1 /* pb_common.c: Common support functions for pb_encode.c and pb_decode.c.
2  *
3  * 2014 Petteri Aimonen <jpa@kapsi.fi>
4  */
5 
6 #include "pb_common.h"
7 
8 bool pb_field_iter_begin(pb_field_iter_t *iter, const pb_field_t *fields, void *dest_struct)
9 {
10     iter->start = fields;
11     iter->pos = fields;
12     iter->required_field_index = 0;
13     iter->dest_struct = dest_struct;
14     iter->pData = (char*)dest_struct + iter->pos->data_offset;
15     iter->pSize = (char*)iter->pData + iter->pos->size_offset;
16 
17     return (iter->pos->tag != 0);
18 }
19 
20 bool pb_field_iter_next(pb_field_iter_t *iter)
21 {
22     const pb_field_t *prev_field = iter->pos;
23 
24     if (prev_field->tag == 0)
25     {
26         /* Handle empty message types, where the first field is already the terminator.
27          * In other cases, the iter->pos never points to the terminator. */
28         return false;
29     }
30 
31     iter->pos++;
32 
33     if (iter->pos->tag == 0)
34     {
35         /* Wrapped back to beginning, reinitialize */
36         (void)pb_field_iter_begin(iter, iter->start, iter->dest_struct);
37         return false;
38     }
39     else
40     {
41         /* Increment the pointers based on previous field size */
42         size_t prev_size = prev_field->data_size;
43 
44         if (PB_HTYPE(prev_field->type) == PB_HTYPE_ONEOF &&
45             PB_HTYPE(iter->pos->type) == PB_HTYPE_ONEOF &&
46             iter->pos->data_offset == PB_SIZE_MAX)
47         {
48             /* Don't advance pointers inside unions */
49             return true;
50         }
51         else if (PB_ATYPE(prev_field->type) == PB_ATYPE_STATIC &&
52                  PB_HTYPE(prev_field->type) == PB_HTYPE_REPEATED)
53         {
54             /* In static arrays, the data_size tells the size of a single entry and
55              * array_size is the number of entries */
56             prev_size *= prev_field->array_size;
57         }
58         else if (PB_ATYPE(prev_field->type) == PB_ATYPE_POINTER)
59         {
60             /* Pointer fields always have a constant size in the main structure.
61              * The data_size only applies to the dynamically allocated area. */
62             prev_size = sizeof(void*);
63         }
64 
65         if (PB_HTYPE(prev_field->type) == PB_HTYPE_REQUIRED)
66         {
67             /* Count the required fields, in order to check their presence in the
68              * decoder. */
69             iter->required_field_index++;
70         }
71 
72         iter->pData = (char*)iter->pData + prev_size + iter->pos->data_offset;
73         iter->pSize = (char*)iter->pData + iter->pos->size_offset;
74         return true;
75     }
76 }
77 
78 bool pb_field_iter_find(pb_field_iter_t *iter, uint32_t tag)
79 {
80     const pb_field_t *start = iter->pos;
81 
82     do {
83         if (iter->pos->tag == tag &&
84             PB_LTYPE(iter->pos->type) != PB_LTYPE_EXTENSION)
85         {
86             /* Found the wanted field */
87             return true;
88         }
89 
90         (void)pb_field_iter_next(iter);
91     } while (iter->pos != start);
92 
93     /* Searched all the way back to start, and found nothing. */
94     return false;
95 }
96 
97 
98