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2069e6faa0
This patch fixes a couple of low-probability bugs that could lead to reporting an irrelevant errno value (and hence possibly a wrong SQLSTATE) concerning directory-open or file-open failures. It also fixes places where we took shortcuts in reporting such errors, either by using elog instead of ereport or by using ereport but forgetting to specify an errcode. And it eliminates a lot of just plain redundant error-handling code. In service of all this, export fd.c's formerly-static function ReadDirExtended, so that external callers can make use of the coding pattern dir = AllocateDir(path); while ((de = ReadDirExtended(dir, path, LOG)) != NULL) if they'd like to treat directory-open failures as mere LOG conditions rather than errors. Also fix FreeDir to be a no-op if we reach it with dir == NULL, as such a coding pattern would cause. Then, remove code at many call sites that was throwing an error or log message for AllocateDir failure, as ReadDir or ReadDirExtended can handle that job just fine. Aside from being a net code savings, this gets rid of a lot of not-quite-up-to-snuff reports, as mentioned above. (In some places these changes result in replacing a custom error message such as "could not open tablespace directory" with more generic wording "could not open directory", but it was agreed that the custom wording buys little as long as we report the directory name.) In some other call sites where we can't just remove code, change the error reports to be fully project-style-compliant. Also reorder code in restoreTwoPhaseData that was acquiring a lock between AllocateDir and ReadDir; in the unlikely but surely not impossible case that LWLockAcquire changes errno, AllocateDir failures would be misreported. There is no great value in opening the directory before acquiring TwoPhaseStateLock, so just do it in the other order. Also fix CheckXLogRemoved to guarantee that it preserves errno, as quite a number of call sites are implicitly assuming. (Again, it's unlikely but I think not impossible that errno could change during a SpinLockAcquire. If so, this function was broken for its own purposes as well as breaking callers.) And change a few places that were using not-per-project-style messages, such as "could not read directory" when "could not open directory" is more correct. Back-patch the exporting of ReadDirExtended, in case we have occasion to back-patch some fix that makes use of it; it's not needed right now but surely making it global is pretty harmless. Also back-patch the restoreTwoPhaseData and CheckXLogRemoved fixes. The rest of this is essentially cosmetic and need not get back-patched. Michael Paquier, with a bit of additional work by me Discussion: https://postgr.es/m/CAB7nPqRpOCxjiirHmebEFhXVTK7V5Jvw4bz82p7Oimtsm3TyZA@mail.gmail.com |
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PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.