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We previously took a hard-line attitude that callers should never print a null string pointer, and doing so is worthy of an assertion failure or crash. However, we've long since flushed out any easy-to-find bugs of that nature. What remains is a lot of code that perhaps could fail that way in hard-to-reach corner cases. For example, in something as simple as ereport(ERROR, (errcode(ERRCODE_UNDEFINED_OBJECT), errmsg("constraint \"%s\" for table \"%s\" does not exist", conname, get_rel_name(relid)))); one must wonder whether it's completely guaranteed that get_rel_name cannot return NULL in this context. If such a situation did occur, the existing policy converts what might be a pretty minor bug into a server crash condition. This is not good for robustness. Hence, let's follow the lead of glibc and print "(null)" instead of failing. We should, of course, still consider it a bug if that behavior is reachable in ordinary use; but crashing seems less desirable than not crashing. This fix works across-the-board in v12 and up, where we always use src/port/snprintf.c. Before that, on most platforms we're at the mercy of the local libc, but it appears that Solaris 10 is the only supported platform where we'd still get a crash. Most other platforms such as *BSD, macOS, and Solaris 11 have adopted glibc's behavior at some point. (AIX and HPUX just print "" not "(null)", but that's close enough.) I've not checked what Windows' native printf would do, but it doesn't matter because we've long used snprintf.c on that platform. In v12 and up, also const-ify related code so that we're not casting away const on the constant string. This is just neatnik-ism, since next to no compilers will warn about that. Discussion: https://postgr.es/m/17098-b960f3616c861f83@postgresql.org |
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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/.