Force Attach() to send a SIGWINCH and redraw

Basically, we want to force the application in the container to
(iff the container was made with a terminal) redraw said terminal
immediately after an attach completes, so the fresh Attach
session will be able to see what's going on (e.g. will have a
shell prompt). Our current attach functions are unfortunately
geared more towards `podman run` than `podman attach` and will
start forwarding resize events *immediately* instead of waiting
until the attach session is alive (much safer for short-lived
`podman run` sessions, but broken for the `podman attach` case).
To avoid a major rewrite, let's just manually send a SIGWINCH
after attach succeeds to force a redraw.

Fixes #6253

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

1 files changed, 4 insertions, 1 deletions

diff --git a/libpod/oci_attach_linux.go b/libpod/oci_attach_linux.go
index 622c613d9..74af449ed 100644
--- a/libpod/oci_attach_linux.go
+++ b/libpod/oci_attach_linux.go
@@ -31,7 +31,7 @@ const (
 // Attach to the given container
 // Does not check if state is appropriate
 // started is only required if startContainer is true
-func (c *Container) attach(streams *define.AttachStreams, keys string, resize <-chan remotecommand.TerminalSize, startContainer bool, started chan bool) error {
+func (c *Container) attach(streams *define.AttachStreams, keys string, resize <-chan remotecommand.TerminalSize, startContainer bool, started chan bool, attachRdy chan<- bool) error {
 	if !streams.AttachOutput && !streams.AttachError && !streams.AttachInput {
 		return errors.Wrapf(define.ErrInvalidArg, "must provide at least one stream to attach to")
 	}
@@ -74,6 +74,9 @@ func (c *Container) attach(streams *define.AttachStreams, keys string, resize <-
 	}
 
 	receiveStdoutError, stdinDone := setupStdioChannels(streams, conn, detachKeys)
+	if attachRdy != nil {
+		attachRdy <- true
+	}
 	return readStdio(streams, receiveStdoutError, stdinDone)
 }