sms at antinode
Sep 7, 2011, 9:33 PM
Post #1 of 4
(211 views)
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GnuPG 1.4.11 v. VMS batch mode
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Greetings:
A victim of my GnuPG 1.4.11 for VMS kit recently ran into an
interesting problem. A DCL procedure (think: "shell script") works when
run interactively, but loops when run as a batch job (think: "at/cron
job"?). I think that I've figured out what's happening, and I thought
that I'd get a consultation on a proposed fix.
The (apparently harmless) problem command looks like this:
pipe gpg -d -o bat.out --passphrase-fd 0 login.com-gpg < pp.txt
The problem seems (to me, at the moment) to be bad general code, but the
problem case may never occur on a UNIX(-like) system, so perhaps no one
else would have noticed it. During the program initialization,
util/ttyio.c:init_ttyfp() gets called. It uses ctermid() to get the
name of the controlling terminal. For a batch job on VMS, this comes
back as the disk name (which is what I'd guess never happens elsewhere).
The program tries to fopen() this, which fails, because it's a disk, not
a terminal. The program then tries to write a "cannot open" error
message to the terminal, but it won't do that until it gets the terminal
I/O set up properly, and for that it calls init_ttyfp(). Lather, rinse,
...
The following change seems to solve the looping in a
plausible/harmless way (slightly enhancing the message, because a
typical VMS user might not otherwise guess why anyone is trying to open
a disk device):
--- util/ttyio.c_orig 2010-09-28 04:39:05 -0500
+++ util/ttyio.c 2011-09-07 22:19:34 -0500
@@ -185,7 +185,8 @@
#else
ttyfp = batchmode? stderr : fopen( tty_get_ttyname (), "r+");
if( !ttyfp ) {
- log_error("cannot open `%s': %s\n",
+ initialized = 1; /* Don't come back again, ever. */
+ log_error("cannot open tty, `%s': %s\n",
tty_get_ttyname (), strerror(errno) );
exit(2);
}
The victim still needs to specify option(s) like "--batch" to avoid the
fatal "cannot open [tty]" error, but this way it dies promptly, emitting
a message like:
gpg: cannot open tty, `_ALP$DKC0:': no such file or directory
which, while not wonderfully informative, certainly beats an endless
loop (and no message).
On VMS, it should be relatively easy to check the process mode during
initialization, and set the "--batch" flag ("batchmode"?) automatically
for a batch job. I haven't yet thought of a good reason not to do this,
but I'm always open to a good counter-argument.
Any wisdom would be gratefully received.
------------------------------------------------------------------------
Steven M. Schweda sms [at] antinode-inf
382 South Warwick Street (+1) 651-699-9818
Saint Paul MN 55105-2547
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