qemu-sockets: add error propagation to Unix socket functions

Before:

    $ qemu-system-x86_64 -monitor unix:/vvv,server=off
    connect(unix:/vvv): No such file or directory
    chardev: opening backend "socket" failed

After:

    $ x86_64-softmmu/qemu-system-x86_64 -monitor unix:/vvv,server=off
    qemu-system-x86_64: -monitor unix:/vvv,server=off: Failed to connect to socket: No such file or directory
    chardev: opening backend "socket" failed

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

qemu-sockets.c

@@ -632,7 +632,7 @@ int unix_listen_opts(QemuOpts *opts, Error **errp)
 
     sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
     if (sock < 0) {
-        perror("socket(unix)");
+        error_set_errno(errp, errno, QERR_SOCKET_CREATE_FAILED);
         return -1;
     }
 
@@ -657,11 +657,11 @@ int unix_listen_opts(QemuOpts *opts, Error **errp)
 
     unlink(un.sun_path);
     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
-        fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));
+        error_set_errno(errp, errno, QERR_SOCKET_BIND_FAILED);
         goto err;
     }
     if (listen(sock, 1) < 0) {
-        fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));
+        error_set_errno(errp, errno, QERR_SOCKET_LISTEN_FAILED);
         goto err;
     }
 
@@ -681,13 +681,13 @@ int unix_connect_opts(QemuOpts *opts, Error **errp,
     int sock, rc;
 
     if (NULL == path) {
-        fprintf(stderr, "unix connect: no path specified\n");
+        error_setg(errp, "unix connect: no path specified\n");
         return -1;
     }
 
     sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
     if (sock < 0) {
-        perror("socket(unix)");
+        error_set_errno(errp, errno, QERR_SOCKET_CREATE_FAILED);
         return -1;
     }
     if (callback != NULL) {
@@ -722,7 +722,7 @@ int unix_connect_opts(QemuOpts *opts, Error **errp,
     }
 
     if (rc < 0) {
-        fprintf(stderr, "connect(unix:%s): %s\n", path, strerror(errno));
+        error_set_errno(errp, -rc, QERR_SOCKET_CONNECT_FAILED);
         close(sock);
         sock = -1;
     }
@@ -735,7 +735,7 @@ int unix_connect_opts(QemuOpts *opts, Error **errp,
 
 int unix_listen_opts(QemuOpts *opts, Error **errp)
 {
-    fprintf(stderr, "unix sockets are not available on windows\n");
+    error_setg(errp, "unix sockets are not available on windows");
     errno = ENOTSUP;
     return -1;
 }
@@ -743,7 +743,7 @@ int unix_listen_opts(QemuOpts *opts, Error **errp)
 int unix_connect_opts(QemuOpts *opts, Error **errp,
                       NonBlockingConnectHandler *callback, void *opaque)
 {
-    fprintf(stderr, "unix sockets are not available on windows\n");
+    error_setg(errp, "unix sockets are not available on windows");
     errno = ENOTSUP;
     return -1;
 }