tsan: add support for passing file descriptors over UNIX domain sockets

tsan was missing new fd's arrived from recvmsg(),
and thus was reporting false positives due to missed synchronization on the fd's

llvm-svn: 195914

1 files changed, 24 insertions, 0 deletions

diff --git a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
index 906b5dc73be..282b2982fdd 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cc
@@ -34,6 +34,7 @@
 #include <sys/mman.h>
 #include <sys/prctl.h>
 #include <sys/syscall.h>
+#include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/resource.h>
@@ -347,6 +348,9 @@ bool IsGlobalVar(uptr addr) {
 }
 
 #ifndef TSAN_GO
+// Extract file descriptors passed to glibc internal __res_iclose function.
+// This is required to properly "close" the fds, because we do not see internal
+// closes within glibc. The code is a pure hack.
 int ExtractResolvFDs(void *state, int *fds, int nfd) {
   int cnt = 0;
   __res_state *statp = (__res_state*)state;
@@ -356,6 +360,26 @@ int ExtractResolvFDs(void *state, int *fds, int nfd) {
   }
   return cnt;
 }
+
+// Extract file descriptors passed via UNIX domain sockets.
+// This is requried to properly handle "open" of these fds.
+// see 'man recvmsg' and 'man 3 cmsg'.
+int ExtractRecvmsgFDs(void *msgp, int *fds, int nfd) {
+  int res = 0;
+  msghdr *msg = (msghdr*)msgp;
+  struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
+  for (; cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+    if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
+      continue;
+    int n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(fds[0]);
+    for (int i = 0; i < n; i++) {
+      fds[res++] = ((int*)CMSG_DATA(cmsg))[i];
+      if (res == nfd)
+        return res;
+    }
+  }
+  return res;
+}
 #endif