整理

include/boost/process/v2/posix/bind_fd.hpp

@@ -0,0 +1,113 @@
+// 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_POSIX_BIND_FD_HPP
+#define BOOST_PROCESS_V2_POSIX_BIND_FD_HPP
+
+#include <boost/process/v2/detail/config.hpp>
+#include <boost/process/v2/default_launcher.hpp>
+
+#include <fcntl.h>
+
+BOOST_PROCESS_V2_BEGIN_NAMESPACE
+
+namespace posix
+{
+
+/// Utility class to bind a file descriptor to an explicit file descriptor for the child process.
+struct bind_fd
+{
+    int target;
+    int fd;
+    bool fd_needs_closing{false};
+
+    ~bind_fd()
+    {
+        if (fd_needs_closing)
+            ::close(fd);
+    }
+
+    bind_fd() = delete;
+    /// Inherit file descriptor with the same value.
+    /**
+     * This will pass descriptor 42 as 42 to the child process:
+     * @code
+     * process p{"test", {},  posix::bind_fd(42)};
+     * @endcode
+     */
+    bind_fd(int target) : target(target), fd(target) {}
+
+    /// Inherit an asio io-object as a given file descriptor to the child process.
+    /**
+     * This will pass the tcp::socket, as 42 to the child process:
+     * @code
+     * extern tcp::socket sock; 
+     * process p{"test", {},  posix::bind_fd(42, sock)};
+     * @endcode
+     */
+
+    template<typename Stream>
+    bind_fd(int target, Stream && str, decltype(std::declval<Stream>().native_handle()) = -1)
+        : bind_fd(target, str.native_handle())
+    {}
+
+    /// Inherit a `FILE` as a given file descriptor to the child process.
+    /**
+     * This will pass the given `FILE*`, as 42 to the child process:
+     * @code
+     * process p{"test", {},  posix::bind_fd(42, stderr)};
+     * @endcode
+     */
+    bind_fd(int target, FILE * f) : bind_fd(target, fileno(f)) {}
+    
+    /// Inherit a file descriptor with as a different value.
+    /**
+     * This will pass 24 as 42 to the child process:
+     * @code
+     * process p{"test", {},  posix::bind_fd(42, 24)};
+     * @endcode
+     */
+    bind_fd(int target, int fd) : target(target), fd(fd) {}
+    
+    /// Inherit a null device as a set descriptor.
+    /**
+     * This will pass 24 as 42 to the child process:
+     * @code
+     * process p{"test", {},  posix::bind_fd(42, nullptr)};
+     * @endcode
+     */
+    bind_fd(int target, std::nullptr_t) : bind_fd(target, filesystem::path("/dev/null")) {}
+
+    /// Inherit a newly opened-file as a set descriptor.
+    /**
+     * This will pass 24 as 42 to the child process:
+     * @code
+     * process p{"test", {},  posix::bind_fd(42, "extra-output.txt")};
+     * @endcode
+     */
+    bind_fd(int target, const filesystem::path & pth, int flags = O_RDWR | O_CREAT)
+            : target(target), fd(::open(pth.c_str(), flags, 0660)), fd_needs_closing(true)
+    {
+    }
+
+    error_code on_setup(posix::default_launcher & launcher, const filesystem::path &, const char * const *)
+    {
+        launcher.fd_whitelist.push_back(target);
+        return {};
+    }
+
+    /// Implementation of the initialization function.
+    error_code on_exec_setup(posix::default_launcher & /*launcher*/, const filesystem::path &, const char * const *)
+    {
+        if (::dup2(fd, target) == -1)
+            return error_code(errno, system_category());
+        return error_code ();
+    }
+};
+
+}
+
+BOOST_PROCESS_V2_END_NAMESPACE
+
+#endif //BOOST_PROCESS_V2_POSIX_BIND_FD_HPP