view tests/test-patch.t @ 47965:f9e6f2bb721d

rhg: Don’t compare ambiguous files one byte at a time

Even though the use of `BufReader` reduces the number of syscalls to read
the file from disk, `.bytes()` yields a separate `Result` for every byte.
Creating those results and dispatching on them is most likely costly.

Instead, this commit opts for simplicity by reading the entire file into memory
and comparing a single pair of byte strings. Note that memory already needs to
contain the entire previous contents of the file, as read from the filelog.
So with an extremely large file this doubles memory use but does not make it
grow by orders of magnitude.

At first I wrote code that still avoids reading the entire file into memory
and compares one buffer at a time with `BufReader`. Find this code below for
posterity. However its correctness is subtle. I ended up preferring the
simplicity of the obviously-correct single comparison.

```rust
let mut reader = BufReader::new(fobj);
let mut expected = &contents_in_p1[..];
loop {
    let buf = reader.fill_buf().when_reading_file(&fs_path)?;
    if buf.is_empty() {
        // Found EOF
        return Ok(expected.is_empty());
    } else if let Some(rest) = expected.drop_prefix(buf) {
        // What we read so far matches the expected content, continue reading
        let buf_len = buf.len();
        reader.consume(buf_len);
        expected = rest
    } else {
        // Found different content
        return Ok(false);
    }
}
```

Differential Revision: https://phab.mercurial-scm.org/D11412

  $ cat > patchtool.py <<EOF
  > from __future__ import absolute_import, print_function
  > import sys
  > print('Using custom patch')
  > if '--binary' in sys.argv:
  >     print('--binary found !')
  > EOF

  $ echo "[ui]" >> $HGRCPATH
  $ echo "patch=\"$PYTHON\" ../patchtool.py" >> $HGRCPATH

  $ hg init a
  $ cd a
  $ echo a > a
  $ hg commit -Ama -d '1 0'
  adding a
  $ echo b >> a
  $ hg commit -Amb -d '2 0'
  $ cd ..

This test checks that:
 - custom patch commands with arguments actually work
 - patch code does not try to add weird arguments like
 --binary when custom patch commands are used. For instance
 --binary is added by default under win32.

check custom patch options are honored

  $ hg --cwd a export -o ../a.diff tip
  $ hg clone -r 0 a b
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 8580ff50825a
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg --cwd b import -v ../a.diff
  applying ../a.diff
  Using custom patch
  applied to working directory

Issue2417: hg import with # comments in description

Prepare source repo and patch:

  $ rm $HGRCPATH
  $ hg init c
  $ cd c
  $ printf "a\rc" > a
  $ hg ci -A -m 0 a -d '0 0'
  $ printf "a\rb\rc" > a
  $ cat << eof > log
  > first line which can't start with '# '
  > # second line is a comment but that shouldn't be a problem.
  > A patch marker like this was more problematic even after d7452292f9d3:
  > # HG changeset patch
  > # User lines looks like this - but it _is_ just a comment
  > eof
  $ hg ci -l log -d '0 0'
  $ hg export -o p 1
  $ cd ..

Clone and apply patch:

  $ hg clone -r 0 c d
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 7fadb901d403
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd d
  $ hg import ../c/p
  applying ../c/p
  $ hg log -v -r 1
  changeset:   1:cd0bde79c428
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       a
  description:
  first line which can't start with '# '
  # second line is a comment but that shouldn't be a problem.
  A patch marker like this was more problematic even after d7452292f9d3:
  # HG changeset patch
  # User lines looks like this - but it _is_ just a comment
  
  

Error exit (issue4746)

  $ cat >> exit1.py <<EOF
  > import sys
  > sys.exit(1)
  > EOF

  $ hg import ../c/p --config ui.patch="\"$PYTHON\" \"`pwd`/exit1.py\""
  applying ../c/p
  abort: patch command failed: exited with status 1
  [255]

  $ cd ..