addr);
330                     if (dtrace_lookup_by_addr(pap->pa_dtp, pc, &sym, &dts) != 0) {
331                               dt_print_hex(fp, addr, size);
332                     } else {
333                               (void) fprintf(fp, "%s`%s", dts.dts_object,
334                                   dts.dts_name);
335                     }
336           }
337 }
338 
339 /*
340  * Print out an array.  This is somewhat complex, as we must manually visit
341  * each member, and recursively invoke ctf_type_visit() for each member.  If
342  * the members are non-structs, then we print them out directly:
343  *
344  *        [ 0x14, 0x2e, 0 ]
345  *
346  * If they are structs, then we print out the necessary leading and trailing
347  * braces, to end up with:
348  *
349  *        [
350  *            type {
351  *            ...
352  *            },
353  *            type {
354  *            ...
355  *            }
356  *        ]
357  *
358  * We also use a heuristic to detect whether the array looks like a character
359  * array.  If the encoding indicates it's a character, and we have all
360  * printable characters followed by a null byte, then we display it as a
361  * string:
362  *
363  *        [ "string" ]
364  */
365 static void
dt_print_array(ctf_id_t base,ulong_t off,dt_printarg_t * pap)366 dt_print_array(ctf_id_t base, ulong_t off, dt_printarg_t *pap)
367 {
368           FILE *fp = pap->pa_file;
369           ctf_file_t *ctfp = pap->pa_ctfp;
370           caddr_t addr = pap->pa_addr + off / NBBY;
371           ctf_arinfo_t car;
372           ssize_t eltsize;
373           ctf_encoding_t e;
374           int i;
375           boolean_t isstring;
376           int kind;
377           ctf_id_t rtype;
378 
379           if (ctf_array_info(ctfp, base, &car) == CTF_ERR) {
380                     (void) fprintf(fp, "0x%p", (void *)addr);
381                     return;
382           }
383 
384           if ((eltsize = ctf_type_size(ctfp, car.ctr_contents)) < 0 ||
385               (rtype = ctf_type_resolve(ctfp, car.ctr_contents)) == CTF_ERR ||
386               (kind = ctf_type_kind(ctfp, rtype)) == CTF_ERR) {
387                     (void) fprintf(fp, "<invalid type %lu>", car.ctr_contents);
388                     return;
389           }
390 
391           /* see if this looks like a string */
392           isstring = B_FALSE;
393           if (kind == CTF_K_INTEGER &&
394               ctf_type_encoding(ctfp, rtype, &e) != CTF_ERR && CTF_IS_CHAR(e)) {
395                     char c;
396                     for (i = 0; i < car.ctr_nelems; i++) {
397                               c = *((char *)addr + eltsize * i);
398                               if (!isprint((unsigned char)c) || c == '\0')
399                                         break;
400                     }
401 
402                     if (i != car.ctr_nelems && c == '\0')
403                               isstring = B_TRUE;
404           }
405 
406           /*
407            * As a slight aesthetic optimization, if we are a top-level type, then
408            * don't bother printing out the brackets.  This lets print("foo") look
409            * like:
410            *
411            *        string "foo"
412            *
413            * As D will internally represent this as a char[256] array.
414            */
415           if (!isstring || pap->pa_depth != 0)
416                     (void) fprintf(fp, "[ ");
417 
418           if (isstring)
419                     (void) fprintf(fp, "\"");
420 
421           for (i = 0; i < car.ctr_nelems; i++) {
422                     if (isstring) {
423                               char c = *((char *)addr + eltsize * i);
424                               if (c == '\0')
425                                         break;
426                               (void) fprintf(fp, "%c", c);
427                     } else {
428                               /*
429                                * Recursively invoke ctf_type_visit() on each member.
430                                * We setup a new printarg struct with 'pa_nest' set to
431                                * indicate that we are within a nested array.
432                                */
433                               dt_printarg_t pa = *pap;
434                               pa.pa_nest += pap->pa_depth + 1;
435                               pa.pa_depth = 0;
436                               pa.pa_addr = addr + eltsize * i;
437                               (void) ctf_type_visit(ctfp, car.ctr_contents,
438                                   dt_print_member, &pa);
439 
440                               dt_print_trailing_braces(&pa, 0);
441                               if (i != car.ctr_nelems - 1)
442                                         (void) fprintf(fp, ", ");
443                               else if (CTF_IS_STRUCTLIKE(kind))
444                                         (void) fprintf(fp, "\n");
445                     }
446           }
447 
448           if (isstring)
449                     (void) fprintf(fp, "\"");
450 
451           if (!isstring || pap->pa_depth != 0) {
452                     if (CTF_IS_STRUCTLIKE(kind))
453                               dt_print_indent(pap);
454                     else
455                               (void) fprintf(fp, " ");
456                     (void) fprintf(fp, "]");
457           }
458 }
459 
460 /*
461  * This isued by both structs and unions to print the leading brace.
462  */
463 /* ARGSUSED */
464 static void
dt_print_structlike(ctf_id_t id,ulong_t off,dt_printarg_t * pap)465 dt_print_structlike(ctf_id_t id, ulong_t off, dt_printarg_t *pap)
466 {
467           (void) fprintf(pap->pa_file, "{");
468 }
469 
470 /*
471  * For enums, we try to print the enum name, and fall back to the value if it
472  * can't be determined.  We do not do any fancy flag processing like mdb.
473  */
474 /* ARGSUSED */
475 static void
dt_print_enum(ctf_id_t base,ulong_t off,dt_printarg_t * pap)476 dt_print_enum(ctf_id_t base, ulong_t off, dt_printarg_t *pap)
477 {
478           FILE *fp = pap->pa_file;
479           ctf_file_t *ctfp = pap->pa_ctfp;
480           const char *ename;
481           ssize_t size;
482           caddr_t addr = pap->pa_addr + off / NBBY;
483           int value = 0;
484 
485           /*
486            * The C standard says that an enum will be at most the sizeof (int).
487            * But if all the values are less than that, the compiler can use a
488            * smaller size. Thanks standards.
489            */
490           size = ctf_type_size(ctfp, base);
491           switch (size) {
492           case sizeof (uint8_t):
493                     value = *(uint8_t *)addr;
494                     break;
495           case sizeof (uint16_t):
496                     value = *(uint16_t *)addr;
497                     break;
498           case sizeof (int32_t):
499                     value = *(int32_t *)addr;
500                     break;
501           default:
502                     (void) fprintf(fp, "<invalid enum size %u>", (uint_t)size);
503                     return;
504           }
505 
506           if ((ename = ctf_enum_name(ctfp, base, value)) != NULL)
507                     (void) fprintf(fp, "%s", ename);
508           else
509                     (void) fprintf(fp, "%d", value);
510 }
511 
512 /*
513  * Forward declaration.  There's not much to do here without the complete
514  * type information, so just print out this fact and drive on.
515  */
516 /* ARGSUSED */
517 static void
dt_print_tag(ctf_id_t base,ulong_t off,dt_printarg_t * pap)518 dt_print_tag(ctf_id_t base, ulong_t off, dt_printarg_t *pap)
519 {
520           (void) fprintf(pap->pa_file, "<forward decl>");
521 }
522 
523 typedef void dt_printarg_f(ctf_id_t, ulong_t, dt_printarg_t *);
524 
525 static dt_printarg_f *const dt_printfuncs[] = {
526           dt_print_int,                 /* CTF_K_INTEGER */
527           dt_print_float,               /* CTF_K_FLOAT */
528           dt_print_ptr,                 /* CTF_K_POINTER */
529           dt_print_array,               /* CTF_K_ARRAY */
530           dt_print_ptr,                 /* CTF_K_FUNCTION */
531           dt_print_structlike,          /* CTF_K_STRUCT */
532           dt_print_structlike,          /* CTF_K_UNION */
533           dt_print_enum,                /* CTF_K_ENUM */
534           dt_print_tag                  /* CTF_K_FORWARD */
535 };
536 
537 /*
538  * Print one member of a structure.  This callback is invoked from
539  * ctf_type_visit() recursively.
540  */
541 static int
dt_print_member(const char * name,ctf_id_t id,ulong_t off,int depth,void * data)542 dt_print_member(const char *name, ctf_id_t id, ulong_t off, int depth,
543     void *data)
544 {
545           char type[DT_TYPE_NAMELEN];
546           int kind;
547           dt_printarg_t *pap = data;
548           FILE *fp = pap->pa_file;
549           ctf_file_t *ctfp = pap->pa_ctfp;
550           boolean_t arraymember;
551           boolean_t brief;
552           ctf_encoding_t e;
553           ctf_id_t rtype;
554 
555           dt_print_trailing_braces(pap, depth);
556           /*
557            * dt_print_trailing_braces() doesn't include the trailing newline; add
558            * it here if necessary.
559            */
560           if (depth < pap->pa_depth)
561                     (void) fprintf(fp, "\n");
562           pap->pa_depth = depth;
563 
564           if ((rtype = ctf_type_resolve(ctfp, id)) == CTF_ERR ||
565               (kind = ctf_type_kind(ctfp, rtype)) == CTF_ERR ||
566               kind < CTF_K_INTEGER || kind > CTF_K_FORWARD) {
567                     dt_print_indent(pap);
568                     (void) fprintf(fp, "%s = <invalid type %lu>", name, id);
569                     return (0);
570           }
571 
572           dt_print_type_name(ctfp, id, type, sizeof (type));
573 
574           arraymember = (pap->pa_nest != 0 && depth == 0);
575           brief = (arraymember && !CTF_IS_STRUCTLIKE(kind));
576 
577           if (!brief) {
578                     /*
579                      * If this is a direct array member and a struct (otherwise
580                      * brief would be true), then print a trailing newline, as the
581                      * array printing code doesn't include it because it might be a
582                      * simple type.
583                      */
584                     if (arraymember)
585                               (void) fprintf(fp, "\n");
586                     dt_print_indent(pap);
587 
588                     /* always print the type */
589                     (void) fprintf(fp, "%s", type);
590                     if (name[0] != '\0') {
591                               /*
592                                * For aesthetics, we don't include a space between the
593                                * type name and member name if the type is a pointer.
594                                * This will give us "void *foo =" instead of "void *
595                                * foo =".  Unions also have the odd behavior that the
596                                * type name is returned as "union ", with a trailing
597                                * space, so we also avoid printing a space if the type
598                                * name already ends with a space.
599                                */
600                               if (type[strlen(type) - 1] != '*' &&
601                                   type[strlen(type) -1] != ' ') {
602                                         (void) fprintf(fp, " ");
603                               }
604                               (void) fprintf(fp, "%s", name);
605 
606                               /*
607                                * If this looks like a bitfield, or is an integer not
608                                * aligned on a byte boundary, print the number of
609                                * bits after the name.
610                                */
611                               if (kind == CTF_K_INTEGER &&
612                                   ctf_type_encoding(ctfp, id, &e) == 0) {
613                                         ulong_t bits = e.cte_bits;
614                                         ulong_t size = bits / NBBY;
615 
616                                         if (bits % NBBY != 0 ||
617                                             off % NBBY != 0 ||
618                                             size > 8 ||
619                                             size != ctf_type_size(ctfp, id)) {
620                                                   (void) fprintf(fp, " :%lu", bits);
621                                         }
622                               }
623 
624                               (void) fprintf(fp, " =");
625                     }
626                     (void) fprintf(fp, " ");
627           }
628 
629           dt_printfuncs[kind - 1](rtype, off, pap);
630 
631           /* direct simple array members are not separated by newlines */
632           if (!brief)
633                     (void) fprintf(fp, "\n");
634 
635           return (0);
636 }
637 
638 /*
639  * Main print function invoked by dt_consume_cpu().
640  */
641 int
dtrace_print(dtrace_hdl_t * dtp,FILE * fp,const char * typename,caddr_t addr,size_t len)642 dtrace_print(dtrace_hdl_t *dtp, FILE *fp, const char *typename,
643     caddr_t addr, size_t len)
644 {
645           const char *s;
646           char *object;
647           dt_printarg_t pa;
648           ctf_id_t id;
649           dt_module_t *dmp;
650           ctf_file_t *ctfp;
651           int libid;
652 
653           /*
654            * Split the fully-qualified type ID (module`id).  This should
655            * always be the format, but if for some reason we don't find the
656            * expected value, return 0 to fall back to the generic trace()
657            * behavior. In the case of userland CTF modules this will actually be
658            * of the format (module`lib`id). This is due to the fact that those
659            * modules have multiple CTF containers which `lib` identifies.
660            */
661           for (s = typename; *s != '\0' && *s != '`'; s++)
662                     ;
663 
664           if (*s != '`')
665                     return (0);
666 
667           object = alloca(s - typename + 1);
668           bcopy(typename, object, s - typename);
669           object[s - typename] = '\0';
670           dmp = dt_module_lookup_by_name(dtp, object);
671           if (dmp == NULL)
672                     return (0);
673 
674           if (dmp->dm_pid != 0) {
675                     libid = atoi(s + 1);
676                     s = strchr(s + 1, '`');
677                     if (s == NULL || libid > dmp->dm_nctflibs)
678                               return (0);
679                     ctfp = dmp->dm_libctfp[libid];
680           } else {
681                     ctfp = dt_module_getctf(dtp, dmp);
682           }
683 
684           id = atoi(s + 1);
685 
686           /*
687            * Try to get the CTF kind for this id.  If something has gone horribly
688            * wrong and we can't resolve the ID, bail out and let trace() do the
689            * work.
690            */
691           if (ctfp == NULL || ctf_type_kind(ctfp, id) == CTF_ERR)
692                     return (0);
693 
694           /* setup the print structure and kick off the main print routine */
695           pa.pa_dtp = dtp;
696           pa.pa_addr = addr;
697           pa.pa_ctfp = ctfp;
698           pa.pa_nest = 0;
699           pa.pa_depth = 0;
700           pa.pa_file = fp;
701           (void) ctf_type_visit(pa.pa_ctfp, id, dt_print_member, &pa);
702 
703           dt_print_trailing_braces(&pa, 0);
704 
705           return (len);
706 }
707