GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/shortstring.h
Date: 2025-07-13 02:35:07
Exec Total Coverage
Lines: 91 108 84.3%
Branches: 34 50 68.0%
Line Branch Exec Source
1 /**
2 * This file is part of the CernVM File System.
3 *
4 * Implements a string class that stores short strings on the stack and
5 * malloc's a std::string on the heap on overflow. Used for file names and
6 * path names that are usually small.
7 */
8
9 #ifndef CVMFS_SHORTSTRING_H_
10 #define CVMFS_SHORTSTRING_H_
11
12 #include <algorithm>
13 #include <cstring>
14 #include <string>
15
16 #include "util/atomic.h"
17
18 #ifdef CVMFS_NAMESPACE_GUARD
19 namespace CVMFS_NAMESPACE_GUARD {
20 #endif
21
22 const unsigned char kDefaultMaxName = 25;
23 const unsigned char kDefaultMaxLink = 25;
24 const unsigned char kDefaultMaxPath = 200;
25
26 template<unsigned char StackSize, char Type>
27 class ShortString {
28 public:
29 83997846 ShortString() : long_string_(NULL), length_(0) {
30 #ifdef DEBUGMSG
31 83997846 atomic_inc64(&num_instances_);
32 #endif
33 83997846 }
34 72846581 ShortString(const ShortString &other) : long_string_(NULL) {
35 #ifdef DEBUGMSG
36 145693162 atomic_inc64(&num_instances_);
37 #endif
38 146188530 Assign(other);
39 145750998 }
40 57207 ShortString(const char *chars, const unsigned length) : long_string_(NULL) {
41 #ifdef DEBUGMSG
42 57207 atomic_inc64(&num_instances_);
43 #endif
44 57410 Assign(chars, length);
45 57256 }
46 61065892 explicit ShortString(const std::string &std_string) : long_string_(NULL) {
47 #ifdef DEBUGMSG
48 61065892 atomic_inc64(&num_instances_);
49 #endif
50 61286476 Assign(std_string.data(), std_string.length());
51 61137208 }
52
53 33241616 ShortString &operator=(const ShortString &other) {
54
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 33241616 if (this != &other)
55 33248532 Assign(other);
56 33101252 return *this;
57 }
58
59
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 263534474 ~ShortString() { delete long_string_; }
60
61 240180926 void Assign(const char *chars, const unsigned length) {
62
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 240180926 delete long_string_;
63 240106126 long_string_ = NULL;
64 240106126 this->length_ = length;
65
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 240106126 if (length > StackSize) {
66 #ifdef DEBUGMSG
67 ✗ atomic_inc64(&num_overflows_);
68 #endif
69 ✗ long_string_ = new std::string(chars, length);
70 } else {
71
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 240106126 if (length)
72 239550860 memcpy(stack_, chars, length);
73 }
74 240106126 }
75
76 179205764 void Assign(const ShortString &other) {
77 179205764 Assign(other.GetChars(), other.GetLength());
78 178854434 }
79
80 220206 void Append(const char *chars, const unsigned length) {
81
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 220206 if (long_string_) {
82 ✗ long_string_->append(chars, length);
83 ✗ return;
84 }
85
86 220206 const unsigned new_length = this->length_ + length;
87
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 220206 if (new_length > StackSize) {
88 #ifdef DEBUGMSG
89 ✗ atomic_inc64(&num_overflows_);
90 #endif
91 ✗ long_string_ = new std::string();
92 ✗ long_string_->reserve(new_length);
93 ✗ long_string_->assign(stack_, length_);
94 ✗ long_string_->append(chars, length);
95 ✗ return;
96 }
97
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 220206 if (length > 0)
98 219946 memcpy(&stack_[this->length_], chars, length);
99 220206 this->length_ = new_length;
100 }
101
102 /**
103 * Truncates the current string to be of size smaller or equal to current size
104 *
105 * Note: Can lead to a heap allocated string that is shorter than
106 * the reserved stack space.
107 */
108 378 void Truncate(unsigned new_length) {
109
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 378 assert(new_length <= this->GetLength());
110
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 378 if (long_string_) {
111 ✗ long_string_->erase(new_length);
112 ✗ return;
113 }
114 378 this->length_ = new_length;
115 }
116
117 void Clear() {
118 delete long_string_;
119 long_string_ = NULL;
120 length_ = 0;
121 }
122
123 240927212 const char *GetChars() const {
124
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 240927212 if (long_string_) {
125 ✗ return long_string_->data();
126 } else {
127 240927212 return stack_;
128 }
129 }
130
131 241750168 unsigned GetLength() const {
132
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 241750168 if (long_string_)
133 ✗ return long_string_->length();
134 241750168 return length_;
135 }
136
137 11114 bool IsEmpty() const { return GetLength() == 0; }
138
139 30726087 std::string ToString() const {
140
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 30726087 return std::string(this->GetChars(), this->GetLength());
141 }
142
143 58251 const char *c_str() const {
144
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 58251 if (long_string_)
145 ✗ return long_string_->c_str();
146
147 58251 char *c = const_cast<char *>(stack_) + length_;
148 58251 *c = '\0';
149 58251 return stack_;
150 }
151
152 35942 bool operator==(const ShortString &other) const {
153 35942 const unsigned this_length = this->GetLength();
154 35942 const unsigned other_length = other.GetLength();
155
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 35942 if (this_length != other_length)
156 27575 return false;
157
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 8367 if (this_length == 0)
158 3297 return true;
159
160 5070 return memcmp(this->GetChars(), other.GetChars(), this_length) == 0;
161 }
162
163 27102 bool operator!=(const ShortString &other) const { return !(*this == other); }
164
165 54914 bool operator<(const ShortString &other) const {
166 54914 const unsigned this_length = this->GetLength();
167 54914 const unsigned other_length = other.GetLength();
168
169
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 54914 if (this_length < other_length)
170 16141 return true;
171
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 38773 if (this_length > other_length)
172 10856 return false;
173
174 27917 const char *this_chars = this->GetChars();
175 27917 const char *other_chars = other.GetChars();
176
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 370445 for (unsigned i = 0; i < this_length; ++i) {
177
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 346431 if (this_chars[i] < other_chars[i])
178 3053 return true;
179
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 343378 if (this_chars[i] > other_chars[i])
180 850 return false;
181 }
182 24014 return false;
183 }
184
185 45760 bool StartsWith(const ShortString &other) const {
186 45760 const unsigned this_length = this->GetLength();
187 45760 const unsigned other_length = other.GetLength();
188
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 45760 if (this_length < other_length)
189 3121 return false;
190
191 42639 return memcmp(this->GetChars(), other.GetChars(), other_length) == 0;
192 }
193
194 19096 ShortString Suffix(const unsigned start_at) const {
195 19096 const unsigned length = this->GetLength();
196
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 19096 if (start_at >= length)
197 8 return ShortString("", 0);
198
199 19088 return ShortString(this->GetChars() + start_at, length - start_at);
200 }
201
202 ✗ static uint64_t num_instances() { return atomic_read64(&num_instances_); }
203 ✗ static uint64_t num_overflows() { return atomic_read64(&num_overflows_); }
204
205 private:
206 std::string *long_string_;
207 char stack_[StackSize + 1]; // +1 to add a final '\0' if necessary
208 unsigned char length_;
209 static atomic_int64 num_overflows_;
210 static atomic_int64 num_instances_;
211 }; // class ShortString
212
213 typedef ShortString<kDefaultMaxPath, 0> PathString;
214 typedef ShortString<kDefaultMaxName, 1> NameString;
215 typedef ShortString<kDefaultMaxLink, 2> LinkString;
216
217 template<unsigned char StackSize, char Type>
218 atomic_int64 ShortString<StackSize, Type>::num_overflows_ = 0;
219 template<unsigned char StackSize, char Type>
220 atomic_int64 ShortString<StackSize, Type>::num_instances_ = 0;
221
222 // See posix.cc for the std::string counterparts
223 PathString GetParentPath(const PathString &path);
224 NameString GetFileName(const PathString &path);
225
226 bool IsSubPath(const PathString &parent, const PathString &path);
227
228
229 #ifdef CVMFS_NAMESPACE_GUARD
230 } // namespace CVMFS_NAMESPACE_GUARD
231 #endif
232
233 #endif // CVMFS_SHORTSTRING_H_
234