librspreload: Support server apps that call fork()

Provide limited support for applications that call fork() after
accepting a connection.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>

diff --git a/src/preload.c b/src/preload.c
index 0d457bf75d4163d2b984fae64757021a6d80979c..177c6216738fbe4c936dd9c0626c2fb63bbd83e5 100644 (file)
--- a/src/preload.c
+++ b/src/preload.c
@@ -92,10 +92,12 @@ static pthread_mutex_t mut = PTHREAD_MUTEX_INITIALIZER;
 static int sq_size;
 static int rq_size;
 static int sq_inline;
+static int fork_support;
 
 enum fd_type {
        fd_normal,
-       fd_rsocket
+       fd_rsocket,
+       fd_fork
 };
 
 struct fd_info {
@@ -207,6 +209,10 @@ void getenv_options(void)
        var = getenv("RS_INLINE");
        if (var)
                sq_inline = atoi(var);
+
+       var = getenv("RDMAV_FORK_SAFE");
+       if (var)
+               fork_support = atoi(var);
 }
 
 static void init_preload(void)
@@ -344,8 +350,16 @@ int socket(int domain, int type, int protocol)
        ret = rsocket(domain, type, protocol);
        recursive = 0;
        if (ret >= 0) {
-               fd_store(index, ret, fd_rsocket);
-               set_rsocket_options(ret);
+               if (fork_support) {
+                       rclose(ret);
+                       ret = real_socket(domain, type, protocol);
+                       if (ret < 0)
+                               return ret;
+                       fd_store(index, ret, fd_fork);
+               } else {
+                       fd_store(index, ret, fd_rsocket);
+                       set_rsocket_options(ret);
+               }
                return index;
        }
        fd_close(index, &ret);
@@ -403,6 +417,29 @@ int accept(int socket, struct sockaddr *addr, socklen_t *addrlen)
        }
 }
 
+static int connect_fork(int socket, const struct sockaddr *addr, socklen_t addrlen)
+{
+       uint32_t msg;
+       int rs, fd, ret;
+
+       fd = fd_getd(socket);
+       ret = real_connect(fd, addr, addrlen);
+       if (!ret)
+               return ret;
+
+       ret = real_read(fd, &msg, sizeof msg);
+       if (ret != sizeof msg)
+               return ret;
+
+       rs = rsocket(domain, type, protocol);
+
+       real_shutdown(fd, SHUT_RDWR);
+       real_close(fd);
+
+       fd_store(socket, fd, fd_rsocket);
+       return connect(socket, addr, addrlen);
+}
+
 int connect(int socket, const struct sockaddr *addr, socklen_t addrlen)
 {
        struct sockaddr_in *sin;