Hi bluhm,
Thanks very much for your time and detailed explanation!
I update the patch, and you can review it when you are free, thanks!
Index: nohup.c
===================================================================
RCS file: /cvs/src/usr.bin/nohup/nohup.c,v
retrieving revision 1.17
diff -u -p -r1.17 nohup.c
--- nohup.c 26 Apr 2018 12:42:51 -0000 1.17
+++ nohup.c 14 Sep 2018 07:04:10 -0000
@@ -78,13 +78,14 @@ main(int argc, char *argv[])
if (argc < 2)
usage();
- if (isatty(STDOUT_FILENO))
+ if (isatty(STDOUT_FILENO) || errno == EBADF)
dofile();
if (pledge("stdio exec", NULL) == -1)
err(1, "pledge");
- if (isatty(STDERR_FILENO) && dup2(STDOUT_FILENO, STDERR_FILENO) == -1) {
+ if ((isatty(STDERR_FILENO) || errno == EBADF) &&
+ dup2(STDOUT_FILENO, STDERR_FILENO) == -1) {
/* may have just closed stderr */
(void)fprintf(stdin, "nohup: %s\n", strerror(errno));
exit(EXIT_MISC);
@@ -125,6 +126,8 @@ dupit:
(void)lseek(fd, (off_t)0, SEEK_END);
if (dup2(fd, STDOUT_FILENO) == -1)
err(EXIT_MISC, NULL);
+ if (fd > STDERR_FILENO)
+ (void)close(fd);
(void)fprintf(stderr, "sending output to %s\n", p);
}
On 9/12/2018 8:17 PM, Alexander Bluhm wrote:
> On Sun, Sep 09, 2018 at 11:13:40AM +0800, Nan Xiao wrote:
>> Honestly, I am still a little confused:
>
> Let's explain more context. Recently I found some deamons that
> accidently closed stdin, so I am sensible for this kind of error.
>
> nohup(1) tries to use nohup.out for stdout or stderr in some cases.
> If the file descriptors are closed in advance, this does not work.
> To fix these additional cases, I think we should also redirect to
> nohup.out if stdout or stderr is closed.
>
>> "nohup true 2>&-" means close stderr of nohup, right?
>
> Yes.
>
>>> errno = 0;
>>> if (isatty(STDOUT_FILENO) || errno == EBADF)
>>
>> Since we close stderr, why do we need additional check of stdout here?
>
> We should check both stdout and stderr. This is just an example
> how the check could work. Logic should be to redirect stdout or
> stderr to nohup.out, if it is a tty or if it has been closed.
>
> bluhm
>
--
Best Regards
Nan Xiao
