Fix PipeClosedWhenNotRedirectedTest.

When checking for a file descriptor open on the child, we now execute a
simple test program that just runs fstat on that file descriptor. This
is more reliable than calling sh on different platforms.

Bug: 26955860
TEST=Ran unittests on edison-eng and Chromium OS.

Change-Id: I5d5d87095564159df1a75e78b0aed29c16bc7eb8

1 files changed, 59 insertions, 0 deletions

diff --git a/test_subprocess.cc b/test_subprocess.cc
new file mode 100644
index 00000000..c7f4a373
--- /dev/null
+++ b/test_subprocess.cc
@@ -0,0 +1,59 @@
+//
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+// This is a simple program used to test interaction with update_engine when
+// executing other programs. This program receives pre-programmed actions in the
+// command line and executes them in order.
+
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <string>
+
+#define EX_USAGE_ERROR 100
+
+void usage(const char* program, const char* error) {
+  if (error)
+    fprintf(stderr, "ERROR: %s\n", error);
+  fprintf(stderr, "Usage: %s <cmd> [args..]\n", program);
+  exit(EX_USAGE_ERROR);
+}
+
+int main(int argc, char** argv, char** envp) {
+  if (argc < 2)
+    usage(argv[0], "No command passed");
+
+  std::string cmd(argv[1]);
+  if (cmd == "fstat") {
+    // Call fstat on the passed file descriptor number
+    if (argc < 3)
+      usage(argv[0], "No fd passed to fstat");
+    int fd = atoi(argv[2]);
+    struct stat buf;
+    int rc = fstat(fd, &buf);
+    if (rc < 0) {
+      int ret = errno;
+      perror("fstat");
+      return ret;
+    }
+    return 0;
+  }
+
+  usage(argv[0], "Unknown command");
+}