1 // Copyright 2020 The Pigweed Authors
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
4 // use this file except in compliance with the License. You may obtain a copy of
5 // the License at
6 //
7 // https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
12 // License for the specific language governing permissions and limitations under
13 // the License.
14
15 // This file defines the functions that encode tokenized logs at runtime. These
16 // are the only pw_tokenizer functions present in a binary that tokenizes
17 // strings. All other tokenizing code is resolved at compile time.
18
19 #include "pw_tokenizer/tokenize.h"
20
21 #include <cstring>
22
23 #include "pw_span/span.h"
24 #include "pw_tokenizer/encode_args.h"
25
26 namespace pw {
27 namespace tokenizer {
28 namespace {
29
30 static_assert(sizeof(PW_TOKENIZER_NESTED_PREFIX_STR) == 2,
31 "The nested prefix must be a single character string");
32
33 // Store metadata about this compilation's string tokenization in the ELF.
34 //
35 // The tokenizer metadata will not go into the on-device executable binary code.
36 // This metadata will be present in the ELF file's .pw_tokenizer.info section,
37 // from which the host-side tooling (Python, Java, etc.) can understand how to
38 // decode tokenized strings for the given binary. Only attributes that affect
39 // the decoding process are recorded.
40 //
41 // Tokenizer metadata is stored in an array of key-value pairs. Each Metadata
42 // object is 32 bytes: a 24-byte string and an 8-byte value. Metadata structs
43 // may be parsed in Python with the struct format '24s<Q'.
PW_PACKED(struct)44 PW_PACKED(struct) Metadata {
45 char name[24]; // name of the metadata field
46 uint64_t value; // value of the field
47 };
48
49 static_assert(sizeof(Metadata) == 32, "Metadata should be exactly 32 bytes");
50
51 // Store tokenization metadata in its own section. Mach-O files are not
52 // supported by pw_tokenizer, but a short, Mach-O compatible section name is
53 // used on macOS so that this file can at least compile.
54 #ifdef __APPLE__
55 #define PW_TOKENIZER_INFO_SECTION PW_KEEP_IN_SECTION(".pw_tokenizer")
56 #else
57 #define PW_TOKENIZER_INFO_SECTION PW_KEEP_IN_SECTION(".pw_tokenizer.info")
58 #endif // __APPLE__
59
60 constexpr Metadata metadata[] PW_TOKENIZER_INFO_SECTION = {
61 {"c_hash_length_bytes", PW_TOKENIZER_CFG_C_HASH_LENGTH},
62 {"sizeof_long", sizeof(long)}, // %l conversion specifier
63 {"sizeof_intmax_t", sizeof(intmax_t)}, // %j conversion specifier
64 {"sizeof_size_t", sizeof(size_t)}, // %z conversion specifier
65 {"sizeof_ptrdiff_t", sizeof(ptrdiff_t)}, // %t conversion specifier
66 };
67
68 } // namespace
69
_pw_tokenizer_ToBuffer(void * buffer,size_t * buffer_size_bytes,Token token,pw_tokenizer_ArgTypes types,...)70 extern "C" void _pw_tokenizer_ToBuffer(void* buffer,
71 size_t* buffer_size_bytes,
72 Token token,
73 pw_tokenizer_ArgTypes types,
74 ...) {
75 if (*buffer_size_bytes < sizeof(token)) {
76 *buffer_size_bytes = 0;
77 return;
78 }
79
80 std::memcpy(buffer, &token, sizeof(token));
81
82 va_list args;
83 va_start(args, types);
84 #if PW_CXX_STANDARD_IS_SUPPORTED(17)
85 const size_t encoded_bytes = EncodeArgs(
86 types,
87 args,
88 span<std::byte>(static_cast<std::byte*>(buffer) + sizeof(token),
89 *buffer_size_bytes - sizeof(token)));
90 #else
91 const size_t encoded_bytes =
92 pw_tokenizer_EncodeArgs(types,
93 args,
94 static_cast<std::byte*>(buffer) + sizeof(token),
95 *buffer_size_bytes - sizeof(token));
96 #endif // PW_CXX_STANDARD_IS_SUPPORTED(17)
97 va_end(args);
98
99 *buffer_size_bytes = sizeof(token) + encoded_bytes;
100 }
101
102 } // namespace tokenizer
103 } // namespace pw
104