[PATCH wayland] extend WAYLAND_DISPLAY semantic and make server socket path configurable using environment
Bryce Harrington
bryce at osg.samsung.com
Wed Mar 11 19:05:02 PDT 2015
On Tue, Feb 24, 2015 at 03:08:36PM +0100, Davide Bettio wrote:
> commit e8b37de8e084d4e50a12bd2911657d54c0ebd9ed
> Author: Davide Bettio <davide.bettio at ispirata.com>
> Date: Tue Feb 24 12:40:49 2015 +0100
>
> * Extend WAYLAND_DISPLAY and name parameter semantics to support
> absolute paths.
> For example WAYLAND_DISPLAY="/my/path/wayland-2" or
> connect_to_socket("/my/path/wayland-2").
>
> * Introduce WAYLAND_SERVER_SOCKET_DIR to change socket directory
> without changing XDG_RUNTIME_DIR.
> This might be useful to change socket directory in case
> wl_display_add_socket_auto is used.
> For example this will change the socket path for weston without
> using any command line argument.
> This envvar is ignored when WAYLAND_SERVER_SOCKET is set to an
> absolute path.
>
> * Introduce WAYLAND_SERVER_SOCKET to change the path where the
> server will create the socket.
> It will be possible for a nested compositor to offer a socket
> located in WAYLAND_SERVER_SOCKET path
> while connecting to the main compositor socket that is located
> in WAYLAND_DISPLAY path.
> That's the reason why a futher WAYLAND_SERVER_SOCKET envvar has
> been introduced.
>
> Wayland clients will not see any new environment variable, while
> compositors may have to deal
> with 2 extra environment variables, this is due the fact that a
> compositor might be a client of
> another compositor and we must make sure that WAYLAND_DISPLAY is
> not used for both client
> and server purposes.
>
> Signed-off-by: Davide Bettio <davide.bettio at ispirata.com>
>
> diff --git a/doc/man/wl_display_connect.xml
> b/doc/man/wl_display_connect.xml
> index 7e6e05c..b78c53f 100644
> --- a/doc/man/wl_display_connect.xml
> +++ b/doc/man/wl_display_connect.xml
> @@ -59,10 +59,10 @@
> find it. The <varname>name</varname> argument specifies
> the name of
> the socket or <constant>NULL</constant> to use the
> default (which is
> <constant>"wayland-0"</constant>). The environment variable
> - <envar>WAYLAND_DISPLAY</envar> replaces the default value. If
> - <envar>WAYLAND_SOCKET</envar> is set, this function
> behaves like
> - <function>wl_display_connect_to_fd</function> with the
> file-descriptor
> - number taken from the environment variable.</para>
> + <envar>WAYLAND_DISPLAY</envar> replaces the default
> value, and eventually uses
> + a different path too. If <envar>WAYLAND_SOCKET</envar> is
> set, this function
> + behaves like
> <function>wl_display_connect_to_fd</function> with the
> + file-descriptor number taken from the environment
> variable.</para>
>
> <para><function>wl_display_connect_to_fd</function> connects to
> a Wayland
> socket with an explicit file-descriptor. The
> file-descriptor is passed
> diff --git a/src/wayland-client.c b/src/wayland-client.c
> index 0f1405c..cc01573 100644
> --- a/src/wayland-client.c
> +++ b/src/wayland-client.c
> @@ -768,14 +768,26 @@ connect_to_socket(const char *name)
>
> memset(&addr, 0, sizeof addr);
> addr.sun_family = AF_LOCAL;
> - name_size =
> - snprintf(addr.sun_path, sizeof addr.sun_path,
> - "%s/%s", runtime_dir, name) + 1;
> + if (name[0] != '/') {
> + name_size =
> + snprintf(addr.sun_path, sizeof addr.sun_path,
> + "%s/%s", runtime_dir, name) + 1;
> + } else {
> + /* absolute path */
> + name_size =
> + snprintf(addr.sun_path, sizeof addr.sun_path,
> + "%s", name) + 1;
> + }
>
> assert(name_size > 0);
> if (name_size > (int)sizeof addr.sun_path) {
> - wl_log("error: socket path \"%s/%s\" plus null terminator"
> - " exceeds 108 bytes\n", runtime_dir, name);
> + if (name[0] != '/') {
> + wl_log("error: socket path \"%s/%s\" plus null terminator"
> + " exceeds 108 bytes\n", runtime_dir, name);
> + } else {
> + wl_log("error: socket path \"%s\" plus null terminator"
> + " exceeds 108 bytes\n", name);
> + }
Perhaps instead of the 108 magic number in the log message, print the
actual numerical value of (int)sizeof addr.sun_path ?
> close(fd);
> /* to prevent programs reporting
> * "failed to add socket: Success" */
> diff --git a/src/wayland-server.c b/src/wayland-server.c
> index 0558634..39ba13f 100644
> --- a/src/wayland-server.c
> +++ b/src/wayland-server.c
> @@ -1093,9 +1093,12 @@ wl_socket_init_for_display_name(struct
> wl_socket *s, const char *name)
> int name_size;
> const char *runtime_dir;
>
> - runtime_dir = getenv("XDG_RUNTIME_DIR");
> + runtime_dir = getenv("WAYLAND_SERVER_SOCKET_DIR");
> if (!runtime_dir) {
> - wl_log("error: XDG_RUNTIME_DIR not set in the environment\n");
> + runtime_dir = getenv("XDG_RUNTIME_DIR");
> + }
> + if (!runtime_dir) {
> + wl_log("error: XDG_RUNTIME_DIR or WAYLAND_SERVER_SOCKET_DIR not
> set in the environment\n");
Maybe reword this to avoid any ambiguity:
wl_log("error: Neither XDG_RUNTIME_DIR nor WAYLAND_SERVER_SOCKET_DIR have been
set in the environment\n");
Or, perhaps less passively:
wl_log("error: Either XDG_RUNTIME_DIR or WAYLAND_SERVER_SOCKET_DIR must be
set in the environment\n");
> /* to prevent programs reporting
> * "failed to add socket: Success" */
> @@ -1104,15 +1107,28 @@ wl_socket_init_for_display_name(struct
> wl_socket *s, const char *name)
> }
>
> s->addr.sun_family = AF_LOCAL;
> - name_size = snprintf(s->addr.sun_path, sizeof s->addr.sun_path,
> - "%s/%s", runtime_dir, name) + 1;
> + if (name[0] != '/') {
> + name_size = snprintf(s->addr.sun_path, sizeof s->addr.sun_path,
> + "%s/%s", runtime_dir, name) + 1;
> +
> + s->display_name = (s->addr.sun_path + name_size - 1) - strlen(name);
I know this is the original code, and I'm probably missing something, but...
If runtime_dir is of length N, and s->addr.sun_path is let's say 2N, and
name is length 8N, then name_size = 2N+1, and only the first N-1 chars are
used from name. I might be off by 1 or 2.
But, now we have
s->display_name = (2N + 2N + 1) - 8N = -4N + 1
Do we have a buffer underflow possibility here?
In any case, may as well check for error return from snprintf
(i.e. name_size < 0).
> + } else {
> + //absolute path
> + name_size = snprintf(s->addr.sun_path, sizeof s->addr.sun_path,
> + "%s", name) + 1;
>
> - s->display_name = (s->addr.sun_path + name_size - 1) - strlen(name);
> + s->display_name = strrchr(s->addr.sun_path, '/') + 1;
> + }
>
> assert(name_size > 0);
> if (name_size > (int)sizeof s->addr.sun_path) {
> - wl_log("error: socket path \"%s/%s\" plus null terminator"
> - " exceeds 108 bytes\n", runtime_dir, name);
> + if (name[0] != '/') {
> + wl_log("error: socket path \"%s/%s\" plus null terminator"
> + " exceeds 108 bytes\n", runtime_dir,
> name);
> + } else {
> + wl_log("error: socket path \"%s\" plus null terminator"
> + " exceeds 108 bytes\n", name);
> + }
108's here too.
> *s->addr.sun_path = 0;
> /* to prevent programs reporting
> * "failed to add socket: Success" */
> @@ -1203,18 +1219,18 @@ wl_display_add_socket_auto(struct wl_display
> *display)
> * This adds a Unix socket to Wayland display which can be used by
> clients to
> * connect to Wayland display.
> *
> - * If NULL is passed as name, then it would look for
> WAYLAND_DISPLAY env
> - * variable for the socket name. If WAYLAND_DISPLAY is not set,
> then default
> - * wayland-0 is used.
> + * If NULL is passed as name, then it would look in order for
> WAYLAND_SERVER_SOCKET
> + * and WAYLAND_SERVER env variable for the socket name. If
> WAYLAND_DISPLAY and
> + * WAYLAND_SERVER_SOCKET are not set, then default wayland-0 is used.
> *
> - * The Unix socket will be created in the directory pointed to by
> environment
> - * variable XDG_RUNTIME_DIR. If XDG_RUNTIME_DIR is not set, then
> this function
> - * fails and returns -1.
> + * The Unix socket will be created in the directory pointed to by
> either environment
> + * variable WAYLAND_SERVER_SOCKET_DIR or XDG_RUNTIME_DIR. If the
> none of the is set,
> + * then this function fails and returns -1.
> *
> - * The length of socket path, i.e., the path set in XDG_RUNTIME_DIR
> and the
> + * The length of socket path, e.g., the path set in XDG_RUNTIME_DIR
> and the
> * socket name, must not exceed the maxium length of a Unix socket
> path.
> * The function also fails if the user do not have write permission
> in the
> - * XDG_RUNTIME_DIR path or if the socket name is already in use.
> + * wayland socket path or if the socket name is already in use.
> *
> * \memberof wl_display
> */
> @@ -1228,6 +1244,8 @@ wl_display_add_socket(struct wl_display
> *display, const char *name)
> return -1;
>
> if (name == NULL)
> + name = getenv("WAYLAND_SERVER_SOCKET");
> + if (name == NULL)
> name = getenv("WAYLAND_DISPLAY");
> if (name == NULL)
> name = "wayland-0";
Aside from that, ditto daniel's review feedback.
>
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