整理

include/boost/process/v2/shell.hpp

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+// Copyright (c) 2022 Klemens D. Morgenstern
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef BOOST_PROCESS_V2_SHELL_HPP
+#define BOOST_PROCESS_V2_SHELL_HPP
+
+#include <boost/core/exchange.hpp>
+#include <boost/process/v2/cstring_ref.hpp>
+#include <boost/process/v2/detail/config.hpp>
+#include <boost/process/v2/detail/utf8.hpp>
+#include <boost/process/v2/detail/throw_error.hpp>
+#include <boost/process/v2/environment.hpp>
+#include <memory>
+#include <string>
+
+BOOST_PROCESS_V2_BEGIN_NAMESPACE
+
+/// Error category used by the shell parser.
+extern BOOST_PROCESS_V2_DECL const error_category& get_shell_category();
+static const error_category& shell_category = get_shell_category();
+
+/// Utility to parse commands 
+/** This utility class parses command lines into tokens
+ * and allows users to executed based on textual inputs.
+ * 
+ * In v1, this was possible directly when starting a process,
+ * but has been removed based on the security risks associated with this.
+ * 
+ * By making the shell parsing explicitly, it encourages
+ * a user to run a sanity check on the executable before launching it.
+ * 
+ * @par Example
+ * @code {.cpp}
+ * asio::io_context ctx;
+ * 
+ * auto cmd = shell("my-app --help");
+ * auto exe = cmd.exe();
+ * check_if_malicious(exe);
+ * 
+ * process proc{ctx, exe, cmd.args()};
+ * 
+ * @endcode
+ * 
+ * 
+ */
+struct shell
+{    
+#if defined(BOOST_PROCESS_V2_WINDOWS)
+    using char_type = wchar_t; 
+    using args_type = const wchar_t *;
+#else
+    using char_type = char;
+    using args_type = const char **;
+#endif
+
+    shell() = default;
+
+    template<typename Char, typename Traits>
+    shell(basic_string_view<Char, Traits> input) 
+        : buffer_(detail::conv_string<char_type>(input.data(), input.size())) 
+    {
+        parse_();
+    }
+
+    shell(basic_cstring_ref<char_type> input) : input_(input) {parse_();}
+    shell(basic_string_view<
+                    typename std::conditional<
+                        std::is_same<char_type, char>::value,
+                        wchar_t, char>::type> input) : buffer_(detail::conv_string<char_type>(input.data(), input.size())) 
+    {
+        parse_();
+    }
+
+    shell(const shell &) = delete;
+    shell& operator=(const shell &) = delete;
+
+    shell(shell && lhs) noexcept 
+        : buffer_(std::move(lhs.buffer_)),
+          input_(std::move(lhs.input_)),
+          argc_(boost::exchange(lhs.argc_, 0)),
+          argv_(boost::exchange(lhs.argv_, nullptr))
+#if defined(BOOST_PROCESS_V2_POSIX)
+        , free_argv_(boost::exchange(lhs.free_argv_, nullptr))
+#endif
+    {
+    }
+    shell& operator=(shell && lhs) noexcept
+    {
+        shell tmp(std::move(*this));
+        buffer_ = std::move(lhs.buffer_);
+        input_ = std::move(lhs.input_);
+        argc_  = boost::exchange(lhs.argc_, 0);
+        argv_ = boost::exchange(lhs.argv_, nullptr);
+#if defined(BOOST_PROCESS_V2_POSIX)
+        free_argv_ = boost::exchange(lhs.free_argv_, nullptr);
+#endif
+        return *this;
+    }
+
+    // the length of the parsed shell, including the executable
+    int argc() const { return argc_; }
+    char_type** argv() const { return argv_; }
+        
+    char_type** begin() const {return argv();}
+    char_type** end()   const {return argv() + argc();}
+
+    bool empty() const {return argc() == 0;}
+    std::size_t size() const {return static_cast<std::size_t>(argc()); }
+    /// Native representation of the arguments to be used - excluding the executable
+    BOOST_PROCESS_V2_DECL args_type args() const;
+    template<typename Environment = environment::current_view>
+    filesystem::path exe(Environment && env = environment::current()) const
+    {
+        if (argc() == 0)
+            return "";
+        else
+            return environment::find_executable(0[argv()], std::forward<Environment>(env)); 
+    }
+    BOOST_PROCESS_V2_DECL ~shell();
+
+  private:
+
+    friend struct make_cmd_shell_;
+
+    BOOST_PROCESS_V2_DECL void parse_();
+    
+    // storage in case we need a conversion
+    std::basic_string<char_type> buffer_;
+    basic_cstring_ref<char_type> input_{buffer_}; 
+    // impl details
+    int argc_ = 0;
+    char_type  ** argv_ = nullptr;
+
+#if defined(BOOST_PROCESS_V2_POSIX)
+    void(*free_argv_)(int, char **);
+#endif
+    
+};
+
+BOOST_PROCESS_V2_END_NAMESPACE
+
+#endif //BOOST_PROCESS_V2_ERROR_HPP