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Diffstat (limited to 'absl/flags/parse.cc')
| -rw-r--r-- | absl/flags/parse.cc | 762 |
1 files changed, 762 insertions, 0 deletions
diff --git a/absl/flags/parse.cc b/absl/flags/parse.cc new file mode 100644 index 00000000..b1961960 --- /dev/null +++ b/absl/flags/parse.cc @@ -0,0 +1,762 @@ +// +// Copyright 2019 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// https://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +#include "absl/flags/parse.h" + +#include <stdlib.h> +#include <fstream> +#include <iostream> +#include <tuple> + +#ifdef _WIN32 +#include <windows.h> +#endif + +#include "absl/flags/flag.h" +#include "absl/flags/internal/program_name.h" +#include "absl/flags/internal/registry.h" +#include "absl/flags/internal/usage.h" +#include "absl/flags/usage_config.h" +#include "absl/strings/str_cat.h" +#include "absl/strings/strip.h" +#include "absl/synchronization/mutex.h" + +// -------------------------------------------------------------------- + +namespace absl { +namespace flags_internal { +namespace { + +ABSL_CONST_INIT absl::Mutex processing_checks_guard(absl::kConstInit); + +ABSL_CONST_INIT bool flagfile_needs_processing + GUARDED_BY(processing_checks_guard) = false; +ABSL_CONST_INIT bool fromenv_needs_processing + GUARDED_BY(processing_checks_guard) = false; +ABSL_CONST_INIT bool tryfromenv_needs_processing + GUARDED_BY(processing_checks_guard) = false; + +} // namespace +} // namespace flags_internal +} // namespace absl + +ABSL_FLAG(std::vector<std::string>, flagfile, {}, + "comma-separated list of files to load flags from") + .OnUpdate([]() { + if (absl::GetFlag(FLAGS_flagfile).empty()) return; + + absl::MutexLock l(&absl::flags_internal::processing_checks_guard); + + // Setting this flag twice before it is handled most likely an internal + // error and should be reviewed by developers. + if (absl::flags_internal::flagfile_needs_processing) { + ABSL_INTERNAL_LOG(WARNING, "flagfile set twice before it is handled"); + } + + absl::flags_internal::flagfile_needs_processing = true; + }); +ABSL_FLAG(std::vector<std::string>, fromenv, {}, + "comma-separated list of flags to set from the environment" + " [use 'export FLAGS_flag1=value']") + .OnUpdate([]() { + if (absl::GetFlag(FLAGS_fromenv).empty()) return; + + absl::MutexLock l(&absl::flags_internal::processing_checks_guard); + + // Setting this flag twice before it is handled most likely an internal + // error and should be reviewed by developers. + if (absl::flags_internal::fromenv_needs_processing) { + ABSL_INTERNAL_LOG(WARNING, "fromenv set twice before it is handled."); + } + + absl::flags_internal::fromenv_needs_processing = true; + }); +ABSL_FLAG(std::vector<std::string>, tryfromenv, {}, + "comma-separated list of flags to try to set from the environment if " + "present") + .OnUpdate([]() { + if (absl::GetFlag(FLAGS_tryfromenv).empty()) return; + + absl::MutexLock l(&absl::flags_internal::processing_checks_guard); + + // Setting this flag twice before it is handled most likely an internal + // error and should be reviewed by developers. + if (absl::flags_internal::tryfromenv_needs_processing) { + ABSL_INTERNAL_LOG(WARNING, + "tryfromenv set twice before it is handled."); + } + + absl::flags_internal::tryfromenv_needs_processing = true; + }); + +ABSL_FLAG(std::vector<std::string>, undefok, {}, + "comma-separated list of flag names that it is okay to specify " + "on the command line even if the program does not define a flag " + "with that name"); + +namespace absl { +namespace flags_internal { + +namespace { + +class ArgsList { + public: + ArgsList() : next_arg_(0) {} + ArgsList(int argc, char* argv[]) : args_(argv, argv + argc), next_arg_(0) {} + explicit ArgsList(const std::vector<std::string>& args) + : args_(args), next_arg_(0) {} + + // Returns success status: true if parsing successful, false otherwise. + bool ReadFromFlagfile(const std::string& flag_file_name); + + int Size() const { return args_.size() - next_arg_; } + int FrontIndex() const { return next_arg_; } + absl::string_view Front() const { return args_[next_arg_]; } + void PopFront() { next_arg_++; } + + private: + std::vector<std::string> args_; + int next_arg_; +}; + +bool ArgsList::ReadFromFlagfile(const std::string& flag_file_name) { + std::ifstream flag_file(flag_file_name); + + if (!flag_file) { + flags_internal::ReportUsageError( + absl::StrCat("Can't open flagfile ", flag_file_name), true); + + return false; + } + + // This argument represents fake argv[0], which should be present in all arg + // lists. + args_.push_back(""); + + std::string line; + bool success = true; + + while (std::getline(flag_file, line)) { + absl::string_view stripped = absl::StripLeadingAsciiWhitespace(line); + + if (stripped.empty() || stripped[0] == '#') { + // Comment or empty line; just ignore. + continue; + } + + if (stripped[0] == '-') { + if (stripped == "--") { + flags_internal::ReportUsageError( + "Flagfile can't contain position arguments or --", true); + + success = false; + break; + } + + args_.push_back(std::string(stripped)); + continue; + } + + flags_internal::ReportUsageError( + absl::StrCat("Unexpected line in the flagfile ", flag_file_name, ": ", + line), + true); + + success = false; + } + + return success; +} + +// -------------------------------------------------------------------- + +// Reads the environment variable with name `name` and stores results in +// `value`. If variable is not present in environment returns false, otherwise +// returns true. +bool GetEnvVar(const char* var_name, std::string* var_value) { +#ifdef _WIN32 + char buf[1024]; + auto get_res = GetEnvironmentVariableA(var_name, buf, sizeof(buf)); + if (get_res >= sizeof(buf)) { + return ""; + } + + if (get_res == 0) { + return false; + } + + *var_value = std::string(buf, get_res); +#else + const char* val = ::getenv(var_name); + if (val == nullptr) { + return false; + } + + *var_value = val; +#endif + + return true; +} + +// -------------------------------------------------------------------- + +// Returns: +// Flag name or empty if arg= -- +// Flag value after = in --flag=value (empty if --foo) +// "Is empty value" status. True if arg= --foo=, false otherwise. This is +// required to separate --foo from --foo=. +// For example: +// arg return values +// "--foo=bar" -> {"foo", "bar", false}. +// "--foo" -> {"foo", "", false}. +// "--foo=" -> {"foo", "", true}. +std::tuple<absl::string_view, absl::string_view, bool> SplitNameAndValue( + absl::string_view arg) { + // Allow -foo and --foo + absl::ConsumePrefix(&arg, "-"); + + if (arg.empty()) { + return std::make_tuple("", "", false); + } + + auto equal_sign_pos = arg.find("="); + + absl::string_view flag_name = arg.substr(0, equal_sign_pos); + + absl::string_view value; + bool is_empty_value = false; + + if (equal_sign_pos != absl::string_view::npos) { + value = arg.substr(equal_sign_pos + 1); + is_empty_value = value.empty(); + } + + return std::make_tuple(flag_name, value, is_empty_value); +} + +// -------------------------------------------------------------------- + +// Returns: +// found flag or nullptr +// is negative in case of --nofoo +std::tuple<CommandLineFlag*, bool> LocateFlag(absl::string_view flag_name) { + CommandLineFlag* flag = flags_internal::FindCommandLineFlag(flag_name); + bool is_negative = false; + + if (!flag && absl::ConsumePrefix(&flag_name, "no")) { + flag = flags_internal::FindCommandLineFlag(flag_name); + is_negative = true; + } + + return std::make_tuple(flag, is_negative); +} + +// -------------------------------------------------------------------- + +// Verify that default values of typed flags must be convertible to string and +// back. +void CheckDefaultValuesParsingRoundtrip() { +#ifndef NDEBUG + flags_internal::ForEachFlag([&](CommandLineFlag* flag) { + if (flag->IsRetired()) return; + +#define IGNORE_TYPE(T) \ + if (flag->IsOfType<T>()) return; + + ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(IGNORE_TYPE) + IGNORE_TYPE(std::string) + IGNORE_TYPE(std::vector<std::string>) +#undef IGNORE_TYPE + + absl::MutexLock lock(InitFlagIfNecessary(flag)); + + std::string v = flag->DefaultValue(); + void* dst = Clone(flag->op, flag->def); + std::string error; + if (!flags_internal::Parse(flag->marshalling_op, v, dst, &error)) { + ABSL_INTERNAL_LOG( + FATAL, + absl::StrCat("Flag ", flag->Name(), " (from ", flag->Filename(), + "): std::string form of default value '", v, + "' could not be parsed; error=", error)); + } + + // We do not compare dst to def since parsing/unparsing may make + // small changes, e.g., precision loss for floating point types. + Delete(flag->op, dst); + }); +#endif +} + +// -------------------------------------------------------------------- + +// Returns success status, which is true if we successfully read all flag files, +// in which case new ArgLists are appended to the input_args in a reverse order +// of file names in the input flagfiles list. This order ensures that flags from +// the first flagfile in the input list are processed before the second flagfile +// etc. +bool ReadFlagfiles(const std::vector<std::string>& flagfiles, + std::vector<ArgsList>* input_args) { + bool success = true; + for (auto it = flagfiles.rbegin(); it != flagfiles.rend(); ++it) { + ArgsList al; + + if (al.ReadFromFlagfile(*it)) { + input_args->push_back(al); + } else { + success = false; + } + } + + return success; +} + +// Returns success status, which is true if were able to locate all environment +// variables correctly or if fail_on_absent_in_env is false. The environment +// variable names are expected to be of the form `FLAGS_<flag_name>`, where +// `flag_name` is a string from the input flag_names list. If successful we +// append a single ArgList at the end of the input_args. +bool ReadFlagsFromEnv(const std::vector<std::string>& flag_names, + std::vector<ArgsList>* input_args, + bool fail_on_absent_in_env) { + bool success = true; + std::vector<std::string> args; + + // This argument represents fake argv[0], which should be present in all arg + // lists. + args.push_back(""); + + for (const auto& flag_name : flag_names) { + // Avoid infinite recursion. + if (flag_name == "fromenv" || flag_name == "tryfromenv") { + flags_internal::ReportUsageError( + absl::StrCat("Infinite recursion on flag ", flag_name), true); + + success = false; + continue; + } + + const std::string envname = absl::StrCat("FLAGS_", flag_name); + std::string envval; + if (!GetEnvVar(envname.c_str(), &envval)) { + if (fail_on_absent_in_env) { + flags_internal::ReportUsageError( + absl::StrCat(envname, " not found in environment"), true); + + success = false; + } + + continue; + } + + args.push_back(absl::StrCat("--", flag_name, "=", envval)); + } + + if (success) { + input_args->emplace_back(args); + } + + return success; +} + +// -------------------------------------------------------------------- + +// Returns success status, which is true if were able to handle all generator +// flags (flagfile, fromenv, tryfromemv) successfully. +bool HandleGeneratorFlags(std::vector<ArgsList>* input_args, + std::vector<std::string>* flagfile_value) { + bool success = true; + + absl::MutexLock l(&flags_internal::processing_checks_guard); + + // flagfile could have been set either on a command line or + // programmatically before invoking ParseCommandLine. Note that we do not + // actually process arguments specified in the flagfile, but instead + // create a secondary arguments list to be processed along with the rest + // of the comamnd line arguments. Since we always the process most recently + // created list of arguments first, this will result in flagfile argument + // being processed before any other argument in the command line. If + // FLAGS_flagfile contains more than one file name we create multiple new + // levels of arguments in a reverse order of file names. Thus we always + // process arguments from first file before arguments containing in a + // second file, etc. If flagfile contains another + // --flagfile inside of it, it will produce new level of arguments and + // processed before the rest of the flagfile. We are also collecting all + // flagfiles set on original command line. Unlike the rest of the flags, + // this flag can be set multiple times and is expected to be handled + // multiple times. We are collecting them all into a single list and set + // the value of FLAGS_flagfile to that value at the end of the parsing. + if (flags_internal::flagfile_needs_processing) { + auto flagfiles = absl::GetFlag(FLAGS_flagfile); + + if (input_args->size() == 1) { + flagfile_value->insert(flagfile_value->end(), flagfiles.begin(), + flagfiles.end()); + } + + success &= ReadFlagfiles(flagfiles, input_args); + + flags_internal::flagfile_needs_processing = false; + } + + // Similar to flagfile fromenv/tryfromemv can be set both + // programmatically and at runtime on a command line. Unlike flagfile these + // can't be recursive. + if (flags_internal::fromenv_needs_processing) { + auto flags_list = absl::GetFlag(FLAGS_fromenv); + + success &= ReadFlagsFromEnv(flags_list, input_args, true); + + flags_internal::fromenv_needs_processing = false; + } + + if (flags_internal::tryfromenv_needs_processing) { + auto flags_list = absl::GetFlag(FLAGS_tryfromenv); + + success &= ReadFlagsFromEnv(flags_list, input_args, false); + + flags_internal::tryfromenv_needs_processing = false; + } + + return success; +} + +// -------------------------------------------------------------------- + +void ResetGeneratorFlags(const std::vector<std::string>& flagfile_value) { + // Setting flagfile to the value which collates all the values set on a + // command line and programmatically. So if command line looked like + // --flagfile=f1 --flagfile=f2 the final value of the FLAGS_flagfile flag is + // going to be {"f1", "f2"} + if (!flagfile_value.empty()) { + absl::SetFlag(&FLAGS_flagfile, flagfile_value); + absl::MutexLock l(&flags_internal::processing_checks_guard); + flags_internal::flagfile_needs_processing = false; + } + + // fromenv/tryfromenv are set to <undefined> value. + if (!absl::GetFlag(FLAGS_fromenv).empty()) { + absl::SetFlag(&FLAGS_fromenv, {}); + } + if (!absl::GetFlag(FLAGS_tryfromenv).empty()) { + absl::SetFlag(&FLAGS_tryfromenv, {}); + } + + absl::MutexLock l(&flags_internal::processing_checks_guard); + flags_internal::fromenv_needs_processing = false; + flags_internal::tryfromenv_needs_processing = false; +} + +// -------------------------------------------------------------------- + +// Returns: +// success status +// deduced value +// We are also mutating curr_list in case if we need to get a hold of next +// argument in the input. +std::tuple<bool, absl::string_view> DeduceFlagValue(const CommandLineFlag& flag, + absl::string_view value, + bool is_negative, + bool is_empty_value, + ArgsList* curr_list) { + // Value is either an argument suffix after `=` in "--foo=<value>" + // or separate argument in case of "--foo" "<value>". + + // boolean flags have these forms: + // --foo + // --nofoo + // --foo=true + // --foo=false + // --nofoo=<value> is not supported + // --foo <value> is not supported + + // non boolean flags have these forms: + // --foo=<value> + // --foo <value> + // --nofoo is not supported + + if (flag.IsOfType<bool>()) { + if (value.empty()) { + if (is_empty_value) { + // "--bool_flag=" case + flags_internal::ReportUsageError( + absl::StrCat( + "Missing the value after assignment for the boolean flag '", + flag.Name(), "'"), + true); + return std::make_tuple(false, ""); + } + + // "--bool_flag" case + value = is_negative ? "0" : "1"; + } else if (is_negative) { + // "--nobool_flag=Y" case + flags_internal::ReportUsageError( + absl::StrCat("Negative form with assignment is not valid for the " + "boolean flag '", + flag.Name(), "'"), + true); + return std::make_tuple(false, ""); + } + } else if (is_negative) { + // "--noint_flag=1" case + flags_internal::ReportUsageError( + absl::StrCat("Negative form is not valid for the flag '", flag.Name(), + "'"), + true); + return std::make_tuple(false, ""); + } else if (value.empty() && (!is_empty_value)) { + if (curr_list->Size() == 1) { + // "--int_flag" case + flags_internal::ReportUsageError( + absl::StrCat("Missing the value for the flag '", flag.Name(), "'"), + true); + return std::make_tuple(false, ""); + } + + // "--int_flag" "10" case + curr_list->PopFront(); + value = curr_list->Front(); + + // Heuristic to detect the case where someone treats a std::string arg + // like a bool or just forgets to pass a value: + // --my_string_var --foo=bar + // We look for a flag of std::string type, whose value begins with a + // dash and corresponds to known flag or standalone --. + if (value[0] == '-' && flag.IsOfType<std::string>()) { + auto maybe_flag_name = std::get<0>(SplitNameAndValue(value.substr(1))); + + if (maybe_flag_name.empty() || + std::get<0>(LocateFlag(maybe_flag_name)) != nullptr) { + // "--string_flag" "--known_flag" case + ABSL_INTERNAL_LOG( + WARNING, + absl::StrCat("Did you really mean to set flag '", flag.Name(), + "' to the value '", value, "'?")); + } + } + } + + return std::make_tuple(true, value); +} + +// -------------------------------------------------------------------- + +bool CanIgnoreUndefinedFlag(absl::string_view flag_name) { + auto undefok = absl::GetFlag(FLAGS_undefok); + if (std::find(undefok.begin(), undefok.end(), flag_name) != undefok.end()) { + return true; + } + + if (absl::ConsumePrefix(&flag_name, "no") && + std::find(undefok.begin(), undefok.end(), flag_name) != undefok.end()) { + return true; + } + + return false; +} + +} // namespace + +// -------------------------------------------------------------------- + +std::vector<char*> ParseCommandLineImpl(int argc, char* argv[], + ArgvListAction arg_list_act, + UsageFlagsAction usage_flag_act, + OnUndefinedFlag on_undef_flag) { + ABSL_INTERNAL_CHECK(argc > 0, "Missing argv[0]"); + + // This routine does not return anything since we abort on failure. + CheckDefaultValuesParsingRoundtrip(); + + std::vector<std::string> flagfile_value; + + std::vector<ArgsList> input_args; + input_args.push_back(ArgsList(argc, argv)); + + std::vector<char*> output_args; + std::vector<char*> positional_args; + output_args.reserve(argc); + + // This is the list of undefined flags. The element of the list is the pair + // consisting of boolean indicating if flag came from command line (vs from + // some flag file we've read) and flag name. + // TODO(rogeeff): Eliminate the first element in the pair after cleanup. + std::vector<std::pair<bool, std::string>> undefined_flag_names; + + // Set program invocation name if it is not set before. + if (ProgramInvocationName() == "UNKNOWN") { + flags_internal::SetProgramInvocationName(argv[0]); + } + output_args.push_back(argv[0]); + + // Iterate through the list of the input arguments. First level are arguments + // originated from argc/argv. Following levels are arguments originated from + // recursive parsing of flagfile(s). + bool success = true; + while (!input_args.empty()) { + // 10. First we process the built-in generator flags. + success &= HandleGeneratorFlags(&input_args, &flagfile_value); + + // 30. Select top-most (most recent) arguments list. If it is empty drop it + // and re-try. + ArgsList& curr_list = input_args.back(); + + curr_list.PopFront(); + + if (curr_list.Size() == 0) { + input_args.pop_back(); + continue; + } + + // 40. Pick up the front remaining argument in the current list. If current + // stack of argument lists contains only one element - we are processing an + // argument from the original argv. + absl::string_view arg(curr_list.Front()); + bool arg_from_argv = input_args.size() == 1; + + // 50. If argument does not start with - or is just "-" - this is + // positional argument. + if (!absl::ConsumePrefix(&arg, "-") || arg.empty()) { + ABSL_INTERNAL_CHECK(arg_from_argv, + "Flagfile cannot contain positional argument"); + + positional_args.push_back(argv[curr_list.FrontIndex()]); + continue; + } + + if (arg_from_argv && (arg_list_act == ArgvListAction::kKeepParsedArgs)) { + output_args.push_back(argv[curr_list.FrontIndex()]); + } + + // 60. Split the current argument on '=' to figure out the argument + // name and value. If flag name is empty it means we've got "--". value + // can be empty either if there were no '=' in argument std::string at all or + // an argument looked like "--foo=". In a latter case is_empty_value is + // true. + absl::string_view flag_name; + absl::string_view value; + bool is_empty_value = false; + + std::tie(flag_name, value, is_empty_value) = SplitNameAndValue(arg); + + // 70. "--" alone means what it does for GNU: stop flags parsing. We do + // not support positional arguments in flagfiles, so we just drop them. + if (flag_name.empty()) { + ABSL_INTERNAL_CHECK(arg_from_argv, + "Flagfile cannot contain positional argument"); + + curr_list.PopFront(); + break; + } + + // 80. Locate the flag based on flag name. Handle both --foo and --nofoo + CommandLineFlag* flag = nullptr; + bool is_negative = false; + std::tie(flag, is_negative) = LocateFlag(flag_name); + + if (flag == nullptr) { + if (on_undef_flag != OnUndefinedFlag::kIgnoreUndefined) { + undefined_flag_names.emplace_back(arg_from_argv, + std::string(flag_name)); + } + continue; + } + + // 90. Deduce flag's value (from this or next argument) + auto curr_index = curr_list.FrontIndex(); + bool value_success = true; + std::tie(value_success, value) = + DeduceFlagValue(*flag, value, is_negative, is_empty_value, &curr_list); + success &= value_success; + + // If above call consumed an argument, it was a standalone value + if (arg_from_argv && (arg_list_act == ArgvListAction::kKeepParsedArgs) && + (curr_index != curr_list.FrontIndex())) { + output_args.push_back(argv[curr_list.FrontIndex()]); + } + + // 100. Set the located flag to a new new value, unless it is retired. + // Setting retired flag fails, but we ignoring it here. + if (flag->IsRetired()) continue; + + std::string error; + if (!flag->SetFromString(value, SET_FLAGS_VALUE, kCommandLine, &error)) { + flags_internal::ReportUsageError(error, true); + success = false; + } + } + + for (const auto& flag_name : undefined_flag_names) { + if (CanIgnoreUndefinedFlag(flag_name.second)) continue; + + flags_internal::ReportUsageError( + absl::StrCat("Unknown command line flag '", flag_name.second, "'"), + true); + + success = false; + } + +#if ABSL_FLAGS_STRIP_NAMES + if (!success) { + flags_internal::ReportUsageError( + "NOTE: command line flags are disabled in this build", true); + } +#endif + + if (!success) { + flags_internal::HandleUsageFlags(std::cout); + std::exit(1); + } + + if (usage_flag_act == UsageFlagsAction::kHandleUsage) { + int exit_code = flags_internal::HandleUsageFlags(std::cout); + + if (exit_code != -1) { + std::exit(exit_code); + } + } + + ResetGeneratorFlags(flagfile_value); + + // Reinstate positional args which were intermixed with flags in the arguments + // list. + for (auto arg : positional_args) { + output_args.push_back(arg); + } + + // All the remaining arguments are positional. + if (!input_args.empty()) { + for (int arg_index = input_args.back().FrontIndex(); arg_index < argc; + ++arg_index) { + output_args.push_back(argv[arg_index]); + } + } + + return output_args; +} + +} // namespace flags_internal + +// -------------------------------------------------------------------- + +std::vector<char*> ParseCommandLine(int argc, char* argv[]) { + return flags_internal::ParseCommandLineImpl( + argc, argv, flags_internal::ArgvListAction::kRemoveParsedArgs, + flags_internal::UsageFlagsAction::kHandleUsage, + flags_internal::OnUndefinedFlag::kAbortIfUndefined); +} + +} // namespace absl |