Fix: don't flush-final for offset 0 if reader is on sub-buffer
[lttng-ust.git] / liblttng-ust-comm / lttng-ust-comm.c
index 078b56a01bb68c49c2322fc2a8f454d597305314..f469567690b3a9a88a2d7f4252417e130a1c6975 100644 (file)
@@ -1,6 +1,6 @@
 /*
  * Copyright (C)  2011 - David Goulet <david.goulet@polymtl.ca>
- * Copyright (C)  2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C)  2011-2013 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
 #include <fcntl.h>
 
 #include <ust-comm.h>
+#include <helper.h>
+#include <lttng/ust-error.h>
+
+#define USTCOMM_CODE_OFFSET(code)      \
+       (code == LTTNG_UST_OK ? 0 : (code - LTTNG_UST_ERR + 1))
+
+#define USTCOMM_MAX_SEND_FDS   4
 
 /*
  * Human readable error message.
  */
 static const char *ustcomm_readable_code[] = {
-       [ USTCOMM_ERR_INDEX(USTCOMM_ERR) ] = "Unknown error",
-       [ USTCOMM_ERR_INDEX(USTCOMM_UND) ] = "Undefined command",
-       [ USTCOMM_ERR_INDEX(USTCOMM_NOT_IMPLEMENTED) ] = "Not implemented",
-       [ USTCOMM_ERR_INDEX(USTCOMM_UNKNOWN_DOMAIN) ] = "Unknown tracing domain",
-       [ USTCOMM_ERR_INDEX(USTCOMM_NO_SESSION) ] = "No session found",
-       [ USTCOMM_ERR_INDEX(USTCOMM_LIST_FAIL) ] = "Unable to list traceable apps",
-       [ USTCOMM_ERR_INDEX(USTCOMM_NO_APPS) ] = "No traceable apps found",
-       [ USTCOMM_ERR_INDEX(USTCOMM_SESS_NOT_FOUND) ] = "Session name not found",
-       [ USTCOMM_ERR_INDEX(USTCOMM_NO_TRACE) ] = "No trace found",
-       [ USTCOMM_ERR_INDEX(USTCOMM_FATAL) ] = "Fatal error of the session daemon",
-       [ USTCOMM_ERR_INDEX(USTCOMM_CREATE_FAIL) ] = "Create trace failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_START_FAIL) ] = "Start trace failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_STOP_FAIL) ] = "Stop trace failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_NO_TRACEABLE) ] = "App is not traceable",
-       [ USTCOMM_ERR_INDEX(USTCOMM_SELECT_SESS) ] = "A session MUST be selected",
-       [ USTCOMM_ERR_INDEX(USTCOMM_EXIST_SESS) ] = "Session name already exist",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_NA) ] = "UST tracer not available",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_EVENT_EXIST) ] = "UST event already exists",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_SESS_FAIL) ] = "UST create session failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_FAIL) ] = "UST create channel failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_NOT_FOUND) ] = "UST channel not found",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_DISABLE_FAIL) ] = "Disable UST channel failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CHAN_ENABLE_FAIL) ] = "Enable UST channel failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CONTEXT_FAIL) ] = "Add UST context failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_ENABLE_FAIL) ] = "Enable UST event failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_DISABLE_FAIL) ] = "Disable UST event failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_META_FAIL) ] = "Opening metadata failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_START_FAIL) ] = "Starting UST trace failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_STOP_FAIL) ] = "Stoping UST trace failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_CONSUMER_FAIL) ] = "UST consumer start failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_STREAM_FAIL) ] = "UST create stream failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_DIR_FAIL) ] = "UST trace directory creation failed",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_DIR_EXIST) ] = "UST trace directory already exist",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_NO_SESSION) ] = "No UST session found",
-       [ USTCOMM_ERR_INDEX(USTCOMM_KERN_LIST_FAIL) ] = "Listing UST events failed",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_COMMAND_SOCK_READY) ] = "UST consumer command socket ready",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_SUCCESS_RECV_FD) ] = "UST consumer success on receiving fds",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_ERROR_RECV_FD) ] = "UST consumer error on receiving fds",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_POLL_ERROR) ] = "UST consumer error in polling thread",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_POLL_NVAL) ] = "UST consumer polling on closed fd",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_POLL_HUP) ] = "UST consumer all fd hung up",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_EXIT_SUCCESS) ] = "UST consumer exiting normally",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_EXIT_FAILURE) ] = "UST consumer exiting on error",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_OUTFD_ERROR) ] = "UST consumer error opening the tracefile",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_EBADF) ] = "UST consumer splice EBADF",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_EINVAL) ] = "UST consumer splice EINVAL",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_ENOMEM) ] = "UST consumer splice ENOMEM",
-       [ USTCOMM_ERR_INDEX(USTCONSUMER_SPLICE_ESPIPE) ] = "UST consumer splice ESPIPE",
-       [ USTCOMM_ERR_INDEX(USTCOMM_NO_EVENT) ] = "Event not found",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_OK) ] = "Success",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR) ] = "Unknown error",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_NOENT) ] = "No entry",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_EXIST) ] = "Object already exists",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_INVAL) ] = "Invalid argument",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_PERM) ] = "Permission denied",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_NOSYS) ] = "Not implemented",
+       [ USTCOMM_CODE_OFFSET(LTTNG_UST_ERR_EXITING) ] = "Process is exiting",
 };
 
 /*
- *  lttcom_get_readable_code
+ * lttng_ust_strerror
  *
- *  Return ptr to string representing a human readable
- *  error code from the ustcomm_return_code enum.
+ * Receives positive error value.
+ * Return ptr to string representing a human readable
+ * error code from the ustcomm_return_code enum.
  */
-const char *ustcomm_get_readable_code(int code)
+const char *lttng_ust_strerror(int code)
 {
-       if (code == USTCOMM_OK) {
-               return "Success";
-       }
-       if (code >= USTCOMM_ERR && code < USTCOMM_NR) {
-               return ustcomm_readable_code[USTCOMM_ERR_INDEX(code)];
-       }
-       return strerror(code);
+       if (code == LTTNG_UST_OK)
+               return ustcomm_readable_code[USTCOMM_CODE_OFFSET(code)];
+       if (code < LTTNG_UST_ERR)
+               return strerror(code);
+       if (code >= LTTNG_UST_ERR_NR)
+               code = LTTNG_UST_ERR;
+       return ustcomm_readable_code[USTCOMM_CODE_OFFSET(code)];
+
 }
 
 /*
- *     ustcomm_connect_unix_sock
+ * ustcomm_connect_unix_sock
  *
- *     Connect to unix socket using the path name.
+ * Connect to unix socket using the path name.
  */
 int ustcomm_connect_unix_sock(const char *pathname)
 {
        struct sockaddr_un sun;
-       int fd;
-       int ret;
+       int fd, ret;
 
        /*
         * libust threads require the close-on-exec flag for all
@@ -123,12 +90,13 @@ int ustcomm_connect_unix_sock(const char *pathname)
        fd = socket(PF_UNIX, SOCK_STREAM, 0);
        if (fd < 0) {
                perror("socket");
-               ret = fd;
+               ret = -errno;
                goto error;
        }
        ret = fcntl(fd, F_SETFD, FD_CLOEXEC);
        if (ret < 0) {
                perror("fcntl");
+               ret = -errno;
                goto error_fcntl;
        }
 
@@ -144,6 +112,7 @@ int ustcomm_connect_unix_sock(const char *pathname)
                 * is used in normal execution to detect if sessiond is
                 * alive.
                 */
+               ret = -errno;
                goto error_connect;
        }
 
@@ -151,16 +120,22 @@ int ustcomm_connect_unix_sock(const char *pathname)
 
 error_connect:
 error_fcntl:
-       close(fd);
+       {
+               int closeret;
+
+               closeret = close(fd);
+               if (closeret)
+                       perror("close");
+       }
 error:
        return ret;
 }
 
 /*
- *     ustcomm_accept_unix_sock
+ * ustcomm_accept_unix_sock
  *
- *     Do an accept(2) on the sock and return the
- *     new file descriptor. The socket MUST be bind(2) before.
+ * Do an accept(2) on the sock and return the
+ * new file descriptor. The socket MUST be bind(2) before.
  */
 int ustcomm_accept_unix_sock(int sock)
 {
@@ -172,30 +147,26 @@ int ustcomm_accept_unix_sock(int sock)
        new_fd = accept(sock, (struct sockaddr *) &sun, &len);
        if (new_fd < 0) {
                perror("accept");
-               goto error;
+               return -errno;
        }
-
        return new_fd;
-
-error:
-       return -1;
 }
 
 /*
- *     ustcomm_create_unix_sock
+ * ustcomm_create_unix_sock
  *
- *     Creates a AF_UNIX local socket using pathname
- *     bind the socket upon creation and return the fd.
+ * Creates a AF_UNIX local socket using pathname
+ * bind the socket upon creation and return the fd.
  */
 int ustcomm_create_unix_sock(const char *pathname)
 {
        struct sockaddr_un sun;
-       int fd;
-       int ret = -1;
+       int fd, ret;
 
        /* Create server socket */
        if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
                perror("socket");
+               ret = -errno;
                goto error;
        }
 
@@ -209,19 +180,29 @@ int ustcomm_create_unix_sock(const char *pathname)
        ret = bind(fd, (struct sockaddr *) &sun, sizeof(sun));
        if (ret < 0) {
                perror("bind");
-               goto error;
+               ret = -errno;
+               goto error_close;
        }
 
        return fd;
 
+error_close:
+       {
+               int closeret;
+
+               closeret = close(fd);
+               if (closeret) {
+                       perror("close");
+               }
+       }
 error:
        return ret;
 }
 
 /*
- *     ustcomm_listen_unix_sock
+ * ustcomm_listen_unix_sock
  *
- *     Make the socket listen using LTTNG_UST_COMM_MAX_LISTEN.
+ * Make the socket listen using LTTNG_UST_COMM_MAX_LISTEN.
  */
 int ustcomm_listen_unix_sock(int sock)
 {
@@ -229,6 +210,7 @@ int ustcomm_listen_unix_sock(int sock)
 
        ret = listen(sock, LTTNG_UST_COMM_MAX_LISTEN);
        if (ret < 0) {
+               ret = -errno;
                perror("listen");
        }
 
@@ -236,17 +218,36 @@ int ustcomm_listen_unix_sock(int sock)
 }
 
 /*
- *     ustcomm_recv_unix_sock
+ * ustcomm_close_unix_sock
  *
- *  Receive data of size len in put that data into
- *  the buf param. Using recvmsg API.
- *  Return the size of received data.
+ * Shutdown cleanly a unix socket.
+ */
+int ustcomm_close_unix_sock(int sock)
+{
+       int ret;
+
+       ret = close(sock);
+       if (ret < 0) {
+               perror("close");
+               ret = -errno;
+       }
+
+       return ret;
+}
+
+/*
+ * ustcomm_recv_unix_sock
+ *
+ * Receive data of size len in put that data into
+ * the buf param. Using recvmsg API.
+ * Return the size of received data.
+ * Return 0 on orderly shutdown.
  */
 ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
 {
        struct msghdr msg;
        struct iovec iov[1];
-       ssize_t ret = -1;
+       ssize_t ret;
 
        memset(&msg, 0, sizeof(msg));
 
@@ -258,24 +259,33 @@ ssize_t ustcomm_recv_unix_sock(int sock, void *buf, size_t len)
        do {
                ret = recvmsg(sock, &msg, 0);
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0 && errno != EPIPE) {
-               perror("recvmsg");
+
+       if (ret < 0) {
+               int shutret;
+
+               if (errno != EPIPE && errno != ECONNRESET)
+                       perror("recvmsg");
+               ret = -errno;
+
+               shutret = shutdown(sock, SHUT_RDWR);
+               if (shutret)
+                       fprintf(stderr, "Socket shutdown error");
        }
 
        return ret;
 }
 
 /*
- *     ustcomm_send_unix_sock
+ * ustcomm_send_unix_sock
  *
- *     Send buf data of size len. Using sendmsg API.
- *     Return the size of sent data.
+ * Send buf data of size len. Using sendmsg API.
+ * Return the size of sent data.
  */
 ssize_t ustcomm_send_unix_sock(int sock, void *buf, size_t len)
 {
        struct msghdr msg;
        struct iovec iov[1];
-       ssize_t ret = -1;
+       ssize_t ret;
 
        memset(&msg, 0, sizeof(msg));
 
@@ -294,36 +304,28 @@ ssize_t ustcomm_send_unix_sock(int sock, void *buf, size_t len)
        do {
                ret = sendmsg(sock, &msg, MSG_NOSIGNAL);
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0 && errno != EPIPE) {
-               perror("sendmsg");
-       }
 
-       return ret;
-}
+       if (ret < 0) {
+               int shutret;
 
-/*
- *  ustcomm_close_unix_sock
- *
- *  Shutdown cleanly a unix socket.
- */
-int ustcomm_close_unix_sock(int sock)
-{
-       int ret;
+               if (errno != EPIPE && errno != ECONNRESET)
+                       perror("sendmsg");
+               ret = -errno;
 
-       ret = close(sock);
-       if (ret < 0) {
-               perror("close");
+               shutret = shutdown(sock, SHUT_RDWR);
+               if (shutret)
+                       fprintf(stderr, "Socket shutdown error");
        }
 
        return ret;
 }
 
 /*
- *  ustcomm_send_fds_unix_sock
+ * Send a message accompanied by fd(s) over a unix socket.
  *
- *  Send multiple fds on a unix socket.
+ * Returns the size of data sent, or negative error value.
  */
-ssize_t ustcomm_send_fds_unix_sock(int sock, void *buf, int *fds, size_t nb_fd, size_t len)
+ssize_t ustcomm_send_fds_unix_sock(int sock, int *fds, size_t nb_fd)
 {
        struct msghdr msg;
        struct cmsghdr *cmptr;
@@ -331,14 +333,13 @@ ssize_t ustcomm_send_fds_unix_sock(int sock, void *buf, int *fds, size_t nb_fd,
        ssize_t ret = -1;
        unsigned int sizeof_fds = nb_fd * sizeof(int);
        char tmp[CMSG_SPACE(sizeof_fds)];
+       char dummy = 0;
 
        memset(&msg, 0, sizeof(msg));
+       memset(tmp, 0, CMSG_SPACE(sizeof_fds) * sizeof(char));
 
-       /*
-        * Note: the consumerd receiver only supports receiving one FD per
-        * message.
-        */
-       assert(nb_fd == 1);
+       if (nb_fd > USTCOMM_MAX_SEND_FDS)
+               return -EINVAL;
 
        msg.msg_control = (caddr_t)tmp;
        msg.msg_controllen = CMSG_LEN(sizeof_fds);
@@ -351,18 +352,100 @@ ssize_t ustcomm_send_fds_unix_sock(int sock, void *buf, int *fds, size_t nb_fd,
        /* 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;
+       iov[0].iov_base = &dummy;
+       iov[0].iov_len = 1;
        msg.msg_iov = iov;
        msg.msg_iovlen = 1;
 
        do {
-               ret = sendmsg(sock, &msg, MSG_NOSIGNAL);
+               ret = sendmsg(sock, &msg, 0);
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0 && errno != EPIPE) {
-               perror("sendmsg");
+       if (ret < 0) {
+               /*
+                * We consider EPIPE and ECONNRESET as expected.
+                */
+               if (errno != EPIPE && errno != ECONNRESET) {
+                       perror("sendmsg");
+               }
        }
+       return ret;
+}
+
+/*
+ * Recv a message accompanied by fd(s) from a unix socket.
+ *
+ * Returns the size of received data, or negative error value.
+ *
+ * Expect at most "nb_fd" file descriptors. Returns the number of fd
+ * actually received in nb_fd.
+ * Returns -EPIPE on orderly shutdown.
+ */
+ssize_t ustcomm_recv_fds_unix_sock(int sock, int *fds, size_t nb_fd)
+{
+       struct iovec iov[1];
+       ssize_t ret = 0;
+       struct cmsghdr *cmsg;
+       size_t sizeof_fds = nb_fd * sizeof(int);
+       char recv_fd[CMSG_SPACE(sizeof_fds)];
+       struct msghdr msg;
+       char dummy;
 
+       memset(&msg, 0, sizeof(msg));
+
+       /* Prepare to receive the structures */
+       iov[0].iov_base = &dummy;
+       iov[0].iov_len = 1;
+       msg.msg_iov = iov;
+       msg.msg_iovlen = 1;
+       msg.msg_control = recv_fd;
+       msg.msg_controllen = sizeof(recv_fd);
+
+       do {
+               ret = recvmsg(sock, &msg, 0);
+       } while (ret < 0 && errno == EINTR);
+       if (ret < 0) {
+               if (errno != EPIPE && errno != ECONNRESET) {
+                       perror("recvmsg fds");
+               }
+               if (errno == EPIPE || errno == ECONNRESET)
+                       ret = -errno;
+               goto end;
+       }
+       if (ret == 0) {
+               /* orderly shutdown */
+               ret = -EPIPE;
+               goto end;
+       }
+       if (ret != 1) {
+               fprintf(stderr, "Error: Received %zd bytes, expected %d\n",
+                               ret, 1);
+               goto end;
+       }
+       if (msg.msg_flags & MSG_CTRUNC) {
+               fprintf(stderr, "Error: Control message truncated.\n");
+               ret = -1;
+               goto end;
+       }
+       cmsg = CMSG_FIRSTHDR(&msg);
+       if (!cmsg) {
+               fprintf(stderr, "Error: Invalid control message header\n");
+               ret = -1;
+               goto end;
+       }
+       if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
+               fprintf(stderr, "Didn't received any fd\n");
+               ret = -1;
+               goto end;
+       }
+       if (cmsg->cmsg_len != CMSG_LEN(sizeof_fds)) {
+               fprintf(stderr, "Error: Received %zu bytes of ancillary data, expected %zu\n",
+                               (size_t) cmsg->cmsg_len, (size_t) CMSG_LEN(sizeof_fds));
+               ret = -1;
+               goto end;
+       }
+       memcpy(fds, CMSG_DATA(cmsg), sizeof_fds);
+       ret = sizeof_fds;
+end:
        return ret;
 }
 
@@ -374,15 +457,13 @@ int ustcomm_send_app_msg(int sock, struct ustcomm_ust_msg *lum)
        switch (len) {
        case sizeof(*lum):
                break;
-       case -1:
-               if (errno == ECONNRESET) {
-                       fprintf(stderr, "remote end closed connection\n");
-                       return 0;
-               }
-               return -1;
        default:
-               fprintf(stderr, "incorrect message size: %zd\n", len);
-               return -1;
+               if (len < 0) {
+                       return len;
+               } else {
+                       fprintf(stderr, "incorrect message size: %zd\n", len);
+                       return -EINVAL;
+               }
        }
        return 0;
 }
@@ -396,36 +477,31 @@ int ustcomm_recv_app_reply(int sock, struct ustcomm_ust_reply *lur,
        len = ustcomm_recv_unix_sock(sock, lur, sizeof(*lur));
        switch (len) {
        case 0: /* orderly shutdown */
-               return -EINVAL;
+               return -EPIPE;
        case sizeof(*lur):
                if (lur->handle != expected_handle) {
-                       fprintf(stderr, "Unexpected result message handle\n");
+                       fprintf(stderr, "Unexpected result message handle: "
+                               "expected: %u vs received: %u\n",
+                               expected_handle, lur->handle);
                        return -EINVAL;
                }
-
                if (lur->cmd != expected_cmd) {
-                       fprintf(stderr, "Unexpected result message command\n");
+                       fprintf(stderr, "Unexpected result message command "
+                               "expected: %u vs received: %u\n",
+                               expected_cmd, lur->cmd);
                        return -EINVAL;
                }
-               if (lur->ret_code != USTCOMM_OK) {
-                       /*
-                        * Some errors are normal.. we should put this
-                        * in a debug level message...
-                        * fprintf(stderr, "remote operation failed with code %d.\n",
-                        *      lur->ret_code);
-                        */
-                       return lur->ret_code;
-               }
-               return 0;
-       case -1:
-               if (errno == ECONNRESET) {
-                       fprintf(stderr, "remote end closed connection\n");
-                       return -EINVAL;
-               }
-               return -1;
+               return lur->ret_code;
        default:
-               fprintf(stderr, "incorrect message size: %zd\n", len);
-               return len > 0 ? -1 : len;
+               if (len < 0) {
+                       /* Transport level error */
+                       if (errno == EPIPE || errno == ECONNRESET)
+                               len = -errno;
+                       return len;
+               } else {
+                       fprintf(stderr, "incorrect message size: %zd\n", len);
+                       return len;
+               }
        }
 }
 
@@ -439,73 +515,68 @@ int ustcomm_send_app_cmd(int sock,
        if (ret)
                return ret;
        ret = ustcomm_recv_app_reply(sock, lur, lum->handle, lum->cmd);
-       if (ret)
-               return ret;
-       return 0;
+       if (ret > 0)
+               return -EIO;
+       return ret;
 }
 
-
 /*
- * Receives a single fd from socket.
- *
- * Returns the size of received data
+ * chan_data is allocated internally if this function returns the
+ * expected var_len.
  */
-int ustcomm_recv_fd(int sock)
+ssize_t ustcomm_recv_channel_from_sessiond(int sock,
+               void **_chan_data, uint64_t var_len)
 {
-       struct iovec iov[1];
-       int ret = 0;
-       int data_fd;
-       struct cmsghdr *cmsg;
-       char recv_fd[CMSG_SPACE(sizeof(int))];
-       struct msghdr msg;
-       union {
-               unsigned char vc[4];
-               int vi;
-       } tmp;
-       int i;
-
-       memset(&msg, 0, sizeof(msg));
-
-       /* Prepare to receive the structures */
-       iov[0].iov_base = &data_fd;
-       iov[0].iov_len = sizeof(data_fd);
-       msg.msg_iov = iov;
-       msg.msg_iovlen = 1;
-       msg.msg_control = recv_fd;
-       msg.msg_controllen = sizeof(recv_fd);
+       void *chan_data;
+       ssize_t len;
 
-       do {
-               ret = recvmsg(sock, &msg, 0);
-       } while (ret < 0 && errno == EINTR);
-       if (ret < 0) {
-               if (errno != EPIPE) {
-                       perror("recvmsg");
-               }
-               goto end;
+       if (var_len > LTTNG_UST_CHANNEL_DATA_MAX_LEN) {
+               len = -EINVAL;
+               goto error_check;
        }
-       if (ret != sizeof(data_fd)) {
-               fprintf(stderr, "Received %d bytes, expected %zd", ret, sizeof(data_fd));
-               goto end;
+       /* Receive variable length data */
+       chan_data = zmalloc(var_len);
+       if (!chan_data) {
+               len = -ENOMEM;
+               goto error_alloc;
        }
-       cmsg = CMSG_FIRSTHDR(&msg);
-       if (!cmsg) {
-               fprintf(stderr, "Invalid control message header\n");
-               ret = -1;
-               goto end;
+       len = ustcomm_recv_unix_sock(sock, chan_data, var_len);
+       if (len != var_len) {
+               goto error_recv;
        }
-       if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) {
-               fprintf(stderr, "Didn't received any fd\n");
-               ret = -1;
-               goto end;
+       *_chan_data = chan_data;
+       return len;
+
+error_recv:
+       free(chan_data);
+error_alloc:
+error_check:
+       return len;
+}
+
+int ustcomm_recv_stream_from_sessiond(int sock,
+               uint64_t *memory_map_size,
+               int *shm_fd, int *wakeup_fd)
+{
+       ssize_t len;
+       int ret;
+       int fds[2];
+
+       /* recv shm fd and wakeup fd */
+       len = ustcomm_recv_fds_unix_sock(sock, fds, 2);
+       if (len <= 0) {
+               if (len < 0) {
+                       ret = len;
+                       goto error;
+               } else {
+                       ret = -EIO;
+                       goto error;
+               }
        }
-       /* this is our fd */
-       for (i = 0; i < sizeof(int); i++)
-               tmp.vc[i] = CMSG_DATA(cmsg)[i];
-       ret = tmp.vi;
-       /*
-        * Useful for fd leak debug.
-        * fprintf(stderr, "received fd %d\n", ret);
-        */
-end:
+       *shm_fd = fds[0];
+       *wakeup_fd = fds[1];
+       return 0;
+
+error:
        return ret;
 }
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