[DistroKit] [PATCH v2] v7a: run: randomise the SSH forwarding port

[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 static), or fall back to a port
between 1025 and 65025 using the shell's PID as a seed, which should
have a good chance of being unused. Also print the port forwarding
before starting qemu, so we don't have to bother with "ps -Af|grep
qemu".

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

---
v2:
  * use PPID instead of RANDOM to make the port reproducable 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 d180ccfa890d..34c9aa017278 100755
--- a/configs/platform-v7a/run
+++ b/configs/platform-v7a/run
@@ -39,7 +39,7 @@ fi
 # the port which an sshd would connect to (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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