Standardize on xoroshiro128** as our basic PRNG algorithm, eliminating
a bunch of platform dependencies as well as fundamentally-obsolete PRNG
code. In addition, this API replacement will ease replacing the
algorithm again in future, should that become necessary.
xoroshiro128** is a few percent slower than the drand48 family,
but it can produce full-width 64-bit random values not only 48-bit,
and it should be much more trustworthy. It's likely to be noticeably
faster than the platform's random(), depending on which platform you
are thinking about; and we can have non-global state vectors easily,
unlike with random(). It is not cryptographically strong, but neither
are the functions it replaces.
Fabien Coelho, reviewed by Dean Rasheed, Aleksander Alekseev, and myself
Discussion: https://postgr.es/m/alpine.DEB.2.22.394.2105241211230.165418@pseudo
This check was used to accommodate a staggering variety in particular
in the type of the third argument of accept(). This is no longer of
concern on currently supported systems. We can just use socklen_t in
the code and put in a simple check that substitutes int for socklen_t
if it's missing, to cover the few stragglers.
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://www.postgresql.org/message-id/3538f4c4-1886-64f2-dcff-aaad8267fb82@enterprisedb.com
Build farm animals running ancient HPUX and Solaris have a non-standard
sigwait() from draft versions of POSIX, so they didn't like commit
7c09d279. To avoid the problem in general, only try to use sigwait() if
it's declared by <signal.h> and matches the expected declaration. To
select the modern declaration on Solaris (even in non-threaded
programs), move -D_POSIX_PTHREAD_SEMANTICS into the right place to
affect all translation units.
Also fix the error checking. Modern sigwait() doesn't set errno.
Thanks to Tom Lane for help with this.
Discussion: https://postgr.es/m/3187588.1626136248%40sss.pgh.pa.us
Apple's mechanism for dealing with functions that are available
in only some OS versions confuses AC_CHECK_FUNCS, and therefore
AC_REPLACE_FUNCS. We can use AC_CHECK_DECLS instead, so long as
we enable -Werror=unguarded-availability-new. This allows people
compiling for macOS to control whether or not preadv/pwritev are
used by setting MACOSX_DEPLOYMENT_TARGET, rather than supplying
a back-rev SDK. (Of course, the latter still works, too.)
James Hilliard
Discussion: https://postgr.es/m/20210122193230.25295-1-james.hilliard1@gmail.com
The separate libldap_r is gone and libldap itself is now always
thread-safe. Unfortunately there seems no easy way to tell by
inspection whether libldap is thread-safe, so we have to take
it on faith that libldap is thread-safe if there's no libldap_r.
That should be okay, as it appears that libldap_r was a standard
part of the installation going back at least 20 years.
Report and patch by Adrian Ho. Back-patch to all supported
branches, since people might try to build any of them with
a newer OpenLDAP.
Discussion: https://postgr.es/m/17083-a19190d9591946a7@postgresql.org
Similarly to the cryptohash implementations, this refactors the existing
HMAC code into a single set of APIs that can be plugged with any crypto
libraries PostgreSQL is built with (only OpenSSL currently). If there
is no such libraries, a fallback implementation is available. Those new
APIs are designed similarly to the existing cryptohash layer, so there
is no real new design here, with the same logic around buffer bound
checks and memory handling.
HMAC has a dependency on cryptohashes, so all the cryptohash types
supported by cryptohash{_openssl}.c can be used with HMAC. This
refactoring is an advantage mainly for SCRAM, that included its own
implementation of HMAC with SHA256 without relying on the existing
crypto libraries even if PostgreSQL was built with their support.
This code has been tested on Windows and Linux, with and without
OpenSSL, across all the versions supported on HEAD from 1.1.1 down to
1.0.1. I have also checked that the implementations are working fine
using some sample results, a custom extension of my own, and doing
cross-checks across different major versions with SCRAM with the client
and the backend.
Author: Michael Paquier
Reviewed-by: Bruce Momjian
Discussion: https://postgr.es/m/X9m0nkEJEzIPXjeZ@paquier.xyz
This seems to have been just copied-and-pasted from some other
header checks. But our C code is entirely unprepared to support
such a header name, so it's only wasting cycles to look for it.
If we did need to support it, some #ifdefs would be required.
(A quick trawl at codesearch.debian.net finds some packages that
reference lz4/lz4.h; but they use *only* that spelling, and
appear to be intending to reference their own copy rather than
a system-level installation of liblz4. There's no evidence of
freestanding installations that require this spelling.)
Discussion: https://postgr.es/m/457962.1616362509@sss.pgh.pa.us
It's not okay to just shove the pkg_config results right into our
build flags, for a couple different reasons:
* This fails to maintain the separation between CPPFLAGS and CFLAGS,
as well as that between LDFLAGS and LIBS. (The CPPFLAGS angle is,
I believe, the reason for warning messages reported when building
with MacPorts' liblz4.)
* If pkg_config emits anything other than -I/-D/-L/-l switches,
it's highly unlikely that we want to absorb those. That'd be more
likely to break the build than do anything helpful. (Even the -D
case is questionable; but we're doing that for libxml2, so I kept it.)
Also, it's not okay to skip doing an AC_CHECK_LIB probe, as
evidenced by recent build failure on topminnow; that should
have been caught at configure time.
Model fixes for this on configure's libxml2 support.
It appears that somebody overlooked an autoheader run, too.
Discussion: https://postgr.es/m/20210119190720.GL8560@telsasoft.com
Since commit 2ce439f3 we have opened every file in the data directory
and called fsync() at the start of crash recovery. This can be very
slow if there are many files, leading to field complaints of systems
taking minutes or even hours to begin crash recovery.
Provide an alternative method, for Linux only, where we call syncfs() on
every possibly different filesystem under the data directory. This is
equivalent, but avoids faulting in potentially many inodes from
potentially slow storage.
The new mode comes with some caveats, described in the documentation, so
the default value for the new setting is "fsync", preserving the older
behavior.
Reported-by: Michael Brown <michael.brown@discourse.org>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Paul Guo <guopa@vmware.com>
Reviewed-by: Bruce Momjian <bruce@momjian.us>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: David Steele <david@pgmasters.net>
Discussion: https://postgr.es/m/11bc2bb7-ecb5-3ad0-b39f-df632734cd81%40discourse.org
Discussion: https://postgr.es/m/CAEET0ZHGnbXmi8yF3ywsDZvb3m9CbdsGZgfTXscQ6agcbzcZAw%40mail.gmail.com
There is now a per-column COMPRESSION option which can be set to pglz
(the default, and the only option in up until now) or lz4. Or, if you
like, you can set the new default_toast_compression GUC to lz4, and
then that will be the default for new table columns for which no value
is specified. We don't have lz4 support in the PostgreSQL code, so
to use lz4 compression, PostgreSQL must be built --with-lz4.
In general, TOAST compression means compression of individual column
values, not the whole tuple, and those values can either be compressed
inline within the tuple or compressed and then stored externally in
the TOAST table, so those properties also apply to this feature.
Prior to this commit, a TOAST pointer has two unused bits as part of
the va_extsize field, and a compessed datum has two unused bits as
part of the va_rawsize field. These bits are unused because the length
of a varlena is limited to 1GB; we now use them to indicate the
compression type that was used. This means we only have bit space for
2 more built-in compresison types, but we could work around that
problem, if necessary, by introducing a new vartag_external value for
any further types we end up wanting to add. Hopefully, it won't be
too important to offer a wide selection of algorithms here, since
each one we add not only takes more coding but also adds a build
dependency for every packager. Nevertheless, it seems worth doing
at least this much, because LZ4 gets better compression than PGLZ
with less CPU usage.
It's possible for LZ4-compressed datums to leak into composite type
values stored on disk, just as it is for PGLZ. It's also possible for
LZ4-compressed attributes to be copied into a different table via SQL
commands such as CREATE TABLE AS or INSERT .. SELECT. It would be
expensive to force such values to be decompressed, so PostgreSQL has
never done so. For the same reasons, we also don't force recompression
of already-compressed values even if the target table prefers a
different compression method than was used for the source data. These
architectural decisions are perhaps arguable but revisiting them is
well beyond the scope of what seemed possible to do as part of this
project. However, it's relatively cheap to recompress as part of
VACUUM FULL or CLUSTER, so this commit adjusts those commands to do
so, if the configured compression method of the table happens not to
match what was used for some column value stored therein.
Dilip Kumar. The original patches on which this work was based were
written by Ildus Kurbangaliev, and those were patches were based on
even earlier work by Nikita Glukhov, but the design has since changed
very substantially, since allow a potentially large number of
compression methods that could be added and dropped on a running
system proved too problematic given some of the architectural issues
mentioned above; the choice of which specific compression method to
add first is now different; and a lot of the code has been heavily
refactored. More recently, Justin Przyby helped quite a bit with
testing and reviewing and this version also includes some code
contributions from him. Other design input and review from Tomas
Vondra, Álvaro Herrera, Andres Freund, Oleg Bartunov, Alexander
Korotkov, and me.
Discussion: http://postgr.es/m/20170907194236.4cefce96%40wp.localdomain
Discussion: http://postgr.es/m/CAFiTN-uUpX3ck%3DK0mLEk-G_kUQY%3DSNOTeqdaNRR9FMdQrHKebw%40mail.gmail.com
This is a replacement for the existing --with-openssl, extending the
logic to make easier the addition of new SSL libraries. The grammar is
chosen to be similar to --with-uuid, where multiple values can be
chosen, with "openssl" as the only supported value for now.
The original switch, --with-openssl, is kept for compatibility.
Author: Daniel Gustafsson, Michael Paquier
Reviewed-by: Jacob Champion
Discussion: https://postgr.es/m/FAB21FC8-0F62-434F-AA78-6BD9336D630A@yesql.se
Provide synchronous vectored file I/O routines. These map to preadv()
and pwritev(), with fallback implementations for systems that don't have
them. Also provide a wrapper pg_pwritev_with_retry() that automatically
retries on short writes.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA%2BhUKGJA%2Bu-220VONeoREBXJ9P3S94Y7J%2BkqCnTYmahvZJwM%3Dg%40mail.gmail.com
Since at least 2001 we've used putenv() and avoided setenv(), on the
grounds that the latter was unportable and not in POSIX. However,
POSIX added it that same year, and by now the situation has reversed:
setenv() is probably more portable than putenv(), since POSIX now
treats the latter as not being a core function. And setenv() has
cleaner semantics too. So, let's reverse that old policy.
This commit adds a simple src/port/ implementation of setenv() for
any stragglers (we have one in the buildfarm, but I'd not be surprised
if that code is never used in the field). More importantly, extend
win32env.c to also support setenv(). Then, replace usages of putenv()
with setenv(), and get rid of some ad-hoc implementations of setenv()
wannabees.
Also, adjust our src/port/ implementation of unsetenv() to follow the
POSIX spec that it returns an error indicator, rather than returning
void as per the ancient BSD convention. I don't feel a need to make
all the call sites check for errors, but the portability stub ought
to match real-world practice.
Discussion: https://postgr.es/m/2065122.1609212051@sss.pgh.pa.us
Remove the ability to select random number generator independently from
SSL library. Instead, use the random number generator from the SSL
library (today only OpenSSL supported) if one is configured. If no SSL
library is configured, use the platform default (which means use
CryptoAPI on Win32 and /dev/urandom on Linux).
This also restructures pg_strong_random.c to have three clearly separate
sections, one for each implementation, with two functions in each,
instead of a scattered set of ifdefs throughout the whole file.
Author: Daniel Gustafsson, Magnus Hagander, Michael Paquier
Discussion: https://postgr.es/m/632623.1605460616@sss.pgh.pa.us
As of Windows 10 version 1803, Unix-domain sockets are supported on
Windows. But it's not automatically detected by configure because it
looks for struct sockaddr_un and Windows doesn't define that. So we
just make our own definition on Windows and override the configure
result.
Set DEFAULT_PGSOCKET_DIR to empty on Windows so by default no
Unix-domain socket is used, because there is no good standard
location.
In pg_upgrade, we have to do some extra tweaking to preserve the
existing behavior of not using Unix-domain sockets on Windows. Adding
support would be desirable, but it needs further work, in particular a
way to select whether to use Unix-domain sockets from the command-line
or with a run-time test.
The pg_upgrade test script needs a fix. The previous code passed
"localhost" to postgres -k, which only happened to work because
Windows used to ignore the -k argument value altogether. We instead
need to pass an empty string to get the desired effect.
The test suites will continue to not use Unix-domain sockets on
Windows. This requires a small tweak in pg_regress.c. The TAP tests
don't need to be changed because they decide by the operating system
rather than HAVE_UNIX_SOCKETS.
Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Discussion: https://www.postgresql.org/message-id/flat/54bde68c-d134-4eb8-5bd3-8af33b72a010@2ndquadrant.com
This removes another relic from the old nmake-based Windows build.
version_stamp.pl put version number information into win32ver.rc. But
win32ver.rc already gets other version number information from the
preprocessor at build time, so it would make more sense if all version
number information would be handled in the same way and we don't have
two places that do it.
What we need for this is having the major version number and the minor
version number as separate integer symbols. Both configure and
Solution.pm already have that logic, because they compute
PG_VERSION_NUM. So we just keep all the logic there now. Put the
minor version number into a new symbol PG_MINORVERSION_NUM. Also, add
a symbol PG_MAJORVERSION_NUM, which is a number, alongside the
existing PG_MAJORVERSION, which is a string.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/1ee46ac4-a9b2-4531-bf54-5ec2e374634d@2ndquadrant.com
These compiler features are required by C99, so remove the configure
probes for them.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
Windows has this, and so do all other live platforms according to the
buildfarm; it's been required by POSIX since SUSv2. So remove the
configure probe and tests of HAVE_WCHAR_H.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
These are required by POSIX since SUSv2, and no live platforms fail
to provide them. On Windows, utime() exists and we bring our own
<utime.h>, so we're good there too. So remove the configure probes
and ad-hoc substitute code. We don't need to check for utimes()
anymore either, since that was only used as a substitute.
In passing, make the Windows build include <sys/utime.h> only where
we need it, not everywhere.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
Windows has this since _MSC_VER >= 1200, and so do all other live
platforms according to the buildfarm, so remove the configure probe
and src/port/ substitution.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
Windows has this, and so do all other live platforms according to the
buildfarm, so remove the configure probe and c.h's substitute code.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
Windows has this, and so do all other live platforms according to the
buildfarm, so remove the configure probe and float.c's substitute code.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
Windows has this, and so do all other live platforms according to the
buildfarm, so remove the configure probe and src/port/ substitution.
This also lets us get rid of some configure probes that existed only
to support src/port/isinf.c. I kept the port.h hack to force using
__builtin_isinf() on clang, though.
This is part of a series of commits to get rid of no-longer-relevant
configure checks and dead src/port/ code. I'm committing them separately
to make it easier to back out individual changes if they prove less
portable than I expect.
Discussion: https://postgr.es/m/15379.1582221614@sss.pgh.pa.us
stdint.h belongs to the compiler (as opposed to inttypes.h), so by
requiring a C99 compiler we can also require stdint.h
unconditionally. Remove configure checks and other workarounds for
it.
This also removes a few steps in the required portability adjustments
to the imported time zone code, which can be applied on the next
import.
When using GCC on a platform that is otherwise pre-C99, this will now
require at least GCC 4.5, which is the first release that supplied a
standard-conforming stdint.h if the native platform didn't have it.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/5d398bbb-262a-5fed-d839-d0e5cff3c0d7%402ndquadrant.com
The previous system had configure put the value into the makefiles and
then have the makefiles pass them to the build of pg_config. That was
put in place when pg_config was a shell script. We can simplify that
by having configure put the value into pg_config.h directly. This
also makes the standard build system match how the MSVC build system
already does it.
Discussion: https://www.postgresql.org/message-id/flat/6e457870-cef5-5f1d-b57c-fc89cfb8a788%402ndquadrant.com
Use kevent(2) to wait for events on the BSD family of operating
systems and macOS. This is similar to the epoll(2) support added
for Linux by commit 98a64d0bd.
Author: Thomas Munro
Reviewed-by: Andres Freund, Marko Tiikkaja, Tom Lane
Tested-by: Mateusz Guzik, Matteo Beccati, Keith Fiske, Heikki Linnakangas, Michael Paquier, Peter Eisentraut, Rui DeSousa, Tom Lane, Mark Wong
Discussion: https://postgr.es/m/CAEepm%3D37oF84-iXDTQ9MrGjENwVGds%2B5zTr38ca73kWR7ez_tA%40mail.gmail.com
I had supposed that all versions of Readline that have filename
quoting hooks also have the rl_completion_suppress_quote variable.
But it seems OpenBSD managed to find a version someplace that does
not, so we'll have to expend a separate configure probe for that.
(Light testing suggests that this version also lacks the bugs that
make it necessary to frob that variable. Hooray!)
Per buildfarm.
The Readline library contains a fair amount of knowledge about how to
tab-complete filenames, but it turns out that that doesn't work too well
unless we follow its expectation that we use its filename quoting hooks
to quote and de-quote filenames. We were trying to do such quote handling
within complete_from_files(), and that's still what we have to do if we're
using libedit, which lacks those hooks. But for Readline, it works a lot
better if we tell Readline that single-quote is a quoting character and
then provide hooks that know the details of the quoting rules for SQL
and psql meta-commands.
Hence, resurrect the quoting hook functions that existed in the original
version of tab-complete.c (and were disabled by commit f6689a328 because
they "didn't work so well yet"), and whack on them until they do seem to
work well.
Notably, this fixes bug #16059 from Steven Winfield, who pointed out
that the previous coding would strip quote marks from filenames in SQL
COPY commands, even though they're syntactically necessary there.
Now, we not only don't do that, but we'll add a quote mark when you
tab-complete, even if you didn't type one.
Getting this to work across a range of libedit versions (and, to a
lesser extent, libreadline versions) was depressingly difficult.
It will be interesting to see whether the new regression test cases
pass everywhere in the buildfarm.
Some future patch might try to handle quoted SQL identifiers with
similar explicit quoting/dequoting logic, but that's for another day.
Patch by me, reviewed by Peter Eisentraut.
Discussion: https://postgr.es/m/16059-8836946734c02b84@postgresql.org
This function is supported down to OpenSSL 0.9.8, which is the oldest
version supported since 593d4e4 (from Postgres 10 onwards), and is used
since e3bdb2d (from 11 onwards). It is defined as a macro from OpenSSL
0.9.8 to 1.0.2, and as a function in 1.1.0 and newer versions. However,
the configure check present is only adapted for functions. So, even if
the code would be able to compile, configure fails to detect the macro,
causing it to be ignored when compiling the code with OpenSSL from 0.9.8
to 1.0.2.
The code needs a configure check as per a364dfa, which has fixed a
compilation issue with a past version of LibreSSL in NetBSD 5.1. On
HEAD, just remove the configure check as the last release of NetBSD 5 is
from 2014 (and we have no more buildfarm members for it). In 11 and 12,
improve the configure logic so as both macros and functions are
correctly detected. This makes NetBSD 5 still work on already-released
branches, but not for 13 onwards.
The patch for HEAD is from me, and Daniel has written the version to use
for the back-branches.
Author: Michael Paquier, Daniel Gustaffson
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20191205083252.GE5064@paquier.xyz
Discussion: https://postgr.es/m/98F7F99E-1129-41D8-B86B-FE3B1E286881@yesql.se
Backpatch-through: 11
This build option was once useful to maintain compatibility with
version-0 functions, but those are no longer supported, so this option
is no longer useful for end users. We keep the option available to
developers in pg_config_manual.h so that it is easy to test the
pass-by-reference code paths without having to fire up a 32-bit
machine.
Discussion: https://www.postgresql.org/message-id/flat/f3e1e576-2749-bbd7-2d57-3f9dcf75255a@2ndquadrant.com
This completes the task begun in commit 1408d5d86, to synchronize
ECPG's exported definitions with the definition of bool used by
c.h (and, therefore, the one actually in use in the ECPG library).
On practically all modern platforms, ecpglib.h will now just
include <stdbool.h>, which should surprise nobody anymore.
That removes a header-inclusion-order hazard for ECPG clients,
who previously might get build failures or unexpected behavior
depending on whether they'd included <stdbool.h> themselves,
and if so, whether before or after ecpglib.h.
On platforms where sizeof(_Bool) is not 1 (only old PPC-based
Mac systems, as far as I know), things are still messy, as
inclusion of <stdbool.h> could still break ECPG client code.
There doesn't seem to be any clean fix for that, and given the
probably-negligible population of users who would care anymore,
it's not clear we should go far out of our way to cope with it.
This change at least fixes some header-inclusion-order hazards
for our own code, since c.h and ecpglib.h previously disagreed
on whether bool should be char or unsigned char.
To implement this with minimal invasion of ECPG client namespace,
move the choice of whether to rely on <stdbool.h> into configure,
and have it export a configuration symbol PG_USE_STDBOOL.
ecpglib.h no longer exports definitions for TRUE and FALSE,
only their lowercase brethren. We could undo that if we get
push-back about it.
Ideally we'd back-patch this as far as v11, which is where c.h
started to rely on <stdbool.h>. But the odds of creating problems
for formerly-working ECPG client code seem about as large as the
odds of fixing any non-working cases, so we'll just do this in HEAD.
Discussion: https://postgr.es/m/CAA4eK1LmaKO7Du9M9Lo=kxGU8sB6aL8fa3sF6z6d5yYYVe3BuQ@mail.gmail.com
Add some support for automatically showing backtraces in certain error
situations in the server. Backtraces are shown on assertion failure;
also, a new setting backtrace_functions can be set to a list of C
function names, and all ereport()s and elog()s from the mentioned
functions will have backtraces generated. Finally, the function
errbacktrace() can be manually added to an ereport() call to generate a
backtrace for that call.
Authors: Peter Eisentraut, Álvaro Herrera
Discussion: https://postgr.es/m//5f48cb47-bf1e-05b6-7aae-3bf2cd01586d@2ndquadrant.com
Discussion: https://postgr.es/m/CAMsr+YGL+yfWE=JvbUbnpWtrRZNey7hJ07+zT4bYJdVp4Szdrg@mail.gmail.com
This reverts commit e7ff59686e. It
defined pg_atomic_fetch_add_u32_impl() without defining
pg_atomic_compare_exchange_u32_impl(), which is incompatible with
src/include/port/atomics/fallback.h. Per buildfarm member prairiedog.
Discussion: https://postgr.es/m/7517.1568470247@sss.pgh.pa.us
Use the explicit_bzero() function in places where it is important that
security information such as passwords is cleared from memory. There
might be other places where it could be useful; this is just an
initial collection.
For platforms that don't have explicit_bzero(), provide various
fallback implementations. (explicit_bzero() itself isn't standard,
but as Linux/glibc, FreeBSD, and OpenBSD have it, it's the most common
spelling, so it makes sense to make that the invocation point.)
Discussion: https://www.postgresql.org/message-id/flat/42d26bde-5d5b-c90d-87ae-6cab875f73be%402ndquadrant.com
fe0a0b5 has removed the last use of this routine from pgcrypto, leading
to a useless symbol definition and an extra configure check.
Author: Michael Paquier
Reviewed-by: Daniel Gustafsson, Tom Lane
Discussion: https://postgr.es/m/20190626142544.GN1714@paquier.xyz
Test for the compiler builtins __builtin_clz, __builtin_ctz, and
__builtin_popcount, and make use of these in preference to
handwritten C code if they're available. Create src/port
infrastructure for "leftmost one", "rightmost one", and "popcount"
so as to centralize these decisions.
On x86_64, __builtin_popcount generally won't make use of the POPCNT
opcode because that's not universally supported yet. Provide code
that checks CPUID and then calls POPCNT via asm() if available.
This requires indirecting through a function pointer, which is
an annoying amount of overhead for a one-instruction operation,
but it's probably not worth working harder than this for our
current use-cases.
I'm not sure we've found all the existing places that could profit
from this new infrastructure; but we at least touched all the
ones that used copied-and-pasted versions of the bitmapset.c code,
and got rid of multiple copies of the associated constant arrays.
While at it, replace c-compiler.m4's one-per-builtin-function
macros with a single one that can handle all the cases we need
to worry about so far. Also, because I'm paranoid, make those
checks into AC_LINK checks rather than just AC_COMPILE; the
former coding failed to verify that libgcc has support for the
builtin, in cases where it's not inline code.
David Rowley, Thomas Munro, Alvaro Herrera, Tom Lane
Discussion: https://postgr.es/m/CAKJS1f9WTAGG1tPeJnD18hiQW5gAk59fQ6WK-vfdAKEHyRg2RA@mail.gmail.com
This reverts commits fc6c72747a, 109de05cbb, d0b4663c23 and
711bab1e4d.
Somebody will have to try harder before submitting this patch again.
I've spent entirely too much time on it already, and the #ifdef maze yet
to be written in order for it to build at all got on my nerves. The
amount of work needed to get a platform-specific performance improvement
that's barely above the noise level is not worth it.
Tom Lane
Peter Eisentraut
Thomas Munro
Michael Paquier
Robert Haas
Magnus Hagander
Alvaro Herrera
Noah Misch