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061f8f49c6
This adds an "in-process" interpretation of dup2s, allowing for fish to output directly to the correct file descriptor without having to perform an in-kernel dup2 sequence.
111 lines
4.0 KiB
C++
111 lines
4.0 KiB
C++
#include "config.h" // IWYU pragma: keep
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#include "redirection.h"
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#include "wutil.h"
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#include <fcntl.h>
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/// File descriptor redirection error message.
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#define FD_ERROR "An error occurred while redirecting file descriptor %s"
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#define NOCLOB_ERROR _(L"The file '%s' already exists")
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#define FILE_ERROR _(L"An error occurred while redirecting file '%s'")
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/// Base open mode to pass to calls to open.
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#define OPEN_MASK 0666
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dup2_list_t::~dup2_list_t() = default;
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maybe_t<dup2_list_t> dup2_list_t::resolve_chain(const io_chain_t &io_chain) {
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ASSERT_IS_NOT_FORKED_CHILD();
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dup2_list_t result;
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for (const auto &io_ref : io_chain) {
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switch (io_ref->io_mode) {
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case io_mode_t::file: {
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// Here we definitely do not want to set CLO_EXEC because our child needs access.
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// Open the file.
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const io_file_t *io_file = static_cast<const io_file_t *>(io_ref.get());
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int file_fd = open(io_file->filename_cstr, io_file->flags, OPEN_MASK);
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if (file_fd < 0) {
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if ((io_file->flags & O_EXCL) && (errno == EEXIST)) {
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debug(1, NOCLOB_ERROR, io_file->filename_cstr);
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} else {
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debug(1, FILE_ERROR, io_file->filename_cstr);
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if (should_debug(1)) wperror(L"open");
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}
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return none();
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}
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// If by chance we got the file we want, we're done. Otherwise move the fd to an
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// unused place and dup2 it.
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// Note move_fd_to_unused() will close the incoming file_fd.
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if (file_fd != io_file->fd) {
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file_fd = move_fd_to_unused(file_fd, io_chain, false /* cloexec */);
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if (file_fd < 0) {
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debug(1, FILE_ERROR, io_file->filename_cstr);
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if (should_debug(1)) wperror(L"dup");
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return none();
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}
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}
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// Record that we opened this file, so we will auto-close it.
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assert(file_fd >= 0 && "Should have a valid file_fd");
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result.opened_fds_.emplace_back(file_fd);
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// Mark our dup2 and our close actions.
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result.add_dup2(file_fd, io_file->fd);
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result.add_close(file_fd);
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break;
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}
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case io_mode_t::close: {
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const io_close_t *io = static_cast<const io_close_t *>(io_ref.get());
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result.add_close(io->fd);
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break;
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}
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case io_mode_t::fd: {
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const io_fd_t *io = static_cast<const io_fd_t *>(io_ref.get());
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result.add_dup2(io->old_fd, io->fd);
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break;
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}
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case io_mode_t::pipe: {
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const io_pipe_t *io = static_cast<const io_pipe_t *>(io_ref.get());
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result.add_dup2(io->pipe_fd(), io->fd);
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result.add_close(io->pipe_fd());
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break;
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}
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case io_mode_t::bufferfill: {
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const io_bufferfill_t *io = static_cast<const io_bufferfill_t *>(io_ref.get());
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result.add_dup2(io->write_fd(), io->fd);
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result.add_close(io->write_fd());
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break;
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}
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}
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}
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return {std::move(result)};
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}
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int dup2_list_t::fd_for_target_fd(int target) const {
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// Paranoia.
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if (target < 0) {
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return target;
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}
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// Note we can simply walk our action list backwards, looking for src -> target dups.
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int cursor = target;
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for (auto iter = actions_.rbegin(); iter != actions_.rend(); ++iter) {
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if (iter->target == cursor) {
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// cursor is replaced by iter->src
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cursor = iter->src;
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} else if (iter->src == cursor && iter->target < 0) {
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// cursor is closed.
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cursor = -1;
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break;
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}
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}
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return cursor;
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}
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