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This coding technique is undesirable because (a) it leaks the FD for the rest of the transaction if the SRF is not run to completion, and (b) allocated FDs are a scarce resource, but multiple interleaved uses of the relevant functions could eat many such FDs. In v11 and later, a query such as "SELECT pg_ls_waldir() LIMIT 1" yields a warning about the leaked FD, and the only reason there's no warning in earlier branches is that fd.c didn't whine about such leaks before commit 9cb7db3f0. Even disregarding the warning, it wouldn't be too hard to run a backend out of FDs with careless use of these SQL functions. Hence, rewrite the function so that it reads the directory within a single call, returning the results as a tuplestore rather than via value-per-call mode. There are half a dozen other built-in SRFs with similar problems, but let's fix this one to start with, just to see if the buildfarm finds anything wrong with the code. In passing, fix bogus error report for stat() failure: it was whining about the directory when it should be fingering the individual file. Doubtless a copy-and-paste error. Back-patch to v10 where this function was added. Justin Pryzby, with cosmetic tweaks and test cases by me Discussion: https://postgr.es/m/20200308173103.GC1357@telsasoft.com
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/.