1 /*
2 * Copyright (c) 2009-2022, Google LLC
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of Google LLC nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL Google LLC BE LIABLE FOR ANY DIRECT,
20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include "upb/io/chunked_input_stream.h"
29
30 // Must be last.
31 #include "upb/port/def.inc"
32
33 typedef struct {
34 upb_ZeroCopyInputStream base;
35
36 const char* data;
37 size_t size;
38 size_t limit;
39 size_t position;
40 size_t last_returned_size;
41 } upb_ChunkedInputStream;
42
upb_ChunkedInputStream_Next(upb_ZeroCopyInputStream * z,size_t * count,upb_Status * status)43 static const void* upb_ChunkedInputStream_Next(upb_ZeroCopyInputStream* z,
44 size_t* count,
45 upb_Status* status) {
46 upb_ChunkedInputStream* c = (upb_ChunkedInputStream*)z;
47 UPB_ASSERT(c->position <= c->size);
48
49 const char* out = c->data + c->position;
50
51 const size_t chunk = UPB_MIN(c->limit, c->size - c->position);
52 c->position += chunk;
53 c->last_returned_size = chunk;
54 *count = chunk;
55
56 return chunk ? out : NULL;
57 }
58
upb_ChunkedInputStream_BackUp(upb_ZeroCopyInputStream * z,size_t count)59 static void upb_ChunkedInputStream_BackUp(upb_ZeroCopyInputStream* z,
60 size_t count) {
61 upb_ChunkedInputStream* c = (upb_ChunkedInputStream*)z;
62
63 UPB_ASSERT(c->last_returned_size >= count);
64 c->position -= count;
65 c->last_returned_size -= count;
66 }
67
upb_ChunkedInputStream_Skip(upb_ZeroCopyInputStream * z,size_t count)68 static bool upb_ChunkedInputStream_Skip(upb_ZeroCopyInputStream* z,
69 size_t count) {
70 upb_ChunkedInputStream* c = (upb_ChunkedInputStream*)z;
71
72 c->last_returned_size = 0; // Don't let caller back up.
73 if (count > c->size - c->position) {
74 c->position = c->size;
75 return false;
76 }
77
78 c->position += count;
79 return true;
80 }
81
upb_ChunkedInputStream_ByteCount(const upb_ZeroCopyInputStream * z)82 static size_t upb_ChunkedInputStream_ByteCount(
83 const upb_ZeroCopyInputStream* z) {
84 const upb_ChunkedInputStream* c = (const upb_ChunkedInputStream*)z;
85
86 return c->position;
87 }
88
89 static const _upb_ZeroCopyInputStream_VTable upb_ChunkedInputStream_vtable = {
90 upb_ChunkedInputStream_Next,
91 upb_ChunkedInputStream_BackUp,
92 upb_ChunkedInputStream_Skip,
93 upb_ChunkedInputStream_ByteCount,
94 };
95
upb_ChunkedInputStream_New(const void * data,size_t size,size_t limit,upb_Arena * arena)96 upb_ZeroCopyInputStream* upb_ChunkedInputStream_New(const void* data,
97 size_t size, size_t limit,
98 upb_Arena* arena) {
99 upb_ChunkedInputStream* c = upb_Arena_Malloc(arena, sizeof(*c));
100 if (!c || !limit) return NULL;
101
102 c->base.vtable = &upb_ChunkedInputStream_vtable;
103 c->data = data;
104 c->size = size;
105 c->limit = limit;
106 c->position = 0;
107 c->last_returned_size = 0;
108
109 return (upb_ZeroCopyInputStream*)c;
110 }
111