Change Details

Previously, we would only use a temporary file if explicitly asked to with the `-S` option, and even then, only if the target file already existed. This meant that an outside observer looking for the target file might see a partial file, and might see the file disappear and then reappear. With this patch, we always use a temporary file, ensuring atomicity. The downside is slightly increased disk usage. The upside is never having to worry about, for instance, cron jobs randomly failing if they happen to run simultaneously with `make installworld`. MFC after: 1 week Sponsored by: Klara, Inc.

Previously, we would only use a temporary file if explicitly asked to with the `-S` option, and even then, only if the target file already existed. This meant that an outside observer looking for the target file might see a partial file, and might see the file disappear and then reappear. With this patch, we always use a temporary file, ensuring atomicity. The downside is slightly increased disk usage. The upside is never having to worry about, for instance, cron jobs randomly failing if they happen to run simultaneously with `make installworld`. The `-S` option is retained, partly for compatibility, and partly to control the use of `fsync(2)`, which has a non-negligible cost (approximately 10% increase in wall time for `make installworld`). MFC after: 1 week Sponsored by: Klara, Inc.

Previously, we would only use a temporary file if explicitly asked to with the `-S` option, and even then, only if the target file already existed. This meant that an outside observer looking for the target file might see a partial file, and might see the file disappear and then reappear. With this patch, we always use a temporary file, ensuring atomicity. The downside is slightly increased disk usage. The upside is never having to worry about, for instance, cron jobs randomly failing if they happen to run simultaneously with `make installworld`. The `-S` option is retained, partly for compatibility, and partly to control the use of `fsync(2)`, which has a non-negligible cost (approximately 10% increase in wall time for `make installworld`). MFC after: 1 week Sponsored by: Klara, Inc.