1 //
2 // Copyright 2019 The Abseil Authors.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // https://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15
16 #include "absl/flags/usage_config.h"
17
18 #include <functional>
19 #include <iostream>
20 #include <string>
21
22 #include "absl/base/attributes.h"
23 #include "absl/base/config.h"
24 #include "absl/base/const_init.h"
25 #include "absl/base/no_destructor.h"
26 #include "absl/base/thread_annotations.h"
27 #include "absl/flags/internal/path_util.h"
28 #include "absl/flags/internal/program_name.h"
29 #include "absl/strings/match.h"
30 #include "absl/strings/string_view.h"
31 #include "absl/strings/strip.h"
32 #include "absl/synchronization/mutex.h"
33
34 extern "C" {
35
36 // Additional report of fatal usage error message before we std::exit. Error is
37 // fatal if is_fatal argument to ReportUsageError is true.
ABSL_INTERNAL_C_SYMBOL(AbslInternalReportFatalUsageError)38 ABSL_ATTRIBUTE_WEAK void ABSL_INTERNAL_C_SYMBOL(
39 AbslInternalReportFatalUsageError)(absl::string_view) {}
40
41 } // extern "C"
42
43 namespace absl {
44 ABSL_NAMESPACE_BEGIN
45 namespace flags_internal {
46
47 namespace {
48
49 // --------------------------------------------------------------------
50 // Returns true if flags defined in the filename should be reported with
51 // -helpshort flag.
52
ContainsHelpshortFlags(absl::string_view filename)53 bool ContainsHelpshortFlags(absl::string_view filename) {
54 // By default we only want flags in binary's main. We expect the main
55 // routine to reside in <program>.cc or <program>-main.cc or
56 // <program>_main.cc, where the <program> is the name of the binary
57 // (without .exe on Windows).
58 auto suffix = flags_internal::Basename(filename);
59 auto program_name = flags_internal::ShortProgramInvocationName();
60 absl::string_view program_name_ref = program_name;
61 #if defined(_WIN32)
62 absl::ConsumeSuffix(&program_name_ref, ".exe");
63 #endif
64 if (!absl::ConsumePrefix(&suffix, program_name_ref))
65 return false;
66 return absl::StartsWith(suffix, ".") || absl::StartsWith(suffix, "-main.") ||
67 absl::StartsWith(suffix, "_main.");
68 }
69
70 // --------------------------------------------------------------------
71 // Returns true if flags defined in the filename should be reported with
72 // -helppackage flag.
73
ContainsHelppackageFlags(absl::string_view filename)74 bool ContainsHelppackageFlags(absl::string_view filename) {
75 // TODO(rogeeff): implement properly when registry is available.
76 return ContainsHelpshortFlags(filename);
77 }
78
79 // --------------------------------------------------------------------
80 // Generates program version information into supplied output.
81
VersionString()82 std::string VersionString() {
83 std::string version_str(flags_internal::ShortProgramInvocationName());
84
85 version_str += "\n";
86
87 #if !defined(NDEBUG)
88 version_str += "Debug build (NDEBUG not #defined)\n";
89 #endif
90
91 return version_str;
92 }
93
94 // --------------------------------------------------------------------
95 // Normalizes the filename specific to the build system/filesystem used.
96
NormalizeFilename(absl::string_view filename)97 std::string NormalizeFilename(absl::string_view filename) {
98 // Skip any leading slashes
99 auto pos = filename.find_first_not_of("\\/");
100 if (pos == absl::string_view::npos) return "";
101
102 filename.remove_prefix(pos);
103 return std::string(filename);
104 }
105
106 // --------------------------------------------------------------------
107
CustomUsageConfigMutex()108 absl::Mutex* CustomUsageConfigMutex() {
109 static absl::NoDestructor<absl::Mutex> mutex;
110 return mutex.get();
111 }
112 ABSL_CONST_INIT FlagsUsageConfig* custom_usage_config
113 ABSL_GUARDED_BY(CustomUsageConfigMutex())
114 ABSL_PT_GUARDED_BY(CustomUsageConfigMutex()) = nullptr;
115
116 } // namespace
117
GetUsageConfig()118 FlagsUsageConfig GetUsageConfig() {
119 absl::MutexLock l(CustomUsageConfigMutex());
120
121 if (custom_usage_config) return *custom_usage_config;
122
123 FlagsUsageConfig default_config;
124 default_config.contains_helpshort_flags = &ContainsHelpshortFlags;
125 default_config.contains_help_flags = &ContainsHelppackageFlags;
126 default_config.contains_helppackage_flags = &ContainsHelppackageFlags;
127 default_config.version_string = &VersionString;
128 default_config.normalize_filename = &NormalizeFilename;
129
130 return default_config;
131 }
132
ReportUsageError(absl::string_view msg,bool is_fatal)133 void ReportUsageError(absl::string_view msg, bool is_fatal) {
134 std::cerr << "ERROR: " << msg << std::endl;
135
136 if (is_fatal) {
137 ABSL_INTERNAL_C_SYMBOL(AbslInternalReportFatalUsageError)(msg);
138 }
139 }
140
141 } // namespace flags_internal
142
SetFlagsUsageConfig(FlagsUsageConfig usage_config)143 void SetFlagsUsageConfig(FlagsUsageConfig usage_config) {
144 absl::MutexLock l(flags_internal::CustomUsageConfigMutex());
145
146 if (!usage_config.contains_helpshort_flags)
147 usage_config.contains_helpshort_flags =
148 flags_internal::ContainsHelpshortFlags;
149
150 if (!usage_config.contains_help_flags)
151 usage_config.contains_help_flags = flags_internal::ContainsHelppackageFlags;
152
153 if (!usage_config.contains_helppackage_flags)
154 usage_config.contains_helppackage_flags =
155 flags_internal::ContainsHelppackageFlags;
156
157 if (!usage_config.version_string)
158 usage_config.version_string = flags_internal::VersionString;
159
160 if (!usage_config.normalize_filename)
161 usage_config.normalize_filename = flags_internal::NormalizeFilename;
162
163 if (flags_internal::custom_usage_config)
164 *flags_internal::custom_usage_config = usage_config;
165 else
166 flags_internal::custom_usage_config = new FlagsUsageConfig(usage_config);
167 }
168
169 ABSL_NAMESPACE_END
170 } // namespace absl
171