Integrate PR 12649's race detector directly in the testsuite machinery

This integrates Jan Kratochvil's nice race reproducer from PR
testsuite/12649 into the testsuite infrustructure directly.

With this, one only has to do either 'make check-read1' or 'make check
READ1="1"' to preload the read1.so library into expect.

Currently only enabled for glibc/GNU systems, and if
build==host==target.

gdb/testsuite/ChangeLog:

	* Makefile.in (EXTRA_RULES, CC): New variables, get from
	configure.
	(EXPECT): Handle READ1 being set.
	(all): Depend on EXTRA_RULES.
	(check-read1, expect-read1, read1.so, read1): New rules.
	* README (Testsuite Parameters): Document the READ1 make variable.
	(Race detection): New section.
	* configure: Regenerate.
	* configure.ac: If build==host==target, and running under a
	GNU/glibc system, add read1 to the extra Makefile rules.
	(EXTRA_RULES): AC_SUBST it.
	* lib/read1.c: New file.

gdb/ChangeLog:

	* Makefile.in (check-read1): New rule.

1 files changed, 40 insertions, 4 deletions

diff --git a/gdb/testsuite/Makefile.in b/gdb/testsuite/Makefile.in
index 0020a0f..1c923cd 100644
--- a/gdb/testsuite/Makefile.in
+++ b/gdb/testsuite/Makefile.in
@@ -39,9 +39,17 @@ ALL_SUBDIRS = gdb.ada gdb.arch gdb.asm gdb.base gdb.btrace gdb.cell gdb.cp \
 	gdb.stabs gdb.reverse gdb.threads gdb.trace gdb.xml \
 	$(SUBDIRS)
 
-EXPECT = `if [ -f $${rootme}/../../expect/expect ] ; then \
-          echo $${rootme}/../../expect/expect ; \
-          else echo expect ; fi`
+EXTRA_RULES = @EXTRA_RULES@
+
+CC=@CC@
+
+EXPECT = `if [ "$${READ1}" != "" ] ; then \
+            echo $${rootme}/expect-read1; \
+          elif [ -f $${rootme}/../../expect/expect ] ; then \
+            echo $${rootme}/../../expect/expect ; \
+          else \
+            echo expect ; \
+          fi`
 
 RUNTEST = $(RUNTEST_FOR_TARGET)
 
@@ -84,7 +92,7 @@ TARGET_FLAGS_TO_PASS = \
         "RUNTEST=$(RUNTEST)" \
         "RUNTESTFLAGS=$(RUNTESTFLAGS)"
 
-all:
+all: $(EXTRA_RULES)
 	@echo "Nothing to be done for all..."
 
 .NOEXPORT:
@@ -146,6 +154,9 @@ installcheck:
 check: all $(abs_builddir)/site.exp
 	$(MAKE) $(CHECK_TARGET)
 
+check-read1:
+	$(MAKE) READ1="1" check
+
 # All the hair to invoke dejagnu.  A given invocation can just append
 # $(RUNTESTFLAGS)
 DO_RUNTEST = \
@@ -230,6 +241,7 @@ clean mostlyclean:
 	-rm -f core.* *.tf *.cl *.py tracecommandsscript copy1.txt zzz-gdbscript
 	-rm -f *.dwo *.dwp
 	-rm -rf outputs temp cache
+	-rm -f read1.so expect-read1
 	if [ x"${ALL_SUBDIRS}" != x ] ; then \
 	    for dir in ${ALL_SUBDIRS}; \
 	    do \
@@ -263,3 +275,27 @@ config.status: configure
 TAGS: force
 	find $(srcdir) -name '*.exp' -print | \
 	    etags --regex='/proc[ \t]+\([^ \t]+\)/\1/' -
+
+# Build the expect wrapper script that preloads the read1.so library.
+expect-read1:
+	@echo Making expect-read1
+	@rm -f expect-read1-tmp
+	@touch expect-read1-tmp
+	@echo "# THIS FILE IS GENERATED -*- buffer-read-only: t -*- \n" >>expect-read1-tmp
+	@echo "# vi:set ro: */\n\n" >>expect-read1-tmp
+	@echo "# To regenerate this file, run:\n" >>expect-read1-tmp
+	@echo "#      make clean; make/\n" >>expect-read1-tmp
+	@echo "export LD_PRELOAD=`pwd`/read1.so" >>expect-read1-tmp
+	@echo 'exec expect "$$@"' >>expect-read1-tmp
+	@chmod +x expect-read1-tmp
+	@mv expect-read1-tmp expect-read1
+
+# Build the read1.so preload library.  This overrides the `read'
+# function, making it read one byte at a time.  Running the testsuite
+# with this catches racy tests.
+read1.so: lib/read1.c
+	$(CC) -o $@ ${srcdir}/lib/read1.c -Wall -g -shared -fPIC $(CFLAGS)
+
+# Build the read1 machinery.
+.PHONY: read1
+read1: read1.so expect-read1