Created a class in util called chunkbuffer that buffers reads from an

iterator over strings (aka chunks).

Also added to util (for future use) is a generator function that
iterates over a file n bytes at a time.

Lastly, localrepo was changed to use this new chunkbuffer class when
reading changegroups form the local repository.

mercurial/localrepo.py

@@ -1,1404 +1,1390 b''
 # localrepo.py - read/write repository class for mercurial
 #
 # Copyright 2005 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.
 
 import struct, os, util
 import filelog, manifest, changelog, dirstate, repo
 from node import *
 from demandload import *
 demandload(globals(), "re lock transaction tempfile stat mdiff")
 
 class localrepository:
     def __init__(self, ui, path=None, create=0):
         if not path:
             p = os.getcwd()
             while not os.path.isdir(os.path.join(p, ".hg")):
                 oldp = p
                 p = os.path.dirname(p)
                 if p == oldp: raise repo.RepoError("no repo found")
             path = p
         self.path = os.path.join(path, ".hg")
 
         if not create and not os.path.isdir(self.path):
             raise repo.RepoError("repository %s not found" % self.path)
 
         self.root = os.path.abspath(path)
         self.ui = ui
         self.opener = util.opener(self.path)
         self.wopener = util.opener(self.root)
         self.manifest = manifest.manifest(self.opener)
         self.changelog = changelog.changelog(self.opener)
         self.tagscache = None
         self.nodetagscache = None
 
         if create:
             os.mkdir(self.path)
             os.mkdir(self.join("data"))
             f = self.opener("hgrc", "w")
             f.write("[web]\n")
             f.write("contact = %s\n" % ui.shortuser(ui.username()))
 
         self.dirstate = dirstate.dirstate(self.opener, ui, self.root)
         try:
             self.ui.readconfig(self.opener("hgrc"))
         except IOError: pass
 
     def hook(self, name, **args):
         s = self.ui.config("hooks", name)
         if s:
             self.ui.note("running hook %s: %s\n" % (name, s))
             old = {}
             for k, v in args.items():
                 k = k.upper()
                 old[k] = os.environ.get(k, None)
                 os.environ[k] = v
 
             r = os.system(s)
 
             for k, v in old.items():
                 if v != None:
                     os.environ[k] = v
                 else:
                     del os.environ[k]
 
             if r:
                 self.ui.warn("abort: %s hook failed with status %d!\n" %
                              (name, r))
                 return False
         return True
 
     def tags(self):
         '''return a mapping of tag to node'''
         if not self.tagscache:
             self.tagscache = {}
             def addtag(self, k, n):
                 try:
                     bin_n = bin(n)
                 except TypeError:
                     bin_n = ''
                 self.tagscache[k.strip()] = bin_n
 
             try:
                 # read each head of the tags file, ending with the tip
                 # and add each tag found to the map, with "newer" ones
                 # taking precedence
                 fl = self.file(".hgtags")
                 h = fl.heads()
                 h.reverse()
                 for r in h:
                     for l in fl.read(r).splitlines():
                         if l:
                             n, k = l.split(" ", 1)
                             addtag(self, k, n)
             except KeyError:
                 pass
 
             try:
                 f = self.opener("localtags")
                 for l in f:
                     n, k = l.split(" ", 1)
                     addtag(self, k, n)
             except IOError:
                 pass
 
             self.tagscache['tip'] = self.changelog.tip()
 
         return self.tagscache
 
     def tagslist(self):
         '''return a list of tags ordered by revision'''
         l = []
         for t, n in self.tags().items():
             try:
                 r = self.changelog.rev(n)
             except:
                 r = -2 # sort to the beginning of the list if unknown
             l.append((r,t,n))
         l.sort()
         return [(t,n) for r,t,n in l]
 
     def nodetags(self, node):
         '''return the tags associated with a node'''
         if not self.nodetagscache:
             self.nodetagscache = {}
             for t,n in self.tags().items():
                 self.nodetagscache.setdefault(n,[]).append(t)
         return self.nodetagscache.get(node, [])
 
     def lookup(self, key):
         try:
             return self.tags()[key]
         except KeyError:
             try:
                 return self.changelog.lookup(key)
             except:
                 raise repo.RepoError("unknown revision '%s'" % key)
 
     def dev(self):
         return os.stat(self.path).st_dev
 
     def local(self):
         return True
 
     def join(self, f):
         return os.path.join(self.path, f)
 
     def wjoin(self, f):
         return os.path.join(self.root, f)
 
     def file(self, f):
         if f[0] == '/': f = f[1:]
         return filelog.filelog(self.opener, f)
 
     def getcwd(self):
         return self.dirstate.getcwd()
 
     def wfile(self, f, mode='r'):
         return self.wopener(f, mode)
 
     def wread(self, filename):
         return self.wopener(filename, 'r').read()
 
     def wwrite(self, filename, data, fd=None):
         if fd:
             return fd.write(data)
         return self.wopener(filename, 'w').write(data)
 
     def transaction(self):
         # save dirstate for undo
         try:
             ds = self.opener("dirstate").read()
         except IOError:
             ds = ""
         self.opener("journal.dirstate", "w").write(ds)
 
         def after():
             util.rename(self.join("journal"), self.join("undo"))
             util.rename(self.join("journal.dirstate"),
                         self.join("undo.dirstate"))
 
         return transaction.transaction(self.ui.warn, self.opener,
                                        self.join("journal"), after)
 
     def recover(self):
         lock = self.lock()
         if os.path.exists(self.join("journal")):
             self.ui.status("rolling back interrupted transaction\n")
             return transaction.rollback(self.opener, self.join("journal"))
         else:
             self.ui.warn("no interrupted transaction available\n")
 
     def undo(self):
         lock = self.lock()
         if os.path.exists(self.join("undo")):
             self.ui.status("rolling back last transaction\n")
             transaction.rollback(self.opener, self.join("undo"))
             self.dirstate = None
             util.rename(self.join("undo.dirstate"), self.join("dirstate"))
             self.dirstate = dirstate.dirstate(self.opener, self.ui, self.root)
         else:
             self.ui.warn("no undo information available\n")
 
     def lock(self, wait=1):
         try:
             return lock.lock(self.join("lock"), 0)
         except lock.LockHeld, inst:
             if wait:
                 self.ui.warn("waiting for lock held by %s\n" % inst.args[0])
                 return lock.lock(self.join("lock"), wait)
             raise inst
 
     def rawcommit(self, files, text, user, date, p1=None, p2=None):
         orig_parent = self.dirstate.parents()[0] or nullid
         p1 = p1 or self.dirstate.parents()[0] or nullid
         p2 = p2 or self.dirstate.parents()[1] or nullid
         c1 = self.changelog.read(p1)
         c2 = self.changelog.read(p2)
         m1 = self.manifest.read(c1[0])
         mf1 = self.manifest.readflags(c1[0])
         m2 = self.manifest.read(c2[0])
         changed = []
 
         if orig_parent == p1:
             update_dirstate = 1
         else:
             update_dirstate = 0
 
         tr = self.transaction()
         mm = m1.copy()
         mfm = mf1.copy()
         linkrev = self.changelog.count()
         for f in files:
             try:
                 t = self.wread(f)
                 tm = util.is_exec(self.wjoin(f), mfm.get(f, False))
                 r = self.file(f)
                 mfm[f] = tm
 
                 fp1 = m1.get(f, nullid)
                 fp2 = m2.get(f, nullid)
 
                 # is the same revision on two branches of a merge?
                 if fp2 == fp1:
                     fp2 = nullid
 
                 if fp2 != nullid:
                     # is one parent an ancestor of the other?
                     fpa = r.ancestor(fp1, fp2)
                     if fpa == fp1:
                         fp1, fp2 = fp2, nullid
                     elif fpa == fp2:
                         fp2 = nullid
 
                     # is the file unmodified from the parent?
                     if t == r.read(fp1):
                         # record the proper existing parent in manifest
                         # no need to add a revision
                         mm[f] = fp1
                         continue
 
                 mm[f] = r.add(t, {}, tr, linkrev, fp1, fp2)
                 changed.append(f)
                 if update_dirstate:
                     self.dirstate.update([f], "n")
             except IOError:
                 try:
                     del mm[f]
                     del mfm[f]
                     if update_dirstate:
                         self.dirstate.forget([f])
                 except:
                     # deleted from p2?
                     pass
 
         mnode = self.manifest.add(mm, mfm, tr, linkrev, c1[0], c2[0])
         user = user or self.ui.username()
         n = self.changelog.add(mnode, changed, text, tr, p1, p2, user, date)
         tr.close()
         if update_dirstate:
             self.dirstate.setparents(n, nullid)
 
     def commit(self, files = None, text = "", user = None, date = None,
                match = util.always, force=False):
         commit = []
         remove = []
         changed = []
 
         if files:
             for f in files:
                 s = self.dirstate.state(f)
                 if s in 'nmai':
                     commit.append(f)
                 elif s == 'r':
                     remove.append(f)
                 else:
                     self.ui.warn("%s not tracked!\n" % f)
         else:
             (c, a, d, u) = self.changes(match=match)
             commit = c + a
             remove = d
 
         p1, p2 = self.dirstate.parents()
         c1 = self.changelog.read(p1)
         c2 = self.changelog.read(p2)
         m1 = self.manifest.read(c1[0])
         mf1 = self.manifest.readflags(c1[0])
         m2 = self.manifest.read(c2[0])
 
         if not commit and not remove and not force and p2 == nullid:
             self.ui.status("nothing changed\n")
             return None
 
         if not self.hook("precommit"):
             return None
 
         lock = self.lock()
         tr = self.transaction()
 
         # check in files
         new = {}
         linkrev = self.changelog.count()
         commit.sort()
         for f in commit:
             self.ui.note(f + "\n")
             try:
                 mf1[f] = util.is_exec(self.wjoin(f), mf1.get(f, False))
                 t = self.wread(f)
             except IOError:
                 self.ui.warn("trouble committing %s!\n" % f)
                 raise
 
             r = self.file(f)
 
             meta = {}
             cp = self.dirstate.copied(f)
             if cp:
                 meta["copy"] = cp
                 meta["copyrev"] = hex(m1.get(cp, m2.get(cp, nullid)))
                 self.ui.debug(" %s: copy %s:%s\n" % (f, cp, meta["copyrev"]))
                 fp1, fp2 = nullid, nullid
             else:
                 fp1 = m1.get(f, nullid)
                 fp2 = m2.get(f, nullid)
 
             # is the same revision on two branches of a merge?
             if fp2 == fp1:
                 fp2 = nullid
 
             if fp2 != nullid:
                 # is one parent an ancestor of the other?
                 fpa = r.ancestor(fp1, fp2)
                 if fpa == fp1:
                     fp1, fp2 = fp2, nullid
                 elif fpa == fp2:
                     fp2 = nullid
 
                 # is the file unmodified from the parent?
                 if not meta and t == r.read(fp1):
                     # record the proper existing parent in manifest
                     # no need to add a revision
                     new[f] = fp1
                     continue
 
             new[f] = r.add(t, meta, tr, linkrev, fp1, fp2)
             # remember what we've added so that we can later calculate
             # the files to pull from a set of changesets
             changed.append(f)
 
         # update manifest
         m1.update(new)
         for f in remove:
             if f in m1:
                 del m1[f]
         mn = self.manifest.add(m1, mf1, tr, linkrev, c1[0], c2[0],
                                (new, remove))
 
         # add changeset
         new = new.keys()
         new.sort()
 
         if not text:
             edittext = ""
             if p2 != nullid:
                 edittext += "HG: branch merge\n"
             edittext += "\n" + "HG: manifest hash %s\n" % hex(mn)
             edittext += "".join(["HG: changed %s\n" % f for f in changed])
             edittext += "".join(["HG: removed %s\n" % f for f in remove])
             if not changed and not remove:
                 edittext += "HG: no files changed\n"
             edittext = self.ui.edit(edittext)
             if not edittext.rstrip():
                 return None
             text = edittext
 
         user = user or self.ui.username()
         n = self.changelog.add(mn, changed, text, tr, p1, p2, user, date)
         tr.close()
 
         self.dirstate.setparents(n)
         self.dirstate.update(new, "n")
         self.dirstate.forget(remove)
 
         if not self.hook("commit", node=hex(n)):
             return None
         return n
 
     def walk(self, node=None, files=[], match=util.always):
         if node:
             for fn in self.manifest.read(self.changelog.read(node)[0]):
                 if match(fn): yield 'm', fn
         else:
             for src, fn in self.dirstate.walk(files, match):
                 yield src, fn
 
     def changes(self, node1 = None, node2 = None, files = [],
                 match = util.always):
         mf2, u = None, []
 
         def fcmp(fn, mf):
             t1 = self.wread(fn)
             t2 = self.file(fn).read(mf.get(fn, nullid))
             return cmp(t1, t2)
 
         def mfmatches(node):
             mf = dict(self.manifest.read(node))
             for fn in mf.keys():
                 if not match(fn):
                     del mf[fn]
             return mf
 
         # are we comparing the working directory?
         if not node2:
             l, c, a, d, u = self.dirstate.changes(files, match)
 
             # are we comparing working dir against its parent?
             if not node1:
                 if l:
                     # do a full compare of any files that might have changed
                     change = self.changelog.read(self.dirstate.parents()[0])
                     mf2 = mfmatches(change[0])
                     for f in l:
                         if fcmp(f, mf2):
                             c.append(f)
 
                 for l in c, a, d, u:
                     l.sort()
 
                 return (c, a, d, u)
 
         # are we comparing working dir against non-tip?
         # generate a pseudo-manifest for the working dir
         if not node2:
             if not mf2:
                 change = self.changelog.read(self.dirstate.parents()[0])
                 mf2 = mfmatches(change[0])
             for f in a + c + l:
                 mf2[f] = ""
             for f in d:
                 if f in mf2: del mf2[f]
         else:
             change = self.changelog.read(node2)
             mf2 = mfmatches(change[0])
 
         # flush lists from dirstate before comparing manifests
         c, a = [], []
 
         change = self.changelog.read(node1)
         mf1 = mfmatches(change[0])
 
         for fn in mf2:
             if mf1.has_key(fn):
                 if mf1[fn] != mf2[fn]:
                     if mf2[fn] != "" or fcmp(fn, mf1):
                         c.append(fn)
                 del mf1[fn]
             else:
                 a.append(fn)
 
         d = mf1.keys()
 
         for l in c, a, d, u:
             l.sort()
 
         return (c, a, d, u)
 
     def add(self, list):
         for f in list:
             p = self.wjoin(f)
             if not os.path.exists(p):
                 self.ui.warn("%s does not exist!\n" % f)
             elif not os.path.isfile(p):
                 self.ui.warn("%s not added: only files supported currently\n" % f)
             elif self.dirstate.state(f) in 'an':
                 self.ui.warn("%s already tracked!\n" % f)
             else:
                 self.dirstate.update([f], "a")
 
     def forget(self, list):
         for f in list:
             if self.dirstate.state(f) not in 'ai':
                 self.ui.warn("%s not added!\n" % f)
             else:
                 self.dirstate.forget([f])
 
     def remove(self, list):
         for f in list:
             p = self.wjoin(f)
             if os.path.exists(p):
                 self.ui.warn("%s still exists!\n" % f)
             elif self.dirstate.state(f) == 'a':
                 self.ui.warn("%s never committed!\n" % f)
                 self.dirstate.forget([f])
             elif f not in self.dirstate:
                 self.ui.warn("%s not tracked!\n" % f)
             else:
                 self.dirstate.update([f], "r")
 
     def copy(self, source, dest):
         p = self.wjoin(dest)
         if not os.path.exists(p):
             self.ui.warn("%s does not exist!\n" % dest)
         elif not os.path.isfile(p):
             self.ui.warn("copy failed: %s is not a file\n" % dest)
         else:
             if self.dirstate.state(dest) == '?':
                 self.dirstate.update([dest], "a")
             self.dirstate.copy(source, dest)
 
     def heads(self):
         return self.changelog.heads()
 
     # branchlookup returns a dict giving a list of branches for
     # each head.  A branch is defined as the tag of a node or
     # the branch of the node's parents.  If a node has multiple
     # branch tags, tags are eliminated if they are visible from other
     # branch tags.
     #
     # So, for this graph:  a->b->c->d->e
     #                       \         /
     #                        aa -----/
     # a has tag 2.6.12
     # d has tag 2.6.13
     # e would have branch tags for 2.6.12 and 2.6.13.  Because the node
     # for 2.6.12 can be reached from the node 2.6.13, that is eliminated
     # from the list.
     #
     # It is possible that more than one head will have the same branch tag.
     # callers need to check the result for multiple heads under the same
     # branch tag if that is a problem for them (ie checkout of a specific
     # branch).
     #
     # passing in a specific branch will limit the depth of the search
     # through the parents.  It won't limit the branches returned in the
     # result though.
     def branchlookup(self, heads=None, branch=None):
         if not heads:
             heads = self.heads()
         headt = [ h for h in heads ]
         chlog = self.changelog
         branches = {}
         merges = []
         seenmerge = {}
 
         # traverse the tree once for each head, recording in the branches
         # dict which tags are visible from this head.  The branches
         # dict also records which tags are visible from each tag
         # while we traverse.
         while headt or merges:
             if merges:
                 n, found = merges.pop()
                 visit = [n]
             else:
                 h = headt.pop()
                 visit = [h]
                 found = [h]
                 seen = {}
             while visit:
                 n = visit.pop()
                 if n in seen:
                     continue
                 pp = chlog.parents(n)
                 tags = self.nodetags(n)
                 if tags:
                     for x in tags:
                         if x == 'tip':
                             continue
                         for f in found:
                             branches.setdefault(f, {})[n] = 1
                         branches.setdefault(n, {})[n] = 1
                         break
                     if n not in found:
                         found.append(n)
                     if branch in tags:
                         continue
                 seen[n] = 1
                 if pp[1] != nullid and n not in seenmerge:
                     merges.append((pp[1], [x for x in found]))
                     seenmerge[n] = 1
                 if pp[0] != nullid:
                     visit.append(pp[0])
         # traverse the branches dict, eliminating branch tags from each
         # head that are visible from another branch tag for that head.
         out = {}
         viscache = {}
         for h in heads:
             def visible(node):
                 if node in viscache:
                     return viscache[node]
                 ret = {}
                 visit = [node]
                 while visit:
                     x = visit.pop()
                     if x in viscache:
                         ret.update(viscache[x])
                     elif x not in ret:
                         ret[x] = 1
                         if x in branches:
                             visit[len(visit):] = branches[x].keys()
                 viscache[node] = ret
                 return ret
             if h not in branches:
                 continue
             # O(n^2), but somewhat limited.  This only searches the
             # tags visible from a specific head, not all the tags in the
             # whole repo.
             for b in branches[h]:
                 vis = False
                 for bb in branches[h].keys():
                     if b != bb:
                         if b in visible(bb):
                             vis = True
                             break
                 if not vis:
                     l = out.setdefault(h, [])
                     l[len(l):] = self.nodetags(b)
         return out
 
     def branches(self, nodes):
         if not nodes: nodes = [self.changelog.tip()]
         b = []
         for n in nodes:
             t = n
             while n:
                 p = self.changelog.parents(n)
                 if p[1] != nullid or p[0] == nullid:
                     b.append((t, n, p[0], p[1]))
                     break
                 n = p[0]
         return b
 
     def between(self, pairs):
         r = []
 
         for top, bottom in pairs:
             n, l, i = top, [], 0
             f = 1
 
             while n != bottom:
                 p = self.changelog.parents(n)[0]
                 if i == f:
                     l.append(n)
                     f = f * 2
                 n = p
                 i += 1
 
             r.append(l)
 
         return r
 
     def newer(self, nodes):
         m = {}
         nl = []
         pm = {}
         cl = self.changelog
         t = l = cl.count()
 
         # find the lowest numbered node
         for n in nodes:
             l = min(l, cl.rev(n))
             m[n] = 1
 
         for i in xrange(l, t):
             n = cl.node(i)
             if n in m: # explicitly listed
                 pm[n] = 1
                 nl.append(n)
                 continue
             for p in cl.parents(n):
                 if p in pm: # parent listed
                     pm[n] = 1
                     nl.append(n)
                     break
 
         return nl
 
     def findincoming(self, remote, base=None, heads=None):
         m = self.changelog.nodemap
         search = []
         fetch = {}
         seen = {}
         seenbranch = {}
         if base == None:
             base = {}
 
         # assume we're closer to the tip than the root
         # and start by examining the heads
         self.ui.status("searching for changes\n")
 
         if not heads:
             heads = remote.heads()
 
         unknown = []
         for h in heads:
             if h not in m:
                 unknown.append(h)
             else:
                 base[h] = 1
 
         if not unknown:
             return None
 
         rep = {}
         reqcnt = 0
 
         # search through remote branches
         # a 'branch' here is a linear segment of history, with four parts:
         # head, root, first parent, second parent
         # (a branch always has two parents (or none) by definition)
         unknown = remote.branches(unknown)
         while unknown:
             r = []
             while unknown:
                 n = unknown.pop(0)
                 if n[0] in seen:
                     continue
 
                 self.ui.debug("examining %s:%s\n" % (short(n[0]), short(n[1])))
                 if n[0] == nullid:
                     break
                 if n in seenbranch:
                     self.ui.debug("branch already found\n")
                     continue
                 if n[1] and n[1] in m: # do we know the base?
                     self.ui.debug("found incomplete branch %s:%s\n"
                                   % (short(n[0]), short(n[1])))
                     search.append(n) # schedule branch range for scanning
                     seenbranch[n] = 1
                 else:
                     if n[1] not in seen and n[1] not in fetch:
                         if n[2] in m and n[3] in m:
                             self.ui.debug("found new changeset %s\n" %
                                           short(n[1]))
                             fetch[n[1]] = 1 # earliest unknown
                             base[n[2]] = 1 # latest known
                             continue
 
                     for a in n[2:4]:
                         if a not in rep:
                             r.append(a)
                             rep[a] = 1
 
                 seen[n[0]] = 1
 
             if r:
                 reqcnt += 1
                 self.ui.debug("request %d: %s\n" %
                             (reqcnt, " ".join(map(short, r))))
                 for p in range(0, len(r), 10):
                     for b in remote.branches(r[p:p+10]):
                         self.ui.debug("received %s:%s\n" %
                                       (short(b[0]), short(b[1])))
                         if b[0] in m:
                             self.ui.debug("found base node %s\n" % short(b[0]))
                             base[b[0]] = 1
                         elif b[0] not in seen:
                             unknown.append(b)
 
         # do binary search on the branches we found
         while search:
             n = search.pop(0)
             reqcnt += 1
             l = remote.between([(n[0], n[1])])[0]
             l.append(n[1])
             p = n[0]
             f = 1
             for i in l:
                 self.ui.debug("narrowing %d:%d %s\n" % (f, len(l), short(i)))
                 if i in m:
                     if f <= 2:
                         self.ui.debug("found new branch changeset %s\n" %
                                           short(p))
                         fetch[p] = 1
                         base[i] = 1
                     else:
                         self.ui.debug("narrowed branch search to %s:%s\n"
                                       % (short(p), short(i)))
                         search.append((p, i))
                     break
                 p, f = i, f * 2
 
         # sanity check our fetch list
         for f in fetch.keys():
             if f in m:
                 raise repo.RepoError("already have changeset " + short(f[:4]))
 
         if base.keys() == [nullid]:
             self.ui.warn("warning: pulling from an unrelated repository!\n")
 
         self.ui.note("found new changesets starting at " +
                      " ".join([short(f) for f in fetch]) + "\n")
 
         self.ui.debug("%d total queries\n" % reqcnt)
 
         return fetch.keys()
 
     def findoutgoing(self, remote, base=None, heads=None):
         if base == None:
             base = {}
             self.findincoming(remote, base, heads)
 
         self.ui.debug("common changesets up to "
                       + " ".join(map(short, base.keys())) + "\n")
 
         remain = dict.fromkeys(self.changelog.nodemap)
 
         # prune everything remote has from the tree
         del remain[nullid]
         remove = base.keys()
         while remove:
             n = remove.pop(0)
             if n in remain:
                 del remain[n]
                 for p in self.changelog.parents(n):
                     remove.append(p)
 
         # find every node whose parents have been pruned
         subset = []
         for n in remain:
             p1, p2 = self.changelog.parents(n)
             if p1 not in remain and p2 not in remain:
                 subset.append(n)
 
         # this is the set of all roots we have to push
         return subset
 
     def pull(self, remote):
         lock = self.lock()
 
         # if we have an empty repo, fetch everything
         if self.changelog.tip() == nullid:
             self.ui.status("requesting all changes\n")
             fetch = [nullid]
         else:
             fetch = self.findincoming(remote)
 
         if not fetch:
             self.ui.status("no changes found\n")
             return 1
 
         cg = remote.changegroup(fetch)
         return self.addchangegroup(cg)
 
     def push(self, remote, force=False):
         lock = remote.lock()
 
         base = {}
         heads = remote.heads()
         inc = self.findincoming(remote, base, heads)
         if not force and inc:
             self.ui.warn("abort: unsynced remote changes!\n")
             self.ui.status("(did you forget to sync? use push -f to force)\n")
             return 1
 
         update = self.findoutgoing(remote, base)
         if not update:
             self.ui.status("no changes found\n")
             return 1
         elif not force:
             if len(heads) < len(self.changelog.heads()):
                 self.ui.warn("abort: push creates new remote branches!\n")
                 self.ui.status("(did you forget to merge?" +
                                " use push -f to force)\n")
                 return 1
 
         cg = self.changegroup(update)
         return remote.addchangegroup(cg)
 
     def changegroup(self, basenodes):
-        class genread:
-            def __init__(self, generator):
-                self.g = generator
-                self.buf = ""
-            def fillbuf(self):
-                self.buf += "".join(self.g)
-
-            def read(self, l):
-                while l > len(self.buf):
-                    try:
-                        self.buf += self.g.next()
-                    except StopIteration:
-                        break
-                d, self.buf = self.buf[:l], self.buf[l:]
-                return d
+        genread = util.chunkbuffer
 
         def gengroup():
             nodes = self.newer(basenodes)
 
             # construct the link map
             linkmap = {}
             for n in nodes:
                 linkmap[self.changelog.rev(n)] = n
 
             # construct a list of all changed files
             changed = {}
             for n in nodes:
                 c = self.changelog.read(n)
                 for f in c[3]:
                     changed[f] = 1
             changed = changed.keys()
             changed.sort()
 
             # the changegroup is changesets + manifests + all file revs
             revs = [ self.changelog.rev(n) for n in nodes ]
 
             for y in self.changelog.group(linkmap): yield y
             for y in self.manifest.group(linkmap): yield y
             for f in changed:
                 yield struct.pack(">l", len(f) + 4) + f
                 g = self.file(f).group(linkmap)
                 for y in g:
                     yield y
 
             yield struct.pack(">l", 0)
 
         return genread(gengroup())
 
     def addchangegroup(self, source):
 
         def getchunk():
             d = source.read(4)
             if not d: return ""
             l = struct.unpack(">l", d)[0]
             if l <= 4: return ""
             return source.read(l - 4)
 
         def getgroup():
             while 1:
                 c = getchunk()
                 if not c: break
                 yield c
 
         def csmap(x):
             self.ui.debug("add changeset %s\n" % short(x))
             return self.changelog.count()
 
         def revmap(x):
             return self.changelog.rev(x)
 
         if not source: return
         changesets = files = revisions = 0
 
         tr = self.transaction()
 
         oldheads = len(self.changelog.heads())
 
         # pull off the changeset group
         self.ui.status("adding changesets\n")
         co = self.changelog.tip()
         cn = self.changelog.addgroup(getgroup(), csmap, tr, 1) # unique
         changesets = self.changelog.rev(cn) - self.changelog.rev(co)
 
         # pull off the manifest group
         self.ui.status("adding manifests\n")
         mm = self.manifest.tip()
         mo = self.manifest.addgroup(getgroup(), revmap, tr)
 
         # process the files
         self.ui.status("adding file changes\n")
         while 1:
             f = getchunk()
             if not f: break
             self.ui.debug("adding %s revisions\n" % f)
             fl = self.file(f)
             o = fl.count()
             n = fl.addgroup(getgroup(), revmap, tr)
             revisions += fl.count() - o
             files += 1
 
         newheads = len(self.changelog.heads())
         heads = ""
         if oldheads and newheads > oldheads:
             heads = " (+%d heads)" % (newheads - oldheads)
 
         self.ui.status(("added %d changesets" +
                         " with %d changes to %d files%s\n")
                        % (changesets, revisions, files, heads))
 
         tr.close()
 
         if not self.hook("changegroup"):
             return 1
 
         return
 
     def update(self, node, allow=False, force=False, choose=None,
                moddirstate=True):
         pl = self.dirstate.parents()
         if not force and pl[1] != nullid:
             self.ui.warn("aborting: outstanding uncommitted merges\n")
             return 1
 
         p1, p2 = pl[0], node
         pa = self.changelog.ancestor(p1, p2)
         m1n = self.changelog.read(p1)[0]
         m2n = self.changelog.read(p2)[0]
         man = self.manifest.ancestor(m1n, m2n)
         m1 = self.manifest.read(m1n)
         mf1 = self.manifest.readflags(m1n)
         m2 = self.manifest.read(m2n)
         mf2 = self.manifest.readflags(m2n)
         ma = self.manifest.read(man)
         mfa = self.manifest.readflags(man)
 
         (c, a, d, u) = self.changes()
 
         # is this a jump, or a merge?  i.e. is there a linear path
         # from p1 to p2?
         linear_path = (pa == p1 or pa == p2)
 
         # resolve the manifest to determine which files
         # we care about merging
         self.ui.note("resolving manifests\n")
         self.ui.debug(" force %s allow %s moddirstate %s linear %s\n" %
                       (force, allow, moddirstate, linear_path))
         self.ui.debug(" ancestor %s local %s remote %s\n" %
                       (short(man), short(m1n), short(m2n)))
 
         merge = {}
         get = {}
         remove = []
 
         # construct a working dir manifest
         mw = m1.copy()
         mfw = mf1.copy()
         umap = dict.fromkeys(u)
 
         for f in a + c + u:
             mw[f] = ""
             mfw[f] = util.is_exec(self.wjoin(f), mfw.get(f, False))
 
         for f in d:
             if f in mw: del mw[f]
 
             # If we're jumping between revisions (as opposed to merging),
             # and if neither the working directory nor the target rev has
             # the file, then we need to remove it from the dirstate, to
             # prevent the dirstate from listing the file when it is no
             # longer in the manifest.
             if moddirstate and linear_path and f not in m2:
                 self.dirstate.forget((f,))
 
         # Compare manifests
         for f, n in mw.iteritems():
             if choose and not choose(f): continue
             if f in m2:
                 s = 0
 
                 # is the wfile new since m1, and match m2?
                 if f not in m1:
                     t1 = self.wread(f)
                     t2 = self.file(f).read(m2[f])
                     if cmp(t1, t2) == 0:
                         n = m2[f]
                     del t1, t2
 
                 # are files different?
                 if n != m2[f]:
                     a = ma.get(f, nullid)
                     # are both different from the ancestor?
                     if n != a and m2[f] != a:
                         self.ui.debug(" %s versions differ, resolve\n" % f)
                         # merge executable bits
                         # "if we changed or they changed, change in merge"
                         a, b, c = mfa.get(f, 0), mfw[f], mf2[f]
                         mode = ((a^b) | (a^c)) ^ a
                         merge[f] = (m1.get(f, nullid), m2[f], mode)
                         s = 1
                     # are we clobbering?
                     # is remote's version newer?
                     # or are we going back in time?
                     elif force or m2[f] != a or (p2 == pa and mw[f] == m1[f]):
                         self.ui.debug(" remote %s is newer, get\n" % f)
                         get[f] = m2[f]
                         s = 1
                 elif f in umap:
                     # this unknown file is the same as the checkout
                     get[f] = m2[f]
 
                 if not s and mfw[f] != mf2[f]:
                     if force:
                         self.ui.debug(" updating permissions for %s\n" % f)
                         util.set_exec(self.wjoin(f), mf2[f])
                     else:
                         a, b, c = mfa.get(f, 0), mfw[f], mf2[f]
                         mode = ((a^b) | (a^c)) ^ a
                         if mode != b:
                             self.ui.debug(" updating permissions for %s\n" % f)
                             util.set_exec(self.wjoin(f), mode)
                 del m2[f]
             elif f in ma:
                 if n != ma[f]:
                     r = "d"
                     if not force and (linear_path or allow):
                         r = self.ui.prompt(
                             (" local changed %s which remote deleted\n" % f) +
                             "(k)eep or (d)elete?", "[kd]", "k")
                     if r == "d":
                         remove.append(f)
                 else:
                     self.ui.debug("other deleted %s\n" % f)
                     remove.append(f) # other deleted it
             else:
                 if n == m1.get(f, nullid): # same as parent
                     if p2 == pa: # going backwards?
                         self.ui.debug("remote deleted %s\n" % f)
                         remove.append(f)
                     else:
                         self.ui.debug("local created %s, keeping\n" % f)
                 else:
                     self.ui.debug("working dir created %s, keeping\n" % f)
 
         for f, n in m2.iteritems():
             if choose and not choose(f): continue
             if f[0] == "/": continue
             if f in ma and n != ma[f]:
                 r = "k"
                 if not force and (linear_path or allow):
                     r = self.ui.prompt(
                         ("remote changed %s which local deleted\n" % f) +
                         "(k)eep or (d)elete?", "[kd]", "k")
                 if r == "k": get[f] = n
             elif f not in ma:
                 self.ui.debug("remote created %s\n" % f)
                 get[f] = n
             else:
                 if force or p2 == pa: # going backwards?
                     self.ui.debug("local deleted %s, recreating\n" % f)
                     get[f] = n
                 else:
                     self.ui.debug("local deleted %s\n" % f)
 
         del mw, m1, m2, ma
 
         if force:
             for f in merge:
                 get[f] = merge[f][1]
             merge = {}
 
         if linear_path or force:
             # we don't need to do any magic, just jump to the new rev
             branch_merge = False
             p1, p2 = p2, nullid
         else:
             if not allow:
                 self.ui.status("this update spans a branch" +
                                " affecting the following files:\n")
                 fl = merge.keys() + get.keys()
                 fl.sort()
                 for f in fl:
                     cf = ""
                     if f in merge: cf = " (resolve)"
                     self.ui.status(" %s%s\n" % (f, cf))
                 self.ui.warn("aborting update spanning branches!\n")
                 self.ui.status("(use update -m to merge across branches" +
                                " or -C to lose changes)\n")
                 return 1
             branch_merge = True
 
         if moddirstate:
             self.dirstate.setparents(p1, p2)
 
         # get the files we don't need to change
         files = get.keys()
         files.sort()
         for f in files:
             if f[0] == "/": continue
             self.ui.note("getting %s\n" % f)
             t = self.file(f).read(get[f])
             try:
                 self.wwrite(f, t)
             except IOError:
                 os.makedirs(os.path.dirname(self.wjoin(f)))
                 self.wwrite(f, t)
             util.set_exec(self.wjoin(f), mf2[f])
             if moddirstate:
                 if branch_merge:
                     self.dirstate.update([f], 'n', st_mtime=-1)
                 else:
                     self.dirstate.update([f], 'n')
 
         # merge the tricky bits
         files = merge.keys()
         files.sort()
         for f in files:
             self.ui.status("merging %s\n" % f)
             my, other, flag = merge[f]
             self.merge3(f, my, other)
             util.set_exec(self.wjoin(f), flag)
             if moddirstate:
                 if branch_merge:
                     # We've done a branch merge, mark this file as merged
                     # so that we properly record the merger later
                     self.dirstate.update([f], 'm')
                 else:
                     # We've update-merged a locally modified file, so
                     # we set the dirstate to emulate a normal checkout
                     # of that file some time in the past. Thus our
                     # merge will appear as a normal local file
                     # modification.
                     f_len = len(self.file(f).read(other))
                     self.dirstate.update([f], 'n', st_size=f_len, st_mtime=-1)
 
         remove.sort()
         for f in remove:
             self.ui.note("removing %s\n" % f)
             try:
                 os.unlink(self.wjoin(f))
             except OSError, inst:
                 self.ui.warn("update failed to remove %s: %s!\n" % (f, inst))
             # try removing directories that might now be empty
             try: os.removedirs(os.path.dirname(self.wjoin(f)))
             except: pass
         if moddirstate:
             if branch_merge:
                 self.dirstate.update(remove, 'r')
             else:
                 self.dirstate.forget(remove)
 
     def merge3(self, fn, my, other):
         """perform a 3-way merge in the working directory"""
 
         def temp(prefix, node):
             pre = "%s~%s." % (os.path.basename(fn), prefix)
             (fd, name) = tempfile.mkstemp("", pre)
             f = os.fdopen(fd, "wb")
             self.wwrite(fn, fl.read(node), f)
             f.close()
             return name
 
         fl = self.file(fn)
         base = fl.ancestor(my, other)
         a = self.wjoin(fn)
         b = temp("base", base)
         c = temp("other", other)
 
         self.ui.note("resolving %s\n" % fn)
         self.ui.debug("file %s: other %s ancestor %s\n" %
                               (fn, short(other), short(base)))
 
         cmd = (os.environ.get("HGMERGE") or self.ui.config("ui", "merge")
                or "hgmerge")
         r = os.system("%s %s %s %s" % (cmd, a, b, c))
         if r:
             self.ui.warn("merging %s failed!\n" % fn)
 
         os.unlink(b)
         os.unlink(c)
 
     def verify(self):
         filelinkrevs = {}
         filenodes = {}
         changesets = revisions = files = 0
         errors = 0
 
         seen = {}
         self.ui.status("checking changesets\n")
         for i in range(self.changelog.count()):
             changesets += 1
             n = self.changelog.node(i)
             if n in seen:
                 self.ui.warn("duplicate changeset at revision %d\n" % i)
                 errors += 1
             seen[n] = 1
 
             for p in self.changelog.parents(n):
                 if p not in self.changelog.nodemap:
                     self.ui.warn("changeset %s has unknown parent %s\n" %
                                  (short(n), short(p)))
                     errors += 1
             try:
                 changes = self.changelog.read(n)
             except Exception, inst:
                 self.ui.warn("unpacking changeset %s: %s\n" % (short(n), inst))
                 errors += 1
 
             for f in changes[3]:
                 filelinkrevs.setdefault(f, []).append(i)
 
         seen = {}
         self.ui.status("checking manifests\n")
         for i in range(self.manifest.count()):
             n = self.manifest.node(i)
             if n in seen:
                 self.ui.warn("duplicate manifest at revision %d\n" % i)
                 errors += 1
             seen[n] = 1
 
             for p in self.manifest.parents(n):
                 if p not in self.manifest.nodemap:
                     self.ui.warn("manifest %s has unknown parent %s\n" %
                             (short(n), short(p)))
                     errors += 1
 
             try:
                 delta = mdiff.patchtext(self.manifest.delta(n))
             except KeyboardInterrupt:
                 self.ui.warn("interrupted")
                 raise
             except Exception, inst:
                 self.ui.warn("unpacking manifest %s: %s\n"
                              % (short(n), inst))
                 errors += 1
 
             ff = [ l.split('\0') for l in delta.splitlines() ]
             for f, fn in ff:
                 filenodes.setdefault(f, {})[bin(fn[:40])] = 1
 
         self.ui.status("crosschecking files in changesets and manifests\n")
         for f in filenodes:
             if f not in filelinkrevs:
                 self.ui.warn("file %s in manifest but not in changesets\n" % f)
                 errors += 1
 
         for f in filelinkrevs:
             if f not in filenodes:
                 self.ui.warn("file %s in changeset but not in manifest\n" % f)
                 errors += 1
 
         self.ui.status("checking files\n")
         ff = filenodes.keys()
         ff.sort()
         for f in ff:
             if f == "/dev/null": continue
             files += 1
             fl = self.file(f)
             nodes = { nullid: 1 }
             seen = {}
             for i in range(fl.count()):
                 revisions += 1
                 n = fl.node(i)
 
                 if n in seen:
                     self.ui.warn("%s: duplicate revision %d\n" % (f, i))
                     errors += 1
 
                 if n not in filenodes[f]:
                     self.ui.warn("%s: %d:%s not in manifests\n"
                                  % (f, i, short(n)))
                     errors += 1
                 else:
                     del filenodes[f][n]
 
                 flr = fl.linkrev(n)
                 if flr not in filelinkrevs[f]:
                     self.ui.warn("%s:%s points to unexpected changeset %d\n"
                             % (f, short(n), fl.linkrev(n)))
                     errors += 1
                 else:
                     filelinkrevs[f].remove(flr)
 
                 # verify contents
                 try:
                     t = fl.read(n)
                 except Exception, inst:
                     self.ui.warn("unpacking file %s %s: %s\n"
                                  % (f, short(n), inst))
                     errors += 1
 
                 # verify parents
                 (p1, p2) = fl.parents(n)
                 if p1 not in nodes:
                     self.ui.warn("file %s:%s unknown parent 1 %s" %
                             (f, short(n), short(p1)))
                     errors += 1
                 if p2 not in nodes:
                     self.ui.warn("file %s:%s unknown parent 2 %s" %
                             (f, short(n), short(p1)))
                     errors += 1
                 nodes[n] = 1
 
             # cross-check
             for node in filenodes[f]:
                 self.ui.warn("node %s in manifests not in %s\n"
                              % (hex(node), f))
                 errors += 1
 
         self.ui.status("%d files, %d changesets, %d total revisions\n" %
                        (files, changesets, revisions))
 
         if errors:
             self.ui.warn("%d integrity errors encountered!\n" % errors)
             return 1

mercurial/util.py

@@ -1,354 +1,422 b''
 """
 util.py - Mercurial utility functions and platform specfic implementations
 
  Copyright 2005 K. Thananchayan <[e-mail]>
 
 This software may be used and distributed according to the terms
 of the GNU General Public License, incorporated herein by reference.
 
 This contains helper routines that are independent of the SCM core and hide
 platform-specific details from the core.
 """
 
 import os, errno
 from demandload import *
-demandload(globals(), "re")
+demandload(globals(), "re cStringIO")
 
 def binary(s):
     """return true if a string is binary data using diff's heuristic"""
     if s and '\0' in s[:4096]:
         return True
     return False
 
 def unique(g):
     """return the uniq elements of iterable g"""
     seen = {}
     for f in g:
         if f not in seen:
             seen[f] = 1
             yield f
 
 class Abort(Exception):
     """Raised if a command needs to print an error and exit."""
 
 def always(fn): return True
 def never(fn): return False
 
 def globre(pat, head='^', tail='$'):
     "convert a glob pattern into a regexp"
     i, n = 0, len(pat)
     res = ''
     group = False
     def peek(): return i < n and pat[i]
     while i < n:
         c = pat[i]
         i = i+1
         if c == '*':
             if peek() == '*':
                 i += 1
                 res += '.*'
             else:
                 res += '[^/]*'
         elif c == '?':
             res += '.'
         elif c == '[':
             j = i
             if j < n and pat[j] in '!]':
                 j += 1
             while j < n and pat[j] != ']':
                 j += 1
             if j >= n:
                 res += '\\['
             else:
                 stuff = pat[i:j].replace('\\','\\\\')
                 i = j + 1
                 if stuff[0] == '!':
                     stuff = '^' + stuff[1:]
                 elif stuff[0] == '^':
                     stuff = '\\' + stuff
                 res = '%s[%s]' % (res, stuff)
         elif c == '{':
             group = True
             res += '(?:'
         elif c == '}' and group:
             res += ')'
             group = False
         elif c == ',' and group:
             res += '|'
         else:
             res += re.escape(c)
     return head + res + tail
 
 _globchars = {'[': 1, '{': 1, '*': 1, '?': 1}
 
 def pathto(n1, n2):
     '''return the relative path from one place to another.
     this returns a path in the form used by the local filesystem, not hg.'''
     if not n1: return localpath(n2)
     a, b = n1.split('/'), n2.split('/')
     a.reverse(), b.reverse()
     while a and b and a[-1] == b[-1]:
         a.pop(), b.pop()
     b.reverse()
     return os.sep.join((['..'] * len(a)) + b)
 
 def canonpath(root, cwd, myname):
     """return the canonical path of myname, given cwd and root"""
     rootsep = root + os.sep
     name = myname
     if not name.startswith(os.sep):
         name = os.path.join(root, cwd, name)
     name = os.path.normpath(name)
     if name.startswith(rootsep):
         return pconvert(name[len(rootsep):])
     elif name == root:
         return ''
     else:
         raise Abort('%s not under root' % myname)
 
 def matcher(canonroot, cwd, names, inc, exc, head=''):
     """build a function to match a set of file patterns
 
     arguments:
     canonroot - the canonical root of the tree you're matching against
     cwd - the current working directory, if relevant
     names - patterns to find
     inc - patterns to include
     exc - patterns to exclude
     head - a regex to prepend to patterns to control whether a match is rooted
 
     a pattern is one of:
     're:<regex>'
     'glob:<shellglob>'
     'path:<explicit path>'
     'relpath:<relative path>'
     '<relative path>'
 
     returns:
     a 3-tuple containing
     - list of explicit non-pattern names passed in
     - a bool match(filename) function
     - a bool indicating if any patterns were passed in
 
     todo:
     make head regex a rooted bool
     """
 
     def patkind(name):
         for prefix in 're:', 'glob:', 'path:', 'relpath:':
             if name.startswith(prefix): return name.split(':', 1)
         for c in name:
             if c in _globchars: return 'glob', name
         return 'relpath', name
 
     def regex(kind, name, tail):
         '''convert a pattern into a regular expression'''
         if kind == 're':
             return name
         elif kind == 'path':
             return '^' + re.escape(name) + '(?:/|$)'
         elif kind == 'relpath':
             return head + re.escape(name) + tail
         return head + globre(name, '', tail)
 
     def matchfn(pats, tail):
         """build a matching function from a set of patterns"""
         if pats:
             pat = '(?:%s)' % '|'.join([regex(k, p, tail) for (k, p) in pats])
             return re.compile(pat).match
 
     def globprefix(pat):
         '''return the non-glob prefix of a path, e.g. foo/* -> foo'''
         root = []
         for p in pat.split(os.sep):
             if patkind(p)[0] == 'glob': break
             root.append(p)
         return '/'.join(root)
 
     pats = []
     files = []
     roots = []
     for kind, name in map(patkind, names):
         if kind in ('glob', 'relpath'):
             name = canonpath(canonroot, cwd, name)
             if name == '':
                 kind, name = 'glob', '**'
         if kind in ('glob', 'path', 're'):
             pats.append((kind, name))
         if kind == 'glob':
             root = globprefix(name)
             if root: roots.append(root)
         elif kind == 'relpath':
             files.append((kind, name))
             roots.append(name)
 
     patmatch = matchfn(pats, '$') or always
     filematch = matchfn(files, '(?:/|$)') or always
     incmatch = always
     if inc:
         incmatch = matchfn(map(patkind, inc), '(?:/|$)')
     excmatch = lambda fn: False
     if exc:
         excmatch = matchfn(map(patkind, exc), '(?:/|$)')
 
     return (roots,
             lambda fn: (incmatch(fn) and not excmatch(fn) and
                         (fn.endswith('/') or
                          (not pats and not files) or
                          (pats and patmatch(fn)) or
                          (files and filematch(fn)))),
             (inc or exc or (pats and pats != [('glob', '**')])) and True)
 
 def system(cmd, errprefix=None):
     """execute a shell command that must succeed"""
     rc = os.system(cmd)
     if rc:
         errmsg = "%s %s" % (os.path.basename(cmd.split(None, 1)[0]),
                             explain_exit(rc)[0])
         if errprefix:
             errmsg = "%s: %s" % (errprefix, errmsg)
         raise Abort(errmsg)
 
 def rename(src, dst):
     """forcibly rename a file"""
     try:
         os.rename(src, dst)
     except:
         os.unlink(dst)
         os.rename(src, dst)
 
 def copytree(src, dst, copyfile):
     """Copy a directory tree, files are copied using 'copyfile'."""
     names = os.listdir(src)
     os.mkdir(dst)
 
     for name in names:
         srcname = os.path.join(src, name)
         dstname = os.path.join(dst, name)
         if os.path.isdir(srcname):
             copytree(srcname, dstname, copyfile)
         elif os.path.isfile(srcname):
             copyfile(srcname, dstname)
         else:
             pass
 
 def opener(base):
     """
     return a function that opens files relative to base
 
     this function is used to hide the details of COW semantics and
     remote file access from higher level code.
     """
     p = base
     def o(path, mode="r"):
         f = os.path.join(p, path)
 
         mode += "b" # for that other OS
 
         if mode[0] != "r":
             try:
                 s = os.stat(f)
             except OSError:
                 d = os.path.dirname(f)
                 if not os.path.isdir(d):
                     os.makedirs(d)
             else:
                 if s.st_nlink > 1:
                     file(f + ".tmp", "wb").write(file(f, "rb").read())
                     rename(f+".tmp", f)
 
         return file(f, mode)
 
     return o
 
 def _makelock_file(info, pathname):
     ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
     os.write(ld, info)
     os.close(ld)
 
 def _readlock_file(pathname):
     return file(pathname).read()
 
 # Platform specific variants
 if os.name == 'nt':
     nulldev = 'NUL:'
 
     def is_exec(f, last):
         return last
 
     def set_exec(f, mode):
         pass
 
     def pconvert(path):
         return path.replace("\\", "/")
 
     def localpath(path):
         return path.replace('/', '\\')
 
     def normpath(path):
         return pconvert(os.path.normpath(path))
 
     makelock = _makelock_file
     readlock = _readlock_file
 
     def explain_exit(code):
         return "exited with status %d" % code, code
 
 else:
     nulldev = '/dev/null'
 
     def is_exec(f, last):
         """check whether a file is executable"""
         return (os.stat(f).st_mode & 0100 != 0)
 
     def set_exec(f, mode):
         s = os.stat(f).st_mode
         if (s & 0100 != 0) == mode:
             return
         if mode:
             # Turn on +x for every +r bit when making a file executable
             # and obey umask.
             umask = os.umask(0)
             os.umask(umask)
             os.chmod(f, s | (s & 0444) >> 2 & ~umask)
         else:
             os.chmod(f, s & 0666)
 
     def pconvert(path):
         return path
 
     def localpath(path):
         return path
 
     normpath = os.path.normpath
 
     def makelock(info, pathname):
         try:
             os.symlink(info, pathname)
         except OSError, why:
             if why.errno == errno.EEXIST:
                 raise
             else:
                 _makelock_file(info, pathname)
 
     def readlock(pathname):
         try:
             return os.readlink(pathname)
         except OSError, why:
             if why.errno == errno.EINVAL:
                 return _readlock_file(pathname)
             else:
                 raise
 
     def explain_exit(code):
         """return a 2-tuple (desc, code) describing a process's status"""
         if os.WIFEXITED(code):
             val = os.WEXITSTATUS(code)
             return "exited with status %d" % val, val
         elif os.WIFSIGNALED(code):
             val = os.WTERMSIG(code)
             return "killed by signal %d" % val, val
         elif os.WIFSTOPPED(code):
             val = os.WSTOPSIG(code)
             return "stopped by signal %d" % val, val
         raise ValueError("invalid exit code")
+
+class chunkbuffer(object):
+    """Allow arbitrary sized chunks of data to be efficiently read from an
+    iterator over chunks of arbitrary size."""
+    def __init__(self, in_iter, targetsize = 2**16):
+        """in_iter is the iterator that's iterating over the input chunks.
+        targetsize is how big a buffer to try to maintain."""
+        self.in_iter = iter(in_iter)
+        self.buf = ''
+        targetsize = int(targetsize)
+        if (targetsize <= 0):
+            raise ValueError("targetsize must be greater than 0, was %d" % targetsize)
+        self.targetsize = int(targetsize)
+        self.iterempty = False
+    def fillbuf(self):
+        """x.fillbuf()
+
+        Ignore the target size, and just read every chunk from the iterator
+        until it's empty."""
+        if not self.iterempty:
+            collector = cStringIO.StringIO()
+            collector.write(self.buf)
+            for ch in self.in_iter:
+                collector.write(ch)
+            self.buf = collector.getvalue()
+            collector.close()
+            collector = None
+            self.iterempty = True
+
+    def read(self, l):
+        """x.read(l) -> str
+        Read l bytes of data from the iterator of chunks of data.  Returns less
+        than l bytes if the iterator runs dry."""
+        if l > len(self.buf) and not self.iterempty:
+            # Clamp to a multiple of self.targetsize
+            targetsize = self.targetsize * ((l // self.targetsize) + 1)
+            collector = cStringIO.StringIO()
+            collector.write(self.buf)
+            collected = len(self.buf)
+            for chunk in self.in_iter:
+                collector.write(chunk)
+                collected += len(chunk)
+                if collected >= targetsize:
+                    break
+            if collected < targetsize:
+                self.iterempty = True
+            self.buf = collector.getvalue()
+            collector.close()
+            collector = None
+        s = self.buf[:l]
+        self.buf = buffer(self.buf, l)
+        return s
+    def __repr__(self):
+        return "<%s.%s targetsize = %u buffered = %u bytes>" % \
+               (self.__class__.__module__, self.__class__.__name__,
+                self.targetsize, len(self.buf))
+
+def filechunkiter(f, size = 65536):
+    """filechunkiter(file[, size]) -> generator
+
+    Create a generator that produces all the data in the file size (default
+    65536) bytes at a time.  Chunks may be less than size bytes if the
+    chunk is the last chunk in the file, or the file is a socket or some
+    other type of file that sometimes reads less data than is requested."""
+    s = f.read(size)
+    while len(s) >= 0:
+        yield s
+        s = f.read(size)