New and its helpers used to create the cache directories several times
over. They now only do so once. The added test ensures that the cache is
produced in a consistent state when parts are deleted.
The ioutil functions are deprecated since Go 1.17 and only wrap another
library function. Thus directly call the underlying function.
This commit only mechanically replaces the function calls.
if x { return true } return false => return x
fmt.Sprintf("%v", x) => fmt.Sprint(x) or x.String()
The fmt.Sprintf idiom is still used in the SecretString tests, where it
serves security hardening.
Failing to process data requested from the cache usually indicates a
problem with the returned data. Assume that the cache entry is somehow
damaged and retry downloading it once.
Instead of first checking whether a file is in the repository cache and
then opening it, we just can open the file. This saves one stat call. If
the file is in the cache, everything is fine and otherwise the code
follows its normal fallback path.
Because there is no guarantee that a cleanup of these directories will occur
after the "restic check", we extend the behavior to detect and manage these
specific cache directories and allow their cleanup too.
This enables the backends to request the calculation of a
backend-specific hash. For the currently supported backends this will
always be MD5. The hash calculation happens as early as possible, for
pack files this is during assembly of the pack file. That way the hash
would even capture corruptions of the temporary pack file on disk.
Many instances of errors.Wrap in this package would produce messages
like "Open: open <filename>: no such file or directory"; those now omit
the first "Open:" (or "Stat:", or "MkdirAll"). The function readVersion
now appends its own name to the error message, rather than the function
that failed, to make it easier to spot. Other function names (e.g.,
Load) are already added further up in the call chain.
This commit changes the signatures for repository.LoadAndDecrypt and
utils.LoadAll to allow passing in a []byte as the buffer to use. This
buffer is enlarged as needed, and returned back to the caller for
further use.
In later commits, this allows reducing allocations by reusing a buffer
for multiple calls, e.g. in a worker function.
Sometimes, users run restic without retaining the local cache
directories. This was reported several times in the past.
Restic will now print a message whenever a new cache directory is
created from scratch (i.e. it did not exist before), so users have a
chance to recognize when the cache is not kept between different runs of
restic.
Accessing beyond the end of the file now removes the file from the cache
because it is assumed to be truncated. Usually, this means that the data
is fetched directly from the backend instead.
