hgweb.cgi

cmdutil: apply dirstate.normallookup on (maybe partially) committed files

To detect change of a file without redundant comparison of file
content, dirstate recognizes a file as certainly clean, if:

  (1) it is already known as "normal",
  (2) dirstate entry for it has valid (= not "-1") timestamp, and
  (3) mode, size and timestamp of it on the filesystem are as same as
      ones expected in dirstate

This works as expected in many cases, but doesn't in the corner case
that changing a file keeps mode, size and timestamp of it on the
filesystem.

The timetable below shows steps in one of typical such situations:

  ---- ----------------------------------- ----------------
                                           timestamp of "f"
                                           ----------------
                                           dirstate   file-
  time          action                     mem  file  system
  ---- ----------------------------------- ---- ----- -----
  N                                              ***   ***
       - change "f"                                     N

       - execute 'hg commit -i'
         - backup "f" with timestamp N
         - revert "f" by 'merge.update()'               N
           with 'partially'
         - apply selected hunks                         N
           by 'patch.patch()'

         - 'repo.commit()'
           - 'dirstate.normal("f")'         N
  N+1
           - 'dirstate.write()'             N    N

         - restore "f"                                  N+1
         - restore timestamp of "f"                     N

       - 'hg status' shows "f" as "clean"   N    N      N
  ---- ----------------------------------- ---- ----- -----

The most important point is that 'dirstate.write()' is executed at N+1
or later. This causes writing dirstate timestamp N of "f" out
successfully. If it is executed at N, 'parsers.pack_dirstate()'
replaces timestamp N with "-1" before actual writing dirstate out.

This issue can occur when 'hg commit -i' satisfies conditions below:

  - the file is committed partially, and
  - mode and size of the file aren't changed before and after committing

The root cause of this issue is that (maybe partially changed) files
are restored with original timestamp but dirstate isn't updated for
them.

To detect changes of files correctly, this patch applies
'dirstate.normallookup()' on restored files. Status check is needed
before 'dirstate.normallookup()', because status other than "n(ormal)"
should be kept at failure of committing.

This patch doesn't examine whether each files are committed fully or
partially, because interactive hunk selection makes it difficult.

After this change, timetable is changed as below:

  ---- ----------------------------------- ----------------
                                           timestamp of "f"
                                           ----------------
                                           dirstate   file-
  time          action                     mem  file  system
  ---- ----------------------------------- ---- ----- -----
  N                                              ***   ***
       - change "f"                                     N

       - execute 'hg commit -i'
         - backup "f" with timestamp N
         - revert "f" by 'merge.update()'               N
           with 'partially'
         - apply selected hunks                         N
           by 'patch.internalpatch()'

         - 'repo.commit()'
           - 'dirstate.normal("f")'         N
  N+1
           - 'dirstate.write()'             N    N

         - restore "f"                                  N+1
         - restore timestamp of "f"                     N
       ----------------------------------- ---- ----- -----
         - normallookup("f")                -1
         - release wlock
           - 'dirstate.write()'             -1   -1     N
       ----------------------------------- ---- ----- -----

       - 'hg status' shows "f" as "clean"   -1   -1     N
  ---- ----------------------------------- ---- ----- -----

To reproduce this issue in tests certainly, this patch emulates some
timing critical actions as below:

  - change "f" at N

    'touch -t 200001010000' before command invocation changes mtime of
    "f" to "2000-01-01 00:00" (= N).

  - apply selected hunks at N

    'patch.internalpatch()' with 'fakepatchtime.py' explicitly changes
    mtime of patched files to "2000-01-01 00:00" (= N).

  - 'dirstate.write()' at N+1 (or "not at N")

    'pack_dirstate()' uses actual timestamp at runtime as "now", and
    it should be different from the "2000-01-01 00:00" of "f".

BTW, in 'test-commit-interactive.t', files are sometimes treated as
modified , even though they are just committed fully via 'hg commit
-i' and 'hg diff' shows nothing for them.

Enabling win32text causes EOL style mismatching below:

  - files are changed in LF style EOL

    => files restored after committing uses LF style EOL (1)

  - 'merge.update()' reverts files in CRLF style EOL
  - 'patch.internalpatch()' changes files in CRLF style EOL

    => 'dirstate.normal()' via 'repo.commit()' uses the size of files
       in CRLF style EOL (2)

Therefore, fully committed files are treated as "modified", because
'lstat()' returns size of (1) restored files in LF style EOL, but
dirstate expects size of (2) committed files in CRLF style EOL.

After this patch, 'dirstate.normallookup()' on committed files forces
subsequent 'hg status' to examine changes exactly, and fully committed
files are treated as clean as expected.

This is reason why this patch also does:

  - add some 'hg status' checking status of fully committed files
  - clear win32text configuration before size/timestamp sensitive examination

#!/usr/bin/env python
#
# An example hgweb CGI script, edit as necessary
# See also http://mercurial.selenic.com/wiki/PublishingRepositories

# Path to repo or hgweb config to serve (see 'hg help hgweb')
config = "/path/to/repo/or/config"

# Uncomment and adjust if Mercurial is not installed system-wide
# (consult "installed modules" path from 'hg debuginstall'):
#import sys; sys.path.insert(0, "/path/to/python/lib")

# Uncomment to send python tracebacks to the browser if an error occurs:
#import cgitb; cgitb.enable()

from mercurial import demandimport; demandimport.enable()
from mercurial.hgweb import hgweb, wsgicgi
application = hgweb(config)
wsgicgi.launch(application)