TempFile.TmpName + ": " +
MBOrErr.getError().message() + "\n");
- // This is atomic on POSIX systems.
- // On Windows, it can fail with permission denied if the destination
- // file already exists. Since the existing file should be semantically
- // equivalent to the one we are trying to write, we give AddBuffer
- // a copy of the bytes we wrote in that case. We do this instead of
- // just using the existing file, because the pruner might delete the
- // file before we get a chance to use it.
+ // On POSIX systems, this will atomically replace the destination if
+ // it already exists. We try to emulate this on Windows, but this may
+ // fail with a permission denied error (for example, if the destination
+ // is currently opened by another process that does not give us the
+ // sharing permissions we need). Since the existing file should be
+ // semantically equivalent to the one we are trying to write, we give
+ // AddBuffer a copy of the bytes we wrote in that case. We do this
+ // instead of just using the existing file, because the pruner might
+ // delete the file before we get a chance to use it.
Error E = TempFile.keep(EntryPath);
E = handleErrors(std::move(E), [&](const ECError &E) -> Error {
std::error_code EC = E.convertToErrorCode();