exec: honor ConsoleSize so the terminal is sized at creation#28957
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shuaiyuanxx wants to merge 1 commit into
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exec: honor ConsoleSize so the terminal is sized at creation#28957shuaiyuanxx wants to merge 1 commit into
shuaiyuanxx wants to merge 1 commit into
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The exec API accepts a ConsoleSize but it is dropped: the exec pseudo-terminal is created at its default size and only corrected afterwards by an asynchronous resize. A short-lived exec that reads its window size at startup (e.g. `stty size`) can therefore observe the wrong size, because the resize may arrive after the process has already read it. docker applies the size at creation. Carry the requested ConsoleSize through ExecConfig and into the exec OCI process spec (process.consoleSize) so the runtime sizes the terminal before the process starts, removing the race. The local and remote CLIs capture the caller's terminal size when -t is given and pass it through ExecOptions, matching the behavior of `podman run`. Re-enable the previously flaky `podman exec` case in the interactive system test, which this change makes deterministic. Signed-off-by: Shuai Yuan <shuaiyuanzju@gmail.com>
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mheon
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Jun 18, 2026
Luap99
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| if [[ "$output" =~ stty ]]; then | ||
| echo "# stty flaked, retrying: $output" >&3 | ||
| sleep 1 | ||
| run_podman exec -it mystty stty size <$PODMAN_TEST_PTY | ||
| fi |
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why is there a flake retry here? If you claim this is race free than we should test that it is and never flakes, this will hide a flake
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What this does
The exec API accepts a
ConsoleSize, but it is dropped: the exec pseudo-terminal is created at its default size and only corrected afterwards by an asynchronous resize. A short-lived exec that reads its window size at startup (e.g.stty size) cantherefore observe the wrong size, because the resize may arrive after the process has already read it. Docker applies the size at creation.
This change carries the requested
ConsoleSizethroughExecConfigand into the exec OCI process spec (process.consoleSize), so the runtime sizes the terminal before the process starts, removing the race. The local and remote CLIs capture the caller's terminal size when-tis given and pass it throughExecOptions, matching the behavior ofpodman run.How to test
Re-enables the previously flaky podman exec case in test/system/450-interactive.bats, which this change makes deterministic.
Checklist
Does this PR introduce a user-facing change?
exec: the requested console size is now applied when the exec terminal is created, so a process that reads its window size at startup (e.g.
stty size) sees the correct value.