Files
spring-framework/spring-core
Sam Brannen a4720ccf77 Guard all AsynchronousFileChannel#write call sites in DataBufferUtils
Prior to this commit, only the very first AsynchronousFileChannel#write
call in DataBufferUtils$WriteCompletionHandler#hookOnNext(DataBuffer)
was guarded against exceptions escaping synchronously, and even then
only via `catch (RuntimeException ex)`, per the original fix for
gh-36184.

While widening that guard to match the read side's `catch (Throwable
ex)` combined with `Exceptions.throwIfFatal(ex)` (see gh-37143), we
discovered that completed(Integer, Attachment) contains two more direct
`this.channel.write(...)` calls -- for continuing a partial write and
for advancing to the next ByteBuffer within the same DataBuffer's
iterator -- neither of which was guarded at all. Since completed() is
invoked by the channel's own completion callback, typically on a
different thread than the one that issued the original write, a
synchronous exception escaping either of those calls has no path back
to the FluxSink, and the resulting Flux hangs indefinitely, exactly as
described in gh-37143, for any write that receives a partial OS write
or spans multiple ByteBuffers.

To address that, this commit extracts a private write(ByteBuffer, long,
Attachment) helper that wraps the channel.write(...) call with a
try/catch block, routing any non-fatal Throwable -- via
Exceptions.throwIfFatal() -- to the existing failed(Throwable,
Attachment) handler. All three call sites (hookOnNext() and both
branches in completed()) now go through this helper, ensuring the
Flux always terminates with a proper error signal instead of hanging
silently, regardless of which write attempt fails or which thread it
fails on.

See gh-36184
See gh-37143
Closes gh-37145
2026-08-18 17:13:56 +02:00
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