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16e3ad5d14
Since %c only passes a C "char" to printf, it's incapable of dealing with multibyte characters. Passing just the first byte of such a character leads to an output string that is visibly not correctly encoded, resulting in undesirable behavior such as encoding conversion failures while sending error messages to clients. We've lived with this issue for a long time because it was inconvenient to avoid in a portable fashion. However, now that we always use our own snprintf code, it's reasonable to use the %.*s format to print just one possibly-multibyte character in a string. (We previously avoided that obvious-looking answer in order to work around glibc's bug #6530, cf commits 54cd4f045 and ed437e2b2.) Hence, run around and fix a bunch of places that used %c to report a character found in a user-supplied string. For simplicity, I did not touch places that were emitting non-user-facing debug messages, or reporting catalog data that should always be ASCII. (It's also unclear how useful this approach could be in frontend code, where it's less certain that we know what encoding we're dealing with.) In passing, improve a couple of poorly-written error messages in pageinspect/heapfuncs.c. This is a longstanding issue, but I'm hesitant to back-patch because of the impact on translatable message strings. In any case this fix would not work reliably before v12. Tom Lane and Quan Zongliang Discussion: https://postgr.es/m/a120087c-4c88-d9d4-1ec5-808d7a7f133d@gmail.com
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.