Cygwin: Ensure temporary directory used by tests exists

By default, libltp tests will create temporary files in a subdirectory
of /tmp, which will (nowadays) be located relative to the test DLL (by
assuming that it is in /bin).  This will evaluate to the directory
$target_builddir/winsup/tmp, which doesn't exist.

The location used for these temporary files can be explicitly controlled
by setting the TDIRECTORY env var.  Arrange to set that env var to the
/cygdrive path of a tmp subdirectory of the build directory.

Unfortunately, libltp doesn't clean the temporary directory if
TDIRECTORY is set, and some tests assume they are started in a clean
directory, so we need to do that in tcl.

winsup/testsuite/Makefile.in

@@ -97,7 +97,8 @@ force:
 install:
 
 clean:
-	-rm -f *.o *.dll *.a *.exp junk *.bak *.base *.exe testsuite/* *.d *.dat
+	-rm -f *.o *.dll *.a *.exp junk *.bak *.base *.exe *.d *.dat
+	-rm -rf testsuite
 
 maintainer-clean realclean: clean
 	@echo "This command is intended for maintainers to use;"
@@ -123,6 +124,11 @@ $(RUNTIME) : $(cygwin_build)/Makefile
 # Set to $(target_alias)/ for cross.
 target_subdir = @target_subdir@
 
+# temporary directory to be used for files created by tests (as an absolute,
+# /cygdrive path, so it can be understood by the test DLL, which will have
+# different mount table)
+tmpdir = $(shell cygpath -ma $(objdir)/testsuite/tmp/ | sed -e 's#^\([A-Z]\):#/cygdrive/\L\1#')
+
 site.exp: ./config.status Makefile
 	@echo "Making a new config file..."
 	-@rm -f ./tmp?
@@ -142,7 +148,7 @@ site.exp: ./config.status Makefile
 # CFLAGS is set even though it's empty to show we reserve the right to set it.
 	@echo "set CFLAGS \"$(ALL_CFLAGS)\"" >> ./tmp0
 	@echo "set MINGW_CXX \"$(MINGW_CXX)\"" >> ./tmp0
-	echo "set tmpdir $(objdir)/testsuite" >> ./tmp0
+	@echo "set tmpdir $(tmpdir)" >> ./tmp0
 	@echo "set ltp_includes \"$(realpath $(libltp_srcdir))/include\"" >> ./tmp0
 	@echo "## All variables above are generated by configure. Do Not Edit ##" >> ./tmp0
 	@cat ./tmp0 > site.exp

winsup/testsuite/cygrun.c

@@ -25,10 +25,13 @@ main (int argc, char **argv)
 
   if (argc < 2)
     {
-      fprintf (stderr, "Usage: cygrun [program]\n");
+      fprintf (stderr, "Usage: cygrun [program] [tmpdir]\n");
       exit (0);
     }
 
+  if (argc >= 3)
+    SetEnvironmentVariable ("TDIRECTORY", argv[2]);
+
   SetEnvironmentVariable ("CYGWIN_TESTING", "1");
   if ((p = getenv ("CYGWIN")) == NULL || (strstr (p, "ntsec") == NULL))
     {

winsup/testsuite/winsup.api/winsup.exp

@@ -68,7 +68,9 @@ foreach src [lsort [glob -nocomplain $srcdir/$subdir/*.c $srcdir/$subdir/*/*.{cc
 	    } else {
 	       set redirect_output /dev/null
 	    }
-	    ws_spawn "$rootme/cygrun ./$base.exe > $redirect_output"
+	    file mkdir $tmpdir/$base
+	    ws_spawn "$rootme/cygrun ./$base.exe $tmpdir/$base > $redirect_output"
+	    file delete -force $tmpdir/$base
 	    if { $rv } {
 		fail "$testcase (execute)"
 		if { $xfail_expected } {