Cygwin: testsuite: Setup test prereqs in 'installation' the tests run in

Do some setup in the Cygwin 'installation' at testsuite/testinst/:

* Ensure /tmp exists

* Use BusyBox to provide executables needed by tests which use system()
(sh, sleep, ls)

This enables tests which use system(), or require /tmp to exist to pass.

Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>

.github/workflows/cygwin.yml

@@ -71,6 +71,7 @@ jobs:
         packages: >-
           autoconf,
           automake,
+          busybox,
           cocom,
           dblatex,
           dejagnu,
@@ -116,6 +117,6 @@ jobs:
         export PATH=/usr/bin:$(cygpath ${SYSTEMROOT})/system32 &&
         export MAKEFLAGS=-j$(nproc) &&
         cd build &&
-        (export PATH=${{ matrix.target }}/winsup/testsuite/runtime:${PATH} && cmd /c $(cygpath -wa ${{ matrix.target }}/winsup/cygserver/cygserver) &) &&
+        (export PATH=${{ matrix.target }}/winsup/testsuite/testinst/bin:${PATH} && cmd /c $(cygpath -wa ${{ matrix.target }}/winsup/cygserver/cygserver) &) &&
         (cd ${{ matrix.target }}/winsup; make check || true)
       shell: C:\cygwin\bin\bash.exe --noprofile --norc -eo pipefail '{0}'

winsup/cygwin/Makefile.am

@@ -602,8 +602,8 @@ $(NEW_DLL_NAME): $(LDSCRIPT) libdll.a $(VERSION_OFILES) $(LIBSERVER)\
 	$(newlib_build)/libm.a \
 	$(newlib_build)/libc.a \
 	-lgcc -lkernel32 -lntdll -Wl,-Map,cygwin.map
-	@$(MKDIR_P) ${target_builddir}/winsup/testsuite/runtime/
-	$(AM_V_at)$(INSTALL_PROGRAM) $(NEW_DLL_NAME) ${target_builddir}/winsup/testsuite/runtime/$(DLL_NAME)
+	@$(MKDIR_P) ${target_builddir}/winsup/testsuite/testinst/bin/
+	$(AM_V_at)$(INSTALL_PROGRAM) $(NEW_DLL_NAME) ${target_builddir}/winsup/testsuite/testinst/bin/$(DLL_NAME)
 
 # cygwin import library
 toolopts=--cpu=@target_cpu@ --ar=@AR@ --as=@AS@ --nm=@NM@ --objcopy=@OBJCOPY@

winsup/doc/faq-programming.xml

@@ -697,7 +697,8 @@ Building these programs can be disabled with the <literal>--without-cross-bootst
 option to <literal>configure</literal>.
 </para>
 
-<!-- If you want to run the tests, <literal>dejagnu</literal> is also required. -->
+<!-- If you want to run the tests, <literal>dejagnu</literal> and
+     <literal>busybox</literal> are also required. -->
 
 <para>
 Building the documentation also requires the <literal>dblatex</literal>,

winsup/testsuite/Makefile.am

@@ -339,7 +339,7 @@ testdll_tmpdir = $(shell cygpath -ma $(tmpdir) | sed -e 's#^\([A-Z]\):#/cygdrive
 
 site-extra.exp: ../config.status Makefile
 	@rm -f ./tmp0
-	@echo "set runtime_root \"`pwd`/runtime\"" >> ./tmp0
+	@echo "set runtime_root \"`pwd`/testinst/bin\"" >> ./tmp0
 	@echo "set tmpdir $(tmpdir)" >> ./tmp0
 	@echo "set testdll_tmpdir $(testdll_tmpdir)" >> ./tmp0
 	@echo "set cygrun \"`pwd`/mingw/cygrun\"" >> ./tmp0
@@ -347,6 +347,29 @@ site-extra.exp: ../config.status Makefile
 
 EXTRA_DEJAGNU_SITE_CONFIG = site-extra.exp
 
+# Set up things in the Cygwin 'installation' at testsuite/testinst/ to provide
+# things which tests need to work
+#
+# * Create /tmp
+# * Ensure there is a /usr/bin/sh for tests which use system()
+# * Ensure there is a /usr/bin/sleep for tests which use system("sleep 10")
+# * Ensure there is a /usr/bin/ls for tests which  use system("ls")
+#
+# copy to avoid all the complexities: hardlink will fail if builddir is on a
+# separate filesystem, symlink would need to be constructed with regard to the
+# mounts of the test installation, and making it into /bin/ will cause
+# CreateProcess() to load cygwin1.dll from there.
+#
+# use busybox executables as they don't have any other shared library
+# dependencies other than cygwin1.dll.
+#
+
+check-local:
+	$(MKDIR_P) ${builddir}/testinst/tmp
+	cd ${builddir}/testinst/bin && cp /usr/libexec/busybox/bin/busybox.exe sh.exe
+	cd ${builddir}/testinst/bin && cp /usr/libexec/busybox/bin/busybox.exe sleep.exe
+	cd ${builddir}/testinst/bin && cp /usr/libexec/busybox/bin/busybox.exe ls.exe
+
 # target to build all the programs needed by check, without running check
 check_programs: $(check_PROGRAMS)