Fix: libc internal mutex races with run_as

[lttng-tools.git] / src / common / sessiond-comm / unix.c

diff --git a/src/common/sessiond-comm/unix.c b/src/common/sessiond-comm/unix.c
index 0d7c95a7637638f066b28f0c2dbe14dc2bbd393d..4b6416168afa9f465406dd4bcce73d5d129180fe 100644 (file)
--- a/src/common/sessiond-comm/unix.c
+++ b/src/common/sessiond-comm/unix.c
@@ -17,6 +17,7 @@
  */
 
 #define _GNU_SOURCE
+#define _LGPL_SOURCE
 #include <assert.h>
 #include <limits.h>
 #include <stdio.h>
@@ -92,6 +93,16 @@ int lttcomm_accept_unix_sock(int sock)
        return new_fd;
 }
 
+LTTNG_HIDDEN
+int lttcomm_create_anon_unix_socketpair(int *fds)
+{
+       if (socketpair(PF_UNIX, SOCK_STREAM, 0, fds) < 0) {
+               PERROR("socketpair");
+               return -1;
+       }
+       return 0;
+}
+
 /*
  * Creates a AF_UNIX local socket using pathname bind the socket upon creation
  * and return the fd.
@@ -172,7 +183,7 @@ ssize_t lttcomm_recv_unix_sock(int sock, void *buf, size_t len)
 
        do {
                len_last = iov[0].iov_len;
-               ret = recvmsg(sock, &msg, 0);
+               ret = recvmsg(sock, &msg, MSG_NOSIGNAL);
                if (ret > 0) {
                        iov[0].iov_base += ret;
                        iov[0].iov_len -= ret;
@@ -435,6 +446,7 @@ ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
        struct msghdr msg;
        struct iovec iov[1];
        ssize_t ret;
+       size_t len_last;
 #ifdef __linux__
        struct cmsghdr *cmptr;
        size_t sizeof_cred = sizeof(lttng_sock_cred);
@@ -461,12 +473,21 @@ ssize_t lttcomm_recv_creds_unix_sock(int sock, void *buf, size_t len,
 #endif /* __linux__ */
 
        do {
+               len_last = iov[0].iov_len;
                ret = recvmsg(sock, &msg, 0);
-       } while (ret < 0 && errno == EINTR);
+               if (ret > 0) {
+                       iov[0].iov_base += ret;
+                       iov[0].iov_len -= ret;
+                       assert(ret <= len_last);
+               }
+       } while ((ret > 0 && ret < len_last) || (ret < 0 && errno == EINTR));
        if (ret < 0) {
                PERROR("recvmsg fds");
                goto end;
+       } else if (ret > 0) {
+               ret = len;
        }
+       /* Else ret = 0 meaning an orderly shutdown. */
 
 #ifdef __linux__
        if (msg.msg_flags & MSG_CTRUNC) {