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Work around critical issue in eventcore's cancelRead/cancelWrite.

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The file I/O versions of cancelRead and cancelWrite in eventcore currently do not reliably cancel the operation in a synchronous fashion, leading to continued buffer accesses after the cancellation call. In case of the Windows version, this also means that the OVERLAPPED structure can be illegally reused for the next operation, while the previous one hasn't been canceled, yet.

A solution to this issue may require a fundamental change in the file I/O API of eventcore, and the optimal design of that still needs to be worked out. For this reason, we simply avoid using the cancellation functions in vibe-core for now to avoid memory corruption issues. This does mean that interrupting a task that does file I/O won't work anymore.
This commit is contained in:
Sönke Ludwig 2020-09-18 10:00:30 +02:00
parent bc7521ed1f
commit f5c6099656
1 changed files with 10 additions and 6 deletions
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16
source/vibe/core/file.d
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@ -607,9 +607,11 @@ struct FileStream {
size_t read(ubyte[] dst, IOMode mode)
{
auto res = asyncAwait!(FileIOCallback,
cb => eventDriver.files.read(m_fd, ctx.ptr, dst, mode, cb),
cb => eventDriver.files.cancelRead(m_fd)
// NOTE: cancelRead is currently not behaving as specified and cannot
// be relied upon. For this reason, we MUST use the uninterruptible
// version of asyncAwait here!
auto res = asyncAwaitUninterruptible!(FileIOCallback,
cb => eventDriver.files.read(m_fd, ctx.ptr, dst, mode, cb)
);
ctx.ptr += res[2];
enforce(res[1] == IOStatus.ok, "Failed to read data from disk.");
@ -624,9 +626,11 @@ struct FileStream {
size_t write(in ubyte[] bytes, IOMode mode)
{
auto res = asyncAwait!(FileIOCallback,
cb => eventDriver.files.write(m_fd, ctx.ptr, bytes, mode, cb),
cb => eventDriver.files.cancelWrite(m_fd)
// NOTE: cancelWrite is currently not behaving as specified and cannot
// be relied upon. For this reason, we MUST use the uninterruptible
// version of asyncAwait here!
auto res = asyncAwaitUninterruptible!(FileIOCallback,
cb => eventDriver.files.write(m_fd, ctx.ptr, bytes, mode, cb)
);
ctx.ptr += res[2];
if (ctx.ptr > ctx.size) ctx.size = ctx.ptr;