Re: issue with meson builds on msys2 - Mailing list pgsql-hackers

Hi,

On 2023-05-15 13:13:26 -0700, Andres Freund wrote:
> It wouldn't really - the echo $? inside the system() would report the
> error. Which it doesn't - note the "0" in the second output.

Ah. Interesting. Part of the issue is perl (or msys?) swalling some error
details.

I could see more details in strace once I added another layer of shell
evaluation inside the system() call.

  190  478261 [main] bash 44432 frok::parent: CreateProcessW (C:\tools\nmsys64\usr\bin\bash.exe,
C:\tools\nmsys64\usr\bin\bash.exe,0, 0, 1, 0x420, 0, 0, 0x7FFFFBE10, 0x7FFFF
 
BDB0)
--- Process 7152 created
[...]
 1556  196093 [main] bash 44433 child_info_spawn::worker: pid 44433, prog_arg
./tmp_install/tools/nmsys64/home/pgrunner/bf/root/HEAD/inst/bin/pg_ctl,cmd line C:\tools\nmsys6
 
4\home\pgrunner\bf\root\HEAD\pgsql.build\tmp_install\tools\nmsys64\home\pgrunner\bf\root\HEAD\inst\bin\pg_ctl.exe -D t
-w-l logfile stop)
 
  128  196221 [main] bash 44433! child_info_spawn::worker: new process name
\\?\C:\tools\nmsys64\home\pgrunner\bf\root\HEAD\pgsql.build\tmp_install\tools\nmsys64\home\pgrunne
r\bf\root\HEAD\inst\bin\pg_ctl.exe
[...]
--- Process 6136 (pid: 44433) exited with status 0x0
[...]
--- Process 7152 exited with status 0xc000013a
5292450 5816310 [waitproc] bash 44432 pinfo::maybe_set_exit_code_from_windows: pid 44433, exit value - old 0x0, windows
0xC000013A,MSYS 0x8000002
 

So indeed, pg_ctl exits with 0, but bash ends up with a different exit code.

What's very interesting here is that the error is 0xC000013A, which is quite
different from the 33280 that perl then reports.  From what I can see bash
actually returns 0xC000013A - I don't know how perl ends up with 33280 /
0x8200 from that.

Either way, 0xC000013A is interesting - that's 0xC000013A,
STATUS_CONTROL_C_EXIT.


Very interestingly the problem vanishes as soon as I add a redirection for
standard input into the mix.  Notably it suffices to redirect stdin in the
pg_ctl *start*, even if not done for pg_ctl stop.  There also is no issue if
perl's stdin is redirected from /dev/null.

My guess is that msys has an issue with refcounting consoles across multiple
processes.


After that I was able to reproduce the issue without really involving perl:

bash -c './tmp_install/tools/nmsys64/home/pgrunner/bf/root/HEAD/inst/bin/pg_ctl -D t -w -l logfile start > startlog
2>&1;./tmp_install/tools/nmsys64/home/pgrunner/bf/root/HEAD/inst/bin/pg_ctl -D t -w -l logfile stop > stoplog 2>&1;
echoinner: $?'; echo outer: $?
 

+ bash -c './tmp_install/tools/nmsys64/home/pgrunner/bf/root/HEAD/inst/bin/pg_ctl -D t -w -l logfile start > startlog
2>&1;./tmp_install/tools/nmsys64/home/pgrunner/bf/root/HEAD/inst/bin/pg_ctl -D t -w -l logfile stop > stoplog 2>&1;
echoinner: $?'
 
inner: 130
+ echo outer: 0
outer: 0

If you add -e, the inner: is obviously "transferred" to the outer: output.

As soon as either the pg_ctl for the start, or the whole bash invocation, has
stdin redirected, the problem vanishes.

Greetings,

Andres Freund