c.h #includes a number of core libc header files, such as <stdio.h>.
There's no point in re-including these after having read postgres.h,
postgres_fe.h, or c.h; so remove code that did so.
While at it, also fix some places that were ignoring our standard pattern
of "include postgres[_fe].h, then system header files, then other Postgres
header files". While there's not any great magic in doing it that way
rather than system headers last, it's silly to have just a few files
deviating from the general pattern. (But I didn't attempt to enforce this
globally, only in files I was touching anyway.)
I'd be the first to say that this is mostly compulsive neatnik-ism,
but over time it might save enough compile cycles to be useful.
Rename these newly-extern functions with terms more typical of their new
neighbors. No functional changes; a subsequent commit will use them in
more places. Back-patch to 9.1 (all supported versions). Back branches
lack src/fe_utils, so instead rename the functions in place; the
subsequent commit will copy them into the other programs using them.
Security: CVE-2016-5424
It's easy to forget using SYSTEMQUOTEs when constructing command strings
for system() or popen(). Even if we fix all the places missing it now, it is
bound to be forgotten again in the future. Introduce wrapper functions that
do the the extra quoting for you, and get rid of SYSTEMQUOTEs in all the
callers.
We previosly used SYSTEMQUOTEs in all the hard-coded command strings, and
this doesn't change the behavior of those. But user-supplied commands, like
archive_command, restore_command, COPY TO/FROM PROGRAM calls, as well as
pgbench's \shell, will now gain an extra pair of quotes. That is desirable,
but if you have existing scripts or config files that include an extra
pair of quotes, those might need to be adjusted.
Reviewed by Amit Kapila and Tom Lane
