[DistroKit] [PATCH v3] v7a: run: make the SSH forwarding port multiprocess-compatible

[Roland Hieber <rhi@pengutronix.de>]

When multiple ./configs/platform-v7a/run scripts are run at the same
time, the first qemu process will open port 4445, and following runs
will fail. To prevent that, first look at the environment variable
QEMU_SSH_PORT to determine the port to be used (so that users can set
this in their shell to keep the port constant), or fall back to a port
between 1025 and 65025 based on the shell's PID, which should have a
good chance of choosing an unused, but stable port.

Also print the port forwarding before starting qemu, so we don't have to
bother about grepping the process list.

Signed-off-by: Roland Hieber <rhi@pengutronix.de>

---
v3:
  * rebase onto next
  * adapt subject and log message (Robert Schwebel)
v2:
  * use PPID instead of RANDOM to make the port reproducible in the same
    shell session (Michael Olbrich)
---
 configs/platform-v7a/run | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/configs/platform-v7a/run b/configs/platform-v7a/run
index ed8ab1ba47c3..8af190f11eb4 100755
--- a/configs/platform-v7a/run
+++ b/configs/platform-v7a/run
@@ -39,7 +39,7 @@ fi
 # the port to which an sshd would connect (in the emulated sysem)
 SSH_INTERNAL_PORT=22
 # the port which QEMU opens at the host side to give access to the ${SSH_INTERNAL_PORT}
-SSH_EXTERNAL_PORT=4445
+SSH_EXTERNAL_PORT=${QEMU_SSH_PORT:-${PPID%64000+1025}}
 
 # check if vde is available for networking
 if [ -z "${VDE_SOCKET}" ]; then
@@ -59,6 +59,7 @@ fi
 # fall back to user network if necessary
 if [ -z "${QEMU_NET}" ]; then
 	QEMU_NET=(-netdev user,id=net1,hostfwd=tcp:127.0.0.1:${SSH_EXTERNAL_PORT}-:${SSH_INTERNAL_PORT} )
+	echo "Forwarding SSH port 127.0.0.1:${SSH_EXTERNAL_PORT} -> qemu:${SSH_INTERNAL_PORT}"
 fi
 
 BASE_CMDLINE="console=ttyAMA0,115200 loglevel=5 systemd.log_level=warning systemd.show_status=auto"
-- 
2.29.2


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