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d4a43b2837
The protections added by commit 3b00fdba9f introduced race conditions to this function that can lead to bogus return values. Since nobody seems to inspect the return value, this is of little consequence, but it would have been nice to convert it to a void function to avoid any possibility of a bogus return value. I originally thought that doing so would have required also modifying legacy-pqsignal.c's version of the function (which would've required an SONAME bump), but commit 9a45a89c38 gave legacy-pqsignal.c its own dedicated extern for pqsignal(), thereby decoupling it enough that libpgport's pqsignal() can be modified. This commit also adds an assertion for the return value of sigaction()/signal(). Since a failure most likely indicates a coding error, and nobody has ever bothered to check pqsignal()'s return value, it's probably not worth the effort to do anything fancier. Reviewed-by: Tom Lane Discussion: https://postgr.es/m/Z4chOKfnthRH71mw%40nathan
src/port/README
libpgport
=========
libpgport must have special behavior. It supplies functions to both
libraries and applications. However, there are two complexities:
1) Libraries need to use object files that are compiled with exactly
the same flags as the library. libpgport might not use the same flags,
so it is necessary to recompile the object files for individual
libraries. This is done by removing -lpgport from the link line:
# Need to recompile any libpgport object files
LIBS := $(filter-out -lpgport, $(LIBS))
and adding infrastructure to recompile the object files:
OBJS= execute.o typename.o descriptor.o data.o error.o prepare.o memory.o \
connect.o misc.o path.o exec.o \
$(filter strlcat.o, $(LIBOBJS))
The problem is that there is no testing of which object files need to be
added, but missing functions usually show up when linking user
applications.
2) For applications, we use -lpgport before -lpq, so the static files
from libpgport are linked first. This avoids having applications
dependent on symbols that are _used_ by libpq, but not intended to be
exported by libpq. libpq's libpgport usage changes over time, so such a
dependency is a problem. Windows, Linux, and macOS use an export
list to control the symbols exported by libpq.