Linux: move SyncIPC function from Skia to base.

I'll be needing in some pending WebKit changes.

http://codereview.chromium.org/131006


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@18676 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 65 insertions, 0 deletions

diff --git a/base/unix_domain_socket_posix.cc b/base/unix_domain_socket_posix.cc
index 55cb186..024c086 100644
--- a/base/unix_domain_socket_posix.cc
+++ b/base/unix_domain_socket_posix.cc
@@ -10,6 +10,7 @@
 
 #include "base/eintr_wrapper.h"
 #include "base/logging.h"
+#include "base/pickle.h"
 
 namespace base {
 
@@ -94,4 +95,50 @@ ssize_t RecvMsg(int fd, void* buf, size_t length, std::vector<int>* fds) {
   return r;
 }
 
+ssize_t SendRecvMsg(int fd, uint8_t* reply, unsigned max_reply_len, int* result_fd,
+                    const Pickle& request) {
+  int fds[2];
+
+  // This socketpair is only used for the IPC and is cleaned up before
+  // returning.
+  if (socketpair(AF_UNIX, SOCK_DGRAM, 0, fds) == -1)
+      return false;
+
+  std::vector<int> fd_vector;
+  fd_vector.push_back(fds[1]);
+  if (!SendMsg(fd, request.data(), request.size(), fd_vector)) {
+    close(fds[0]);
+    close(fds[1]);
+    return -1;
+  }
+  close(fds[1]);
+
+  fd_vector.clear();
+  const ssize_t reply_len = RecvMsg(fds[0], reply, max_reply_len, &fd_vector);
+  close(fds[0]);
+  if (reply_len == -1)
+    return -1;
+
+  if ((fd_vector.size() > 0 && result_fd == NULL) || fd_vector.size() > 1) {
+    for (std::vector<int>::const_iterator
+         i = fd_vector.begin(); i != fd_vector.end(); ++i) {
+      close(*i);
+    }
+
+    NOTREACHED();
+
+    return -1;
+  }
+
+  if (result_fd) {
+    if (fd_vector.size() == 0) {
+      *result_fd = -1;
+    } else {
+      *result_fd = fd_vector[0];
+    }
+  }
+
+  return reply_len;
+}
+
 }  // namespace base
diff --git a/base/unix_domain_socket_posix.h b/base/unix_domain_socket_posix.h
index c0b40e8..4274a64 100644
--- a/base/unix_domain_socket_posix.h
+++ b/base/unix_domain_socket_posix.h
@@ -8,6 +8,8 @@
 #include <sys/types.h>
 #include <vector>
 
+class Pickle;
+
 namespace base {
 
 // Use sendmsg to write the given msg and include a vector
@@ -17,6 +19,22 @@ bool SendMsg(int fd, const void* msg, size_t length,
 // Use recvmsg to read a message and an array of file descriptors. Returns
 // -1 on failure. Note: will read, at most, 16 descriptors.
 ssize_t RecvMsg(int fd, void* msg, size_t length, std::vector<int>* fds);
+// Perform a sendmsg/recvmsg pair.
+//   1. This process creates a UNIX DGRAM socketpair.
+//   2. This proces writes a request to |fd| with an SCM_RIGHTS control message
+//      containing on end of the fresh socket pair.
+//   3. This process blocks reading from the other end of the fresh socketpair.
+//   4. The target process receives the request, processes it and writes the
+//      reply to the end of the socketpair contained in the request.
+//   5. This process wakes up and continues.
+//
+//   fd: descriptor to send the request on
+//   reply: buffer for the reply
+//   reply_len: size of |reply|
+//   result_fd: (may be NULL) the file descriptor returned in the reply (if any)
+//   request: the bytes to send in the request
+ssize_t SendRecvMsg(int fd, uint8_t* reply, unsigned reply_len, int* result_fd,
+                    const Pickle& request);
 
 }  // namespace base