Fix handling of sessiond respawn after a SIGKILL

[lttng-tools.git] / liblttsessiondcomm / liblttsessiondcomm.c

diff --git a/liblttsessiondcomm/liblttsessiondcomm.c b/liblttsessiondcomm/liblttsessiondcomm.c
index 8fadccf1b884807cfe4ec88e68b6429ec5581eaa..e7e4204339d61dc0b1daa97cdadd3b1c6fd8033c 100644 (file)
--- a/liblttsessiondcomm/liblttsessiondcomm.c
+++ b/liblttsessiondcomm/liblttsessiondcomm.c
@@ -26,6 +26,7 @@
 #include <sys/types.h>
 #include <sys/un.h>
 #include <unistd.h>
+#include <assert.h>
 
 #include "liblttsessiondcomm.h"
 
@@ -185,6 +186,8 @@ int lttcomm_create_unix_sock(const char *pathname)
        sun.sun_family = AF_UNIX;
        strncpy(sun.sun_path, pathname, strlen(pathname));
 
+       /* Unlink the old file if present */
+       (void) unlink(pathname);
        ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
        if (ret < 0) {
                perror("bind");
@@ -223,12 +226,10 @@ int lttcomm_listen_unix_sock(int sock)
  */
 ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 {
-       struct msghdr msg;
+       struct msghdr msg = { 0 };
        struct iovec iov[1];
        ssize_t ret = -1;
 
-       memset(&msg, 0, sizeof(msg));
-
        iov[0].iov_base = buf;
        iov[0].iov_len = len;
        msg.msg_iov = iov;
@@ -250,12 +251,10 @@ ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
  */
 ssize_t lttcomm_send_unix_sock(int sock, void *buf, size_t len)
 {
-       struct msghdr msg;
+       struct msghdr msg = { 0 };
        struct iovec iov[1];
        ssize_t ret = -1;
 
-       memset(&msg, 0, sizeof(msg));
-
        iov[0].iov_base = buf;
        iov[0].iov_len = len;
        msg.msg_iov = iov;
@@ -294,23 +293,29 @@ int lttcomm_close_unix_sock(int sock)
  */
 ssize_t lttcomm_send_fds_unix_sock(int sock, void *buf, int *fds, size_t nb_fd, size_t len)
 {
-       struct msghdr msg;
+       struct msghdr msg = { 0 };
        struct cmsghdr *cmptr;
        struct iovec iov[1];
        ssize_t ret = -1;
        unsigned int sizeof_fds = nb_fd * sizeof(int);
        char tmp[CMSG_SPACE(sizeof_fds)];
 
-       memset(&msg, 0, sizeof(msg));
+       /*
+        * Note: the consumerd receiver only supports receiving one FD per
+        * message.
+        */
+       assert(nb_fd == 1);
 
        msg.msg_control = (caddr_t)tmp;
        msg.msg_controllen = CMSG_LEN(sizeof_fds);
 
        cmptr = CMSG_FIRSTHDR(&msg);
-       cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
        cmptr->cmsg_level = SOL_SOCKET;
        cmptr->cmsg_type = SCM_RIGHTS;
+       cmptr->cmsg_len = CMSG_LEN(sizeof_fds);
        memcpy(CMSG_DATA(cmptr), fds, sizeof_fds);
+       /* Sum of the length of all control messages in the buffer: */
+       msg.msg_controllen = cmptr->cmsg_len;
 
        iov[0].iov_base = buf;
        iov[0].iov_len = len;