tests: test behavior of IOError during transactions (issue5658)

ui._write(), ui._write_err(), and ui.flush() all trap IOError and
re-raise as error.StdioError. If a caller doesn't catch StdioError
when writing to stdio, it could bubble all the way to dispatch.

This commit adds tests for I/O failures around various transaction
operations.

The most notable badness is during abort. Here, an uncaught StdioError
will result in incomplete transaction rollback, requiring an
`hg rollback` to recover. This can result in a client "corrupting"
a remote repo via terminated HTTP and SSH socket.

tests/test-rollback.t

@@ -1,212 +1,485 b''
 setup repo
   $ hg init t
   $ cd t
   $ echo a > a
   $ hg commit -Am'add a'
   adding a
   $ hg verify
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   1 files, 1 changesets, 1 total revisions
   $ hg parents
   changeset:   0:1f0dee641bb7
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     add a
   
 
 rollback to null revision
   $ hg status
   $ hg rollback
   repository tip rolled back to revision -1 (undo commit)
   working directory now based on revision -1
   $ hg verify
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   0 files, 0 changesets, 0 total revisions
   $ hg parents
   $ hg status
   A a
 
 Two changesets this time so we rollback to a real changeset
   $ hg commit -m'add a again'
   $ echo a >> a
   $ hg commit -m'modify a'
 
 Test issue 902 (current branch is preserved)
   $ hg branch test
   marked working directory as branch test
   (branches are permanent and global, did you want a bookmark?)
   $ hg rollback
   repository tip rolled back to revision 0 (undo commit)
   working directory now based on revision 0
   $ hg branch
   default
 
 Test issue 1635 (commit message saved)
   $ cat .hg/last-message.txt ; echo
   modify a
 
 Test rollback of hg before issue 902 was fixed
 
   $ hg commit -m "test3"
   $ hg branch test
   marked working directory as branch test
   (branches are permanent and global, did you want a bookmark?)
   $ rm .hg/undo.branch
   $ hg rollback
   repository tip rolled back to revision 0 (undo commit)
   named branch could not be reset: current branch is still 'test'
   working directory now based on revision 0
   $ hg branch
   test
 
 working dir unaffected by rollback: do not restore dirstate et. al.
   $ hg log --template '{rev}  {branch}  {desc|firstline}\n'
   0  default  add a again
   $ hg status
   M a
   $ hg bookmark foo
   $ hg commit -m'modify a again'
   $ echo b > b
   $ hg bookmark bar -r default #making bar active, before the transaction
   $ hg commit -Am'add b'
   adding b
   $ hg log --template '{rev}  {branch}  {desc|firstline}\n'
   2  test  add b
   1  test  modify a again
   0  default  add a again
   $ hg update bar
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   (activating bookmark bar)
   $ cat .hg/undo.branch ; echo
   test
   $ hg rollback -f
   repository tip rolled back to revision 1 (undo commit)
   $ hg id -n
   0
   $ hg branch
   default
   $ cat .hg/bookmarks.current ; echo
   bar
   $ hg bookmark --delete foo bar
 
 rollback by pretxncommit saves commit message (issue1635)
 
   $ echo a >> a
   $ hg --config hooks.pretxncommit=false commit -m"precious commit message"
   transaction abort!
   rollback completed
   abort: pretxncommit hook exited with status * (glob)
   [255]
   $ cat .hg/last-message.txt ; echo
   precious commit message
 
 same thing, but run $EDITOR
 
   $ cat > editor.sh << '__EOF__'
   > echo "another precious commit message" > "$1"
   > __EOF__
   $ HGEDITOR="\"sh\" \"`pwd`/editor.sh\"" hg --config hooks.pretxncommit=false commit 2>&1
   note: commit message saved in .hg/last-message.txt
   transaction abort!
   rollback completed
   abort: pretxncommit hook exited with status * (glob)
   [255]
   $ cat .hg/last-message.txt
   another precious commit message
 
 test rollback on served repository
 
 #if serve
   $ hg commit -m "precious commit message"
   $ hg serve -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
   $ cat hg.pid >> $DAEMON_PIDS
   $ cd ..
   $ hg clone http://localhost:$HGPORT u
   requesting all changes
   adding changesets
   adding manifests
   adding file changes
   added 3 changesets with 2 changes to 1 files (+1 heads)
   updating to branch default
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ cd u
   $ hg id default
   068774709090
 
 now rollback and observe that 'hg serve' reloads the repository and
 presents the correct tip changeset:
 
   $ hg -R ../t rollback
   repository tip rolled back to revision 1 (undo commit)
   working directory now based on revision 0
   $ hg id default
   791dd2169706
 
   $ killdaemons.py
 #endif
 
 update to older changeset and then refuse rollback, because
 that would lose data (issue2998)
   $ cd ../t
   $ hg -q update
   $ rm `hg status -un`
   $ template='{rev}:{node|short}  [{branch}]  {desc|firstline}\n'
   $ echo 'valuable new file' > b
   $ echo 'valuable modification' >> a
   $ hg commit -A -m'a valuable change'
   adding b
   $ hg update 0
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg rollback
   abort: rollback of last commit while not checked out may lose data
   (use -f to force)
   [255]
   $ hg tip -q
   2:4d9cd3795eea
   $ hg rollback -f
   repository tip rolled back to revision 1 (undo commit)
   $ hg status
   $ hg log --removed b   # yep, it's gone
 
 same again, but emulate an old client that doesn't write undo.desc
   $ hg -q update
   $ echo 'valuable modification redux' >> a
   $ hg commit -m'a valuable change redux'
   $ rm .hg/undo.desc
   $ hg update 0
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg rollback
   rolling back unknown transaction
   $ cat a
   a
 
 corrupt journal test
   $ echo "foo" > .hg/store/journal
   $ hg recover
   rolling back interrupted transaction
   couldn't read journal entry 'foo\n'!
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   1 files, 2 changesets, 2 total revisions
 
 rollback disabled by config
   $ cat >> $HGRCPATH <<EOF
   > [ui]
   > rollback = false
   > EOF
   $ echo narf >> pinky-sayings.txt
   $ hg add pinky-sayings.txt
   $ hg ci -m 'First one.'
   $ hg rollback
   abort: rollback is disabled because it is unsafe
   (see `hg help -v rollback` for information)
   [255]
+
+  $ cd ..
+
+I/O errors on stdio are handled properly (issue5658)
+
+  $ cat > badui.py << EOF
+  > import errno
+  > from mercurial.i18n import _
+  > from mercurial import (
+  >     error,
+  >     ui as uimod,
+  > )
+  > 
+  > def pretxncommit(ui, repo, **kwargs):
+  >     ui.warn('warn during pretxncommit\n')
+  > 
+  > def pretxnclose(ui, repo, **kwargs):
+  >     ui.warn('warn during pretxnclose\n')
+  > 
+  > def txnclose(ui, repo, **kwargs):
+  >     ui.warn('warn during txnclose\n')
+  > 
+  > def txnabort(ui, repo, **kwargs):
+  >     ui.warn('warn during abort\n')
+  > 
+  > class fdproxy(object):
+  >     def __init__(self, ui, o):
+  >         self._ui = ui
+  >         self._o = o
+  > 
+  >     def __getattr__(self, attr):
+  >         return getattr(self._o, attr)
+  > 
+  >     def write(self, msg):
+  >         errors = set(self._ui.configlist('ui', 'ioerrors', []))
+  >         pretxncommit = msg == 'warn during pretxncommit\n'
+  >         pretxnclose = msg == 'warn during pretxnclose\n'
+  >         txnclose = msg == 'warn during txnclose\n'
+  >         txnabort = msg == 'warn during abort\n'
+  >         msgabort = msg == _('transaction abort!\n')
+  >         msgrollback = msg == _('rollback completed\n')
+  > 
+  >         if pretxncommit and 'pretxncommit' in errors:
+  >             raise IOError(errno.EPIPE, 'simulated epipe')
+  >         if pretxnclose and 'pretxnclose' in errors:
+  >             raise IOError(errno.EIO, 'simulated eio')
+  >         if txnclose and 'txnclose' in errors:
+  >             raise IOError(errno.EBADF, 'simulated badf')
+  >         if txnabort and 'txnabort' in errors:
+  >             raise IOError(errno.EPIPE, 'simulated epipe')
+  >         if msgabort and 'msgabort' in errors:
+  >             raise IOError(errno.EBADF, 'simulated ebadf')
+  >         if msgrollback and 'msgrollback' in errors:
+  >             raise IOError(errno.EIO, 'simulated eio')
+  > 
+  >         return self._o.write(msg)
+  > 
+  > def uisetup(ui):
+  >     class badui(ui.__class__):
+  >         def write_err(self, *args, **kwargs):
+  >             olderr = self.ferr
+  >             try:
+  >                 self.ferr = fdproxy(self, olderr)
+  >                 return super(badui, self).write_err(*args, **kwargs)
+  >             finally:
+  >                 self.ferr = olderr
+  > 
+  >     ui.__class__ = badui
+  > 
+  > def reposetup(ui, repo):
+  >     ui.setconfig('hooks', 'pretxnclose.badui', pretxnclose, 'badui')
+  >     ui.setconfig('hooks', 'txnclose.badui', txnclose, 'badui')
+  >     ui.setconfig('hooks', 'pretxncommit.badui', pretxncommit, 'badui')
+  >     ui.setconfig('hooks', 'txnabort.badui', txnabort, 'badui')
+  > EOF
+
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > badui = $TESTTMP/badui.py
+  > EOF
+
+An I/O error during pretxncommit is handled
+
+  $ hg init ioerror-pretxncommit
+  $ cd ioerror-pretxncommit
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+  $ echo 1 > foo
+  $ hg --config ui.ioerrors=pretxncommit commit -m 'error during pretxncommit'
+  error: pretxncommit.badui hook raised an exception: [Errno *] simulated epipe (glob)
+  transaction abort!
+  warn during abort
+  rollback completed
+  [255]
+
+  $ hg commit -m 'commit 1'
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ cd ..
+
+An I/O error during pretxnclose is handled
+
+  $ hg init ioerror-pretxnclose
+  $ cd ioerror-pretxnclose
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ echo 1 > foo
+  $ hg --config ui.ioerrors=pretxnclose commit -m 'error during pretxnclose'
+  warn during pretxncommit
+  error: pretxnclose.badui hook raised an exception: [Errno *] simulated eio (glob)
+  transaction abort!
+  warn during abort
+  rollback completed
+  abort: simulated eio
+  [255]
+
+  $ hg commit -m 'commit 1'
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ cd ..
+
+An I/O error during txnclose is handled
+
+  $ hg init ioerror-txnclose
+  $ cd ioerror-txnclose
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ echo 1 > foo
+  $ hg --config ui.ioerrors=txnclose commit -m 'error during txnclose'
+  warn during pretxncommit
+  warn during pretxnclose
+  error: txnclose.badui hook raised an exception: [Errno *] simulated badf (glob)
+  (run with --traceback for stack trace)
+
+  $ hg commit -m 'commit 1'
+  nothing changed
+  [1]
+
+  $ cd ..
+
+An I/O error writing "transaction abort" is handled
+
+  $ hg init ioerror-msgabort
+  $ cd ioerror-msgabort
+
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ echo 1 > foo
+  $ hg --config ui.ioerrors=msgabort --config hooks.pretxncommit=false commit -m 'error during abort message'
+  abort: simulated ebadf
+  *: DeprecationWarning: use lock.release instead of del lock (glob)
+    return -1
+  [255]
+
+  $ hg commit -m 'commit 1'
+  abort: abandoned transaction found!
+  (run 'hg recover' to clean up transaction)
+  [255]
+
+  $ cd ..
+
+An I/O error during txnabort should still result in rollback
+
+  $ hg init ioerror-txnabort
+  $ cd ioerror-txnabort
+
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ echo 1 > foo
+  $ hg --config ui.ioerrors=txnabort --config hooks.pretxncommit=false commit -m 'error during abort'
+  transaction abort!
+  error: txnabort.badui hook raised an exception: [Errno *] simulated epipe (glob)
+  (run with --traceback for stack trace)
+  rollback completed
+  abort: pretxncommit hook exited with status 1
+  [255]
+
+  $ hg commit -m 'commit 1'
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ cd ..
+
+An I/O error writing "rollback completed" is handled
+
+  $ hg init ioerror-msgrollback
+  $ cd ioerror-msgrollback
+
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ echo 1 > foo
+
+  $ hg --config ui.ioerrors=msgrollback --config hooks.pretxncommit=false commit -m 'error during rollback message'
+  transaction abort!
+  warn during abort
+  rollback failed - please run hg recover
+  abort: pretxncommit hook exited with status 1
+  [255]
+
+  $ hg verify
+  checking changesets
+  checking manifests
+  crosschecking files in changesets and manifests
+  checking files
+  1 files, 1 changesets, 1 total revisions
+
+  $ cd ..
+
+Multiple I/O errors after transaction open are handled.
+This is effectively what happens if a peer disconnects in the middle
+of a transaction.
+
+  $ hg init ioerror-multiple
+  $ cd ioerror-multiple
+  $ echo 0 > foo
+  $ hg -q commit -A -m initial
+  warn during pretxncommit
+  warn during pretxnclose
+  warn during txnclose
+
+  $ echo 1 > foo
+
+  $ hg --config ui.ioerrors=pretxncommit,pretxnclose,txnclose,txnabort,msgabort,msgrollback commit -m 'multiple errors'
+  error: pretxncommit.badui hook raised an exception: [Errno *] simulated epipe (glob)
+  abort: simulated ebadf
+  *: DeprecationWarning: use lock.release instead of del lock (glob)
+    return -1
+  [255]
+
+  $ hg verify
+  abandoned transaction found - run hg recover
+  checking changesets
+  checking manifests
+   manifest@?: rev 1 points to nonexistent changeset 1
+   manifest@?: 94e0ee43dbfe not in changesets
+  crosschecking files in changesets and manifests
+  checking files
+   foo@?: rev 1 points to nonexistent changeset 1
+   (expected 0)
+  1 files, 1 changesets, 2 total revisions
+  1 warnings encountered!
+  3 integrity errors encountered!
+  [1]
+
+  $ cd ..