This keeps things fast by making the function inline, but also prevents
people from having to know about the `0xFF` implementation detail
directly, instead making one go through a `std::optional` (which could be
fused away with a sufficiently smart compiler).
Additionally, the base "nix32" implementation is moved to its own header
file pair, as it is logically distinct and prior to the `Hash` data
type. It would probably be nice to do this with all the hash format
implementations.
Some binary caches (incorrectly) use this header to indicate lack of
compression, inspired by the valid "identity" token in the
"Accept-Encoding" header.
The changes include:
* Defining nix32Chars as a constexpr char[].
* Adding a constexpr std::array<unsigned char, 256> (reverseNix32Map) to map characters to their base-32 digit values at compile time.
* Replacing the slow character search loop with a direct lookup using reverseNix32Map.
* Removing std::once_flag/isBase32 logic in references.cc in favor of reverseNix32Map
Signed-off-by: Alexander V. Nikolaev <avn@avnik.info>
GCC doesn't really benefit as much as Clang does from
using precompiled headers. Another aspect to consider is that
clangd doesn't really like GCC's PCH flags in the compilation database,
so GCC based devshells would continue to work with clangd.
This also has the slight advantage of ensuring that our includes are in
order, since we build with both Clang and GCC.
SHA-256 is Git's next hash algorithm. The world is still basically stuck
on SHA-1 with git, but shouldn't be. We can at least do our part to get
ready.
On the C++ implementation side, only a little bit of generalization was
needed, and that was fairly straight-forward. The tests (unit and
system) were actually bigger, and care was taken to make sure they were
all cover both algorithms equally.
Boost.URL is a significantly more RFC-compliant parser
than what libutil currently has a bundle of incomprehensible
regexes.
One aspect of this change is that RFC4007 ZoneId IPv6 literals
are represented in URIs according to RFC6874 [1].
Previously they were represented naively like so: [fe80::818c:da4d:8975:415c\%enp0s25].
This is not entirely correct, because the percent itself has to be pct-encoded:
> "%" is always treated as
an escape character in a URI, so, according to the established URI
syntax [RFC3986] any occurrences of literal "%" symbols in a URI MUST
be percent-encoded and represented in the form "%25". Thus, the
scoped address fe80::a%en1 would appear in a URI as
http://[fe80::a%25en1].
[1]: https://datatracker.ietf.org/doc/html/rfc6874
Co-authored-by: Jörg Thalheim <joerg@thalheim.io>
The myriad of hand-rolled URL parsing and validation code
is a constant source of problems. Regexes are not a great way
of writing parsers and there's a history of getting them wrong.
Boost.URL is a good library we can outsource most of the heavy
lifting to.
* It is tough to contribute to a project that doesn't use a formatter,
* It is extra hard to contribute to a project which has configured the formatter, but ignores it for some files
* Code formatting makes it harder to hide obscure / weird bugs by accident or on purpose,
Let's rip the bandaid off?
Note that PRs currently in flight should be able to be merged relatively easily by applying `clang-format` to their tip prior to merge.
Previous use of symlink_status() always translated into a stat call, leading
to huge performance penalties for by-name-overlay in nixpkgs. The comment
below references the possible caching, but that seemed to be erroneous, since
the correct way to make use of the caching API is by calling a bunch of `is_*`
functions [1]. For example, here's how libstdc++ does that [2], [3].
This translates to great nixpkgs eval performance improvements:
```
Benchmark 1: GC_INITIAL_HEAP_SIZE=4G result/bin/nix-instantiate ../nixpkgs -A hello --readonly-mode
Time (mean ± σ): 186.7 ms ± 6.7 ms [User: 121.3 ms, System: 64.9 ms]
Range (min … max): 179.4 ms … 201.6 ms 16 runs
Benchmark 2: GC_INITIAL_HEAP_SIZE=4G nix-instantiate ../nixpkgs -A hello --readonly-mode
Time (mean ± σ): 230.6 ms ± 5.0 ms [User: 126.9 ms, System: 103.1 ms]
Range (min … max): 225.1 ms … 241.4 ms 13 runs
```
[1]: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0317r1.html
[2]: 8ea555b7b4/libstdc%2B%2B-v3/include/bits/fs_dir.h (L341-L348)
[3]: 8ea555b7b4/libstdc%2B%2B-v3/include/bits/fs_dir.h (L161-L163)
When calling `_deletePath` with a parent file descriptor, `openat` is
made effective by using relative paths to the directory file descriptor.
To avoid the problem, the signature is changed to resist misuse with an
assert in the prologue of the function.
Change-Id: I6b3fc766bad2afe54dc27d47d1df3873e188de96
Signed-off-by: Raito Bezarius <raito@lix.systems>
`writeFile` lose its `sync` boolean flag to make things simpler.
A new `writeFileAndSync` function is created and all call sites are
converted to it.
Change-Id: Ib871a5283a9c047db1e4fe48a241506e4aab9192
Signed-off-by: Raito Bezarius <raito@lix.systems>
This is useful for certain error recovery paths (no pun intended) that
does not thread through the original path name.
Change-Id: I2d800740cb4f9912e64c923120d3f977c58ccb7e
Signed-off-by: Raito Bezarius <raito@lix.systems>
Unlike std::sort and std::stable_sort, this implementation
does not lead to out-of-bounds memory reads or other undefined
behavior when the predicate is not strict weak ordering.
This makes it possible to use this function in libexpr for
builtins.sort, where an incorrectly implemented comparator
in the user nix code currently can crash and burn the evaluator
by invoking C++ UB.
This adds a meson.format file that mostly mirrors the projects
meson style and a pre-commit hook to enforce this style.
Some low-diff files are formatted.
There's actually no mutation happening so there's no point in using
a mutable shared_ptr. Furthermore, this makes it much more evident to
the reader that no actual mutation (especially in multithreaded case)
is happening.
Also get rid of redundant constructor that isn't actually used anywhere
other than `Pos::operator std::shared_ptr<Pos>` which just passes in &*this,
(identical to just `this`), which can't be nullptr.
Judging by the comment for `makeEmptySourceAccessor` the prefix has
to be empty:
> Return a source accessor that contains only an empty root directory.
Fixes#13295.
This is the utility changes from #9968, which were easier to rebase
first.
I (@Ericson2314) didn't write this code; I just rebased it.
Co-Authored-By: Artemis Tosini <me@artem.ist>
Co-Authored-By: Audrey Dutcher <audrey@rhelmot.io>
