When we eliminated "unnecessary" wakeups of the syslogger process, we
broke size-based logfile rotation on Windows, because on that platform
data transfer is done in a separate thread.  While non-Windows platforms
would recheck the output file size after every log message, Windows only
did so when the control thread woke up for some other reason, which might
be quite infrequent.  Per bug #7814 from Tsunezumi.  Back-patch to 9.2
where the problem was introduced.

Jeff Janes

Fully update git head, and update back branches in ./COPYRIGHT and
legal.sgml files.

We need to avoid calling WaitLatch with timeouts exceeding INT_MAX.
Fortunately a simple clamp will do the trick, since no harm is done if
the wait times out before it's really time to rotate the log file.
Per bug #7670 (probably bug #7545 is the same thing, too).

In passing, fix bogus definition of log_rotation_age's maximum value in
guc.c --- it was numerically right, but only because MINS_PER_HOUR and
SECS_PER_MINUTE have the same value.

Back-patch to 9.2.  Before that, syslogger wasn't using WaitLatch.

In the previous coding, new backend processes would attempt to create their
self-pipe during the OwnLatch call in InitProcess.  However, pipe creation
could fail if the kernel is short of resources; and the system does not
recover gracefully from a FATAL error right there, since we have armed the
dead-man switch for this process and not yet set up the on_shmem_exit
callback that would disarm it.  The postmaster then forces an unnecessary
database-wide crash and restart, as reported by Sean Chittenden.

There are various ways we could rearrange the code to fix this, but the
simplest and sanest seems to be to split out creation of the self-pipe into
a new function InitializeLatchSupport, which must be called from a place
where failure is allowed.  For most processes that gets called in
InitProcess or InitAuxiliaryProcess, but processes that don't call either
but still use latches need their own calls.

Back-patch to 9.1, which has only a part of the latch logic that 9.2 and
HEAD have, but nonetheless includes this bug.

In the original coding of the log rotation stuff, we did not bother to make
the truncation logic work for the very first rotation after postmaster
start (or after a syslogger crash and restart).  It just always appended
in that case.  It did not seem terribly important at the time, but we've
recently had two separate complaints from people who expected it to work
unsurprisingly.  (Both users tend to restart the postmaster about as often
as a log rotation is configured to happen, which is maybe not typical use,
but still...)  Since the initial log file is opened in the postmaster,
fixing this requires passing down some more state to the syslogger child
process.

It's always been like this, so back-patch to all supported branches.

There was a wild mix of calling conventions: Some were declared to
return void and didn't return, some returned an int exit code, some
claimed to return an exit code, which the callers checked, but
actually never returned, and so on.

Now all of these functions are declared to return void and decorated
with attribute noreturn and don't return.  That's easiest, and most
code already worked that way.

commit-fest.

syslogger was coded to wake up once per second whether there was anything
useful to do or not.  As part of our campaign to reduce the server's idle
power consumption, change it to use a latch for waiting.  Now, in the
absence of any data to log or any signals to service, it will only wake up
at the programmed logfile rotation times (if any).

If it fails to open a new log file, the syslogger assumes there's something
wrong with its parameters (such as log_directory), and stops attempting
automatic time-based or size-based log file rotations.  Sending it SIGHUP
is supposed to start that up again.  However, the original coding for that
was really bogus, involving clobbering a couple of GUC variables and hoping
that SIGHUP processing would restore them.  Get rid of that technique in
favor of maintaining a separate flag showing we've turned rotation off.
Per report from Mark Kirkwood.

Also, the syslogger will automatically attempt to create the log_directory
directory if it doesn't exist, but that was only happening at startup.
For consistency and ease of use, it should do the same whenever the value
of log_directory is changed by SIGHUP.

Back-patch to all supported branches.

The original coding of the syslogger had an arbitrary limit of 20 large
messages concurrently in progress, after which it would just punt and dump
message fragments to the output file separately.  Our ambitions are a bit
higher than that now, so allow the data structure to expand as necessary.

Reported and patched by Andrew Dunstan; some editing by Tom

This causes an exception when running under a debugger or in particular
when running on a debug version of Windows.

Patch from MauMau

Purely cosmetic patch to make our coding standards more consistent ---
we were doing symbolic some places and octal other places.  This patch
fixes all C-coded uses of mkdir, chmod, and umask.  There might be some
other calls I missed.  Inconsistency noted while researching tablespace
directory permissions issue.

log files created by the syslogger process.

In passing, make unix_file_permissions display its value in octal, same
as log_file_mode now does.

Martin Pihlak

reload and rotation signals, and a helper thread reads messages from the
pipe and writes them to the log file. However, server code isn't generally
thread-safe, so if both try to do e.g palloc()/pfree() at the same time,
bad things will happen. To fix that, use a critical section (which is like
a mutex) to enforce that only one the threads are active at a time.

Windows, thanks to a feature in CRT called Parameter Validation.

Backpatch to 8.2, which is the oldest version supported on Windows. In
8.2 and 8.3 also backpatch the earlier change to use DEVNULL instead of
NULL_DEV #define for a /dev/null-like device. NULL_DEV was hard-coded to
"/dev/null" regardless of platform, which didn't work on Windows, while
DEVNULL works on all platforms. Restarting syslogger didn't work on
Windows on versions 8.3 and below because of that.

Tsutomu Yamada

output filename if CSV logging was enabled and only one of the two possible
output files got rotated during a particular call (which would, in fact,
typically be the case during a size-based rotation).  This would amount to
about MAXPGPATH (1KB) per rotation, and it's been there since the CSV
code was put in, so it's surprising that nobody noticed it before.
Per bug #5196 from Thomas Poindessous.

Pointed out by Debian's lintian.

provided by Andrew.

the cause of the "could not write to log file: Bad file descriptor"
errors reported at
http://archives.postgresql.org//pgsql-general/2008-06/msg00193.php

Backpatch to 8.3, the race condition was introduced by the CSV logging
patch.

Analysis and patch by Gurjeet Singh.

Robert Haas

unnecessary thread address output parameter, to make this code look more
like that in pg_restore.

platform-specific spellings of /dev/null.  But one should be enough, so
settle on DEVNULL.

data structures and backend internal APIs.  This solves problems we've seen
recently with inconsistent layout of pg_control between machines that have
32-bit time_t and those that have already migrated to 64-bit time_t.  Also,
we can get out from under the problem that Windows' Unix-API emulation is not
consistent about the width of time_t.

There are a few remaining places where local time_t variables are used to hold
the current or recent result of time(NULL).  I didn't bother changing these
since they do not affect any cross-module APIs and surely all platforms will
have 64-bit time_t before overflow becomes an actual risk.  time_t should
be avoided for anything visible to extension modules, however.

a double-pfree crash and another that effectively disabled size-based rotation
for CSV logs.  Also suppress a memory leak and make some trivial cosmetic
improvements.  Per bug #3901 from Chris Hoover and additional code-reading.

avoid this problem in the future.)

per ITAGAKI Takahiro.  Also, rewrite syslogger_forkexec() in hopes of
eliminating the confusion in the first place.