problem with glibc strerror messages translation (was: Could not open file pg_xlog/000000010....)

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> Victor <only-victor(at)mail(dot)ru> writes:
> > Oct 12 17:53:25 localhost postgres[26997]: [1753-1] PANIC: could not
> > open file "pg_xlog/000000010000000000000007" (log file 0, segment
> > 7): ???????????? ????????
>
> Hm, where's the rest of that error message? You should certainly not
> have gotten just question-marks there.

IMHO you can receive question-marks here if lc_messages in postgresql.conf
do not match with locale from environment at server start, for example:

correctly translated and displayed:
$ LANG=ru_RU.UTF-8 ../bin/postgres -D d -k`pwd`/s
2010-10-13 05:34:39 MSD 14796 4cb50caf.39cc FATAL: XX000: could not create shared memory segment: Недопустимый аргумент

incorrect, question-marks only:
$ LANG=C ../bin/postgres -D d -k`pwd`/s
2010-10-13 05:34:54 MSD 14798 4cb50cbd.39ce FATAL: XX000: could not create shared memory segment: ???????????? ????????

error message received from function strerror(). It use gettext (in glibc) for messages translation.
man gettext say this:
In both cases, the functions also use the LC_CTYPE locale facet in order to
convert the translated message from the translator's codeset to the current
locale's codeset, unless overridden by a prior call to the
bind_textdomain_codeset function.

but when postgres starting, it set LC_CTYPE to current locale (I used gdb for monitoring):

$ LANG=C gdb --args ../bin/postgres -D d -k`pwd`/s
(gdb) break setlocale
Breakpoint 1 at 0x453118
(gdb) commands
Type commands for when breakpoint 1 is hit, one per line.
End with a line saying just "end".
>p {"LC_CTYPE ", "LC_NUMERIC ", "LC_TIME ", "LC_COLLATE ", "LC_MONETARY ", "LC_MESSAGES ", "LC_ALL ", "LC_PAPER ", "LC_NAME ", "LC_ADDRESS ", "LC_TELEPHONE ", "LC_MEASUREMENT ", "LC_IDENTIFICATION"}[category]
>c
>end
(gdb) set pagination off
(gdb) r
Starting program: /home/seb/inst/pg-dev/bin/postgres -D d -k/home/seb/inst/pg-dev/var/s
Breakpoint 1, *__GI_setlocale (category=3, locale=0x7ff627 "") at setlocale.c:199
199 setlocale.c: No such file or directory.
in setlocale.c
$1 = "LC_COLLATE "

Breakpoint 1, *__GI_setlocale (category=0, locale=0x7ff627 "") at setlocale.c:199
199 in setlocale.c
$2 = "LC_CTYPE "

Breakpoint 1, *__GI_setlocale (category=5, locale=0x7ff627 "") at setlocale.c:199
199 in setlocale.c
$3 = "LC_MESSAGES "

. . .

Breakpoint 1, *__GI_setlocale (category=5, locale=0xb31e10 "ru_RU.UTF-8") at setlocale.c:199
199 in setlocale.c
$29 = "LC_MESSAGES "

so, if current environment do not match with lc_messages in postgresql.conf
- glibc cannot translate error message.

simple test program in attachment