2 Commits (a5e98df3395b0e18a96c8a264227fe7a403dc0fb)

Author	SHA1	Message	Date
Martin Atkins	2332a7ab47	replacefile: don't create the temporary file in TMPDIR ... ioutil.TempFile has a special case where an empty string for its dir argument is interpreted as a request to automatically look up the system temporary directory, which is commonly /tmp . We don't want that behavior here because we're specifically trying to create the temporary file in the same directory as the file we're hoping to replace. If the file gets created in /tmp then it might be on a different device and thus the later atomic rename won't work. Instead, we'll add our own special case to explicitly use "." when the given filename is in the current working directory. That overrides the special automatic behavior of ioutil.TempFile and thus forces the behavior we need. This hadn't previously mattered for earlier callers of this code because they were creating files in subdirectories, but this codepath was failing for the dependency lock file due to it always being created directly in the current working directory. Unfortunately since this is a picky implementation detail I couldn't find a good way to write a unit test for it without considerable refactoring. Instead, I verified manually that the temporary filename wasn't in /tmp on my Linux system, and hope that the comment inline will explain this situation well enough to avoid an accidental regression in future maintenence.	6 years ago
Martin Atkins	55e6f64977	internal/depsfile: Factor out our atomic file replacement logic ... This originated in the cliconfig code to write out credentials files. The Windows implementation of this in particular was quite onerous to get right because it needs a very specific sequence of operations to avoid running into exclusive file locks, and so by factoring this out with only cosmetic modification we can avoid repeating all of that engineering effort for other atomic file writing use-cases.	6 years ago