Thread: initdb --pwfile /dev/zero

Hi,

A colleague tried PG 14 internally and it failed during cluster creation, when
using the PGDG rpm packages. A bit of debugging shows that the problem is
that the packaging script specifies the password using --pwfile /dev/zero.

In 14+ this turns out to lead to an endless loop in pg_get_line_append().

The --pwfile /dev/zero was added in
https://git.postgresql.org/gitweb/?p=pgrpms.git;a=commitdiff;h=8ca418709ef49a1781f0ea8e6166b139106135ff

Devrim, what was the goal? Even in 13 this didn't achieve anything?


While I don't think passing /dev/zero is a good idea (it mostly seems to
circumvent ""password file \"%s\" is empty", without achieving anything, given
the password will be empty). I think we still ought to make pg_get_line() a
bit more resilient against '\0'?


Greetings,

Andres Freund

Andres Freund <andres@anarazel.de> writes:
> A colleague tried PG 14 internally and it failed during cluster creation, when
> using the PGDG rpm packages. A bit of debugging shows that the problem is
> that the packaging script specifies the password using --pwfile /dev/zero.

> In 14+ this turns out to lead to an endless loop in pg_get_line_append().

Well, that's because that file will source an infinite amount of stuff.

> I think we still ought to make pg_get_line() a
> bit more resilient against '\0'?

I don't think '\0' is the problem.  The only fix for this would be to
re-introduce some fixed limit on how long a line we'll read, which
I'm not too thrilled about.  I think this is better classified as
user error.

            regards, tom lane

Andres Freund <andres@anarazel.de> writes:
> On 2021-09-17 14:48:42 -0400, Tom Lane wrote:
>> I don't think '\0' is the problem.  The only fix for this would be to
>> re-introduce some fixed limit on how long a line we'll read, which
>> I'm not too thrilled about.

> Well, '\0' can be classified as the end of a line imo. So I don't think it'd
> require a line lenght limit.

Meh.  Those functions are specified to act like fgets(), which does not
think that \0 terminates a line AFAIK.

            regards, tom lane