Attempting to use an interval of time less than 1ms would cause \watch
to hang. This was confusing, so let's change the logic so as an
interval lower than 1ms behaves the same as 0.
Comments are added to mention that the internals of do_watch() had
better rely on "sleep_ms", the interval value in milliseconds. While on
it, this commit adds a test to check the behavior of interval values
less than 1ms.
\watch hanging for interval values less than 1ms existed before
6f9ee74d45aa, that has changed the code to support an interval value of
0.
Reported-by: Heikki Linnakangas
Author: Andrey M. Borodin, Michael Paquier
Discussion: https://postgr.es/m/88445e0e-3156-4b9d-afae-9a1a7b1631f6@iki.fi
Backpatch-through: 16
This fixes a couple of issues with the psql meta-commands mentioned
above when called repeatedly:
- The statement name is reset for each call. If a command errors out,
its send_mode would still be set, causing an incorrect path to be taken
when processing a query. For \bind_named, this could trigger an
assertion failure as a statement name is always expected for this
meta-command. This issue has been introduced by d55322b0da60.
- The memory allocated for bind parameters can be leaked. This is a bug
enlarged by d55322b0da60 that exists since 5b66de3433e2, as it is also
possible to leak memory with \bind in v16 and v17. This requires a fix
that will be done on the affected branches separately. This issue is
taken care of here for HEAD.
This patch tightens the cleanup of the state used for the extended
protocol meta-commands (bind parameters, send mode, statement name) by
doing it before running each meta-command on top of doing it once a
query has been processed, avoiding any leaks and the inconsistencies
when mixing calls, by refactoring the cleanup in a single routine used
in all the code paths where this step is required.
Reported-by: Alexander Lakhin
Author: Anthonin Bonnefoy
Discussion: https://postgr.es/m/2e5b89af-a351-ff0a-000c-037ac28314ab@gmail.com
Currently, only unnamed prepared statement are supported by psql with
the meta-command \bind. With only this command, it is not possible to
test named statement creation, execution or close through the extended
protocol.
This commit introduces three additional commands:
* \parse creates a prepared statement using the extended protocol,
acting as a wrapper of libpq's PQsendPrepare().
* \bind_named binds and executes an existing prepared statement using
the extended protocol, for PQsendQueryPrepared().
* \close closes an existing prepared statement using the extended
protocol, for PQsendClosePrepared().
This is going to be useful to add regression tests for the extended
query protocol, and I have some plans for that on separate threads.
Note that \bind relies on PQsendQueryParams().
The code of psql is refactored so as bind_flag is replaced by an enum in
_psqlSettings that tracks the type of libpq routine to execute, based on
the meta-command involved, with the default being PQsendQuery(). This
refactoring piece has been written by me, while Anthonin has implemented
the rest.
Author: Anthonin Bonnefoy, Michael Paquier
Reviewed-by: Aleksander Alekseev, Jelte Fennema-Nio
Discussion: https://postgr.es/m/CAO6_XqpSq0Q0kQcVLCbtagY94V2GxNP3zCnR6WnOM8WqXPK4nw@mail.gmail.com
Commit f5e4dedfa exposed libpq's internal function PQsocketPoll
without a lot of thought about whether that was an API we really
wanted to chisel in stone. The main problem with it is the use of
time_t to specify the timeout. While we do want an absolute time
so that a loop around PQsocketPoll doesn't have problems with
timeout slippage, time_t has only 1-second resolution. That's
already problematic for libpq's own internal usage --- for example,
pqConnectDBComplete has long had a kluge to treat "connect_timeout=1"
as 2 seconds so that it doesn't accidentally round to nearly zero.
And it's even less likely to be satisfactory for external callers.
Hence, let's change this while we still can.
The best idea seems to be to use an int64 count of microseconds since
the epoch --- basically the same thing as the backend's TimestampTz,
but let's use the standard Unix epoch (1970-01-01) since that's more
likely for clients to be easy to calculate. Millisecond resolution
would be plenty for foreseeable uses, but maybe the day will come that
we're glad we used microseconds.
Also, since time(2) isn't especially helpful for computing timeouts
defined this way, introduce a new function PQgetCurrentTimeUSec
to get the current time in this form.
Remove the hack in pqConnectDBComplete, so that "connect_timeout=1"
now means what you'd expect.
We can also remove the "#include <time.h>" that f5e4dedfa added to
libpq-fe.h, since there's no longer a need for time_t in that header.
It seems better for v17 not to enlarge libpq-fe.h's include footprint
from what it's historically been, anyway.
I also failed to resist the temptation to do some wordsmithing
on PQsocketPoll's documentation.
Patch by me, per complaint from Dominique Devienne.
Discussion: https://postgr.es/m/913559.1718055575@sss.pgh.pa.us
The documentation says that PQsslAttribute(conn, "alpn") returns an
empty string if ALPN is not used, but the code actually returned
NULL. Fix the code to match the documentation.
Reported-by: Michael Paquier
Discussion: https://www.postgresql.org/message-id/ZideNHji0G4gxmc3@paquier.xyz
libpq now always tries to send ALPN. With the traditional negotiated
SSL connections, the server accepts the ALPN, and refuses the
connection if it's not what we expect, but connecting without ALPN is
still OK. With the new direct SSL connections, ALPN is mandatory.
NOTE: This uses "TBD-pgsql" as the protocol ID. We must register a
proper one with IANA before the release!
Author: Greg Stark, Heikki Linnakangas
Reviewed-by: Matthias van de Meent, Jacob Champion
After installing the SIGINT handler in psql, SIGINT can no longer cancel
database reconnections. For instance, if the user starts a reconnection
and then needs to do some form of interaction (ie psql is polling),
there is no way to cancel the reconnection process currently.
Use PQconnectStartParams() in order to insert a cancel_pressed check
into the polling loop.
Tristan Partin, reviewed by Gurjeet Singh, Heikki Linnakangas, Jelte
Fennema-Nio, and me.
Discussion: http://postgr.es/m/D08WWCPVHKHN.3QELIKZJ2D9RZ@neon.tech
do_watch had some leftover logic for enabling siglongjmp out of
waiting for input. That's never done anything on Windows (cf.
psql_cancel_callback), and do_watch no longer relies on it for
non-Windows, so let's drop it.
Also, when the user cancels \watch by pressing ^C, the Windows
code would run the query one more time before exiting. That doesn't
seem very desirable, and it's not what happens on other platforms.
Use the "done" flag similarly to non-Windows to avoid the extra query
execution.
Yugo Nagata (with minor fixes by me)
Discussion: https://postgr.es/m/20240305220552.85fd4afd6b6b8103bf4fe3d0@sraoss.co.jp
All commands accepting arguments, handling them with OT_NORMAL, OT_SQLID
or OT_SQLIDHACK, should call ignore_slash_options() in inactive branch
to scan and discard extra arguments. All the backslash commands that
handle arguments do so, except \bind.
This commit adds the missing ignore_slash_options to \bind's inactive
branch. This inconsistency is a logic bug, however the behavior happens
to be unchanged as any extra arguments are discarded later in
HandleSlashCmds(), so no backpatch is done.
While on it, this adds \bind to the list of backslash commands where
inactive \if branches are checked in the tests for psql.
Reported-by: Jelte Fennema-Nio
Author: Anthonin Bonnefoy
Discussion: https://postgr.es/m/CAGECzQR1+udGKz+FbHiCQ7CWDiF1fCGi2xYuvQUODdMAfJbaLA@mail.gmail.com
Many psql backslash commands tolerate trailing semicolons, even
though that's not part of the official syntax. These did not.
They tried to, by passing semicolon = true to psql_scan_slash_option,
but that function ignored this parameter in OT_WHOLE_LINE mode.
Teach it to do the right thing, and remove the now-duplicative
logic in exec_command_help.
Discussion: https://postgr.es/m/2012251.1704746912@sss.pgh.pa.us
Essentially this moves the non-interactive part of psql's "\password"
command into an exported client function. The password is not sent to the
server in cleartext because it is "encrypted" (in the case of scram and md5
it is actually hashed, but we have called these encrypted passwords for a
long time now) on the client side. This is good because it ensures the
cleartext password is never known by the server, and therefore won't end up
in logs, pg_stat displays, etc.
In other words, it exists for the same reason as PQencryptPasswordConn(), but
is more convenient as it both builds and runs the "ALTER USER" command for
you. PQchangePassword() uses PQencryptPasswordConn() to do the password
encryption. PQencryptPasswordConn() is passed a NULL for the algorithm
argument, hence encryption is done according to the server's
password_encryption setting.
Also modify the psql client to use the new function. That provides a builtin
test case. Ultimately drivers built on top of libpq should expose this
function and its use should be generally encouraged over doing ALTER USER
directly for password changes.
Author: Joe Conway
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/flat/b75955f7-e8cc-4bbd-817f-ef536bacbe93%40joeconway.com
Since C99, there can be a trailing comma after the last value in an
enum definition. A lot of new code has been introducing this style on
the fly. Some new patches are now taking an inconsistent approach to
this. Some add the last comma on the fly if they add a new last
value, some are trying to preserve the existing style in each place,
some are even dropping the last comma if there was one. We could
nudge this all in a consistent direction if we just add the trailing
commas everywhere once.
I omitted a few places where there was a fixed "last" value that will
always stay last. I also skipped the header files of libpq and ecpg,
in case people want to use those with older compilers. There were
also a small number of cases where the enum type wasn't used anywhere
(but the enum values were), which ended up confusing pgindent a bit,
so I left those alone.
Discussion: https://www.postgresql.org/message-id/flat/386f8c45-c8ac-4681-8add-e3b0852c1620%40eisentraut.org
If any of these commands fail during editing or pre-processing, the
command stored in the query buffer would remain around without being
executed immediately as PSQL_CMD_ERROR is returned as status. The next
command provided by the user would run it, likely causing failures as
this could include silently some of the contents generated automatically
for views or functions.
The problems would be different depending on the psql meta-command used:
- For \ev and \ef, some errors can happen in a predictable way while
doing an object lookup or while creating an object command. A failure
while editing is equally problematic, but the class of failures
happening in the code path of do_edit() are unlikely. The query reset
is kept in exec_command_ef_ev() as a query may be unchanged.
- For \e, error can happen while editing.
In both cases, the query buffer is reset on error for an incorrect file
number provided, whose value check is done before filling up the query
buffer.
This is a slight change of behavior compared to the past for some of the
predictable error patterns for \ev and \ef, so for now I have made the
choice to not backpatch this commit (argument particularly available for
v11 that's going to be EOL'd soon). Perhaps this could be revisited
later depending on the feedback of this new behavior.
Author: Ryoga Yoshida, Michael Paquier
Reviewed-by: Aleksander Alekseev, Kyotaro Horiguchi
Discussion: https://postgr.es/m/01419622d84ef093fd4fe585520bf03c@oss.nttdata.com
When running a repeat query with \watch in psql, it can be
helpful to be able to stop the watch process when the query
no longer returns the expected amount of rows. An example
would be to watch for the presence of a certain event in
pg_stat_activity and stopping when the event is no longer
present, or to watch an index creation and stop when the
index is created.
This adds a min_rows=MIN parameter to \watch which can be
set to a non-negative integer, and the watch query will
stop executing when it returns less than MIN rows.
Author: Greg Sabino Mullane <htamfids@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CAKAnmmKStATuddYxP71L+p0DHtp9Rvjze3XRoy0Dyw67VQ45UA@mail.gmail.com
psql's --echo-hidden, --log-file, and --single-step options
generate extra lines to clearly separate queries from other output.
Presently, these extra lines are not valid SQL comments, which
makes them a hazard for anyone trying to copy/paste the decorated
queries into a client or query editor. This commit replaces the
starting and ending asterisks in these extra lines with forward
slashes so that they are valid SQL comments that can be copy/pasted
without incident.
Author: Kirk Wolak
Reviewed-by: Pavel Stehule, Laurenz Albe, Tom Lane, Alvaro Herrera, Andrey Borodin
Discussion: https://postgr.es/m/CACLU5mTFJRJYtbvmZ26txGgmXWQo0hkGhH2o3hEquUPmSbGtBw%40mail.gmail.com
With the addition of INHERIT and SET options for role grants,
the historical display of role memberships in \du/\dg is woefully
inadequate. Besides those options, there are pre-existing
shortcomings that you can't see the ADMIN option nor the grantor.
To fix this, remove the "Member of" column from \du/\dg altogether
(making that output usefully narrower), and invent a new meta-command
"\drg" that is specifically for displaying role memberships. It
shows one row for each role granted to the selected role(s), with
the grant options and grantor.
We would not normally back-patch such a feature addition post
feature freeze, but in this case the change is mainly driven by
v16 changes in the server, so it seems appropriate to include it
in v16.
Pavel Luzanov, with bikeshedding and review from a lot of people,
but particularly David Johnston
Discussion: https://postgr.es/m/b9be2d0e-a9bc-0a30-492f-a4f68e4f7740@postgrespro.ru
Run pgindent, pgperltidy, and reformat-dat-files.
This set of diffs is a bit larger than typical. We've updated to
pg_bsd_indent 2.1.2, which properly indents variable declarations that
have multi-line initialization expressions (the continuation lines are
now indented one tab stop). We've also updated to perltidy version
20230309 and changed some of its settings, which reduces its desire to
add whitespace to lines to make assignments etc. line up. Going
forward, that should make for fewer random-seeming changes to existing
code.
Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
Don't use PSQL_WATCH_PAGER when stdin/stdout are not a terminal.
This corresponds to the restrictions on when other commands will
use [PSQL_]PAGER. There isn't a lot of sense in trying to use a
pager in non-interactive cases, and doing so allows an environment
setting to break our tests.
Also, ignore PSQL_WATCH_PAGER if it is set but empty or all-blank,
for the same reasons we ignore such settings of [PSQL_]PAGER (see
commit 18f8f784c).
No documentation change is really needed, since there is nothing
suggesting that these constraints on [PSQL_]PAGER didn't already
apply to PSQL_WATCH_PAGER too. But I rearranged the text
a little to make it read more naturally (IMHO anyway).
Per report from Pavel Stehule. Back-patch to v15 where
PSQL_WATCH_PAGER was introduced.
Discussion: https://postgr.es/m/CAFj8pRDTwFzmEWdA-gdAcUh0ZnxUioSfTMre71WyB_wNJy-8gw@mail.gmail.com
Make the \g, \o, \w, and \copy commands set these variables
when closing a pipe. We missed doing this in commit b0d8f2d98,
but it seems like a good idea.
There are some remaining places in psql that intentionally don't
update these variables after running a child program:
* pager invocations
* backtick evaluation within a prompt
* \e (edit query buffer)
Corey Huinker and Tom Lane
Discussion: https://postgr.es/m/CADkLM=eSKwRGF-rnRqhtBORRtL49QsjcVUCa-kLxKTqxypsakw@mail.gmail.com
\watch can now be told to stop after N executions of the query.
With the idea that we might want to add more options to \watch
in future, this patch generalizes the command's syntax to a list
of name=value options, with the interval allowed to omit the name
for backwards compatibility.
Andrey Borodin, reviewed by Kyotaro Horiguchi, Nathan Bossart,
Michael Paquier, Yugo Nagata, and myself
Discussion: https://postgr.es/m/CAAhFRxiZ2-n_L1ErMm9AZjgmUK=qS6VHb+0SaMn8sqqbhF7How@mail.gmail.com
These are set after a \! command or a backtick substitution.
SHELL_ERROR is just "true" for error (nonzero exit status) or "false"
for success, while SHELL_EXIT_CODE records the actual exit status
following standard shell/system(3) conventions.
Corey Huinker, reviewed by Maxim Orlov and myself
Discussion: https://postgr.es/m/CADkLM=cWao2x2f+UDw15W1JkVFr_bsxfstw=NGea7r9m4j-7rQ@mail.gmail.com
A failure in parsing the interval value defined in the \watch command
was silently switched to 1s of interval between two queries, which can
be confusing. This commit improves the error handling, and a couple of
tests are added to check after:
- An incorrect value.
- An out-of-range value.
- A negative value.
A value of zero is able to work now, meaning that there is no interval
of time between two queries in a \watch loop. No backpatch is done, as
it could break existing applications.
Author: Andrey Borodin
Reviewed-by: Kyotaro Horiguchi, Nathan Bossart, Michael Paquier
Discussion: https://postgr.es/m/CAAhFRxiZ2-n_L1ErMm9AZjgmUK=qS6VHb+0SaMn8sqqbhF7How@mail.gmail.com
psql_scan_slash_option() returns a malloc()'d result through a
PQExpBuffer, and exec_command_bind() was doing an extra allocation of
this option for no effect.
Introduced in 5b66de3.
Author: Kyotaro Horiguchi
Reviewed-by: Corey Huinker
Discussion: https://postgr.es/m/20230221.115555.89096938631423206.horikyota.ntt@gmail.com
This allows an optional "S" modifier to be added to \dp and \z, to
have them include system objects in the list.
Note that this also changes the behaviour of a bare \dp or \z without
the "S" modifier to include temp objects in the list, and exclude
information_schema objects, making them consistent with other psql
meta-commands.
Nathan Bossart, reviewed by Maxim Orlov.
Discussion: https://postgr.es/m/20221206193606.GB3078082@nathanxps13
Some options of these commands need to be able to identify the start
of the function body within the output of pg_get_functiondef().
It used to be that that always began with "AS", but since the
introduction of new-style SQL functions, it might also start with
"BEGIN" or "RETURN". Fix that on the psql side, and add some
regression tests.
Noted by me awhile ago, but I didn't do anything about it.
Thanks to David Johnston for a nag.
Discussion: https://postgr.es/m/AM9PR01MB8268D5CDABDF044EE9F42173FE8C9@AM9PR01MB8268.eurprd01.prod.exchangelabs.com
Some callers didn't check the return value of pclose() or
ClosePipeStream() correctly. Either they didn't check it at all or
they treated it like the return of fclose().
The correct way is to first check whether the return value is -1, and
then report errno, and then check the return value like a result from
system(), for which we already have wait_result_to_str() to make it
simpler. To make this more compact, expand wait_result_to_str() to
also handle -1 explicitly.
Reviewed-by: Ankit Kumar Pandey <itsankitkp@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/8cd9fb02-bc26-65f1-a809-b1cb360eef73@enterprisedb.com
This adds a new psql command \bind that sets query parameters and
causes the next query to be sent using the extended query protocol.
Example:
SELECT $1, $2 \bind 'foo' 'bar' \g
This may be useful for psql scripting, but one of the main purposes is
also to be able to test various aspects of the extended query protocol
from psql and to write tests more easily.
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/e8dd1cd5-0e04-3598-0518-a605159fe314@enterprisedb.com
In a similar effort to f01592f91, here we mostly rename shadowed local
variables to remove the warnings produced when compiling with
-Wshadow=compatible-local.
This fixes 63 warnings and leaves just 5.
Author: Justin Pryzby, David Rowley
Reviewed-by: Justin Pryzby
Discussion https://postgr.es/m/20220817145434.GC26426%40telsasoft.com
In a similar effort to f736e188c and 110d81728, fixup various usages of
string functions where a more appropriate function is available and more
fit for purpose.
These changes include:
1. Use cstring_to_text_with_len() instead of cstring_to_text() when
working with a StringInfoData and the length can easily be obtained.
2. Use appendStringInfoString() instead of appendStringInfo() when no
formatting is required.
3. Use pstrdup(...) instead of psprintf("%s", ...)
4. Use pstrdup(...) instead of psprintf(...) (with no formatting)
5. Use appendPQExpBufferChar() instead of appendPQExpBufferStr() when the
length of the string being appended is 1.
6. appendStringInfoChar() instead of appendStringInfo() when no formatting
is required and string is 1 char long.
7. Use appendPQExpBufferStr(b, .) instead of appendPQExpBuffer(b, "%s", .)
8. Don't use pstrdup when it's fine to just point to the string constant.
I (David) did find other cases of #8 but opted to use #4 instead as I
wasn't certain enough that applying #8 was ok (e.g in hba.c)
Author: Ranier Vilela, David Rowley
Discussion: https://postgr.es/m/CAApHDvo2j2+RJBGhNtUz6BxabWWh2Jx16wMUMWKUjv70Ver1vg@mail.gmail.com
More than twenty years ago (79fcde48b), we hacked the postmaster
to avoid a core-dump on systems that didn't support fflush(NULL).
We've mostly, though not completely, hewed to that rule ever since.
But such systems are surely gone in the wild, so in the spirit of
cleaning out no-longer-needed portability hacks let's get rid of
multiple per-file fflush() calls in favor of using fflush(NULL).
Also, we were fairly inconsistent about whether to fflush() before
popen() and system() calls. While we've received no bug reports
about that, it seems likely that at least some of these call sites
are at risk of odd behavior, such as error messages appearing in
an unexpected order. Rather than expend a lot of brain cells
figuring out which places are at hazard, let's just establish a
uniform coding rule that we should fflush(NULL) before these calls.
A no-op fflush() is surely of trivial cost compared to launching
a sub-process via a shell; while if it's not a no-op then we likely
need it.
Discussion: https://postgr.es/m/2923412.1661722825@sss.pgh.pa.us
The setting controls tha maximum length of the header line in expanded
format output. Possible settings are full, column, page, or an integer.
the default is full, the current behaviour, and in this case the header
line is the length of the widest line of output. column causes the
header to be truncated to the width of the first column, page causes it
to be truncated to the width of the terminal page, and an integer causes
it to be truncated to that value. If the full value is less than the
page or integer value no truncation occurs. If given without an argument
this option prints its current setting.
Platon Pronko, somewhat modified by me.
Discussion: https://postgr.es/m/f03d38a3-db96-a56e-d1bc-dbbc80bbde4d@gmail.com
sigwait() is in SUSv2 and all targeted Unix systems have it. An earlier
pre-standard function prototype existed on some older systems, but we
no longer need a workaround for that.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Greg Stark <stark@mit.edu>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/CA+hUKGJ3LHeP9w5Fgzdr4G8AnEtJ=z=p6hGDEm4qYGEUX5B6fQ@mail.gmail.com
When you hit ^C, the terminal driver in Unix-like systems echoes "^C" as
well as sending an interrupt signal (depending on stty settings). At
least libedit (but maybe also libreadline) is then confused about the
current cursor location, and corrupts the display if you try to scroll
back. Fix, by moving to a new line before the next prompt is displayed.
Back-patch to all supported released.
Author: Pavel Stehule <pavel.stehule@gmail.com>
Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/3278793.1626198638%40sss.pgh.pa.us
Get rid of the separate "FATAL" log level, as it was applied
so inconsistently as to be meaningless. This mostly involves
s/pg_log_fatal/pg_log_error/g.
Create a macro pg_fatal() to handle the common use-case of
pg_log_error() immediately followed by exit(1). Various
modules had already invented either this or equivalent macros;
standardize on pg_fatal() and apply it where possible.
Invent the ability to add "detail" and "hint" messages to a
frontend message, much as we have long had in the backend.
Except where rewording was needed to convert existing coding
to detail/hint style, I have (mostly) resisted the temptation
to change existing message wording.
Patch by me. Design and patch reviewed at various stages by
Robert Haas, Kyotaro Horiguchi, Peter Eisentraut and
Daniel Gustafsson.
Discussion: https://postgr.es/m/1363732.1636496441@sss.pgh.pa.us
Plain \dconfig is basically equivalent to SHOW except that you can
give it a pattern with wildcards, either to match multiple GUCs or
because you don't exactly remember the name you want.
\dconfig+ adds type, context, and access-privilege information,
mainly because every other kind of object privilege has a psql command
to show it, so GUC privileges should too. (A form of this command was
in some versions of the patch series leading up to commit a0ffa885e.
We pulled it out then because of doubts that the design and code were
up to snuff, but I think subsequent work has resolved that.)
In passing, fix incorrect completion of GUC names in GRANT/REVOKE
ON PARAMETER: a0ffa885e neglected to use the VERBATIM form of
COMPLETE_WITH_QUERY, so it misbehaved for custom (qualified) GUC
names.
Mark Dilger and Tom Lane
Discussion: https://postgr.es/m/3118455.1649267333@sss.pgh.pa.us
When we need to identify the home directory on non-Windows, first
consult getenv("HOME"). If that's empty or unset, fall back
on our previous method of checking the <pwd.h> database.
Preferring $HOME allows the user to intentionally point at some
other directory, and it seems to be in line with the behavior of
most other utilities. However, we shouldn't rely on it completely,
as $HOME is likely to be unset when running as a daemon.
Anders Kaseorg
Discussion: https://postgr.es/m/1634252654444.90107@mit.edu
The ACL is printed when you add + to the command, similarly to
various other psql backslash commands.
Along the way, move the code for this into describe.c,
where it is a better fit (and can share some code).
Pavel Luzanov, reviewed by Georgios Kokolatos
Discussion: https://postgr.es/m/6d722115-6297-bc53-bb7f-5f150e765299@postgrespro.ru
