1 /*
2 * Copyright 2018 The WebRTC Project Authors. All rights reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "rtc_base/strings/string_builder.h"
12
13 #include <stdarg.h>
14
15 #include <cstdio>
16 #include <cstring>
17
18 #include "rtc_base/checks.h"
19 #include "rtc_base/numerics/safe_minmax.h"
20
21 namespace rtc {
22
SimpleStringBuilder(rtc::ArrayView<char> buffer)23 SimpleStringBuilder::SimpleStringBuilder(rtc::ArrayView<char> buffer)
24 : buffer_(buffer) {
25 buffer_[0] = '\0';
26 RTC_DCHECK(IsConsistent());
27 }
28
operator <<(const char * str)29 SimpleStringBuilder& SimpleStringBuilder::operator<<(const char* str) {
30 return Append(str, strlen(str));
31 }
32
operator <<(char ch)33 SimpleStringBuilder& SimpleStringBuilder::operator<<(char ch) {
34 return Append(&ch, 1);
35 }
36
operator <<(const std::string & str)37 SimpleStringBuilder& SimpleStringBuilder::operator<<(const std::string& str) {
38 return Append(str.c_str(), str.length());
39 }
40
41 // Numeric conversion routines.
42 //
43 // We use std::[v]snprintf instead of std::to_string because:
44 // * std::to_string relies on the current locale for formatting purposes,
45 // and therefore concurrent calls to std::to_string from multiple threads
46 // may result in partial serialization of calls
47 // * snprintf allows us to print the number directly into our buffer.
48 // * avoid allocating a std::string (potential heap alloc).
49 // TODO(tommi): Switch to std::to_chars in C++17.
50
operator <<(int i)51 SimpleStringBuilder& SimpleStringBuilder::operator<<(int i) {
52 return AppendFormat("%d", i);
53 }
54
operator <<(unsigned i)55 SimpleStringBuilder& SimpleStringBuilder::operator<<(unsigned i) {
56 return AppendFormat("%u", i);
57 }
58
operator <<(long i)59 SimpleStringBuilder& SimpleStringBuilder::operator<<(long i) { // NOLINT
60 return AppendFormat("%ld", i);
61 }
62
operator <<(long long i)63 SimpleStringBuilder& SimpleStringBuilder::operator<<(long long i) { // NOLINT
64 return AppendFormat("%lld", i);
65 }
66
operator <<(unsigned long i)67 SimpleStringBuilder& SimpleStringBuilder::operator<<(
68 unsigned long i) { // NOLINT
69 return AppendFormat("%lu", i);
70 }
71
operator <<(unsigned long long i)72 SimpleStringBuilder& SimpleStringBuilder::operator<<(
73 unsigned long long i) { // NOLINT
74 return AppendFormat("%llu", i);
75 }
76
operator <<(float f)77 SimpleStringBuilder& SimpleStringBuilder::operator<<(float f) {
78 return AppendFormat("%g", f);
79 }
80
operator <<(double f)81 SimpleStringBuilder& SimpleStringBuilder::operator<<(double f) {
82 return AppendFormat("%g", f);
83 }
84
operator <<(long double f)85 SimpleStringBuilder& SimpleStringBuilder::operator<<(long double f) {
86 return AppendFormat("%Lg", f);
87 }
88
AppendFormat(const char * fmt,...)89 SimpleStringBuilder& SimpleStringBuilder::AppendFormat(const char* fmt, ...) {
90 va_list args;
91 va_start(args, fmt);
92 const int len =
93 std::vsnprintf(&buffer_[size_], buffer_.size() - size_, fmt, args);
94 if (len >= 0) {
95 const size_t chars_added = rtc::SafeMin(len, buffer_.size() - 1 - size_);
96 size_ += chars_added;
97 RTC_DCHECK_EQ(len, chars_added) << "Buffer size was insufficient";
98 } else {
99 // This should never happen, but we're paranoid, so re-write the
100 // terminator in case vsnprintf() overwrote it.
101 RTC_NOTREACHED();
102 buffer_[size_] = '\0';
103 }
104 va_end(args);
105 RTC_DCHECK(IsConsistent());
106 return *this;
107 }
108
Append(const char * str,size_t length)109 SimpleStringBuilder& SimpleStringBuilder::Append(const char* str,
110 size_t length) {
111 RTC_DCHECK_LT(size_ + length, buffer_.size())
112 << "Buffer size was insufficient";
113 const size_t chars_added = rtc::SafeMin(length, buffer_.size() - size_ - 1);
114 memcpy(&buffer_[size_], str, chars_added);
115 size_ += chars_added;
116 buffer_[size_] = '\0';
117 RTC_DCHECK(IsConsistent());
118 return *this;
119 }
120
AppendFormat(const char * fmt,...)121 StringBuilder& StringBuilder::AppendFormat(const char* fmt, ...) {
122 va_list args, copy;
123 va_start(args, fmt);
124 va_copy(copy, args);
125 const int predicted_length = std::vsnprintf(nullptr, 0, fmt, copy);
126 va_end(copy);
127
128 RTC_DCHECK_GE(predicted_length, 0);
129 if (predicted_length > 0) {
130 const size_t size = str_.size();
131 str_.resize(size + predicted_length);
132 // Pass "+ 1" to vsnprintf to include space for the '\0'.
133 const int actual_length =
134 std::vsnprintf(&str_[size], predicted_length + 1, fmt, args);
135 RTC_DCHECK_GE(actual_length, 0);
136 }
137 va_end(args);
138 return *this;
139 }
140
141 } // namespace rtc
142