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Clean up how pipe fd avoidance works

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fish has to ensure that the pipes it creates do not conflict with any
explicit fds named in redirections. Switch this code to using
autoclose_fd_t to make the ownership logic more explicit, and also
introduce fd_set_t to reduce the dependence on io_chain_t.
This commit is contained in:
ridiculousfish
2019-12-12 14:42:03 -08:00
parent 4e52feb51a
commit be685faeb8
5 changed files with 104 additions and 94 deletions
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23
src/redirection.cpp
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@@ -24,8 +24,8 @@ maybe_t<dup2_list_t> dup2_list_t::resolve_chain(const io_chain_t &io_chain) {
// Here we definitely do not want to set CLO_EXEC because our child needs access.
// Open the file.
const io_file_t *io_file = static_cast<const io_file_t *>(io_ref.get());
int file_fd = wopen(io_file->filename, io_file->flags, OPEN_MASK);
if (file_fd < 0) {
autoclose_fd_t file_fd{wopen(io_file->filename, io_file->flags, OPEN_MASK)};
if (!file_fd.valid()) {
if ((io_file->flags & O_EXCL) && (errno == EEXIST)) {
debug(1, NOCLOB_ERROR, io_file->filename.c_str());
} else {
@@ -38,22 +38,23 @@ maybe_t<dup2_list_t> dup2_list_t::resolve_chain(const io_chain_t &io_chain) {
// If by chance we got the file we want, we're done. Otherwise move the fd to an
// unused place and dup2 it.
// Note move_fd_to_unused() will close the incoming file_fd.
if (file_fd != io_file->fd) {
file_fd = move_fd_to_unused(file_fd, io_chain, false /* cloexec */);
if (file_fd < 0) {
if (file_fd.fd() != io_file->fd) {
file_fd = move_fd_to_unused(std::move(file_fd), io_chain.fd_set(),
false /* cloexec */);
if (!file_fd.valid()) {
debug(1, FILE_ERROR, io_file->filename.c_str());
if (should_debug(1)) wperror(L"dup");
return none();
}
}
// Record that we opened this file, so we will auto-close it.
assert(file_fd >= 0 && "Should have a valid file_fd");
result.opened_fds_.emplace_back(file_fd);
assert(file_fd.valid() && "Should have a valid file_fd");
// Mark our dup2 and our close actions.
result.add_dup2(file_fd, io_file->fd);
result.add_close(file_fd);
result.add_dup2(file_fd.fd(), io_file->fd);
result.add_close(file_fd.fd());
// Store our file.
result.opened_fds_.push_back(std::move(file_fd));
break;
}