The original patch for percentrepl.c c96de2ce17 adopted the error messages from basebackup_to_shell, but that uses terminology that doesn't really fit with the new API naming.
In order to have the option to use O_DIRECT/FILE_FLAG_NO_BUFFERING in a later commit, we need the addresses of user space buffers to be well aligned. The exact requirements vary by OS and file system (typically sectors and/or memory pages). The address alignment size is set to 4096, which is enough for currently known systems: it matches modern sectors and common memory page size. There is no standard governing O_DIRECT's requirements so we might eventually have to reconsider this with more information from the field or future systems. Aligning I/O buffers on memory pages is also known to improve regular buffered I/O performance. Three classes of I/O buffers for regular data pages are adjusted: (1) Heap buffers are now allocated with the new palloc_aligned() or MemoryContextAllocAligned() functions introduced by commit 439f6175. (2) Stack buffers now use a new struct PGIOAlignedBlock to respect PG_IO_ALIGN_SIZE, if possible with this compiler. (3) The buffer pool is also aligned in shared memory. WAL buffers were already aligned on XLOG_BLCKSZ. It's possible for XLOG_BLCKSZ to be configured smaller than PG_IO_ALIGNED_SIZE and thus for O_DIRECT WAL writes to fail to be well aligned, but that's a pre-existing condition and will be addressed by a later commit. BufFiles are not yet addressed (there's no current plan to use O_DIRECT for those, but they could potentially get some incidental speedup even in plain buffered I/O operations through better alignment). If we can't align stack objects suitably using the compiler extensions we know about, we disable the use of O_DIRECT by setting PG_O_DIRECT to 0. This avoids the need to consider systems that have O_DIRECT but can't align stack objects the way we want; such systems could in theory be supported with more work but we don't currently know of any such machines, so it's easier to pretend there is no O_DIRECT support instead. That's an existing and tested class of system. Add assertions that all buffers passed into smgrread(), smgrwrite() and smgrextend() are correctly aligned, unless PG_O_DIRECT is 0 (= stack alignment tricks may be unavailable) or the block size has been set too small to allow arrays of buffers to be all aligned. Author: Thomas Munro <thomas.munro@gmail.com> Author: Andres Freund <andres@anarazel.de> Reviewed-by: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/CA+hUKGK1X532hYqJ_MzFWt0n1zt8trz980D79WbjwnT-yYLZpg@mail.gmail.com
zstd compression supports a special mode for finding matched in distant past, which may result in better compression ratio, at the expense of using more memory (the window size is 128MB). To enable this optional mode, use the "long" keyword when specifying the compression method (--compress=zstd:long). Author: Justin Pryzby Reviewed-by: Tomas Vondra, Jacob Champion Discussion: https://postgr.es/m/20230224191840.GD1653@telsasoft.com Discussion: https://postgr.es/m/20220327205020.GM28503@telsasoft.com
Replace the hardcoded value with a GUC such that the iteration count can be raised in order to increase protection against brute-force attacks. The hardcoded value for SCRAM iteration count was defined to be 4096, which is taken from RFC 7677, so set the default for the GUC to 4096 to match. In RFC 7677 the recommendation is at least 15000 iterations but 4096 is listed as a SHOULD requirement given that it's estimated to yield a 0.5s processing time on a mobile handset of the time of RFC writing (late 2015). Raising the iteration count of SCRAM will make stored passwords more resilient to brute-force attacks at a higher computational cost during connection establishment. Lowering the count will reduce computational overhead during connections at the tradeoff of reducing strength against brute-force attacks. There are however platforms where even a modest iteration count yields a too high computational overhead, with weaker password encryption schemes chosen as a result. In these situations, SCRAM with a very low iteration count still gives benefits over weaker schemes like md5, so we allow the iteration count to be set to one at the low end. The new GUC is intentionally generically named such that it can be made to support future SCRAM standards should they emerge. At that point the value can be made into key:value pairs with an undefined key as a default which will be backwards compatible with this. Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Jonathan S. Katz <jkatz@postgresql.org> Discussion: https://postgr.es/m/F72E7BC7-189F-4B17-BF47-9735EB72C364@yesql.se
Replace the symlink-chasing logic in find_my_exec with realpath(3), which has been required by POSIX since SUSv2. (Windows lacks realpath(), but there we can use _fullpath() which is functionally equivalent.) The main benefit of this is that -- on all modern platforms at least -- realpath() avoids the chdir() shenanigans we used to perform while interpreting symlinks. That had various corner-case failure modes so it's good to get rid of it. There is still ongoing discussion about whether we could skip the replacement of symlinks in some cases, but that's really matter for a separate patch. Meanwhile I want to push this before we get too close to feature freeze, so that we can find out if there are showstopper portability issues. Discussion: https://postgr.es/m/797232.1662075573@sss.pgh.pa.us
These are set after a \! command or a backtick substitution. SHELL_ERROR is just "true" for error (nonzero exit status) or "false" for success, while SHELL_EXIT_CODE records the actual exit status following standard shell/system(3) conventions. Corey Huinker, reviewed by Maxim Orlov and myself Discussion: https://postgr.es/m/CADkLM=cWao2x2f+UDw15W1JkVFr_bsxfstw=NGea7r9m4j-7rQ@mail.gmail.com
.../src/common/file_utils.c: In function ‘pg_pwrite_zeros’:
.../src/common/file_utils.c:543:9: warning: ‘static’ is not at beginning of declaration [-Wold-style-declaration]
543 | const static PGAlignedBlock zbuffer = {{0}}; /* worth BLCKSZ */
The majority of error exit cases in json_lex_string() failed to set lex->token_terminator, causing problems for the error context reporting code: it would see token_terminator less than token_start and do something more or less nuts. In v14 and up the end result could be as bad as a crash in report_json_context(). Older versions accidentally avoided that fate; but all versions produce error context lines that are far less useful than intended, because they'd stop at the end of the prior token instead of continuing to where the actually-bad input is. To fix, invent some macros that make it less notationally painful to do the right thing. Also add documentation about what the function is actually required to do; and in >= v14, add an assertion in report_json_context about token_terminator being sufficiently far advanced. Per report from Nikolay Shaplov. Back-patch to all supported versions. Discussion: https://postgr.es/m/7332649.x5DLKWyVIX@thinkpad-pgpro
Change comments for pg_cryptohash_init(), pg_cryptohash_update(), pg_cryptohash_final() in cryptohash.c to match cryptohash_openssl.c. In particular, the claim that these functions were "designed" to never fail was incorrect, since by design callers need to be prepared to handle failures, for compatibility with the cryptohash_openssl.c versions. Reviewed-by: Daniel Gustafsson <daniel@yesql.se> Discussion: https://www.postgresql.org/message-id/301F4EDD-27B9-460F-B462-B9DB2BDE4ACF@yesql.se
We already didn't use touch (some earlier version of the meson build did ), and cp is only used for updating unicode files. The latter already depends on the optional availability of 'wget', so doing the same for 'cp' makes sense. Eventually we probably want a portable command for updating source code as part of a target, but for now... Reported-by: Andrew Dunstan <andrew@dunslane.net> Discussion: https://postgr.es/m/70e96c34-64ee-e549-8c4a-f91a7a668804@dunslane.net