fish-shell/src/redirection.cpp

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#include "config.h" // IWYU pragma: keep
#include "redirection.h"
#include "wutil.h"
#include <fcntl.h>
/// File descriptor redirection error message.
#define FD_ERROR "An error occurred while redirecting file descriptor %s"
/// Pipe error message.
#define LOCAL_PIPE_ERROR "An error occurred while setting up pipe"
#define NOCLOB_ERROR _(L"The file '%s' already exists")
#define FILE_ERROR _(L"An error occurred while redirecting file '%s'")
/// Base open mode to pass to calls to open.
#define OPEN_MASK 0666
dup2_list_t::~dup2_list_t() = default;
maybe_t<dup2_list_t> dup2_list_t::resolve_chain(const io_chain_t &io_chain) {
ASSERT_IS_NOT_FORKED_CHILD();
dup2_list_t result;
for (const auto &io_ref : io_chain) {
switch (io_ref->io_mode) {
case io_mode_t::file: {
// 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 = open(io_file->filename_cstr, io_file->flags, OPEN_MASK);
if (file_fd < 0) {
if ((io_file->flags & O_EXCL) && (errno == EEXIST)) {
debug(1, NOCLOB_ERROR, io_file->filename_cstr);
} else {
debug(1, FILE_ERROR, io_file->filename_cstr);
if (should_debug(1)) wperror(L"open");
}
return none();
}
// 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) {
debug(1, FILE_ERROR, io_file->filename_cstr);
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);
// Mark our dup2 and our close actions.
result.add_dup2(file_fd, io_file->fd);
result.add_close(file_fd);
break;
}
case io_mode_t::close: {
const io_close_t *io = static_cast<const io_close_t *>(io_ref.get());
result.add_close(io->fd);
break;
}
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);
break;
}
case io_mode_t::buffer:
case io_mode_t::pipe: {
const io_pipe_t *io = static_cast<const io_pipe_t *>(io_ref.get());
// If write_pipe_idx is 0, it means we're connecting to the read end (first pipe
// fd). If it's 1, we're connecting to the write end (second pipe fd).
unsigned int write_pipe_idx = (io->is_input ? 0 : 1);
result.add_dup2(io->pipe_fd[write_pipe_idx], io->fd);
if (io->pipe_fd[0] >= 0) result.add_close(io->pipe_fd[0]);
if (io->pipe_fd[1] >= 0) result.add_close(io->pipe_fd[1]);
break;
}
}
}
return {std::move(result)};
}