1/* pb_decode.c -- decode a protobuf using minimal resources
2 *
3 * 2011 Petteri Aimonen <jpa@kapsi.fi>
4 */
5
6/* Use the GCC warn_unused_result attribute to check that all return values
7 * are propagated correctly. On other compilers and gcc before 3.4.0 just
8 * ignore the annotation.
9 */
10#if !defined(__GNUC__) || ( __GNUC__ < 3) || (__GNUC__ == 3 && __GNUC_MINOR__ < 4)
11    #define checkreturn
12#else
13    #define checkreturn __attribute__((warn_unused_result))
14#endif
15
16#include "pb.h"
17#include "pb_decode.h"
18
19/**************************************
20 * Declarations internal to this file *
21 **************************************/
22
23/* Iterator for pb_field_t list */
24typedef struct {
25    const pb_field_t *start; /* Start of the pb_field_t array */
26    const pb_field_t *pos; /* Current position of the iterator */
27    unsigned field_index; /* Zero-based index of the field. */
28    unsigned required_field_index; /* Zero-based index that counts only the required fields */
29    void *dest_struct; /* Pointer to the destination structure to decode to */
30    void *pData; /* Pointer where to store current field value */
31    void *pSize; /* Pointer where to store the size of current array field */
32} pb_field_iterator_t;
33
34typedef bool (*pb_decoder_t)(pb_istream_t *stream, const pb_field_t *field, void *dest) checkreturn;
35
36static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count);
37static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest);
38static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size);
39static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct);
40static bool pb_field_next(pb_field_iterator_t *iter);
41static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag);
42static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
43static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
44static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
45static bool checkreturn default_extension_decoder(pb_istream_t *stream, pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type);
46static bool checkreturn decode_extension(pb_istream_t *stream, uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter);
47static bool checkreturn find_extension_field(pb_field_iterator_t *iter);
48static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct);
49static bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest);
50static bool checkreturn pb_dec_uvarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
51static bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest);
52static bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest);
53static bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest);
54static bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest);
55static bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest);
56static bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest);
57static bool checkreturn pb_skip_varint(pb_istream_t *stream);
58static bool checkreturn pb_skip_string(pb_istream_t *stream);
59
60/* --- Function pointers to field decoders ---
61 * Order in the array must match pb_action_t LTYPE numbering.
62 */
63static const pb_decoder_t PB_DECODERS[PB_LTYPES_COUNT] = {
64    &pb_dec_varint,
65    &pb_dec_uvarint,
66    &pb_dec_svarint,
67    &pb_dec_fixed32,
68    &pb_dec_fixed64,
69
70    &pb_dec_bytes,
71    &pb_dec_string,
72    &pb_dec_submessage,
73    NULL /* extensions */
74};
75
76/*******************************
77 * pb_istream_t implementation *
78 *******************************/
79
80static bool checkreturn buf_read(pb_istream_t *stream, uint8_t *buf, size_t count)
81{
82    uint8_t *source = (uint8_t*)stream->state;
83    stream->state = source + count;
84
85    if (buf != NULL)
86    {
87        while (count--)
88            *buf++ = *source++;
89    }
90
91    return true;
92}
93
94bool checkreturn pb_read(pb_istream_t *stream, uint8_t *buf, size_t count)
95{
96#ifndef PB_BUFFER_ONLY
97	if (buf == NULL && stream->callback != buf_read)
98	{
99		/* Skip input bytes */
100		uint8_t tmp[16];
101		while (count > 16)
102		{
103			if (!pb_read(stream, tmp, 16))
104				return false;
105
106			count -= 16;
107		}
108
109		return pb_read(stream, tmp, count);
110	}
111#endif
112
113    if (stream->bytes_left < count)
114        PB_RETURN_ERROR(stream, "end-of-stream");
115
116#ifndef PB_BUFFER_ONLY
117    if (!stream->callback(stream, buf, count))
118        PB_RETURN_ERROR(stream, "io error");
119#else
120    if (!buf_read(stream, buf, count))
121        return false;
122#endif
123
124    stream->bytes_left -= count;
125    return true;
126}
127
128/* Read a single byte from input stream. buf may not be NULL.
129 * This is an optimization for the varint decoding. */
130static bool checkreturn pb_readbyte(pb_istream_t *stream, uint8_t *buf)
131{
132    if (stream->bytes_left == 0)
133        PB_RETURN_ERROR(stream, "end-of-stream");
134
135#ifndef PB_BUFFER_ONLY
136    if (!stream->callback(stream, buf, 1))
137        PB_RETURN_ERROR(stream, "io error");
138#else
139    *buf = *(uint8_t*)stream->state;
140    stream->state = (uint8_t*)stream->state + 1;
141#endif
142
143    stream->bytes_left--;
144
145    return true;
146}
147
148pb_istream_t pb_istream_from_buffer(uint8_t *buf, size_t bufsize)
149{
150    pb_istream_t stream;
151#ifdef PB_BUFFER_ONLY
152    stream.callback = NULL;
153#else
154    stream.callback = &buf_read;
155#endif
156    stream.state = buf;
157    stream.bytes_left = bufsize;
158#ifndef PB_NO_ERRMSG
159    stream.errmsg = NULL;
160#endif
161    return stream;
162}
163
164/********************
165 * Helper functions *
166 ********************/
167
168static bool checkreturn pb_decode_varint32(pb_istream_t *stream, uint32_t *dest)
169{
170    uint8_t byte;
171    uint32_t result;
172
173    if (!pb_readbyte(stream, &byte))
174        return false;
175
176    if ((byte & 0x80) == 0)
177    {
178        /* Quick case, 1 byte value */
179        result = byte;
180    }
181    else
182    {
183        /* Multibyte case */
184        uint8_t bitpos = 7;
185        result = byte & 0x7F;
186
187        do
188        {
189            if (bitpos >= 32)
190                PB_RETURN_ERROR(stream, "varint overflow");
191
192            if (!pb_readbyte(stream, &byte))
193                return false;
194
195            result |= (uint32_t)(byte & 0x7F) << bitpos;
196            bitpos = (uint8_t)(bitpos + 7);
197        } while (byte & 0x80);
198   }
199
200   *dest = result;
201   return true;
202}
203
204bool checkreturn pb_decode_varint(pb_istream_t *stream, uint64_t *dest)
205{
206    uint8_t byte;
207    uint8_t bitpos = 0;
208    uint64_t result = 0;
209
210    do
211    {
212        if (bitpos >= 64)
213            PB_RETURN_ERROR(stream, "varint overflow");
214
215        if (!pb_readbyte(stream, &byte))
216            return false;
217
218        result |= (uint64_t)(byte & 0x7F) << bitpos;
219        bitpos = (uint8_t)(bitpos + 7);
220    } while (byte & 0x80);
221
222    *dest = result;
223    return true;
224}
225
226bool checkreturn pb_skip_varint(pb_istream_t *stream)
227{
228    uint8_t byte;
229    do
230    {
231        if (!pb_read(stream, &byte, 1))
232            return false;
233    } while (byte & 0x80);
234    return true;
235}
236
237bool checkreturn pb_skip_string(pb_istream_t *stream)
238{
239    uint32_t length;
240    if (!pb_decode_varint32(stream, &length))
241        return false;
242
243    return pb_read(stream, NULL, length);
244}
245
246bool checkreturn pb_decode_tag(pb_istream_t *stream, pb_wire_type_t *wire_type, uint32_t *tag, bool *eof)
247{
248    uint32_t temp;
249    *eof = false;
250    *wire_type = (pb_wire_type_t) 0;
251    *tag = 0;
252
253    if (!pb_decode_varint32(stream, &temp))
254    {
255        if (stream->bytes_left == 0)
256            *eof = true;
257
258        return false;
259    }
260
261    if (temp == 0)
262    {
263        *eof = true; /* Special feature: allow 0-terminated messages. */
264        return false;
265    }
266
267    *tag = temp >> 3;
268    *wire_type = (pb_wire_type_t)(temp & 7);
269    return true;
270}
271
272bool checkreturn pb_skip_field(pb_istream_t *stream, pb_wire_type_t wire_type)
273{
274    switch (wire_type)
275    {
276        case PB_WT_VARINT: return pb_skip_varint(stream);
277        case PB_WT_64BIT: return pb_read(stream, NULL, 8);
278        case PB_WT_STRING: return pb_skip_string(stream);
279        case PB_WT_32BIT: return pb_read(stream, NULL, 4);
280        default: PB_RETURN_ERROR(stream, "invalid wire_type");
281    }
282}
283
284/* Read a raw value to buffer, for the purpose of passing it to callback as
285 * a substream. Size is maximum size on call, and actual size on return.
286 */
287static bool checkreturn read_raw_value(pb_istream_t *stream, pb_wire_type_t wire_type, uint8_t *buf, size_t *size)
288{
289    size_t max_size = *size;
290    switch (wire_type)
291    {
292        case PB_WT_VARINT:
293            *size = 0;
294            do
295            {
296                (*size)++;
297                if (*size > max_size) return false;
298                if (!pb_read(stream, buf, 1)) return false;
299            } while (*buf++ & 0x80);
300            return true;
301
302        case PB_WT_64BIT:
303            *size = 8;
304            return pb_read(stream, buf, 8);
305
306        case PB_WT_32BIT:
307            *size = 4;
308            return pb_read(stream, buf, 4);
309
310        default: PB_RETURN_ERROR(stream, "invalid wire_type");
311    }
312}
313
314/* Decode string length from stream and return a substream with limited length.
315 * Remember to close the substream using pb_close_string_substream().
316 */
317bool checkreturn pb_make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
318{
319    uint32_t size;
320    if (!pb_decode_varint32(stream, &size))
321        return false;
322
323    *substream = *stream;
324    if (substream->bytes_left < size)
325        PB_RETURN_ERROR(stream, "parent stream too short");
326
327    substream->bytes_left = size;
328    stream->bytes_left -= size;
329    return true;
330}
331
332void pb_close_string_substream(pb_istream_t *stream, pb_istream_t *substream)
333{
334    stream->state = substream->state;
335
336#ifndef PB_NO_ERRMSG
337    stream->errmsg = substream->errmsg;
338#endif
339}
340
341static void pb_field_init(pb_field_iterator_t *iter, const pb_field_t *fields, void *dest_struct)
342{
343    iter->start = iter->pos = fields;
344    iter->field_index = 0;
345    iter->required_field_index = 0;
346    iter->pData = (char*)dest_struct + iter->pos->data_offset;
347    iter->pSize = (char*)iter->pData + iter->pos->size_offset;
348    iter->dest_struct = dest_struct;
349}
350
351static bool pb_field_next(pb_field_iterator_t *iter)
352{
353    bool notwrapped = true;
354    size_t prev_size = iter->pos->data_size;
355
356    if (PB_ATYPE(iter->pos->type) == PB_ATYPE_STATIC &&
357        PB_HTYPE(iter->pos->type) == PB_HTYPE_REPEATED)
358    {
359        prev_size *= iter->pos->array_size;
360    }
361    else if (PB_ATYPE(iter->pos->type) == PB_ATYPE_POINTER)
362    {
363        prev_size = sizeof(void*);
364    }
365
366    if (iter->pos->tag == 0)
367        return false; /* Only happens with empty message types */
368
369    if (PB_HTYPE(iter->pos->type) == PB_HTYPE_REQUIRED)
370        iter->required_field_index++;
371
372    iter->pos++;
373    iter->field_index++;
374    if (iter->pos->tag == 0)
375    {
376        iter->pos = iter->start;
377        iter->field_index = 0;
378        iter->required_field_index = 0;
379        iter->pData = iter->dest_struct;
380        prev_size = 0;
381        notwrapped = false;
382    }
383
384    iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
385    iter->pSize = (char*)iter->pData + iter->pos->size_offset;
386    return notwrapped;
387}
388
389static bool checkreturn pb_field_find(pb_field_iterator_t *iter, uint32_t tag)
390{
391    unsigned start = iter->field_index;
392
393    do {
394        if (iter->pos->tag == tag &&
395            PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
396        {
397            return true;
398        }
399        (void)pb_field_next(iter);
400    } while (iter->field_index != start);
401
402    return false;
403}
404
405/*************************
406 * Decode a single field *
407 *************************/
408
409static bool checkreturn decode_static_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
410{
411    pb_type_t type;
412    pb_decoder_t func;
413
414    type = iter->pos->type;
415    func = PB_DECODERS[PB_LTYPE(type)];
416
417    switch (PB_HTYPE(type))
418    {
419        case PB_HTYPE_REQUIRED:
420            return func(stream, iter->pos, iter->pData);
421
422        case PB_HTYPE_OPTIONAL:
423            *(bool*)iter->pSize = true;
424            return func(stream, iter->pos, iter->pData);
425
426        case PB_HTYPE_REPEATED:
427            if (wire_type == PB_WT_STRING
428                && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
429            {
430                /* Packed array */
431                bool status = true;
432                size_t *size = (size_t*)iter->pSize;
433                pb_istream_t substream;
434                if (!pb_make_string_substream(stream, &substream))
435                    return false;
436
437                while (substream.bytes_left > 0 && *size < iter->pos->array_size)
438                {
439                    void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
440                    if (!func(&substream, iter->pos, pItem))
441                    {
442                        status = false;
443                        break;
444                    }
445                    (*size)++;
446                }
447                pb_close_string_substream(stream, &substream);
448
449                if (substream.bytes_left != 0)
450                    PB_RETURN_ERROR(stream, "array overflow");
451
452                return status;
453            }
454            else
455            {
456                /* Repeated field */
457                size_t *size = (size_t*)iter->pSize;
458                void *pItem = (uint8_t*)iter->pData + iter->pos->data_size * (*size);
459                if (*size >= iter->pos->array_size)
460                    PB_RETURN_ERROR(stream, "array overflow");
461
462                (*size)++;
463                return func(stream, iter->pos, pItem);
464            }
465
466        default:
467            PB_RETURN_ERROR(stream, "invalid field type");
468    }
469}
470
471#ifdef PB_ENABLE_MALLOC
472/* Allocate storage for the field and store the pointer at iter->pData.
473 * array_size is the number of entries to reserve in an array. */
474static bool checkreturn allocate_field(pb_istream_t *stream, void *pData, size_t data_size, size_t array_size)
475{
476    void *ptr = *(void**)pData;
477    size_t size = array_size * data_size;
478
479    /* Allocate new or expand previous allocation */
480    /* Note: on failure the old pointer will remain in the structure,
481     * the message must be freed by caller also on error return. */
482    ptr = pb_realloc(ptr, size);
483    if (ptr == NULL)
484        PB_RETURN_ERROR(stream, "realloc failed");
485
486    *(void**)pData = ptr;
487    return true;
488}
489
490/* Clear a newly allocated item in case it contains a pointer, or is a submessage. */
491static void initialize_pointer_field(void *pItem, pb_field_iterator_t *iter)
492{
493    if (PB_LTYPE(iter->pos->type) == PB_LTYPE_STRING ||
494        PB_LTYPE(iter->pos->type) == PB_LTYPE_BYTES)
495    {
496        *(void**)pItem = NULL;
497    }
498    else if (PB_LTYPE(iter->pos->type) == PB_LTYPE_SUBMESSAGE)
499    {
500        pb_message_set_to_defaults((const pb_field_t *) iter->pos->ptr, pItem);
501    }
502}
503#endif
504
505static bool checkreturn decode_pointer_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
506{
507#ifndef PB_ENABLE_MALLOC
508    UNUSED(wire_type);
509    UNUSED(iter);
510    PB_RETURN_ERROR(stream, "no malloc support");
511#else
512    pb_type_t type;
513    pb_decoder_t func;
514
515    type = iter->pos->type;
516    func = PB_DECODERS[PB_LTYPE(type)];
517
518    switch (PB_HTYPE(type))
519    {
520        case PB_HTYPE_REQUIRED:
521        case PB_HTYPE_OPTIONAL:
522            if (PB_LTYPE(type) == PB_LTYPE_STRING ||
523                PB_LTYPE(type) == PB_LTYPE_BYTES)
524            {
525                return func(stream, iter->pos, iter->pData);
526            }
527            else
528            {
529                if (!allocate_field(stream, iter->pData, iter->pos->data_size, 1))
530                    return false;
531
532                initialize_pointer_field(*(void**)iter->pData, iter);
533                return func(stream, iter->pos, *(void**)iter->pData);
534            }
535
536        case PB_HTYPE_REPEATED:
537            if (wire_type == PB_WT_STRING
538                && PB_LTYPE(type) <= PB_LTYPE_LAST_PACKABLE)
539            {
540                /* Packed array, multiple items come in at once. */
541                bool status = true;
542                size_t *size = (size_t*)iter->pSize;
543                size_t allocated_size = *size;
544                void *pItem;
545                pb_istream_t substream;
546
547                if (!pb_make_string_substream(stream, &substream))
548                    return false;
549
550                while (substream.bytes_left)
551                {
552                    if (*size + 1 > allocated_size)
553                    {
554                        /* Allocate more storage. This tries to guess the
555                         * number of remaining entries. Round the division
556                         * upwards. */
557                        allocated_size += (substream.bytes_left - 1) / iter->pos->data_size + 1;
558
559                        if (!allocate_field(&substream, iter->pData, iter->pos->data_size, allocated_size))
560                        {
561                            status = false;
562                            break;
563                        }
564                    }
565
566                    /* Decode the array entry */
567                    pItem = *(uint8_t**)iter->pData + iter->pos->data_size * (*size);
568                    initialize_pointer_field(pItem, iter);
569                    if (!func(&substream, iter->pos, pItem))
570                    {
571                        status = false;
572                        break;
573                    }
574                    (*size)++;
575                }
576                pb_close_string_substream(stream, &substream);
577
578                return status;
579            }
580            else
581            {
582                /* Normal repeated field, i.e. only one item at a time. */
583                size_t *size = (size_t*)iter->pSize;
584                void *pItem;
585
586                (*size)++;
587                if (!allocate_field(stream, iter->pData, iter->pos->data_size, *size))
588                    return false;
589
590                pItem = *(uint8_t**)iter->pData + iter->pos->data_size * (*size - 1);
591                initialize_pointer_field(pItem, iter);
592                return func(stream, iter->pos, pItem);
593            }
594
595        default:
596            PB_RETURN_ERROR(stream, "invalid field type");
597    }
598#endif
599}
600
601static bool checkreturn decode_callback_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
602{
603    pb_callback_t *pCallback = (pb_callback_t*)iter->pData;
604
605#ifdef PB_OLD_CALLBACK_STYLE
606    void *arg = pCallback->arg;
607#else
608    void **arg = &(pCallback->arg);
609#endif
610
611    if (pCallback->funcs.decode == NULL)
612        return pb_skip_field(stream, wire_type);
613
614    if (wire_type == PB_WT_STRING)
615    {
616        pb_istream_t substream;
617
618        if (!pb_make_string_substream(stream, &substream))
619            return false;
620
621        do
622        {
623            if (!pCallback->funcs.decode(&substream, iter->pos, arg))
624                PB_RETURN_ERROR(stream, "callback failed");
625        } while (substream.bytes_left);
626
627        pb_close_string_substream(stream, &substream);
628        return true;
629    }
630    else
631    {
632        /* Copy the single scalar value to stack.
633         * This is required so that we can limit the stream length,
634         * which in turn allows to use same callback for packed and
635         * not-packed fields. */
636        pb_istream_t substream;
637        uint8_t buffer[10];
638        size_t size = sizeof(buffer);
639
640        if (!read_raw_value(stream, wire_type, buffer, &size))
641            return false;
642        substream = pb_istream_from_buffer(buffer, size);
643
644        return pCallback->funcs.decode(&substream, iter->pos, arg);
645    }
646}
647
648static bool checkreturn decode_field(pb_istream_t *stream, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
649{
650    switch (PB_ATYPE(iter->pos->type))
651    {
652        case PB_ATYPE_STATIC:
653            return decode_static_field(stream, wire_type, iter);
654
655        case PB_ATYPE_POINTER:
656            return decode_pointer_field(stream, wire_type, iter);
657
658        case PB_ATYPE_CALLBACK:
659            return decode_callback_field(stream, wire_type, iter);
660
661        default:
662            PB_RETURN_ERROR(stream, "invalid field type");
663    }
664}
665
666/* Default handler for extension fields. Expects a pb_field_t structure
667 * in extension->type->arg. */
668static bool checkreturn default_extension_decoder(pb_istream_t *stream,
669    pb_extension_t *extension, uint32_t tag, pb_wire_type_t wire_type)
670{
671    const pb_field_t *field = (const pb_field_t*)extension->type->arg;
672    pb_field_iterator_t iter;
673
674    if (field->tag != tag)
675        return true;
676
677    iter.start = field;
678    iter.pos = field;
679    iter.field_index = 0;
680    iter.required_field_index = 0;
681    iter.dest_struct = extension->dest;
682    iter.pData = extension->dest;
683    iter.pSize = &extension->found;
684
685    return decode_field(stream, wire_type, &iter);
686}
687
688/* Try to decode an unknown field as an extension field. Tries each extension
689 * decoder in turn, until one of them handles the field or loop ends. */
690static bool checkreturn decode_extension(pb_istream_t *stream,
691    uint32_t tag, pb_wire_type_t wire_type, pb_field_iterator_t *iter)
692{
693    pb_extension_t *extension = *(pb_extension_t* const *)iter->pData;
694    size_t pos = stream->bytes_left;
695
696    while (extension != NULL && pos == stream->bytes_left)
697    {
698        bool status;
699        if (extension->type->decode)
700            status = extension->type->decode(stream, extension, tag, wire_type);
701        else
702            status = default_extension_decoder(stream, extension, tag, wire_type);
703
704        if (!status)
705            return false;
706
707        extension = extension->next;
708    }
709
710    return true;
711}
712
713/* Step through the iterator until an extension field is found or until all
714 * entries have been checked. There can be only one extension field per
715 * message. Returns false if no extension field is found. */
716static bool checkreturn find_extension_field(pb_field_iterator_t *iter)
717{
718    unsigned start = iter->field_index;
719
720    do {
721        if (PB_LTYPE(iter->pos->type) == PB_LTYPE_EXTENSION)
722            return true;
723        (void)pb_field_next(iter);
724    } while (iter->field_index != start);
725
726    return false;
727}
728
729/* Initialize message fields to default values, recursively */
730static void pb_message_set_to_defaults(const pb_field_t fields[], void *dest_struct)
731{
732    pb_field_iterator_t iter;
733    pb_field_init(&iter, fields, dest_struct);
734
735    do
736    {
737        pb_type_t type;
738        type = iter.pos->type;
739
740        /* Avoid crash on empty message types (zero fields) */
741        if (iter.pos->tag == 0)
742            continue;
743
744        if (PB_ATYPE(type) == PB_ATYPE_STATIC)
745        {
746            if (PB_HTYPE(type) == PB_HTYPE_OPTIONAL)
747            {
748                /* Set has_field to false. Still initialize the optional field
749                 * itself also. */
750                *(bool*)iter.pSize = false;
751            }
752            else if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
753            {
754                /* Set array count to 0, no need to initialize contents. */
755                *(size_t*)iter.pSize = 0;
756                continue;
757            }
758
759            if (PB_LTYPE(iter.pos->type) == PB_LTYPE_SUBMESSAGE)
760            {
761                /* Initialize submessage to defaults */
762                pb_message_set_to_defaults((const pb_field_t *) iter.pos->ptr, iter.pData);
763            }
764            else if (iter.pos->ptr != NULL)
765            {
766                /* Initialize to default value */
767                memcpy(iter.pData, iter.pos->ptr, iter.pos->data_size);
768            }
769            else
770            {
771                /* Initialize to zeros */
772                memset(iter.pData, 0, iter.pos->data_size);
773            }
774        }
775        else if (PB_ATYPE(type) == PB_ATYPE_POINTER)
776        {
777            /* Initialize the pointer to NULL. */
778            *(void**)iter.pData = NULL;
779
780            /* Initialize array count to 0. */
781            if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
782            {
783                *(size_t*)iter.pSize = 0;
784            }
785        }
786        else if (PB_ATYPE(type) == PB_ATYPE_CALLBACK)
787        {
788            /* Don't overwrite callback */
789        }
790    } while (pb_field_next(&iter));
791}
792
793/*********************
794 * Decode all fields *
795 *********************/
796
797bool checkreturn pb_decode_noinit(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
798{
799    uint8_t fields_seen[(PB_MAX_REQUIRED_FIELDS + 7) / 8] = {0, 0, 0, 0, 0, 0, 0, 0};
800    uint32_t extension_range_start = 0;
801    pb_field_iterator_t iter;
802
803    pb_field_init(&iter, fields, dest_struct);
804
805    while (stream->bytes_left)
806    {
807        uint32_t tag;
808        pb_wire_type_t wire_type;
809        bool eof;
810
811        if (!pb_decode_tag(stream, &wire_type, &tag, &eof))
812        {
813            if (eof)
814                break;
815            else
816                return false;
817        }
818
819        if (!pb_field_find(&iter, tag))
820        {
821            /* No match found, check if it matches an extension. */
822            if (tag >= extension_range_start)
823            {
824                if (!find_extension_field(&iter))
825                    extension_range_start = (uint32_t)-1;
826                else
827                    extension_range_start = iter.pos->tag;
828
829                if (tag >= extension_range_start)
830                {
831                    size_t pos = stream->bytes_left;
832
833                    if (!decode_extension(stream, tag, wire_type, &iter))
834                        return false;
835
836                    if (pos != stream->bytes_left)
837                    {
838                        /* The field was handled */
839                        continue;
840                    }
841                }
842            }
843
844            /* No match found, skip data */
845            if (!pb_skip_field(stream, wire_type))
846                return false;
847            continue;
848        }
849
850        if (PB_HTYPE(iter.pos->type) == PB_HTYPE_REQUIRED
851            && iter.required_field_index < PB_MAX_REQUIRED_FIELDS)
852        {
853            fields_seen[iter.required_field_index >> 3] |= (uint8_t)(1 << (iter.required_field_index & 7));
854        }
855
856        if (!decode_field(stream, wire_type, &iter))
857            return false;
858    }
859
860    /* Check that all required fields were present. */
861    {
862        /* First figure out the number of required fields by
863         * seeking to the end of the field array. Usually we
864         * are already close to end after decoding.
865         */
866        unsigned req_field_count;
867        pb_type_t last_type;
868        unsigned i;
869        do {
870            req_field_count = iter.required_field_index;
871            last_type = iter.pos->type;
872        } while (pb_field_next(&iter));
873
874        /* Fixup if last field was also required. */
875        if (PB_HTYPE(last_type) == PB_HTYPE_REQUIRED && iter.pos->tag != 0)
876            req_field_count++;
877
878        /* Check the whole bytes */
879        for (i = 0; i < (req_field_count >> 3); i++)
880        {
881            if (fields_seen[i] != 0xFF)
882                PB_RETURN_ERROR(stream, "missing required field");
883        }
884
885        /* Check the remaining bits */
886        if (fields_seen[req_field_count >> 3] != (0xFF >> (8 - (req_field_count & 7))))
887            PB_RETURN_ERROR(stream, "missing required field");
888    }
889
890    return true;
891}
892
893bool checkreturn pb_decode(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
894{
895    bool status;
896    pb_message_set_to_defaults(fields, dest_struct);
897    status = pb_decode_noinit(stream, fields, dest_struct);
898
899#ifdef PB_ENABLE_MALLOC
900    if (!status)
901        pb_release(fields, dest_struct);
902#endif
903
904    return status;
905}
906
907bool pb_decode_delimited(pb_istream_t *stream, const pb_field_t fields[], void *dest_struct)
908{
909    pb_istream_t substream;
910    bool status;
911
912    if (!pb_make_string_substream(stream, &substream))
913        return false;
914
915    status = pb_decode(&substream, fields, dest_struct);
916    pb_close_string_substream(stream, &substream);
917    return status;
918}
919
920#ifdef PB_ENABLE_MALLOC
921void pb_release(const pb_field_t fields[], void *dest_struct)
922{
923    pb_field_iterator_t iter;
924    pb_field_init(&iter, fields, dest_struct);
925
926    do
927    {
928        pb_type_t type;
929        type = iter.pos->type;
930
931        /* Avoid crash on empty message types (zero fields) */
932        if (iter.pos->tag == 0)
933            continue;
934
935        if (PB_ATYPE(type) == PB_ATYPE_POINTER)
936        {
937            if (PB_HTYPE(type) == PB_HTYPE_REPEATED &&
938                (PB_LTYPE(type) == PB_LTYPE_STRING ||
939                 PB_LTYPE(type) == PB_LTYPE_BYTES))
940            {
941                /* Release entries in repeated string or bytes array */
942                void **pItem = *(void***)iter.pData;
943                size_t count = *(size_t*)iter.pSize;
944                while (count--)
945                {
946                    pb_free(*pItem);
947                    *pItem++ = NULL;
948                }
949            }
950            else if (PB_LTYPE(type) == PB_LTYPE_SUBMESSAGE)
951            {
952                /* Release fields in submessages */
953                void *pItem = *(void**)iter.pData;
954                size_t count = (pItem ? 1 : 0);
955
956                if (PB_HTYPE(type) == PB_HTYPE_REPEATED)
957                {
958                    count = *(size_t*)iter.pSize;
959                }
960
961                while (count--)
962                {
963                    pb_release((const pb_field_t*)iter.pos->ptr, pItem);
964                    pItem = (uint8_t*)pItem + iter.pos->data_size;
965                }
966            }
967
968            /* Release main item */
969            pb_free(*(void**)iter.pData);
970            *(void**)iter.pData = NULL;
971        }
972    } while (pb_field_next(&iter));
973}
974#endif
975
976/* Field decoders */
977
978bool pb_decode_svarint(pb_istream_t *stream, int64_t *dest)
979{
980    uint64_t value;
981    if (!pb_decode_varint(stream, &value))
982        return false;
983
984    if (value & 1)
985        *dest = (int64_t)(~(value >> 1));
986    else
987        *dest = (int64_t)(value >> 1);
988
989    return true;
990}
991
992bool pb_decode_fixed32(pb_istream_t *stream, void *dest)
993{
994    #ifdef __BIG_ENDIAN__
995    uint8_t *bytes = (uint8_t*)dest;
996    uint8_t lebytes[4];
997
998    if (!pb_read(stream, lebytes, 4))
999        return false;
1000
1001    bytes[0] = lebytes[3];
1002    bytes[1] = lebytes[2];
1003    bytes[2] = lebytes[1];
1004    bytes[3] = lebytes[0];
1005    return true;
1006    #else
1007    return pb_read(stream, (uint8_t*)dest, 4);
1008    #endif
1009}
1010
1011bool pb_decode_fixed64(pb_istream_t *stream, void *dest)
1012{
1013    #ifdef __BIG_ENDIAN__
1014    uint8_t *bytes = (uint8_t*)dest;
1015    uint8_t lebytes[8];
1016
1017    if (!pb_read(stream, lebytes, 8))
1018        return false;
1019
1020    bytes[0] = lebytes[7];
1021    bytes[1] = lebytes[6];
1022    bytes[2] = lebytes[5];
1023    bytes[3] = lebytes[4];
1024    bytes[4] = lebytes[3];
1025    bytes[5] = lebytes[2];
1026    bytes[6] = lebytes[1];
1027    bytes[7] = lebytes[0];
1028    return true;
1029    #else
1030    return pb_read(stream, (uint8_t*)dest, 8);
1031    #endif
1032}
1033
1034static bool checkreturn pb_dec_varint(pb_istream_t *stream, const pb_field_t *field, void *dest)
1035{
1036    uint64_t value;
1037    if (!pb_decode_varint(stream, &value))
1038        return false;
1039
1040    switch (field->data_size)
1041    {
1042        case 1: *(int8_t*)dest = (int8_t)value; break;
1043        case 2: *(int16_t*)dest = (int16_t)value; break;
1044        case 4: *(int32_t*)dest = (int32_t)value; break;
1045        case 8: *(int64_t*)dest = (int64_t)value; break;
1046        default: PB_RETURN_ERROR(stream, "invalid data_size");
1047    }
1048
1049    return true;
1050}
1051
1052static bool checkreturn pb_dec_uvarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
1053{
1054    uint64_t value;
1055    if (!pb_decode_varint(stream, &value))
1056        return false;
1057
1058    switch (field->data_size)
1059    {
1060        case 4: *(uint32_t*)dest = (uint32_t)value; break;
1061        case 8: *(uint64_t*)dest = value; break;
1062        default: PB_RETURN_ERROR(stream, "invalid data_size");
1063    }
1064
1065    return true;
1066}
1067
1068static bool checkreturn pb_dec_svarint(pb_istream_t *stream, const pb_field_t *field, void *dest)
1069{
1070    int64_t value;
1071    if (!pb_decode_svarint(stream, &value))
1072        return false;
1073
1074    switch (field->data_size)
1075    {
1076        case 4: *(int32_t*)dest = (int32_t)value; break;
1077        case 8: *(int64_t*)dest = value; break;
1078        default: PB_RETURN_ERROR(stream, "invalid data_size");
1079    }
1080
1081    return true;
1082}
1083
1084static bool checkreturn pb_dec_fixed32(pb_istream_t *stream, const pb_field_t *field, void *dest)
1085{
1086    UNUSED(field);
1087    return pb_decode_fixed32(stream, dest);
1088}
1089
1090static bool checkreturn pb_dec_fixed64(pb_istream_t *stream, const pb_field_t *field, void *dest)
1091{
1092    UNUSED(field);
1093    return pb_decode_fixed64(stream, dest);
1094}
1095
1096static bool checkreturn pb_dec_bytes(pb_istream_t *stream, const pb_field_t *field, void *dest)
1097{
1098    uint32_t size;
1099    pb_bytes_array_t *bdest;
1100
1101    if (!pb_decode_varint32(stream, &size))
1102        return false;
1103
1104    if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
1105    {
1106#ifndef PB_ENABLE_MALLOC
1107        PB_RETURN_ERROR(stream, "no malloc support");
1108#else
1109        if (!allocate_field(stream, dest, PB_BYTES_ARRAY_T_ALLOCSIZE(size), 1))
1110            return false;
1111        bdest = *(pb_bytes_array_t**)dest;
1112#endif
1113    }
1114    else
1115    {
1116        if (PB_BYTES_ARRAY_T_ALLOCSIZE(size) > field->data_size)
1117            PB_RETURN_ERROR(stream, "bytes overflow");
1118        bdest = (pb_bytes_array_t*)dest;
1119    }
1120
1121    bdest->size = size;
1122    return pb_read(stream, bdest->bytes, size);
1123}
1124
1125static bool checkreturn pb_dec_string(pb_istream_t *stream, const pb_field_t *field, void *dest)
1126{
1127    uint32_t size;
1128    size_t alloc_size;
1129    bool status;
1130    if (!pb_decode_varint32(stream, &size))
1131        return false;
1132
1133    /* Space for null terminator */
1134    alloc_size = size + 1;
1135
1136    if (PB_ATYPE(field->type) == PB_ATYPE_POINTER)
1137    {
1138#ifndef PB_ENABLE_MALLOC
1139        PB_RETURN_ERROR(stream, "no malloc support");
1140#else
1141        if (!allocate_field(stream, dest, alloc_size, 1))
1142            return false;
1143        dest = *(void**)dest;
1144#endif
1145    }
1146    else
1147    {
1148        if (alloc_size > field->data_size)
1149            PB_RETURN_ERROR(stream, "string overflow");
1150    }
1151
1152    status = pb_read(stream, (uint8_t*)dest, size);
1153    *((uint8_t*)dest + size) = 0;
1154    return status;
1155}
1156
1157static bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
1158{
1159    bool status;
1160    pb_istream_t substream;
1161    const pb_field_t* submsg_fields = (const pb_field_t*)field->ptr;
1162
1163    if (!pb_make_string_substream(stream, &substream))
1164        return false;
1165
1166    if (field->ptr == NULL)
1167        PB_RETURN_ERROR(stream, "invalid field descriptor");
1168
1169    /* New array entries need to be initialized, while required and optional
1170     * submessages have already been initialized in the top-level pb_decode. */
1171    if (PB_HTYPE(field->type) == PB_HTYPE_REPEATED)
1172        status = pb_decode(&substream, submsg_fields, dest);
1173    else
1174        status = pb_decode_noinit(&substream, submsg_fields, dest);
1175
1176    pb_close_string_substream(stream, &substream);
1177    return status;
1178}
1179