Index: compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
===================================================================
--- compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
+++ compiler-rt/trunk/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
@@ -101,6 +101,46 @@
   return DemangleCXXABI(name);
 }
 
+static bool CreateTwoHighNumberedPipes(int *infd_, int *outfd_) {
+  int *infd = NULL;
+  int *outfd = NULL;
+  // The client program may close its stdin and/or stdout and/or stderr
+  // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
+  // In this case the communication between the forked processes may be
+  // broken if either the parent or the child tries to close or duplicate
+  // these descriptors. The loop below produces two pairs of file
+  // descriptors, each greater than 2 (stderr).
+  int sock_pair[5][2];
+  for (int i = 0; i < 5; i++) {
+    if (pipe(sock_pair[i]) == -1) {
+      for (int j = 0; j < i; j++) {
+        internal_close(sock_pair[j][0]);
+        internal_close(sock_pair[j][1]);
+      }
+      return false;
+    } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
+      if (infd == NULL) {
+        infd = sock_pair[i];
+      } else {
+        outfd = sock_pair[i];
+        for (int j = 0; j < i; j++) {
+          if (sock_pair[j] == infd) continue;
+          internal_close(sock_pair[j][0]);
+          internal_close(sock_pair[j][1]);
+        }
+        break;
+      }
+    }
+  }
+  CHECK(infd);
+  CHECK(outfd);
+  infd_[0] = infd[0];
+  infd_[1] = infd[1];
+  outfd_[0] = outfd[0];
+  outfd_[1] = outfd[1];
+  return true;
+}
+
 bool SymbolizerProcess::StartSymbolizerSubprocess() {
   if (!FileExists(path_)) {
     if (!reported_invalid_path_) {
@@ -110,7 +150,16 @@
     return false;
   }
 
-  int pid;
+  int pid = -1;
+
+  int infd[2] = {};
+  int outfd[2] = {};
+  if (!CreateTwoHighNumberedPipes(infd, outfd)) {
+    Report("WARNING: Can't create a socket pair to start "
+           "external symbolizer (errno: %d)\n", errno);
+    return false;
+  }
+
   if (use_forkpty_) {
 #if SANITIZER_MAC
     fd_t fd = kInvalidFd;
@@ -121,6 +170,10 @@
     int saved_stderr = dup(STDERR_FILENO);
     CHECK_GE(saved_stderr, 0);
 
+    // We only need one pipe, for stdin of the child.
+    close(outfd[0]);
+    close(outfd[1]);
+
     // Use forkpty to disable buffering in the new terminal.
     pid = internal_forkpty(&fd);
     if (pid == -1) {
@@ -131,6 +184,13 @@
     } else if (pid == 0) {
       // Child subprocess.
 
+      // infd[0] is the child's reading end.
+      close(infd[1]);
+
+      // Set up stdin to read from the pipe.
+      CHECK_GE(dup2(infd[0], STDIN_FILENO), 0);
+      close(infd[0]);
+
       // Restore stderr.
       CHECK_GE(dup2(saved_stderr, STDERR_FILENO), 0);
       close(saved_stderr);
@@ -141,8 +201,12 @@
       internal__exit(1);
     }
 
+    // Input for the child, infd[1] is our writing end.
+    output_fd_ = infd[1];
+    close(infd[0]);
+
     // Continue execution in parent process.
-    input_fd_ = output_fd_ = fd;
+    input_fd_ = fd;
 
     close(saved_stderr);
 
@@ -156,41 +220,6 @@
     UNIMPLEMENTED();
 #endif  // SANITIZER_MAC
   } else {
-    int *infd = NULL;
-    int *outfd = NULL;
-    // The client program may close its stdin and/or stdout and/or stderr
-    // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
-    // In this case the communication between the forked processes may be
-    // broken if either the parent or the child tries to close or duplicate
-    // these descriptors. The loop below produces two pairs of file
-    // descriptors, each greater than 2 (stderr).
-    int sock_pair[5][2];
-    for (int i = 0; i < 5; i++) {
-      if (pipe(sock_pair[i]) == -1) {
-        for (int j = 0; j < i; j++) {
-          internal_close(sock_pair[j][0]);
-          internal_close(sock_pair[j][1]);
-        }
-        Report("WARNING: Can't create a socket pair to start "
-               "external symbolizer (errno: %d)\n", errno);
-        return false;
-      } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
-        if (infd == NULL) {
-          infd = sock_pair[i];
-        } else {
-          outfd = sock_pair[i];
-          for (int j = 0; j < i; j++) {
-            if (sock_pair[j] == infd) continue;
-            internal_close(sock_pair[j][0]);
-            internal_close(sock_pair[j][1]);
-          }
-          break;
-        }
-      }
-    }
-    CHECK(infd);
-    CHECK(outfd);
-
     const char *argv[kArgVMax];
     GetArgV(path_, argv);
     pid = StartSubprocess(path_, argv, /* stdin */ outfd[0],
@@ -205,6 +234,8 @@
     output_fd_ = outfd[1];
   }
 
+  CHECK_GT(pid, 0);
+
   // Check that symbolizer subprocess started successfully.
   SleepForMillis(kSymbolizerStartupTimeMillis);
   if (!IsProcessRunning(pid)) {