erts: Fix uds socket handling for os x

OS X is very strict in what it requires of you and also
gives strange error codes for some errors. In this commit
we remap EMSGSIZE to EMFILE and also precisely tune the
amount of data we send on the socket so that we can recv
only that data. If we try to recv more, recvmsg fails with
EPIPE if the remote end has been closed.

1 files changed, 8 insertions, 0 deletions

diff --git a/erts/emulator/sys/unix/sys_uds.c b/erts/emulator/sys/unix/sys_uds.c
index daebcb307b..015d0346a1 100644
--- a/erts/emulator/sys/unix/sys_uds.c
+++ b/erts/emulator/sys/unix/sys_uds.c
@@ -38,6 +38,14 @@ sys_uds_readv(int fd, struct iovec *iov, size_t iov_len,
     msg.msg_controllen = sizeof(ancillary_buff);
 
     if((res = recvmsg(fd, &msg, flags)) < 0) {
+#if defined(__APPLE__) && defined(__MACH__) && !defined(__DARWIN__)
+        /* When some OS X versions run out of fd's
+           they give EMSGSIZE instead of EMFILE.
+           We remap this as we want the correct
+           error to appear for the user */
+        if (errno == EMSGSIZE)
+            errno = EMFILE;
+#endif
         return res;
     }