Re: [HACKERS] Potential issue with alter system

[Joshua D. Drake]

On 05/04/2017 12:49 PM, Tom Lane wrote:

"Joshua D. Drake"  writes:

So I did this:




If you have other entries you want to keep in the postgresql.auto.conf
file, you could get away with manually editing it to remove the newline.


Got it. Thanks for digging in. This is actually a very real and easy way 
to explain to people why they need to keep up to date on their dot releases.


Thanks,

JD



regards, tom lane




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Re: [HACKERS] Potential issue with alter system

[Tom Lane]

"Joshua D. Drake"  writes:
> So I did this:

> postgres=# alter system set archive_command to 'rsynv -av %p 
> postgres@52.3.141.224:/data/archive/%f
> ';

> Note the new line. It properly created in postgresql.auto.conf:

> archive_command = 'rsynv -av %p postgres@52.3.141.224:/data/archive/%f
> '
> (note the new line)

Ugh.  That's broken --- we don't support newlines within values in
postgresql.conf files.

[ pokes around ... ]  HEAD seems to reject this properly:

regression=# alter system set archive_command to 'rsynv -av %p 
postgres@52.3.141.224:/data/archive/%f
regression'# ';
ERROR:  parameter value for ALTER SYSTEM must not contain a newline

> This is 9.5.2 (Yes, I know... I am in the process of setting up 
> replication to 9.5.6 for failover).

Ah.  [ digs further... ]  Yup, we fixed that in 9.5.3:

Author: Tom Lane 
Branch: master Release: REL9_6_BR [99f3b5613] 2016-04-04 18:05:23 -0400
Branch: REL9_5_STABLE Release: REL9_5_3 [f3d17491c] 2016-04-04 18:05:23 -0400
Branch: REL9_4_STABLE Release: REL9_4_8 [28148e258] 2016-04-04 18:05:24 -0400

Disallow newlines in parameter values to be set in ALTER SYSTEM.

As noted by Julian Schauder in bug #14063, the configuration-file parser
doesn't support embedded newlines in string literals.  While there might
someday be a good reason to remove that restriction, there doesn't seem
to be one right now.  However, ALTER SYSTEM SET could accept strings
containing newlines, since many of the variable-specific value-checking
routines would just see a newline as whitespace.  This led to writing a
postgresql.auto.conf file that was broken and had to be removed manually.

Pending a reason to work harder, just throw an error if someone tries this.

In passing, fix several places in the ALTER SYSTEM logic that failed to
provide an errcode() for an ereport(), and thus would falsely log the
failure as an internal XX000 error.

Back-patch to 9.4 where ALTER SYSTEM was introduced.


If you have other entries you want to keep in the postgresql.auto.conf
file, you could get away with manually editing it to remove the newline.

regards, tom lane


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[HACKERS] Potential issue with alter system

[Joshua D. Drake]

Folks,

So I did this:

postgres=# alter system set archive_command to 'rsynv -av %p 
postgres@52.3.141.224:/data/archive/%f

';

Note the new line. It properly created in postgresql.auto.conf:

archive_command = 'rsynv -av %p postgres@52.3.141.224:/data/archive/%f
'
(note the new line)

I noticed I spelled rsync wrong and now I get this:

postgres=# alter system set archive_command to 'rsync -av %p 
postgres@52.3.141.224:/data/archive/%f'

;
ERROR:  could not parse contents of file "postgresql.auto.conf"

This is 9.5.2 (Yes, I know... I am in the process of setting up 
replication to 9.5.6 for failover).


JD

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PostgreSQL Centered full stack support, consulting and development.
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Unless otherwise stated, opinions are my own.


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