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[5.9] Clamp the length for WriteFile calls on win32 pipes. #802

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Dec 6, 2023
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[5.9] Clamp the length for WriteFile calls on win32 pipes. #802

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17 changes: 17 additions & 0 deletions src/io.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2510,6 +2510,23 @@ _dispatch_operation_perform(dispatch_operation_t op)
}
bSuccess = TRUE;
} else if (GetFileType(hFile) == FILE_TYPE_PIPE) {
// WriteFile with more bytes than are available in the
// buffer of a NOWAIT pipe will immediately return 0,
// so clamp our requested write length to make progress.
IO_STATUS_BLOCK iosb;
FILE_PIPE_LOCAL_INFORMATION fpli;
NTSTATUS status = _dispatch_NtQueryInformationFile(hFile,
&iosb, &fpli, sizeof(fpli), FilePipeLocalInformation);
if (NT_SUCCESS(status)) {
// WriteQuotaAvailable is unreliable in the presence
// of a blocking reader, when it can return zero, so only
// account for it otherwise
if (fpli.WriteQuotaAvailable > 0) {
len = MIN(len, fpli.WriteQuotaAvailable);
}
len = MIN(len, fpli.OutboundQuota);
}

OVERLAPPED ovlOverlapped = {};
bSuccess = WriteFile(hFile, buf, (DWORD)len,
(LPDWORD)&processed, &ovlOverlapped);
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