[PATCH v2 wayland] client: Allow absolute paths in WAYLAND_DISPLAY
Matt Hoosier
matt.hoosier at gmail.com
Fri Nov 10 17:20:42 UTC 2017
From: Matt Hoosier <matt.hoosier at garmin.com>
In order to support system compositor instances, it is necessary to
allow clients' wl_display_connect() to find the compositor's listening
socket somewhere outside of XDG_RUNTIME_DIR. For a full account, see
the discussion beginning here:
https://lists.freedesktop.org/archives/wayland-devel/2017-November/035664.html
This change adjusts the client-side connection logic so that, if
WAYLAND_DISPLAY is formatted as an absolute pathname, the socket
connection attempt is made to just $WAYLAND_DISPLAY rather than
usual user-private location $XDG_RUNTIME_DIR/$WAYLAND_DISPLAY.
This change is based on Davide Bettio's submission of the same concept
at:
https://lists.freedesktop.org/archives/wayland-devel/2015-August/023838.html.
v2 changes:
* Added backward incompatibility note to wl_display_connect() manpage.
* Rephased wl_display_connect() manpage changes to precisely match actual
changed behavior.
* Added mention of new absolute path behavior in wl_display_connect()
doxygen comments.
* Mentioned new absolute path interpretation of WAYLAND_DISPLAY in
protocol documentation.
Signed-off-by: Matt Hoosier <matt.hoosier at gmail.com>
---
doc/man/wl_display_connect.xml | 22 +++++++++++++++++---
doc/publican/sources/Protocol.xml | 5 ++++-
src/wayland-client.c | 43 +++++++++++++++++++++++++++++----------
3 files changed, 55 insertions(+), 15 deletions(-)
diff --git a/doc/man/wl_display_connect.xml b/doc/man/wl_display_connect.xml
index 7e6e05c..7bdfc46 100644
--- a/doc/man/wl_display_connect.xml
+++ b/doc/man/wl_display_connect.xml
@@ -55,14 +55,30 @@
<title>Description</title>
<para><function>wl_display_connect</function> connects to a Wayland socket
that was previously opened by a Wayland server. The server socket must
- be placed in <envar>XDG_RUNTIME_DIR</envar> for this function to
- find it. The <varname>name</varname> argument specifies the name of
+ be placed in <envar>XDG_RUNTIME_DIR</envar> or exist at the absolute
+ path referred to by <envar>WAYLAND_DISPLAY</envar> for this function
+ to 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>
+ number taken from the environment variable. If
+ <envar>WAYLAND_SOCKET</envar> is not set and <varname>name</varname>
+ is <constant>NULL</constant> and <envar>WAYLAND_DISPLAY</envar>
+ is an absolute path, then the path stored in <envar>WAYLAND_DISPLAY</envar>
+ is used as the Wayland socket to which the connection is attempted.</para>
+
+ <para>Support for interpreting <envar>WAYLAND_DISPLAY</envar> as an
+ absolute path is a change in behavior compared to
+ <function>wl_display_connect</function>'s behavior in versions
+ 1.14 and older of Wayland. It is no longer guaranteed in versions
+ 1.15 and higher that the Wayland socket chosen is equivalent to
+ manually constructing a socket pathname by concatenating
+ <envar>XDG_RUNTIME_DIR</envar> and <envar>WAYLAND_DISPLAY</envar>.
+ Manual construction of the socket path must account for the
+ possibility that <envar>WAYLAND_DISPLAY</envar> contains an absolute
+ path.</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/doc/publican/sources/Protocol.xml b/doc/publican/sources/Protocol.xml
index ba6b5f1..dbfed06 100644
--- a/doc/publican/sources/Protocol.xml
+++ b/doc/publican/sources/Protocol.xml
@@ -94,7 +94,10 @@
The protocol is sent over a UNIX domain stream socket, where the endpoint
usually is named <systemitem class="service">wayland-0</systemitem>
(although it can be changed via <emphasis>WAYLAND_DISPLAY</emphasis>
- in the environment).
+ in the environment). In the reference implementation, a client whose
+ <emphasis>WAYLAND_DISPLAY</emphasis> is formatted as an absolute path
+ connects to that path as the endpoint, otherwise the implementation
+ searches in <emphasis>XDG_RUNTIME_DIR</emphasis> for the endpoint.
</para>
<para>
Every message is structured as 32-bit words; values are represented in the
diff --git a/src/wayland-client.c b/src/wayland-client.c
index 3d7361e..d90cbfb 100644
--- a/src/wayland-client.c
+++ b/src/wayland-client.c
@@ -857,9 +857,17 @@ connect_to_socket(const char *name)
socklen_t size;
const char *runtime_dir;
int name_size, fd;
+ bool path_is_absolute;
+
+ if (name == NULL)
+ name = getenv("WAYLAND_DISPLAY");
+ if (name == NULL)
+ name = "wayland-0";
+
+ path_is_absolute = name[0] == '/';
runtime_dir = getenv("XDG_RUNTIME_DIR");
- if (!runtime_dir) {
+ if (!runtime_dir && !path_is_absolute) {
wl_log("error: XDG_RUNTIME_DIR not set in the environment.\n");
/* to prevent programs reporting
* "failed to create display: Success" */
@@ -867,25 +875,32 @@ connect_to_socket(const char *name)
return -1;
}
- if (name == NULL)
- name = getenv("WAYLAND_DISPLAY");
- if (name == NULL)
- name = "wayland-0";
-
fd = wl_os_socket_cloexec(PF_LOCAL, SOCK_STREAM, 0);
if (fd < 0)
return -1;
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 (!path_is_absolute) {
+ 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 (!path_is_absolute) {
+ wl_log("error: socket path \"%s/%s\" plus null terminator"
+ " exceeds %i bytes\n", runtime_dir, name, (int) sizeof(addr.sun_path));
+ } else {
+ wl_log("error: socket path \"%s\" plus null terminator"
+ " exceeds %i bytes\n", name, (int) sizeof(addr.sun_path));
+ }
close(fd);
/* to prevent programs reporting
* "failed to add socket: Success" */
@@ -994,6 +1009,12 @@ wl_display_connect_to_fd(int fd)
* its value will be replaced with the WAYLAND_DISPLAY environment
* variable if it is set, otherwise display "wayland-0" will be used.
*
+ * If \c name is \c NULL and the WAYLAND_DISPLAY environment variable
+ * is set to an absolute pathname, then the pathname stored in
+ * WAYLAND_DISPLAY is used immediately as the location of the
+ * socket at which the Wayland display is listening; no qualification
+ * inside XDG_RUNTIME_DIR is attempted.
+ *
* \memberof wl_display
*/
WL_EXPORT struct wl_display *
--
2.13.6
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