Date: Wed, 30 Jun 2021 09:46:59 -0400
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael@paquier.xyz>,
	Jacob Champion <pchampion@vmware.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>,
	Daniel Gustafsson <daniel@yesql.se>, info@cspug.cz
Subject: Re: Preventing abort() and exit() calls in libpq
Message-ID: <202106301346.c64ysatd7o5l@alvherre.pgsql>
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On 2021-Jun-30, Alvaro Herrera wrote:

> If I remove -fprofile-arcs from CFLAGS, then abort is no longer present,
> but we still get a fail because of __gcov_exit.  I suppose if you'd add
> an exception for __cxa_atexit, the same place could use one for
> __gcov_exit.

I tried the attached patch, and while libpq.so now builds successfully,
it causes anything that tries to link to libpq fail like

gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wcast-function-type -Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard -Wno-format-truncation -Wno-stringop-truncation -g -fprofile-arcs -ftest-coverage   findtimezone.o initdb.o localtime.o -L../../../src/port -L../../../src/common -L../../../src/fe_utils -lpgfeutils -L../../../src/common -lpgcommon -L../../../src/port -lpgport -L../../../src/interfaces/libpq -lpq   -Wl,--as-needed -Wl,-rpath,'/pgsql/install/master-coverage/lib',--enable-new-dtags  -lpgcommon -lpgport -lpthread -lxml2 -lssl -lcrypto -lz -lreadline -lpthread -lrt -ldl -lm  -o initdb
/usr/bin/ld: initdb: hidden symbol `__gcov_merge_add' in /usr/lib/gcc/x86_64-linux-gnu/8/libgcov.a(_gcov_merge_add.o) is referenced by DSO
/usr/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:43: initdb] Error 1

so this doesn't look too promising.

-- 
Álvaro Herrera                        Valdivia, Chile
                        https://www.EnterpriseDB.com/

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	filename="0001-Fix-libpq-build-for-coverage-support.patch"

From db2995171fcf2dad257fdd9d924b1dea916bdbcd Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Wed, 30 Jun 2021 09:41:11 -0400
Subject: [PATCH] Fix libpq build for coverage support

---
 src/Makefile.shlib            | 2 +-
 src/interfaces/libpq/Makefile | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Makefile.shlib b/src/Makefile.shlib
index 29a7f6d38c..c549505e44 100644
--- a/src/Makefile.shlib
+++ b/src/Makefile.shlib
@@ -65,7 +65,7 @@
 #
 
 
-COMPILER = $(CC) $(CFLAGS)
+COMPILER = $(CC) $(filter-out -fprofile-arcs, $(CFLAGS))
 LINK.static = $(AR) $(AROPT)
 
 LDFLAGS_INTERNAL += $(SHLIB_LINK_INTERNAL)
diff --git a/src/interfaces/libpq/Makefile b/src/interfaces/libpq/Makefile
index e8cd07e9c9..8ddb214983 100644
--- a/src/interfaces/libpq/Makefile
+++ b/src/interfaces/libpq/Makefile
@@ -108,7 +108,7 @@ backend_src = $(top_srcdir)/src/backend
 # complaining about <assert.h> infrastructure on ancient macOS releases.
 .PHONY: check-libpq-refs
 check-libpq-refs: $(shlib)
-	! nm -A -g -u $< 2>/dev/null | grep -v '_eprintf\.o:' | grep -e abort -e exit
+	! nm -A -g -u $< 2>/dev/null | grep -v '_eprintf\.o:' | grep -v '__gcov_exit' | grep -e abort -e exit
 
 # Make dependencies on pg_config_paths.h visible in all builds.
 fe-connect.o: fe-connect.c $(top_builddir)/src/port/pg_config_paths.h
-- 
2.30.2


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