io_data_t to store the source_fd directly

Now that all io_data_ts know their source fd, just store it directly in
the base class. This will simplify some uses of io_data_t.

src/exec.cpp

@@ -392,8 +392,8 @@ static bool exec_internal_builtin_proc(parser_t &parser, const std::shared_ptr<j
                 // which is internal to fish. We still respect this redirection in
                 // that we pass it on as a block IO to the code that source runs,
                 // and therefore this is not an error.
-                if (in_fd->old_fd >= 0 && in_fd->old_fd < 3) {
-                    local_builtin_stdin = in_fd->old_fd;
+                if (in_fd->source_fd >= 0 && in_fd->source_fd < 3) {
+                    local_builtin_stdin = in_fd->source_fd;
                 }
                 break;
             }

src/io.cpp

@@ -30,13 +30,13 @@
 io_data_t::~io_data_t() = default;
 
 io_file_t::io_file_t(int f, autoclose_fd_t file)
-    : io_data_t(io_mode_t::file, f), file_fd_(std::move(file)) {
+    : io_data_t(io_mode_t::file, f, file_fd_.fd()), file_fd_(std::move(file)) {
     assert(file_fd_.valid() && "File is not valid");
 }
 
 void io_close_t::print() const { std::fwprintf(stderr, L"close %d\n", fd); }
 
-void io_fd_t::print() const { std::fwprintf(stderr, L"FD map %d -> %d\n", old_fd, fd); }
+void io_fd_t::print() const { std::fwprintf(stderr, L"FD map %d -> %d\n", source_fd, fd); }
 
 void io_file_t::print() const { std::fwprintf(stderr, L"file (%d)\n", file_fd_.fd()); }
 

src/io.h

@@ -169,27 +169,31 @@ enum class io_mode_t { file, pipe, fd, close, bufferfill };
 
 /// Represents an FD redirection.
 class io_data_t {
-   private:
     // No assignment or copying allowed.
-    io_data_t(const io_data_t &rhs);
-    void operator=(const io_data_t &rhs);
+    io_data_t(const io_data_t &rhs) = delete;
+    void operator=(const io_data_t &rhs) = delete;
 
    protected:
-    io_data_t(io_mode_t m, int f) : io_mode(m), fd(f) {}
+    io_data_t(io_mode_t m, int fd, int source_fd) : io_mode(m), fd(fd), source_fd(source_fd) {}
 
    public:
     /// Type of redirect.
     const io_mode_t io_mode;
+
     /// FD to redirect.
     const int fd;
 
+    /// Source fd. This is dup2'd to fd, or if it is -1, then fd is closed.
+    /// That is, we call dup2(source_fd, fd).
+    const int source_fd;
+
     virtual void print() const = 0;
     virtual ~io_data_t() = 0;
 };
 
 class io_close_t : public io_data_t {
    public:
-    explicit io_close_t(int f) : io_data_t(io_mode_t::close, f) {}
+    explicit io_close_t(int f) : io_data_t(io_mode_t::close, f, -1) {}
 
     void print() const override;
     ~io_close_t() override;
@@ -197,14 +201,13 @@ class io_close_t : public io_data_t {
 
 class io_fd_t : public io_data_t {
    public:
-    /// fd to redirect specified fd to. For example, in 2>&1, old_fd is 1, and io_data_t::fd is 2.
-    const int old_fd;
-
     void print() const override;
 
     ~io_fd_t() override;
 
-    io_fd_t(int f, int old) : io_data_t(io_mode_t::fd, f), old_fd(old) {}
+    /// fd to redirect specified fd to. For example, in 2>&1, source_fd is 1, and io_data_t::fd
+    /// is 2.
+    io_fd_t(int f, int source_fd) : io_data_t(io_mode_t::fd, f, source_fd) {}
 };
 
 /// Represents a redirection to or from an opened file.
@@ -235,7 +238,9 @@ class io_pipe_t : public io_data_t {
     void print() const override;
 
     io_pipe_t(int fd, bool is_input, autoclose_fd_t pipe_fd)
-        : io_data_t(io_mode_t::pipe, fd), pipe_fd_(std::move(pipe_fd)), is_input_(is_input) {}
+        : io_data_t(io_mode_t::pipe, fd, pipe_fd.fd()),
+          pipe_fd_(std::move(pipe_fd)),
+          is_input_(is_input) {}
 
     ~io_pipe_t() override;
 
@@ -260,7 +265,7 @@ class io_bufferfill_t : public io_data_t {
     // The ctor is public to support make_shared() in the static create function below.
     // Do not invoke this directly.
     io_bufferfill_t(autoclose_fd_t write_fd, std::shared_ptr<io_buffer_t> buffer)
-        : io_data_t(io_mode_t::bufferfill, STDOUT_FILENO),
+        : io_data_t(io_mode_t::bufferfill, STDOUT_FILENO, write_fd.fd()),
           write_fd_(std::move(write_fd)),
           buffer_(std::move(buffer)) {}
 

src/redirection.cpp

@@ -51,7 +51,7 @@ dup2_list_t dup2_list_t::resolve_chain(const io_chain_t &io_chain) {
 
             case io_mode_t::fd: {
                 const io_fd_t *io = static_cast<const io_fd_t *>(io_ref.get());
-                result.add_dup2(io->old_fd, io->fd);
+                result.add_dup2(io->source_fd, io->fd);
                 break;
             }