view tests/test-verify.t @ 35569:964212780daf

rust: implementation of `hg`

This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.

If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.

Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.

It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable -
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious.

Now onto the implementation.

We're using python27-sys and the cpython crates for talking to the
CPython API. We currently don't use too much functionality of the
cpython crate and could have probably cut it out. However, it does
provide a reasonable abstraction over unsafe {} CPython function
calls. While we still have our fair share of those, at least we're
not dealing with too much refcounting, error checking, etc. So I
think the use of the cpython crate is justified. Plus, there is
not-yet-implemented functionality that could benefit from cpython. I
see our use of this crate only increasing.

The cpython and python27-sys crates are not without their issues.
The cpython crate didn't seem to account for the embedding use case
in its design. Instead, it seems to assume that you are building
a Python extension. It is making some questionable decisions around
certain CPython APIs. For example, it insists that
PyEval_ThreadsInitialized() is called and that the Python code
likely isn't the main thread in the underlying application. It
is also missing some functionality that is important for embedded
use cases (such as exporting the path to the Python interpreter
from its build script). After spending several hours trying to
wrangle python27-sys and cpython, I gave up and forked the project
on GitHub. Our Cargo.toml tracks this fork. I'm optimistic that
the upstream project will accept our contributions and we can
eventually unfork.

There is a non-trivial amount of code in our custom Cargo build
script. Our build.rs (which is called as part of building the hgcli
crate):

* Validates that the Python interpreter that was detected by the
  python27-sys crate provides a shared library (we only support
  shared library linking at this time - although this restriction
  could be loosened).
* Validates that the Python is built with UCS-4 support. This ensures
  maximum Unicode compatibility.
* Exports variables to the crate build allowing the built crate to e.g.
  find the path to the Python interpreter.

The produced rhg should be considered alpha quality. There are several
known deficiencies. Many of these are documented with inline TODOs.

Probably the biggest limitation of rhg is that it assumes it is
running from the ./rust/target/<target> directory of a source
distribution. So, rhg is currently not very practical for real-world
use. But, if you can `cargo build` it, running the binary *should*
yield a working Mercurial CLI.

In order to support using rhg with the test harness, we needed to hack
up run-tests.py so the path to Mercurial's Python files is set properly.
The change is extremely hacky and is only intended to be a stop-gap
until the test harness gains first-class support for installing rhg.
This will likely occur after we support running rhg outside the
source directory.

Despite its officially alpha quality, rhg copes extremely well with
the test harness (at least on Linux). Using
`run-tests.py --with-hg ../rust/target/debug/hg`, I only encounter
the following failures:

* test-run-tests.t -- Warnings emitted about using an unexpected
  Mercurial library. This is due to the hacky nature of setting the
  Python directory when run-tests.py detected rhg.
* test-devel-warnings.t -- Expected stack trace missing frame for `hg`
  (This is expected since we no longer have an `hg` script!)
* test-convert.t -- Test running `$PYTHON "$BINDIR"/hg`, which obviously
  assumes `hg` is a Python script.
* test-merge-tools.t -- Same assumption about `hg` being executable with
  Python.
* test-http-bad-server.t -- Seeing exit code 255 instead of 1 around
  line 358.
* test-blackbox.t -- Exit code 255 instead of 1.
* test-basic.t -- Exit code 255 instead of 1.

It certainly looks like we have a bug around exit code handling. I
don't think it is severe enough to hold up review and landing of this
initial implementation. Perfect is the enemy of good.

Differential Revision: https://phab.mercurial-scm.org/D1581

prepare repo

  $ hg init a
  $ cd a
  $ echo "some text" > FOO.txt
  $ echo "another text" > bar.txt
  $ echo "more text" > QUICK.txt
  $ hg add
  adding FOO.txt
  adding QUICK.txt
  adding bar.txt
  $ hg ci -mtest1

verify

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 1 changesets, 3 total revisions

verify with journal

  $ touch .hg/store/journal
  $ hg verify
  abandoned transaction found - run hg recover
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  3 files, 1 changesets, 3 total revisions
  $ rm .hg/store/journal

introduce some bugs in repo

  $ cd .hg/store/data
  $ mv _f_o_o.txt.i X_f_o_o.txt.i
  $ mv bar.txt.i xbar.txt.i
  $ rm _q_u_i_c_k.txt.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   warning: revlog 'data/FOO.txt.i' not in fncache!
   0: empty or missing FOO.txt
   FOO.txt@0: manifest refers to unknown revision f62022d3d590
   warning: revlog 'data/QUICK.txt.i' not in fncache!
   0: empty or missing QUICK.txt
   QUICK.txt@0: manifest refers to unknown revision 88b857db8eba
   warning: revlog 'data/bar.txt.i' not in fncache!
   0: empty or missing bar.txt
   bar.txt@0: manifest refers to unknown revision 256559129457
  3 files, 1 changesets, 0 total revisions
  3 warnings encountered!
  hint: run "hg debugrebuildfncache" to recover from corrupt fncache
  6 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]

  $ cd ../../..
  $ cd ..

Set up a repo for testing missing revlog entries

  $ hg init missing-entries
  $ cd missing-entries
  $ echo 0 > file
  $ hg ci -Aqm0
  $ cp -R .hg/store .hg/store-partial
  $ echo 1 > file
  $ hg ci -Aqm1
  $ cp -R .hg/store .hg/store-full

Entire changelog missing

  $ rm .hg/store/00changelog.*
  $ hg verify -q
   0: empty or missing changelog
   manifest@0: d0b6632564d4 not in changesets
   manifest@1: 941fc4534185 not in changesets
  3 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Entire manifest log missing

  $ rm .hg/store/00manifest.*
  $ hg verify -q
   0: empty or missing manifest
  1 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Entire filelog missing

  $ rm .hg/store/data/file.*
  $ hg verify -q
   warning: revlog 'data/file.i' not in fncache!
   0: empty or missing file
   file@0: manifest refers to unknown revision 362fef284ce2
   file@1: manifest refers to unknown revision c10f2164107d
  1 warnings encountered!
  hint: run "hg debugrebuildfncache" to recover from corrupt fncache
  3 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Entire changelog and manifest log missing

  $ rm .hg/store/00changelog.*
  $ rm .hg/store/00manifest.*
  $ hg verify -q
  warning: orphan revlog 'data/file.i'
  1 warnings encountered!
  $ cp -R .hg/store-full/. .hg/store

Entire changelog and filelog missing

  $ rm .hg/store/00changelog.*
  $ rm .hg/store/data/file.*
  $ hg verify -q
   0: empty or missing changelog
   manifest@0: d0b6632564d4 not in changesets
   manifest@1: 941fc4534185 not in changesets
   warning: revlog 'data/file.i' not in fncache!
   ?: empty or missing file
   file@0: manifest refers to unknown revision 362fef284ce2
   file@1: manifest refers to unknown revision c10f2164107d
  1 warnings encountered!
  hint: run "hg debugrebuildfncache" to recover from corrupt fncache
  6 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Entire manifest log and filelog missing

  $ rm .hg/store/00manifest.*
  $ rm .hg/store/data/file.*
  $ hg verify -q
   0: empty or missing manifest
   warning: revlog 'data/file.i' not in fncache!
   0: empty or missing file
  1 warnings encountered!
  hint: run "hg debugrebuildfncache" to recover from corrupt fncache
  2 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Changelog missing entry

  $ cp -f .hg/store-partial/00changelog.* .hg/store
  $ hg verify -q
   manifest@?: rev 1 points to nonexistent changeset 1
   manifest@?: 941fc4534185 not in changesets
   file@?: rev 1 points to nonexistent changeset 1
   (expected 0)
  1 warnings encountered!
  3 integrity errors encountered!
  [1]
  $ cp -R .hg/store-full/. .hg/store

Manifest log missing entry

  $ cp -f .hg/store-partial/00manifest.* .hg/store
  $ hg verify -q
   manifest@1: changeset refers to unknown revision 941fc4534185
   file@1: c10f2164107d not in manifests
  2 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Filelog missing entry

  $ cp -f .hg/store-partial/data/file.* .hg/store/data
  $ hg verify -q
   file@1: manifest refers to unknown revision c10f2164107d
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Changelog and manifest log missing entry

  $ cp -f .hg/store-partial/00changelog.* .hg/store
  $ cp -f .hg/store-partial/00manifest.* .hg/store
  $ hg verify -q
   file@?: rev 1 points to nonexistent changeset 1
   (expected 0)
   file@?: c10f2164107d not in manifests
  1 warnings encountered!
  2 integrity errors encountered!
  [1]
  $ cp -R .hg/store-full/. .hg/store

Changelog and filelog missing entry

  $ cp -f .hg/store-partial/00changelog.* .hg/store
  $ cp -f .hg/store-partial/data/file.* .hg/store/data
  $ hg verify -q
   manifest@?: rev 1 points to nonexistent changeset 1
   manifest@?: 941fc4534185 not in changesets
   file@?: manifest refers to unknown revision c10f2164107d
  3 integrity errors encountered!
  [1]
  $ cp -R .hg/store-full/. .hg/store

Manifest and filelog missing entry

  $ cp -f .hg/store-partial/00manifest.* .hg/store
  $ cp -f .hg/store-partial/data/file.* .hg/store/data
  $ hg verify -q
   manifest@1: changeset refers to unknown revision 941fc4534185
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Corrupt changelog base node to cause failure to read revision

  $ printf abcd | dd conv=notrunc of=.hg/store/00changelog.i bs=1 seek=16 \
  >   2> /dev/null
  $ hg verify -q
   0: unpacking changeset 08b1860757c2: * (glob)
   manifest@?: rev 0 points to unexpected changeset 0
   manifest@?: d0b6632564d4 not in changesets
   file@?: rev 0 points to unexpected changeset 0
   (expected 1)
  1 warnings encountered!
  4 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Corrupt manifest log base node to cause failure to read revision

  $ printf abcd | dd conv=notrunc of=.hg/store/00manifest.i bs=1 seek=16 \
  >   2> /dev/null
  $ hg verify -q
   manifest@0: reading delta d0b6632564d4: * (glob)
   file@0: 362fef284ce2 not in manifests
  2 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

Corrupt filelog base node to cause failure to read revision

  $ printf abcd | dd conv=notrunc of=.hg/store/data/file.i bs=1 seek=16 \
  >   2> /dev/null
  $ hg verify -q
   file@0: unpacking 362fef284ce2: * (glob)
  1 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ cp -R .hg/store-full/. .hg/store

  $ cd ..

test changelog without a manifest

  $ hg init b
  $ cd b
  $ hg branch foo
  marked working directory as branch foo
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -m branchfoo
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  0 files, 1 changesets, 0 total revisions

test revlog corruption

  $ touch a
  $ hg add a
  $ hg ci -m a

  $ echo 'corrupted' > b
  $ dd if=.hg/store/data/a.i of=start bs=1 count=20 2>/dev/null
  $ cat start b > .hg/store/data/a.i

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   a@1: broken revlog! (index data/a.i is corrupted)
  warning: orphan revlog 'data/a.i'
  1 files, 2 changesets, 0 total revisions
  1 warnings encountered!
  1 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]

  $ cd ..

test revlog format 0

  $ revlog-formatv0.py
  $ cd formatv0
  $ hg verify
  repository uses revlog format 0
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions
  $ cd ..

test flag processor and skipflags

  $ hg init skipflags
  $ cd skipflags
  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > flagprocessor=$RUNTESTDIR/flagprocessorext.py
  > EOF
  $ echo '[BASE64]content' > base64
  $ hg commit -Aqm 'flag processor content' base64
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

  $ cat >> $TESTTMP/break-base64.py <<EOF
  > from __future__ import absolute_import
  > import base64
  > base64.b64decode=lambda x: x
  > EOF
  $ cat >> .hg/hgrc <<EOF
  > breakbase64=$TESTTMP/break-base64.py
  > EOF

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   base64@0: unpacking 794cee7777cb: integrity check failed on data/base64.i:0
  1 files, 1 changesets, 1 total revisions
  1 integrity errors encountered!
  (first damaged changeset appears to be 0)
  [1]
  $ hg verify --config verify.skipflags=2147483647
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions