Fix process007 with dash as /bin/sh

dash doesn't support 2-digit FD numbers with the 0<&10 syntax, and
some ways were using FDs that high. So now we have a little C program
to do the job instead.

tests/Makefile

@@ -5,3 +5,8 @@
 TOP=../../../testsuite
 include $(TOP)/mk/boilerplate.mk
 include $(TOP)/mk/test.mk
+
+.PHONY: process007_fd
+process007_fd:
+	'$(TEST_HC)' -no-hs-main -no-auto-link-packages process007_fd.c -o process007_fd
+

tests/all.T

@@ -6,7 +6,12 @@ test('T1780', normal, compile_and_run, [''])
 test('process005', normal, compile_and_run, [''])
 test('process006', normal, compile_and_run, [''])
 
-test('process007', [extra_clean(['process007.tmp']), reqlib('unix')], compile_and_run, [''])
+test('process007',
+     [extra_clean(['process007.tmp',
+                   'process007_fd.o', 'process007_fd', 'process007_fd.exe']),
+      reqlib('unix'),
+      pre_cmd('$MAKE -s --no-print-directory process007_fd')],
+     compile_and_run, [''])
 test('process008', normal, compile_and_run, [''])
 
 # not the normal way: this test runs processes from multiple threads, and

tests/process007.hs

@@ -9,9 +9,7 @@ tmpfile = "process007.tmp"
 main = do
   writeFile tmpfile "You bad pie-rats!\n"
   fd <- handleToFd =<< openFile tmpfile ReadMode
-  system ("cat 0<&" ++ show fd)
-  -- or this, but maybe less portable?
-  --    rawSystem "cat" ["/dev/fd/" ++ show fd]
+  rawSystem "./process007_fd" [show fd]
   closeFd fd
 
   fd <- handleToFd =<< openFile tmpfile ReadMode

tests/process007_fd.c

+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#define SIZE 1024
+
+int main(int argc, char **argv) {
+    int fd;
+    char buf[SIZE];
+    int nRead, nWrite;
+
+    if (argc != 2) {
+        printf("Bad arguments\n");
+        exit(1);
+    }
+
+    fd = atoi(argv[1]);
+
+    while (nRead = read(fd, buf, SIZE) != 0) {
+        if (nRead > 0) {
+            nWrite = printf("%s", buf);
+            if (nWrite < 0) {
+                perror("printf failed");
+                exit(1);
+            }
+        }
+        else if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINTR) {
+            perror("read failed");
+            exit(1);
+        }
+    }
+
+    return 0;
+}
+