Add a "clone" option to base/process_util.h:LaunchProcess(). Useful inside Linux sandbox.

BUG=nativeclient:480
TEST=base/process_util_unittest.cc


Review URL: http://codereview.chromium.org/7401002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@92771 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 32 insertions, 9 deletions

diff --git a/base/process_util.h b/base/process_util.h
index 234bb4f..ef1eee8 100644
--- a/base/process_util.h
+++ b/base/process_util.h
@@ -202,7 +202,8 @@ struct LaunchOptions {
                     start_hidden(false), inherit_handles(false), as_user(NULL),
                     empty_desktop_name(false)
 #else
-                    environ(NULL), fds_to_remap(NULL), new_process_group(false)
+                    environ(NULL), fds_to_remap(NULL), new_process_group(false),
+                    clone_flags(0)
 #endif
       {}
 
@@ -243,6 +244,9 @@ struct LaunchOptions {
   // inheriting the parent's process group.  The pgid of the child process
   // will be the same as its pid.
   bool new_process_group;
+
+  // If non-zero, start the process using clone(), using flags as provided.
+  int clone_flags;
 #endif
 };
 
diff --git a/base/process_util_posix.cc b/base/process_util_posix.cc
index 0fc8c0e..3bc4d97 100644
--- a/base/process_util_posix.cc
+++ b/base/process_util_posix.cc
@@ -541,7 +541,16 @@ bool LaunchProcess(const std::vector<std::string>& argv,
   if (options.environ)
     new_environ.reset(AlterEnvironment(*options.environ, GetEnvironment()));
 
-  pid = fork();
+  if (options.clone_flags) {
+#if defined(OS_LINUX)
+    pid = syscall(__NR_clone, options.clone_flags, 0, 0, 0);
+#else
+    pid = -1;  // hygiene; prevent clang warnings
+    NOTREACHED() << "Tried to use clone() on non-Linux system";
+#endif
+  } else {
+    pid = fork();
+  }
   if (pid < 0) {
     PLOG(ERROR) << "fork";
     return false;
diff --git a/base/process_util_unittest.cc b/base/process_util_unittest.cc
index 5256b37..405beb4 100644
--- a/base/process_util_unittest.cc
+++ b/base/process_util_unittest.cc
@@ -24,6 +24,7 @@
 #include <errno.h>
 #include <malloc.h>
 #include <glib.h>
+#include <sched.h>
 #endif
 #if defined(OS_POSIX)
 #include <dlfcn.h>
@@ -495,7 +496,8 @@ TEST_F(ProcessUtilTest, FDRemapping) {
 
 namespace {
 
-std::string TestLaunchProcess(const base::environment_vector& env_changes) {
+std::string TestLaunchProcess(const base::environment_vector& env_changes,
+                              const int clone_flags) {
   std::vector<std::string> args;
   base::file_handle_mapping_vector fds_to_remap;
 
@@ -511,6 +513,7 @@ std::string TestLaunchProcess(const base::environment_vector& env_changes) {
   options.wait = true;
   options.environ = &env_changes;
   options.fds_to_remap = &fds_to_remap;
+  options.clone_flags = clone_flags;
   EXPECT_TRUE(base::LaunchProcess(args, options, NULL));
   PCHECK(HANDLE_EINTR(close(fds[1])) == 0);
 
@@ -536,29 +539,36 @@ const char kLargeString[] =
 
 TEST_F(ProcessUtilTest, LaunchProcess) {
   base::environment_vector env_changes;
+  const int no_clone_flags = 0;
 
   env_changes.push_back(std::make_pair(std::string("BASE_TEST"),
                                        std::string("bar")));
-  EXPECT_EQ("bar\n", TestLaunchProcess(env_changes));
+  EXPECT_EQ("bar\n", TestLaunchProcess(env_changes, no_clone_flags));
   env_changes.clear();
 
   EXPECT_EQ(0, setenv("BASE_TEST", "testing", 1 /* override */));
-  EXPECT_EQ("testing\n", TestLaunchProcess(env_changes));
+  EXPECT_EQ("testing\n", TestLaunchProcess(env_changes, no_clone_flags));
 
   env_changes.push_back(std::make_pair(std::string("BASE_TEST"),
                                        std::string("")));
-  EXPECT_EQ("\n", TestLaunchProcess(env_changes));
+  EXPECT_EQ("\n", TestLaunchProcess(env_changes, no_clone_flags));
 
   env_changes[0].second = "foo";
-  EXPECT_EQ("foo\n", TestLaunchProcess(env_changes));
+  EXPECT_EQ("foo\n", TestLaunchProcess(env_changes, no_clone_flags));
 
   env_changes.clear();
   EXPECT_EQ(0, setenv("BASE_TEST", kLargeString, 1 /* override */));
-  EXPECT_EQ(std::string(kLargeString) + "\n", TestLaunchProcess(env_changes));
+  EXPECT_EQ(std::string(kLargeString) + "\n",
+            TestLaunchProcess(env_changes, no_clone_flags));
 
   env_changes.push_back(std::make_pair(std::string("BASE_TEST"),
                                        std::string("wibble")));
-  EXPECT_EQ("wibble\n", TestLaunchProcess(env_changes));
+  EXPECT_EQ("wibble\n", TestLaunchProcess(env_changes, no_clone_flags));
+
+#if defined(OS_LINUX)
+  // test a non-trival value for clone_flags
+  EXPECT_EQ("wibble\n", TestLaunchProcess(env_changes, CLONE_FS | SIGCHLD));
+#endif
 }
 
 TEST_F(ProcessUtilTest, AlterEnvironment) {