imap: fix SeqMap.Pop runtime error

Fix a runtime error in the SeqMap.Pop function causing a
index-out-of-range panic:

Version: 0.18.2.r22.gfff69046 (go1.22.6 amd64 linux 2024-08-10)
Error: runtime error: index out of range [487] with length 487

goroutine 24430 [running]:
runtime/debug.Stack()
	runtime/debug/stack.go:24 +0x5e
git.sr.ht/~rjarry/aerc/lib/log.PanicHandler()
	git.sr.ht/~rjarry/aerc/lib/log/panic-logger.go:49 +0x66a
panic({0x5dbf5a688020?, 0xc002ab0d80?})
	runtime/panic.go:770 +0x132
git.sr.ht/~rjarry/aerc/worker/imap.(*SeqMap).Pop(0xc0003d4940, 0x1e8)
	git.sr.ht/~rjarry/aerc/worker/imap/seqmap.go:64 +0x17c
git.sr.ht/~rjarry/aerc/worker/imap.(*IMAPWorker).handleImapUpdate(0xc0003d4820, {0x5dbf5a6dbd00, 0xc002068708})
	git.sr.ht/~rjarry/aerc/worker/imap/worker.go:296 +0x26c
git.sr.ht/~rjarry/aerc/worker/imap.(*IMAPWorker).drainUpdates.func1()
	git.sr.ht/~rjarry/aerc/worker/imap/flags.go:29 +0x10c
created by git.sr.ht/~rjarry/aerc/worker/imap.(*IMAPWorker).drainUpdates in goroutine 52
	git.sr.ht/~rjarry/aerc/worker/imap/flags.go:21 +0x78

SeqMap.Pop uses two locks in the same function: first lock grabs the
size of the slice, second lock removes the given index in the slice.
Combine the two locks to prevent a change of the slice size before the
index can be removed.

Reported-by: Moritz Poldrack <moritz@poldrack.dev>
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

0 files changed, 0 insertions, 0 deletions