displayfd switch for xpra

[totaam]

Issue migrated from trac ticket # 1535

component: server | priority: critical | resolution: fixed | keywords: x11

2017-06-05 13:53:03: antoine created the issue

---

We can now start servers via the proxy (#1105) and this may well become the default.
Since we may not know the actual X11 display in advance (we rely on Xorg -displayfd, #172), we check for new sockets and probe them.
A better way would be to provide a "--displayfd" switch and write the display to this file descriptor.

[totaam]

2017-06-20 17:16:55: antoine changed priority from major to critical

[totaam]

2017-06-20 17:16:55: antoine changed status from new to assigned

[totaam]

2017-06-20 17:16:55: antoine commented

---

Would really help speedup the start-via-proxy feature (#1105 aka logind multiseat), so raising.

[totaam]

2017-08-04 14:24:05: antoine uploaded file displayfd-v6.patch (14.3 KiB)

work in progress - doesn't like daemon=yes

[totaam]

2017-08-04 15:47:22: antoine changed status from assigned to closed

[totaam]

2017-08-04 15:47:22: antoine set resolution to fixed

[totaam]

2017-08-04 15:47:22: antoine commented

---

Done in r16612.

Not as useful as I thought it was going to be: we still have to go through the identify_new_socket code because the display may not be available when we get the display value back (sockets take time, may not be accessible, etc).

But at least things should be more reliable than before.
This feature may also be used for other purposes.

[totaam]

2017-08-05 19:11:37: antoine commented

---

Minor related fixes:

• r16636: honour displayfd with "request-start" mode (start via system wide proxy)
• r16631: ignore displayfd=0 (the default), don't try to write there!