dirstate: explain why appending instead of os.path.join() is safe

mercurial/dirstate.py

@@ -1,601 +1,602 b''
 """
 dirstate.py - working directory tracking for mercurial
 
 Copyright 2005-2007 Matt Mackall <[e-mail]>
 
 This software may be used and distributed according to the terms
 of the GNU General Public License, incorporated herein by reference.
 """
 
 from node import nullid
 from i18n import _
 import struct, os, bisect, stat, util, errno, ignore
 import cStringIO, osutil, sys
 
 _unknown = ('?', 0, 0, 0)
 _format = ">cllll"
 
 def _finddirs(path):
     pos = len(path)
     while 1:
         pos = path.rfind('/', 0, pos)
         if pos == -1:
             break
         yield path[:pos]
 
 class dirstate(object):
 
     def __init__(self, opener, ui, root):
         self._opener = opener
         self._root = root
         self._rootdir = os.path.join(root, '')
         self._dirty = False
         self._dirtypl = False
         self._ui = ui
 
     def __getattr__(self, name):
         if name == '_map':
             self._read()
             return self._map
         elif name == '_copymap':
             self._read()
             return self._copymap
         elif name == '_foldmap':
             _foldmap = {}
             for name in self._map:
                 norm = os.path.normcase(os.path.normpath(name))
                 _foldmap[norm] = name
             self._foldmap = _foldmap
             return self._foldmap
         elif name == '_branch':
             try:
                 self._branch = (self._opener("branch").read().strip()
                                 or "default")
             except IOError:
                 self._branch = "default"
             return self._branch
         elif name == '_pl':
             self._pl = [nullid, nullid]
             try:
                 st = self._opener("dirstate").read(40)
                 if len(st) == 40:
                     self._pl = st[:20], st[20:40]
             except IOError, err:
                 if err.errno != errno.ENOENT: raise
             return self._pl
         elif name == '_dirs':
             dirs = {}
             for f,s in self._map.items():
                 if s[0] != 'r':
                     for base in _finddirs(f):
                         dirs[base] = dirs.get(base, 0) + 1
             self._dirs = dirs
             return self._dirs
         elif name == '_ignore':
             files = [self._join('.hgignore')]
             for name, path in self._ui.configitems("ui"):
                 if name == 'ignore' or name.startswith('ignore.'):
                     files.append(os.path.expanduser(path))
             self._ignore = ignore.ignore(self._root, files, self._ui.warn)
             return self._ignore
         elif name == '_slash':
             self._slash = self._ui.configbool('ui', 'slash') and os.sep != '/'
             return self._slash
         elif name == '_checklink':
             self._checklink = util.checklink(self._root)
             return self._checklink
         elif name == '_checkexec':
             self._checkexec = util.checkexec(self._root)
             return self._checkexec
         elif name == '_checkcase':
             self._checkcase = not util.checkcase(self._join('.hg'))
             return self._checkcase
         elif name == 'normalize':
             if self._checkcase:
                 self.normalize = self._normalize
             else:
                 self.normalize = lambda x: x
             return self.normalize
         else:
             raise AttributeError, name
 
     def _join(self, f):
         # much faster than os.path.join()
+        # it's safe because f is always a relative path
         return self._rootdir + f
 
     def flagfunc(self, fallback):
         if self._checklink:
             if self._checkexec:
                 def f(x):
                     p = self._join(x)
                     if os.path.islink(p):
                         return 'l'
                     if util.is_exec(p):
                         return 'x'
                     return ''
                 return f
             def f(x):
                 if os.path.islink(self._join(x)):
                     return 'l'
                 if 'x' in fallback(x):
                     return 'x'
                 return ''
             return f
         if self._checkexec:
             def f(x):
                 if 'l' in fallback(x):
                     return 'l'
                 if util.is_exec(self._join(x)):
                     return 'x'
                 return ''
             return f
         return fallback
 
     def getcwd(self):
         cwd = os.getcwd()
         if cwd == self._root: return ''
         # self._root ends with a path separator if self._root is '/' or 'C:\'
         rootsep = self._root
         if not util.endswithsep(rootsep):
             rootsep += os.sep
         if cwd.startswith(rootsep):
             return cwd[len(rootsep):]
         else:
             # we're outside the repo. return an absolute path.
             return cwd
 
     def pathto(self, f, cwd=None):
         if cwd is None:
             cwd = self.getcwd()
         path = util.pathto(self._root, cwd, f)
         if self._slash:
             return util.normpath(path)
         return path
 
     def __getitem__(self, key):
         ''' current states:
         n  normal
         m  needs merging
         r  marked for removal
         a  marked for addition
         ?  not tracked'''
         return self._map.get(key, ("?",))[0]
 
     def __contains__(self, key):
         return key in self._map
 
     def __iter__(self):
         for x in util.sort(self._map):
             yield x
 
     def parents(self):
         return self._pl
 
     def branch(self):
         return self._branch
 
     def setparents(self, p1, p2=nullid):
         self._dirty = self._dirtypl = True
         self._pl = p1, p2
 
     def setbranch(self, branch):
         self._branch = branch
         self._opener("branch", "w").write(branch + '\n')
 
     def _read(self):
         self._map = {}
         self._copymap = {}
         if not self._dirtypl:
             self._pl = [nullid, nullid]
         try:
             st = self._opener("dirstate").read()
         except IOError, err:
             if err.errno != errno.ENOENT: raise
             return
         if not st:
             return
 
         if not self._dirtypl:
             self._pl = [st[:20], st[20: 40]]
 
         # deref fields so they will be local in loop
         dmap = self._map
         copymap = self._copymap
         unpack = struct.unpack
         e_size = struct.calcsize(_format)
         pos1 = 40
         l = len(st)
 
         # the inner loop
         while pos1 < l:
             pos2 = pos1 + e_size
             e = unpack(">cllll", st[pos1:pos2]) # a literal here is faster
             pos1 = pos2 + e[4]
             f = st[pos2:pos1]
             if '\0' in f:
                 f, c = f.split('\0')
                 copymap[f] = c
             dmap[f] = e # we hold onto e[4] because making a subtuple is slow
 
     def invalidate(self):
         for a in "_map _copymap _foldmap _branch _pl _dirs _ignore".split():
             if a in self.__dict__:
                 delattr(self, a)
         self._dirty = False
 
     def copy(self, source, dest):
         if source == dest:
             return
         self._dirty = True
         self._copymap[dest] = source
 
     def copied(self, file):
         return self._copymap.get(file, None)
 
     def copies(self):
         return self._copymap
 
     def _droppath(self, f):
         if self[f] not in "?r" and "_dirs" in self.__dict__:
             dirs = self._dirs
             for base in _finddirs(f):
                 if dirs[base] == 1:
                     del dirs[base]
                 else:
                     dirs[base] -= 1
 
     def _addpath(self, f, check=False):
         oldstate = self[f]
         if check or oldstate == "r":
             if '\r' in f or '\n' in f:
                 raise util.Abort(
                     _("'\\n' and '\\r' disallowed in filenames: %r") % f)
             if f in self._dirs:
                 raise util.Abort(_('directory %r already in dirstate') % f)
             # shadows
             for d in _finddirs(f):
                 if d in self._dirs:
                     break
                 if d in self._map and self[d] != 'r':
                     raise util.Abort(
                         _('file %r in dirstate clashes with %r') % (d, f))
         if oldstate in "?r" and "_dirs" in self.__dict__:
             dirs = self._dirs
             for base in _finddirs(f):
                 dirs[base] = dirs.get(base, 0) + 1
 
     def normal(self, f):
         'mark a file normal and clean'
         self._dirty = True
         self._addpath(f)
         s = os.lstat(self._join(f))
         self._map[f] = ('n', s.st_mode, s.st_size, s.st_mtime, 0)
         if f in self._copymap:
             del self._copymap[f]
 
     def normallookup(self, f):
         'mark a file normal, but possibly dirty'
         if self._pl[1] != nullid and f in self._map:
             # if there is a merge going on and the file was either
             # in state 'm' or dirty before being removed, restore that state.
             entry = self._map[f]
             if entry[0] == 'r' and entry[2] in (-1, -2):
                 source = self._copymap.get(f)
                 if entry[2] == -1:
                     self.merge(f)
                 elif entry[2] == -2:
                     self.normaldirty(f)
                 if source:
                     self.copy(source, f)
                 return
             if entry[0] == 'm' or entry[0] == 'n' and entry[2] == -2:
                 return
         self._dirty = True
         self._addpath(f)
         self._map[f] = ('n', 0, -1, -1, 0)
         if f in self._copymap:
             del self._copymap[f]
 
     def normaldirty(self, f):
         'mark a file normal, but dirty'
         self._dirty = True
         self._addpath(f)
         self._map[f] = ('n', 0, -2, -1, 0)
         if f in self._copymap:
             del self._copymap[f]
 
     def add(self, f):
         'mark a file added'
         self._dirty = True
         self._addpath(f, True)
         self._map[f] = ('a', 0, -1, -1, 0)
         if f in self._copymap:
             del self._copymap[f]
 
     def remove(self, f):
         'mark a file removed'
         self._dirty = True
         self._droppath(f)
         size = 0
         if self._pl[1] != nullid and f in self._map:
             entry = self._map[f]
             if entry[0] == 'm':
                 size = -1
             elif entry[0] == 'n' and entry[2] == -2:
                 size = -2
         self._map[f] = ('r', 0, size, 0, 0)
         if size == 0 and f in self._copymap:
             del self._copymap[f]
 
     def merge(self, f):
         'mark a file merged'
         self._dirty = True
         s = os.lstat(self._join(f))
         self._addpath(f)
         self._map[f] = ('m', s.st_mode, s.st_size, s.st_mtime, 0)
         if f in self._copymap:
             del self._copymap[f]
 
     def forget(self, f):
         'forget a file'
         self._dirty = True
         try:
             self._droppath(f)
             del self._map[f]
         except KeyError:
             self._ui.warn(_("not in dirstate: %s\n") % f)
 
     def _normalize(self, path):
         if path not in self._foldmap:
             if not os.path.exists(path):
                 return path
             self._foldmap[path] = util.fspath(path, self._root)
         return self._foldmap[path]
 
     def clear(self):
         self._map = {}
         if "_dirs" in self.__dict__:
             delattr(self, "_dirs");
         self._copymap = {}
         self._pl = [nullid, nullid]
         self._dirty = True
 
     def rebuild(self, parent, files):
         self.clear()
         for f in files:
             if 'x' in files.flags(f):
                 self._map[f] = ('n', 0777, -1, 0, 0)
             else:
                 self._map[f] = ('n', 0666, -1, 0, 0)
         self._pl = (parent, nullid)
         self._dirty = True
 
     def write(self):
         if not self._dirty:
             return
         st = self._opener("dirstate", "w", atomictemp=True)
 
         try:
             gran = int(self._ui.config('dirstate', 'granularity', 1))
         except ValueError:
             gran = 1
         limit = sys.maxint
         if gran > 0:
             limit = util.fstat(st).st_mtime - gran
 
         cs = cStringIO.StringIO()
         copymap = self._copymap
         pack = struct.pack
         write = cs.write
         write("".join(self._pl))
         for f, e in self._map.iteritems():
             if f in copymap:
                 f = "%s\0%s" % (f, copymap[f])
             if e[3] > limit and e[0] == 'n':
                 e = (e[0], 0, -1, -1, 0)
             e = pack(_format, e[0], e[1], e[2], e[3], len(f))
             write(e)
             write(f)
         st.write(cs.getvalue())
         st.rename()
         self._dirty = self._dirtypl = False
 
     def _dirignore(self, f):
         if f == '.':
             return False
         if self._ignore(f):
             return True
         for p in _finddirs(f):
             if self._ignore(p):
                 return True
         return False
 
     def walk(self, match, unknown, ignored):
         '''
         walk recursively through the directory tree, finding all files
         matched by the match function
 
         results are yielded in a tuple (filename, stat), where stat
         and st is the stat result if the file was found in the directory.
         '''
 
         def fwarn(f, msg):
             self._ui.warn('%s: %s\n' % (self.pathto(ff), msg))
             return False
         badfn = fwarn
         if hasattr(match, 'bad'):
             badfn = match.bad
 
         def badtype(f, mode):
             kind = 'unknown'
             if stat.S_ISCHR(mode): kind = _('character device')
             elif stat.S_ISBLK(mode): kind = _('block device')
             elif stat.S_ISFIFO(mode): kind = _('fifo')
             elif stat.S_ISSOCK(mode): kind = _('socket')
             elif stat.S_ISDIR(mode): kind = _('directory')
             self._ui.warn(_('%s: unsupported file type (type is %s)\n')
                           % (self.pathto(f), kind))
 
         ignore = self._ignore
         dirignore = self._dirignore
         if ignored:
             ignore = util.never
             dirignore = util.never
         elif not unknown:
             # if unknown and ignored are False, skip step 2
             ignore = util.always
             dirignore = util.always
 
         matchfn = match.matchfn
         dmap = self._map
         normpath = util.normpath
         normalize = self.normalize
         listdir = osutil.listdir
         lstat = os.lstat
         bisect_left = bisect.bisect_left
         pconvert = util.pconvert
         getkind = stat.S_IFMT
         dirkind = stat.S_IFDIR
         regkind = stat.S_IFREG
         lnkkind = stat.S_IFLNK
         join = self._join
         work = []
         wadd = work.append
 
         files = util.unique(match.files())
         if not files or '.' in files:
             files = ['']
         results = {'.hg': None}
 
         # step 1: find all explicit files
         for ff in util.sort(files):
             nf = normalize(normpath(ff))
             if nf in results:
                 continue
 
             try:
                 st = lstat(join(nf))
                 kind = getkind(st.st_mode)
                 if kind == dirkind:
                     if not dirignore(nf):
                         wadd(nf)
                 elif kind == regkind or kind == lnkkind:
                     results[nf] = st
                 else:
                     badtype(ff, kind)
                     if nf in dmap:
                         results[nf] = None
             except OSError, inst:
                 keep = False
                 prefix = nf + "/"
                 for fn in dmap:
                     if nf == fn or fn.startswith(prefix):
                         keep = True
                         break
                 if not keep:
                     if inst.errno != errno.ENOENT:
                         fwarn(ff, inst.strerror)
                     elif badfn(ff, inst.strerror):
                         if (nf in dmap or not ignore(nf)) and matchfn(nf):
                             results[nf] = None
 
         # step 2: visit subdirectories
         while work:
             nd = work.pop()
             if hasattr(match, 'dir'):
                 match.dir(nd)
             entries = listdir(join(nd), stat=True)
             if nd == '.':
                 nd = ''
             else:
                 # do not recurse into a repo contained in this
                 # one. use bisect to find .hg directory so speed
                 # is good on big directory.
                 hg = bisect_left(entries, ('.hg'))
                 if hg < len(entries) and entries[hg][0] == '.hg' \
                         and entries[hg][1] == dirkind:
                         continue
             for f, kind, st in entries:
                 nf = normalize(nd and (nd + "/" + f) or f)
                 if nf not in results:
                     if kind == dirkind:
                         if not ignore(nf):
                             wadd(nf)
                         if nf in dmap and matchfn(nf):
                             results[nf] = None
                     elif kind == regkind or kind == lnkkind:
                         if nf in dmap:
                             if matchfn(nf):
                                 results[nf] = st
                         elif matchfn(nf) and not ignore(nf):
                             results[nf] = st
                     elif nf in dmap and matchfn(nf):
                         results[nf] = None
 
         # step 3: report unseen items in the dmap hash
         visit = [f for f in dmap if f not in results and match(f)]
         for nf in util.sort(visit):
             results[nf] = None
             try:
                 st = lstat(join(nf))
                 kind = getkind(st.st_mode)
                 if kind == regkind or kind == lnkkind:
                     results[nf] = st
             except OSError, inst:
                 if inst.errno not in (errno.ENOENT, errno.ENOTDIR):
                     raise
 
         del results['.hg']
         return results
 
     def status(self, match, ignored, clean, unknown):
         listignored, listclean, listunknown = ignored, clean, unknown
         lookup, modified, added, unknown, ignored = [], [], [], [], []
         removed, deleted, clean = [], [], []
 
         _join = self._join
         lstat = os.lstat
         cmap = self._copymap
         dmap = self._map
         ladd = lookup.append
         madd = modified.append
         aadd = added.append
         uadd = unknown.append
         iadd = ignored.append
         radd = removed.append
         dadd = deleted.append
         cadd = clean.append
 
         for fn, st in self.walk(match, listunknown, listignored).iteritems():
             if fn not in dmap:
                 if (listignored or match.exact(fn)) and self._dirignore(fn):
                     if listignored:
                         iadd(fn)
                 elif listunknown:
                     uadd(fn)
                 continue
 
             state, mode, size, time, foo = dmap[fn]
 
             if not st and state in "nma":
                 dadd(fn)
             elif state == 'n':
                 if (size >= 0 and
                     (size != st.st_size
                      or ((mode ^ st.st_mode) & 0100 and self._checkexec))
                     or size == -2
                     or fn in self._copymap):
                     madd(fn)
                 elif time != int(st.st_mtime):
                     ladd(fn)
                 elif listclean:
                     cadd(fn)
             elif state == 'm':
                 madd(fn)
             elif state == 'a':
                 aadd(fn)
             elif state == 'r':
                 radd(fn)
 
         return (lookup, modified, added, removed, deleted, unknown, ignored,
                 clean)