Mac: Other approach for IPCing child task_ts.

Based on http://www.foldr.org/~michaelw/log/2009/03/13/ , right now in proof-of-concept quality.

Works for worker processes too and seems more reliable in general. Makes it impossible to call LaunchApp() concurrently though.

Submitting to get perf numbers, will revert.

Review URL: http://codereview.chromium.org/549002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@35883 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 143 insertions, 0 deletions

diff --git a/base/process_util_posix.cc b/base/process_util_posix.cc
index 21626732..ba785e4 100644
--- a/base/process_util_posix.cc
+++ b/base/process_util_posix.cc
@@ -26,6 +26,12 @@
 #include "base/time.h"
 #include "base/waitable_event.h"
 
+#if defined(OS_MACOSX)
+#include "base/mach_broker_mac.h"
+
+
+#endif
+
 const int kMicrosecondsPerSecond = 1000000;
 
 namespace base {
@@ -280,11 +286,148 @@ void SetAllFDsToCloseOnExec() {
   }
 }
 
+#if defined(OS_MACOSX)
+
+#define CHECK_MACH_ERROR(err, s) \
+do { \
+  if (err != KERN_SUCCESS) { \
+    fprintf(stderr, "%s 0x%x", s, (int)err); \
+    exit(1); \
+  } \
+} while (0)
+
+static int
+setup_recv_port (mach_port_t *recv_port)
+{
+    kern_return_t       err;
+    mach_port_t         port = MACH_PORT_NULL;
+    err = mach_port_allocate (mach_task_self (),
+                              MACH_PORT_RIGHT_RECEIVE, &port);
+    CHECK_MACH_ERROR (err, "mach_port_allocate failed:");
+
+    err = mach_port_insert_right (mach_task_self (),
+                                  port,
+                                  port,
+                                  MACH_MSG_TYPE_MAKE_SEND);
+    CHECK_MACH_ERROR (err, "mach_port_insert_right failed:");
+
+    *recv_port = port;
+    return 0;
+}
+
+static int
+send_port (mach_port_t remote_port, mach_port_t port)
+{
+    kern_return_t       err;
+
+    struct {
+        mach_msg_header_t          header;
+        mach_msg_body_t            body;
+        mach_msg_port_descriptor_t task_port;
+    } msg;
+
+    msg.header.msgh_remote_port = remote_port;
+    msg.header.msgh_local_port = MACH_PORT_NULL;
+    msg.header.msgh_bits = MACH_MSGH_BITS (MACH_MSG_TYPE_COPY_SEND, 0) |
+        MACH_MSGH_BITS_COMPLEX;
+    msg.header.msgh_size = sizeof msg;
+
+    msg.body.msgh_descriptor_count = 1;
+    msg.task_port.name = port;
+    msg.task_port.disposition = MACH_MSG_TYPE_COPY_SEND;
+    msg.task_port.type = MACH_MSG_PORT_DESCRIPTOR;
+
+    err = mach_msg_send (&msg.header);
+    CHECK_MACH_ERROR (err, "mach_msg_send failed:");
+
+    return 0;
+}
+
+static int
+recv_port (mach_port_t recv_port, mach_port_t *port)
+{
+    kern_return_t       err;
+    struct {
+        mach_msg_header_t          header;
+        mach_msg_body_t            body;
+        mach_msg_port_descriptor_t task_port;
+        mach_msg_trailer_t         trailer;
+    } msg;
+
+    err = mach_msg (&msg.header, MACH_RCV_MSG,
+                    0, sizeof msg, recv_port,
+                    MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
+    CHECK_MACH_ERROR (err, "mach_msg failed:");
+
+    *port = msg.task_port.name;
+    return 0;
+}
+
+static task_t       child_task = MACH_PORT_NULL;
+
+pid_t
+sampling_fork ()
+{
+    kern_return_t       err;
+    mach_port_t         parent_recv_port = MACH_PORT_NULL;
+    mach_port_t         child_recv_port = MACH_PORT_NULL;
+
+    if (setup_recv_port (&parent_recv_port) != 0)
+        return -1;
+    err = task_set_bootstrap_port (mach_task_self (), parent_recv_port);
+    CHECK_MACH_ERROR (err, "task_set_bootstrap_port failed:");
+
+    pid_t               pid;
+    switch (pid = fork ()) {
+    case -1:
+        err = mach_port_deallocate (mach_task_self(), parent_recv_port);
+        CHECK_MACH_ERROR (err, "mach_port_deallocate failed:");
+        return pid;
+    case 0: /* child */
+        err = task_get_bootstrap_port (mach_task_self (), &parent_recv_port);
+        CHECK_MACH_ERROR (err, "task_get_bootstrap_port failed:");
+        if (setup_recv_port (&child_recv_port) != 0)
+            return -1;
+        if (send_port (parent_recv_port, mach_task_self ()) != 0)
+            return -1;
+        if (send_port (parent_recv_port, child_recv_port) != 0)
+            return -1;
+        if (recv_port (child_recv_port, &bootstrap_port) != 0)
+            return -1;
+        err = task_set_bootstrap_port (mach_task_self (), bootstrap_port);
+        CHECK_MACH_ERROR (err, "task_set_bootstrap_port failed:");
+        break;
+    default: /* parent */
+        err = task_set_bootstrap_port (mach_task_self (), bootstrap_port);
+        CHECK_MACH_ERROR (err, "task_set_bootstrap_port failed:");
+        if (recv_port (parent_recv_port, &child_task) != 0)
+            return -1;
+        if (recv_port (parent_recv_port, &child_recv_port) != 0)
+            return -1;
+        if (send_port (child_recv_port, bootstrap_port) != 0)
+            return -1;
+        err = mach_port_deallocate (mach_task_self(), parent_recv_port);
+        CHECK_MACH_ERROR (err, "mach_port_deallocate failed:");
+        break;
+    }
+
+    return pid;
+}
+#endif
+
 bool LaunchApp(const std::vector<std::string>& argv,
                const environment_vector& environ,
                const file_handle_mapping_vector& fds_to_remap,
                bool wait, ProcessHandle* process_handle) {
+#if defined(OS_MACOSX)
+  // Needs to be mutexed! :-(
+  pid_t pid = sampling_fork();
+  MachBroker::instance()->RegisterPid(
+             pid,
+             MachBroker::MachInfo().SetTask(child_task));
+#else
   pid_t pid = fork();
+#endif
   if (pid < 0)
     return false;