test-lfs: add tests to force server error path coverage

The tests are somewhat fragile in that the extension that forces the errors is
counting how many times some of the functions are being called, so it depends
heavily on the content of the repo.  Maybe we can do something clever like load
an extension on the client, and have it send over instructions in the HTTP
header how to fail.  (I'm trying to avoid killing and restarting the server,
because Windows seems to have issues with doing that a lot.)  But I'd rather fix
issues than polish tests before the freeze.

tests/test-lfs-serve-access.t

@@ -4,7 +4,6 b''
   > [extensions]
   > lfs=
   > [lfs]
-  > url=http://localhost:$HGPORT/.git/info/lfs
   > track=all()
   > [web]
   > push_ssl = False
@@ -149,3 +148,187 b' Blob URIs are correct when --prefix is u'
   $LOCALIP - - [$LOGDATE$] "GET /subdir/mount/point?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bookmarks=1&bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%252C03%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps%250Arev-branch-cache%250Astream%253Dv2&cg=1&common=0000000000000000000000000000000000000000&heads=525251863cad618e55d483555f3d00a2ca99597e&listkeys=bookmarks&phases=1 x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
   $LOCALIP - - [$LOGDATE$] "POST /subdir/mount/point/.git/info/lfs/objects/batch HTTP/1.1" 200 - (glob)
   $LOCALIP - - [$LOGDATE$] "GET /subdir/mount/point/.hg/lfs/objects/f03217a32529a28a42d03b1244fe09b6e0f9fd06d7b966d4d50567be2abe6c0e HTTP/1.1" 200 - (glob)
+
+  $ cat >> $TESTTMP/lfsstoreerror.py <<EOF
+  > import errno
+  > from hgext.lfs import blobstore
+  > 
+  > _numverifies = 0
+  > _readerr = True
+  > 
+  > def reposetup(ui, repo):
+  >     # Nothing to do with a remote repo
+  >     if not repo.local():
+  >         return
+  > 
+  >     store = repo.svfs.lfslocalblobstore
+  >     class badstore(store.__class__):
+  >         def download(self, oid, src):
+  >             '''Called in the server to handle reading from the client in a
+  >             PUT request.'''
+  >             origread = src.read
+  >             def _badread(nbytes):
+  >                 # Simulate bad data/checksum failure from the client
+  >                 return b'0' * len(origread(nbytes))
+  >             src.read = _badread
+  >             super(badstore, self).download(oid, src)
+  > 
+  >         def _read(self, vfs, oid, verify):
+  >             '''Called in the server to read data for a GET request, and then
+  >             calls self._verify() on it before returning.'''
+  >             global _readerr
+  >             # One time simulation of a read error
+  >             if _readerr:
+  >                 _readerr = False
+  >                 raise IOError(errno.EIO, '%s: I/O error' % oid)
+  >             # Simulate corrupt content on client download
+  >             blobstore._verify(oid, 'dummy content')
+  > 
+  >         def verify(self, oid):
+  >             '''Called in the server to populate the Batch API response,
+  >             letting the client re-upload if the file is corrupt.'''
+  >             # Fail verify in Batch API for one clone command and one push
+  >             # command with an IOError.  Then let it through to access other
+  >             # functions.  Checksum failure is tested elsewhere.
+  >             global _numverifies
+  >             _numverifies += 1
+  >             if _numverifies <= 2:
+  >                 raise IOError(errno.EIO, '%s: I/O error' % oid)
+  >             return super(badstore, self).verify(oid)
+  > 
+  >     store.__class__ = badstore
+  > EOF
+
+  $ rm -rf `hg config lfs.usercache`
+  $ rm -f $TESTTMP/access.log $TESTTMP/errors.log
+  $ hg --config "lfs.usercache=$TESTTMP/servercache" \
+  >    --config extensions.lfsstoreerror=$TESTTMP/lfsstoreerror.py \
+  >    -R server serve -d \
+  >    -p $HGPORT1 --pid-file=hg.pid -A $TESTTMP/access.log -E $TESTTMP/errors.log
+  $ cat hg.pid >> $DAEMON_PIDS
+
+Test an I/O error in localstore.verify() (Batch API) with GET
+
+  $ hg clone http://localhost:$HGPORT1 httpclone2
+  requesting all changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files
+  new changesets 525251863cad
+  updating to branch default
+  abort: LFS server error for "lfs.bin": Internal server error!
+  [255]
+
+Test an I/O error in localstore.verify() (Batch API) with PUT
+
+  $ echo foo > client/lfs.bin
+  $ hg -R client ci -m 'mod lfs'
+  $ hg -R client push http://localhost:$HGPORT1
+  pushing to http://localhost:$HGPORT1/
+  searching for changes
+  abort: LFS server error for "unknown": Internal server error!
+  [255]
+TODO: figure out how to associate the file name in the error above
+
+Test a bad checksum sent by the client in the transfer API
+
+  $ hg -R client push http://localhost:$HGPORT1
+  pushing to http://localhost:$HGPORT1/
+  searching for changes
+  abort: HTTP error: HTTP Error 500: Internal Server Error (oid=b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c, action=upload)!
+  [255]
+
+  $ echo 'test lfs file' > server/lfs3.bin
+  $ hg --config experimental.lfs.disableusercache=True \
+  >    -R server ci -Aqm 'another lfs file'
+  $ hg -R client pull -q http://localhost:$HGPORT1
+
+Test an I/O error during the processing of the GET request
+
+  $ hg --config lfs.url=http://localhost:$HGPORT1/.git/info/lfs \
+  >    -R client update -r tip
+  abort: HTTP error: HTTP Error 500: Internal Server Error (oid=276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d, action=download)!
+  [255]
+
+Test a checksum failure during the processing of the GET request
+
+  $ hg --config lfs.url=http://localhost:$HGPORT1/.git/info/lfs \
+  >    -R client update -r tip
+  abort: HTTP error: HTTP Error 500: Internal Server Error (oid=276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d, action=download)!
+  [255]
+
+  $ $PYTHON $RUNTESTDIR/killdaemons.py $DAEMON_PIDS
+
+  $ cat $TESTTMP/access.log
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bookmarks=1&bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%252C03%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps%250Arev-branch-cache%250Astream%253Dv2&cg=1&common=0000000000000000000000000000000000000000&heads=525251863cad618e55d483555f3d00a2ca99597e&listkeys=bookmarks&phases=1 x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "POST /.git/info/lfs/objects/batch HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D392c05922088bacf8e68a6939b480017afbf245d x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=branchmap HTTP/1.1" 200 - x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "POST /.git/info/lfs/objects/batch HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D392c05922088bacf8e68a6939b480017afbf245d x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=phases x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=branchmap HTTP/1.1" 200 - x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=listkeys HTTP/1.1" 200 - x-hgarg-1:namespace=bookmarks x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "POST /.git/info/lfs/objects/batch HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "PUT /.hg/lfs/objects/b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c HTTP/1.1" 500 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=capabilities HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=batch HTTP/1.1" 200 - x-hgarg-1:cmds=heads+%3Bknown+nodes%3D392c05922088bacf8e68a6939b480017afbf245d x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /?cmd=getbundle HTTP/1.1" 200 - x-hgarg-1:bookmarks=1&bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%252C03%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps%250Arev-branch-cache%250Astream%253Dv2&cg=1&common=525251863cad618e55d483555f3d00a2ca99597e&heads=506bf3d83f78c54b89e81c6411adee19fdf02156+525251863cad618e55d483555f3d00a2ca99597e&listkeys=bookmarks&phases=1 x-hgproto-1:0.1 0.2 comp=$USUAL_COMPRESSIONS$ partial-pull (glob)
+  $LOCALIP - - [$LOGDATE$] "POST /.git/info/lfs/objects/batch HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /.hg/lfs/objects/276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d HTTP/1.1" 500 - (glob)
+  $LOCALIP - - [$LOGDATE$] "POST /.git/info/lfs/objects/batch HTTP/1.1" 200 - (glob)
+  $LOCALIP - - [$LOGDATE$] "GET /.hg/lfs/objects/276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d HTTP/1.1" 500 - (glob)
+
+  $ grep -v '  File "' $TESTTMP/errors.log
+  $LOCALIP - - [$ERRDATE$] Exception happened during processing request '/.hg/lfs/objects/b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c': (glob)
+  Traceback (most recent call last):
+      self.do_write()
+      self.do_hgweb()
+      for chunk in self.server.application(env, self._start_response):
+      for r in self._runwsgi(req, res, repo):
+      rctx, req, res, self.check_perm)
+      return func(*(args + a), **kw)
+      lambda perm:
+      localstore.download(oid, req.bodyfh)
+      super(badstore, self).download(oid, src)
+      raise error.Abort(_('corrupt remote lfs object: %s') % oid)
+  Abort: corrupt remote lfs object: b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c
+  
+  $LOCALIP - - [$ERRDATE$] Exception happened during processing request '/.hg/lfs/objects/276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d': (glob)
+  Traceback (most recent call last):
+      self.do_write()
+      self.do_hgweb()
+      for chunk in self.server.application(env, self._start_response):
+      for r in self._runwsgi(req, res, repo):
+      rctx, req, res, self.check_perm)
+      return func(*(args + a), **kw)
+      lambda perm:
+      res.setbodybytes(localstore.read(oid))
+      blob = self._read(self.vfs, oid, verify)
+      raise IOError(errno.EIO, '%s: I/O error' % oid)
+  IOError: [Errno 5] 276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d: I/O error
+  
+  $LOCALIP - - [$ERRDATE$] Exception happened during processing request '/.hg/lfs/objects/276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d': (glob)
+  Traceback (most recent call last):
+      self.do_write()
+      self.do_hgweb()
+      for chunk in self.server.application(env, self._start_response):
+      for r in self._runwsgi(req, res, repo):
+      rctx, req, res, self.check_perm)
+      return func(*(args + a), **kw)
+      lambda perm:
+      res.setbodybytes(localstore.read(oid))
+      blob = self._read(self.vfs, oid, verify)
+      blobstore._verify(oid, 'dummy content')
+      hint=_('run hg verify'))
+  Abort: detected corrupt lfs object: 276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d
+