Linux: move SyncIPC function from Skia to base.

base/unix_domain_socket_posix.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/unix_domain_socket_posix.h"
 
 #include <unistd.h>
 #include <sys/uio.h>
 #include <sys/socket.h>
 
 #include "base/eintr_wrapper.h"
 #include "base/logging.h"
+#include "base/pickle.h"
 
 namespace base {
 
 bool SendMsg(int fd, const void* buf, size_t length, std::vector<int>& fds) {
   struct msghdr msg;
   memset(&msg, 0, sizeof(msg));
   struct iovec iov = {const_cast<void*>(buf), length};
   msg.msg_iov = &iov;
   msg.msg_iovlen = 1;
 
@@ skipping 64 matching lines @@
     errno = EMSGSIZE;
     return -1;
   }
 
   fds->resize(wire_fds_len);
   memcpy(&(*fds)[0], wire_fds, sizeof(int) * wire_fds_len);
 
   return r;
 }
 
+ssize_t SendRecvMsg(int fd, uint8_t* reply, unsigned reply_len, int* result_fd,
+                    const Pickle& request) {
+    int fds[2];

[Evan Martin, 2009/06/18 00:36:08]

2spc tabs

comment in here that this socketpair is used just for this single send/recv, and
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 r = RecvMsg(fds[0], reply, reply_len, &fd_vector);

[Evan Martin, 2009/06/18 00:36:08]

would be nice to not use a single letter variable here, especially when it's
used 21 lines later

+    close(fds[0]);
+    if (r == -1)
+      return -1;
+
+    if ((fd_vector.size() > 0 && result_fd == NULL) || fd_vector.size() > 1) {

[Evan Martin, 2009/06/18 00:36:08]

It seems these sorts of errors are not like the SendMsg one, in that they're
indicating something has more or less gone wrong at compile-time.  That is, if
you're getting a reply it shouldn't have its vector messed up.  Would it make
sense to NOTREACHED here?

+      for (std::vector<int>::const_iterator
+           i = fd_vector.begin(); i != fd_vector.end(); ++i) {
+        close(*i);
+      }
+
+      return -1;
+    }
+
+    if (result_fd) {
+      if (fd_vector.size() == 0) {
+        *result_fd = -1;
+      } else {
+        *result_fd = fd_vector[0];
+      }
+    }
+
+    return r;
+}
+
 }  // namespace base