int move_fd_to_unused(int fd, const io_chain_t &io_chain, bool cloexec) {
if (fd < 0 || io_chain.get_io_for_fd(fd).get() == NULL) {
return fd;
}
// We have fd >= 0, and it's a conflict. dup it and recurse. Note that we recurse before
// anything is closed; this forces the kernel to give us a new one (or report fd exhaustion).
int new_fd = fd;
int tmp_fd;
do {
tmp_fd = dup(fd);
} while (tmp_fd < 0 && errno == EINTR);
assert(tmp_fd != fd);
if (tmp_fd < 0) {
// Likely fd exhaustion.
new_fd = -1;
} else {
// Ok, we have a new candidate fd. Recurse. If we get a valid fd, either it's the same as
// what we gave it, or it's a new fd and what we gave it has been closed. If we get a
// negative value, the fd also has been closed.
if (cloexec) set_cloexec(tmp_fd);
new_fd = move_fd_to_unused(tmp_fd, io_chain);
}
// We're either returning a new fd or an error. In both cases, we promise to close the old one.
assert(new_fd != fd);
int saved_errno = errno;
exec_close(fd);
errno = saved_errno;
return new_fd;
}
shared_ptr<io_data_t> io_chain_get(io_chain_t &src, int fd)
{
return src.get_io_for_fd(fd);
}
/// Execute an internal builtin. Given a parser, a job within that parser, and a process within that
/// job corresponding to a builtin, execute the builtin with the given streams. If pipe_read is set,
/// assign stdin to it; otherwise infer stdin from the IO chain.
/// \return true on success, false if there is an exec error.
static bool exec_internal_builtin_proc(parser_t &parser, job_t *j, process_t *p,
const io_pipe_t *pipe_read, const io_chain_t &proc_io_chain,
io_streams_t &streams) {
assert(p->type == INTERNAL_BUILTIN && "Process must be a builtin");
int local_builtin_stdin = STDIN_FILENO;
bool close_stdin = false;
// If this is the first process, check the io redirections and see where we should
// be reading from.
if (pipe_read) {
local_builtin_stdin = pipe_read->pipe_fd[0];
} else if (const auto in = proc_io_chain.get_io_for_fd(STDIN_FILENO)) {
switch (in->io_mode) {
case IO_FD: {
const io_fd_t *in_fd = static_cast<const io_fd_t *>(in.get());
// Ignore user-supplied fd redirections from an fd other than the
// standard ones. e.g. in source <&3 don't actually read from fd 3,
// 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. Non-user supplied fd
// redirections come about through transmogrification, and we need
// to respect those here.
if (!in_fd->user_supplied || (in_fd->old_fd >= 0 && in_fd->old_fd < 3)) {
local_builtin_stdin = in_fd->old_fd;
}
break;
}
case IO_PIPE: {
const io_pipe_t *in_pipe = static_cast<const io_pipe_t *>(in.get());
local_builtin_stdin = in_pipe->pipe_fd[0];
break;
}
case IO_FILE: {
// Do not set CLO_EXEC because child needs access.
const io_file_t *in_file = static_cast<const io_file_t *>(in.get());
local_builtin_stdin = open(in_file->filename_cstr, in_file->flags, OPEN_MASK);
if (local_builtin_stdin == -1) {
debug(1, FILE_ERROR, in_file->filename_cstr);
wperror(L"open");
} else {
close_stdin = true;
}
break;
}
case IO_CLOSE: {
// FIXME: When requesting that stdin be closed, we really don't do
// anything. How should this be handled?
local_builtin_stdin = -1;
break;
}
default: {
local_builtin_stdin = -1;
debug(1, _(L"Unknown input redirection type %d"), in->io_mode);
break;
}
}
}
if (local_builtin_stdin == -1) return false;
// Determine if we have a "direct" redirection for stdin.
bool stdin_is_directly_redirected;
if (!p->is_first_in_job) {
// We must have a pipe
stdin_is_directly_redirected = true;
} else {
// We are not a pipe. Check if there is a redirection local to the process
// that's not IO_CLOSE.
const shared_ptr<const io_data_t> stdin_io = io_chain_get(p->io_chain(), STDIN_FILENO);
stdin_is_directly_redirected = stdin_io && stdin_io->io_mode != IO_CLOSE;
}
streams.stdin_fd = local_builtin_stdin;
streams.out_is_redirected = has_fd(proc_io_chain, STDOUT_FILENO);
streams.err_is_redirected = has_fd(proc_io_chain, STDERR_FILENO);
streams.stdin_is_directly_redirected = stdin_is_directly_redirected;
streams.io_chain = &proc_io_chain;
// Since this may be the foreground job, and since a builtin may execute another
// foreground job, we need to pretend to suspend this job while running the
// builtin, in order to avoid a situation where two jobs are running at once.
//
// The reason this is done here, and not by the relevant builtins, is that this
// way, the builtin does not need to know what job it is part of. It could
// probably figure that out by walking the job list, but it seems more robust to
// make exec handle things.
const int fg = j->is_foreground();
j->set_flag(job_flag_t::FOREGROUND, false);
// Note this call may block for a long time, while the builtin performs I/O.
p->status = builtin_run(parser, j->pgid, p->get_argv(), streams);
// Restore the fg flag, which is temporarily set to false during builtin
// execution so as not to confuse some job-handling builtins.
j->set_flag(job_flag_t::FOREGROUND, fg);
// If stdin has been redirected, close the redirection stream.
if (close_stdin) {
exec_close(local_builtin_stdin);
}
return true; // "success"
}
