From: Ron Yorston
> Sent: 26 April 2022 16:10
>
> A user reports:
>
> I know this code is wrong but it shouldn't cause the shell to exit:
> echo text >&9999
> This instead cause the creation of a file:
> echo text >&9999999999
>
> I think it would be better if they report Bad file descriptor
>
> The first case happens because save_fd_on_redirect() causes an exit
> when dup_CLOEXEC() returns any error other than EBADF. Despite its
> name dup_CLOEXEC() actually uses fcntl(2) which returns EINVAL when
> the file descriptor is greater than the maximum allowed.
>
> The second case is due to any numeric string longer than nine digits
> being treated as a file name rather than a number. Bash doesn't
> do this.
...
> @@ -9635,7 +9634,7 @@ expredir(union node *n)
> if (fn.list == NULL)
> ash_msg_and_raise_error("redir error");
> #if BASH_REDIR_OUTPUT
> - if (!isdigit_str9(fn.list->text)) {
> + if (!isdigit_str(fn.list->text)) {
> /* >&file, not >&fd */
> if (redir->nfile.fd != 1) /* 123>&file
> - BAD */
> ash_msg_and_raise_error("redir
> error");
> @@ -11945,19 +11944,21 @@ static void
> fixredir(union node *n, const char *text, int err)
> {
> int fd;
> + struct rlimit limit;
>
> TRACE(("Fix redir %s %d\n", text, err));
> if (!err)
> n->ndup.vname = NULL;
>
> + getrlimit(RLIMIT_NOFILE, &limit);
Doing an extra system call seems suboptimal.
Why not just allow EINVAL as equivalent to EBADF later on?
> fd = bb_strtou(text, NULL, 10);
Can't you do this conversion earlier and check the 'unconverted'
character for being '\0'?
Would save scanning the string twice.
> - if (!errno && fd >= 0)
> + if (!errno && fd >= 0 && fd < limit.rlim_cur - 1)
> n->ndup.dupfd = fd;
> else if (LONE_DASH(text))
> n->ndup.dupfd = -1;
> else {
> if (err)
> - raise_error_syntax("bad fd number");
> + raise_error_syntax(strerror(EBADF));
> n->ndup.vname = makename();
...
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT,
UK
Registration No: 1397386 (Wales)
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