view tests/test-mq-git.t @ 46607:e9901d01d135

revlog: add a mechanism to verify expected file position before appending

If someone uses `hg debuglocks`, or some non-hg process writes to the .hg
directory without respecting the locks, or if the repo's on a networked
filesystem, it's possible for the revlog code to write out corrupted data.

The form of this corruption can vary depending on what data was written and how
that happened. We are in the "networked filesystem" case (though I've had users
also do this to themselves with the "`hg debuglocks`" scenario), and most often
see this with the changelog. What ends up happening is we produce two items
(let's call them rev1 and rev2) in the .i file that have the same linkrev,
baserev, and offset into the .d file, while the data in the .d file is appended
properly. rev2's compressed_size is accurate for rev2, but when we go to
decompress the data in the .d file, we use the offset that's recorded in the
index file, which is the same as rev1, and attempt to decompress
rev2.compressed_size bytes of rev1's data. This usually does not succeed. :)

When using inline data, this also fails, though I haven't investigated why too
closely. This shows up as a "patch decode" error. I believe what's happening
there is that we're basically ignoring the offset field, getting the data
properly, but since baserev != rev, it thinks this is a delta based on rev
(instead of a full text) and can't actually apply it as such.

For now, I'm going to make this an optional component and default it to entirely
off. I may increase the default severity of this in the future, once I've
enabled it for my users and we gain more experience with it. Luckily, most of my
users have a versioned filesystem and can roll back to before the corruption has
been written, it's just a hassle to do so and not everyone knows how (so it's a
support burden). Users on other filesystems will not have that luxury, and this
can cause them to have a corrupted repository that they are unlikely to know how
to resolve, and they'll see this as a data-loss event. Refusing to create the
corruption is a much better user experience.

This mechanism is not perfect. There may be false-negatives (racy writes that
are not detected). There should not be any false-positives (non-racy writes that
are detected as such). This is not a mechanism that makes putting a repo on a
networked filesystem "safe" or "supported", just *less* likely to cause
corruption.

Differential Revision: https://phab.mercurial-scm.org/D9952

# Test the plumbing of mq.git option
# Automatic upgrade itself is tested elsewhere.

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > mq =
  > [diff]
  > nodates = 1
  > EOF

  $ hg init repo-auto
  $ cd repo-auto

git=auto: regular patch creation:

  $ echo a > a
  $ hg add a
  $ hg qnew -d '0 0' -f adda

  $ cat .hg/patches/adda
  # HG changeset patch
  # Date 0 0
  # Parent  0000000000000000000000000000000000000000
  
  diff -r 000000000000 -r ef8dafc9fa4c a
  --- /dev/null
  +++ b/a
  @@ -0,0 +1,1 @@
  +a

git=auto: git patch creation with copy:

  $ hg cp a b
  $ hg qnew -d '0 0' -f copy

  $ cat .hg/patches/copy
  # HG changeset patch
  # Date 0 0
  # Parent  ef8dafc9fa4caff80f6e243eb0171bcd60c455b4
  
  diff --git a/a b/b
  copy from a
  copy to b

git=auto: git patch when using --git:

  $ echo regular > regular
  $ hg add regular
  $ hg qnew -d '0 0' --git -f git

  $ cat .hg/patches/git
  # HG changeset patch
  # Date 0 0
  # Parent  99586d5f048c399e20f81cee41fbb3809c0e735d
  
  diff --git a/regular b/regular
  new file mode 100644
  --- /dev/null
  +++ b/regular
  @@ -0,0 +1,1 @@
  +regular

git=auto: regular patch after qrefresh without --git:

  $ hg qrefresh -d '0 0'

  $ cat .hg/patches/git
  # HG changeset patch
  # Date 0 0
  # Parent  99586d5f048c399e20f81cee41fbb3809c0e735d
  
  diff -r 99586d5f048c regular
  --- /dev/null
  +++ b/regular
  @@ -0,0 +1,1 @@
  +regular

  $ cd ..

  $ hg init repo-keep
  $ cd repo-keep
  $ echo '[mq]' > .hg/hgrc
  $ echo 'git = KEEP' >> .hg/hgrc

git=keep: git patch with --git:

  $ echo a > a
  $ hg add a
  $ hg qnew -d '0 0' -f --git git

  $ cat .hg/patches/git
  # HG changeset patch
  # Date 0 0
  # Parent  0000000000000000000000000000000000000000
  
  diff --git a/a b/a
  new file mode 100644
  --- /dev/null
  +++ b/a
  @@ -0,0 +1,1 @@
  +a

git=keep: git patch after qrefresh without --git:

  $ echo a >> a
  $ hg qrefresh -d '0 0'

  $ cat .hg/patches/git
  # HG changeset patch
  # Date 0 0
  # Parent  0000000000000000000000000000000000000000
  
  diff --git a/a b/a
  new file mode 100644
  --- /dev/null
  +++ b/a
  @@ -0,0 +1,2 @@
  +a
  +a
  $ cd ..

  $ hg init repo-yes
  $ cd repo-yes
  $ echo '[mq]' > .hg/hgrc
  $ echo 'git = yes' >> .hg/hgrc

git=yes: git patch:

  $ echo a > a
  $ hg add a
  $ hg qnew -d '0 0' -f git

  $ cat .hg/patches/git
  # HG changeset patch
  # Date 0 0
  # Parent  0000000000000000000000000000000000000000
  
  diff --git a/a b/a
  new file mode 100644
  --- /dev/null
  +++ b/a
  @@ -0,0 +1,1 @@
  +a

git=yes: git patch after qrefresh:

  $ echo a >> a
  $ hg qrefresh -d '0 0'

  $ cat .hg/patches/git
  # HG changeset patch
  # Date 0 0
  # Parent  0000000000000000000000000000000000000000
  
  diff --git a/a b/a
  new file mode 100644
  --- /dev/null
  +++ b/a
  @@ -0,0 +1,2 @@
  +a
  +a
  $ cd ..

  $ hg init repo-no
  $ cd repo-no
  $ echo '[diff]' > .hg/hgrc
  $ echo 'git = True' >> .hg/hgrc
  $ echo '[mq]' > .hg/hgrc
  $ echo 'git = False' >> .hg/hgrc

git=no: regular patch with copy:

  $ echo a > a
  $ hg add a
  $ hg qnew -d '0 0' -f adda
  $ hg cp a b
  $ hg qnew -d '0 0' -f regular

  $ cat .hg/patches/regular
  # HG changeset patch
  # Date 0 0
  # Parent  ef8dafc9fa4caff80f6e243eb0171bcd60c455b4
  
  diff -r ef8dafc9fa4c -r a70404f79ba3 b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +a

git=no: regular patch after qrefresh with copy:

  $ hg cp a c
  $ hg qrefresh -d '0 0'

  $ cat .hg/patches/regular
  # HG changeset patch
  # Date 0 0
  # Parent  ef8dafc9fa4caff80f6e243eb0171bcd60c455b4
  
  diff -r ef8dafc9fa4c b
  --- /dev/null
  +++ b/b
  @@ -0,0 +1,1 @@
  +a
  diff -r ef8dafc9fa4c c
  --- /dev/null
  +++ b/c
  @@ -0,0 +1,1 @@
  +a

Test how [diff] configuration influence and cause invalid or lossy patches:

  $ cat <<EOF >> .hg/hgrc
  > [mq]
  > git = AUTO
  > [diff]
  > nobinary = True
  > noprefix = True
  > showfunc = True
  > ignorews = True
  > ignorewsamount = True
  > ignoreblanklines = True
  > unified = 1
  > EOF

  $ echo ' a' > a
  $ hg qnew prepare -d '0 0'
  $ echo '  a' > a
  $ printf '\0' > b
  $ echo >> c
  $ hg qnew diff -d '0 0'

  $ cat .hg/patches/prepare
  # HG changeset patch
  # Date 0 0
  # Parent  cf0bfe72686a47d8d7d7b4529a3adb8b0b449a9f
  
  diff -r cf0bfe72686a -r fb9c4422b0f3 a
  --- a/a
  +++ b/a
  @@ -1,1 +1,1 @@
  -a
  + a
  $ cat .hg/patches/diff
  # HG changeset patch
  # Date 0 0
  # Parent  fb9c4422b0f37dd576522dd9a3f99b825c177efe
  
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,1 +1,1 @@
  - a
  +  a
  diff --git a/b b/b
  index 78981922613b2afb6025042ff6bd878ac1994e85..f76dd238ade08917e6712764a16a22005a50573d
  GIT binary patch
  literal 1
  Ic${MZ000310RR91
  
  diff --git a/c b/c
  --- a/c
  +++ b/c
  @@ -1,1 +1,2 @@
   a
  +

  $ cd ..