view rust/hg-core/examples/nodemap/index.rs @ 45027:0ea9c86fac89 stable 5.4.2

convert: handle percent-encoded bytes in file URLs like Subversion

75b59d221aa3 added most of the code that gets removed by this patch. It helped
making progress on Python 3, but the reasoning was wrong in many ways. I tried
to retract it while it was queued, but it was too late.

Back then, I was asssuming that what happened on Python 2 (preserving bytes) is
correct and my Python 3 change is a hack. However it turned out that Subversion
interprets percent-encoded bytes as UTF-8. Accepting the same format as
Subversion is a good idea.

Consistency with urlreq.pathname2url() (as described in the removed comment)
doesn’t matter because that function is only used for passing paths to urllib.

This is not a backwards-incompatible change because before 5c0d5b48e58c,
non-ASCII filenames didn’t work at all on Python 2.

When the locale encoding is ISO-8859-15, `svn` accepts `file:///tmp/a%E2%82%AC`
for `/tmp/a€`. Before this patch, this was the case for this extension on
Python 3, but not on Python 2. This patch makes it work like with `svn` on both
Python 2 and Python 3.

// Copyright 2019-2020 Georges Racinet <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

//! Minimal `RevlogIndex`, readable from standard Mercurial file format
use hg::*;
use memmap::*;
use std::fs::File;
use std::ops::Deref;
use std::path::Path;
use std::slice;

pub struct Index {
    data: Box<dyn Deref<Target = [IndexEntry]> + Send>,
}

/// A fixed sized index entry. All numbers are big endian
#[repr(C)]
pub struct IndexEntry {
    not_used_yet: [u8; 24],
    p1: Revision,
    p2: Revision,
    node: Node,
    unused_node: [u8; 12],
}

pub const INDEX_ENTRY_SIZE: usize = 64;

impl IndexEntry {
    fn parents(&self) -> [Revision; 2] {
        [Revision::from_be(self.p1), Revision::from_be(self.p1)]
    }
}

impl RevlogIndex for Index {
    fn len(&self) -> usize {
        self.data.len()
    }

    fn node(&self, rev: Revision) -> Option<&Node> {
        if rev == NULL_REVISION {
            return None;
        }
        let i = rev as usize;
        if i >= self.len() {
            None
        } else {
            Some(&self.data[i].node)
        }
    }
}

impl Graph for &Index {
    fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError> {
        let [p1, p2] = (*self).data[rev as usize].parents();
        let len = (*self).len();
        if p1 < NULL_REVISION
            || p2 < NULL_REVISION
            || p1 as usize >= len
            || p2 as usize >= len
        {
            return Err(GraphError::ParentOutOfRange(rev));
        }
        Ok([p1, p2])
    }
}

struct IndexMmap(Mmap);

impl Deref for IndexMmap {
    type Target = [IndexEntry];

    fn deref(&self) -> &[IndexEntry] {
        let ptr = self.0.as_ptr() as *const IndexEntry;
        // Any misaligned data will be ignored.
        debug_assert_eq!(
            self.0.len() % std::mem::align_of::<IndexEntry>(),
            0,
            "Misaligned data in mmap"
        );
        unsafe { slice::from_raw_parts(ptr, self.0.len() / INDEX_ENTRY_SIZE) }
    }
}

impl Index {
    pub fn load_mmap(path: impl AsRef<Path>) -> Self {
        let file = File::open(path).unwrap();
        let msg = "Index file is missing, or missing permission";
        let mmap = unsafe { MmapOptions::new().map(&file) }.expect(msg);
        Self {
            data: Box::new(IndexMmap(mmap)),
        }
    }
}