bb.fetch: simplify mirror tarball handling in try_mirror_url

index e8fbe89..1b4547d 100644
@@ -954,8 +954,7 @@ def try_mirror_url(fetch, origud, ud, ld, check = False):
         # We may be obtaining a mirror tarball which needs further processing by the real fetcher
         # If that tarball is a local file:// we need to provide a symlink to it
         dldir = ld.getVar("DL_DIR", True)
-        if origud.mirrortarball and os.path.basename(ud.localpath) == os.path.basename(origud.mirrortarball) \
-                and os.path.basename(ud.localpath) != os.path.basename(origud.localpath):
+        if os.path.basename(ud.localpath) != os.path.basename(origud.localpath):
             # Create donestamp in old format to avoid triggering a re-download
             if ud.donestamp:
                 bb.utils.mkdirhier(os.path.dirname(ud.donestamp))

@@ -965,7 +964,7 @@ def try_mirror_url(fetch, origud, ud, ld, check = False):
                 os.symlink(ud.localpath, dest)
             if not verify_donestamp(origud, ld) or origud.method.need_update(origud, ld):
                 origud.method.download(origud, ld)
-                if hasattr(origud.method,"build_mirror_data"):
+                if hasattr(origud.method, "build_mirror_data"):
                     origud.method.build_mirror_data(origud, ld)
             return origud.localpath
         # Otherwise the result is a local file:// and we symlink to it

index 1b4547d..fc38f11 100644
@@ -430,7 +430,7 @@ def encodeurl(decoded):
 
     return url
 
-def uri_replace(ud, uri_find, uri_replace, replacements, d):
+def uri_replace(ud, uri_find, uri_replace, replacements, d, mirrortarball=None):
     if not ud.url or not uri_find or not uri_replace:
         logger.error("uri_replace: passed an undefined value, not replacing")
         return None

@@ -469,9 +469,9 @@ def uri_replace(ud, uri_find, uri_replace, replacements, d):
             if loc == 2:
                 # Handle path manipulations
                 basename = None
-                if uri_decoded[0] != uri_replace_decoded[0] and ud.mirrortarball:
+                if uri_decoded[0] != uri_replace_decoded[0] and mirrortarball:
                     # If the source and destination url types differ, must be a mirrortarball mapping
-                    basename = os.path.basename(ud.mirrortarball)
+                    basename = os.path.basename(mirrortarball)
                     # Kill parameters, they make no sense for mirror tarballs
                     uri_decoded[5] = {}
                 elif ud.localpath and ud.method.supports_checksum(ud):

@@ -869,13 +869,13 @@ def build_mirroruris(origud, mirrors, ld):
     replacements["BASENAME"] = origud.path.split("/")[-1]
     replacements["MIRRORNAME"] = origud.host.replace(':','.') + origud.path.replace('/', '.').replace('*', '.')
 
-    def adduri(ud, uris, uds, mirrors):
+    def adduri(ud, uris, uds, mirrors, tarball):
         for line in mirrors:
             try:
                 (find, replace) = line
             except ValueError:
                 continue
-            newuri = uri_replace(ud, find, replace, replacements, ld)
+            newuri = uri_replace(ud, find, replace, replacements, ld, tarball)
             if not newuri or newuri in uris or newuri == origud.url:
                 continue
 

@@ -898,16 +898,20 @@ def build_mirroruris(origud, mirrors, ld):
                 try:
                     # setup_localpath of file:// urls may fail, we should still see 
                     # if mirrors of the url exist
-                    adduri(newud, uris, uds, localmirrors)
+                    adduri(newud, uris, uds, localmirrors, tarball)
                 except UnboundLocalError:
                     pass
-                continue   
+                continue
             uris.append(newuri)
             uds.append(newud)
 
-            adduri(newud, uris, uds, localmirrors)
+            adduri(newud, uris, uds, localmirrors, tarball)
 
-    adduri(origud, uris, uds, mirrors)
+    if hasattr(origud, 'mirrortarballs'):
+        for tarball in origud.mirrortarballs:
+            adduri(origud, uris, uds, mirrors, tarball)
+    else:
+        adduri(origud, uris, uds, mirrors, getattr(origud, 'mirrortarball', None))
 
     return uris, uds
 

index 526668b..51d7537 100644
@@ -66,9 +66,13 @@ Supported SRC_URI options are:
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+import collections
 import errno
+import itertools
 import os
 import re
+import subprocess
+import tempfile
 import bb
 import errno
 from   bb    import data

@@ -76,6 +80,23 @@ from   bb.fetch2 import FetchMethod
 from   bb.fetch2 import runfetchcmd
 from   bb.fetch2 import logger
 
+
+def iter_except(func, exception, start=None):
+    """Yield a function repeatedly until it raises an exception."""
+    try:
+        if start is not None:
+            yield start()
+        while True:
+            yield func()
+    except exception:
+        pass
+
+
+def iter_extend(iterable, length, obj=None):
+    """Ensure that iterable is the specified length by extending with obj"""
+    return itertools.islice(itertools.chain(iterable, itertools.repeat(obj)), length)
+
+
 class Git(FetchMethod):
     """Class to fetch a module or modules from git repositories"""
     def init(self, d):

@@ -120,15 +141,43 @@ class Git(FetchMethod):
         branches = ud.parm.get("branch", "master").split(',')
         if len(branches) != len(ud.names):
             raise bb.fetch2.ParameterError("The number of name and branch parameters is not balanced", ud.url)
+
+        ud.shallow = d.getVar("BB_GIT_SHALLOW", True) == "1"
+        ud.shallow_revs = (d.getVar("BB_GIT_SHALLOW_REVS", True) or "").split()
+        trim_refs = d.getVar("BB_GIT_SHALLOW_TRIM_REFS", True)
+        ud.trim_refs = not trim_refs or trim_refs == "0"
+        ud.shallow_extra_refs = (d.getVar("BB_GIT_SHALLOW_EXTRA_REFS", True) or "").split()
+
+        depth_default = d.getVar("BB_GIT_SHALLOW_DEPTH", True)
+        if depth_default is not None:
+            try:
+                depth_default = int(depth_default)
+            except ValueError:
+                raise bb.fetch2.FetchError("Invalid depth for BB_GIT_SHALLOW_DEPTH: %s" % depth_default)
+        else:
+            depth_default = 1
+        ud.shallow_depths = collections.defaultdict(lambda: depth_default)
+
         ud.branches = {}
-        for name in ud.names:
-            branch = branches[ud.names.index(name)]
+        for pos, name in enumerate(ud.names):
+            branch = branches[pos]
             ud.branches[name] = branch
             ud.unresolvedrev[name] = branch
 
+            shallow_depth = d.getVar("BB_GIT_SHALLOW_DEPTH_%s" % name, True)
+            if shallow_depth and shallow_depth != "0":
+                try:
+                    shallow_depth = int(shallow_depth)
+                except ValueError:
+                    raise bb.fetch2.FetchError("Invalid depth for BB_GIT_SHALLOW_DEPTH_%s: %s" % (name, shallow_depth))
+                else:
+                    ud.shallow_depths[name] = shallow_depth
+
         ud.basecmd = data.getVar("FETCHCMD_git", d, True) or "git -c core.fsyncobjectfiles=0"
 
-        ud.write_tarballs = ((data.getVar("BB_GENERATE_MIRROR_TARBALLS", d, True) or "0") != "0") or ud.rebaseable
+        write_tarballs = d.getVar("BB_GENERATE_MIRROR_TARBALLS", True) or "0"
+        ud.write_tarballs = write_tarballs != "0" or ud.rebaseable
+        ud.write_shallow_tarballs = (d.getVar("BB_GENERATE_SHALLOW_TARBALLS", True) or write_tarballs) != "0"
 
         ud.setup_revisons(d)
 

@@ -150,13 +199,36 @@ class Git(FetchMethod):
         if ud.rebaseable:
             for name in ud.names:
                 gitsrcname = gitsrcname + '_' + ud.revisions[name]
-        ud.mirrortarball = 'git2_%s.tar.gz' % (gitsrcname)
-        ud.fullmirror = os.path.join(d.getVar("DL_DIR", True), ud.mirrortarball)
-        gitdir = d.getVar("GITDIR", True) or (d.getVar("DL_DIR", True) + "/git2/")
-        ud.clonedir = os.path.join(gitdir, gitsrcname)
 
+        dl_dir = d.getVar("DL_DIR", True)
+        gitdir = d.getVar("GITDIR", True) or (dl_dir + "/git2/")
+        ud.clonedir = os.path.join(gitdir, gitsrcname)
         ud.localfile = ud.clonedir
 
+        ud.mirrortarball = 'git2_%s.tar.gz' % gitsrcname
+        ud.fullmirror = os.path.join(dl_dir, ud.mirrortarball)
+        if ud.shallow:
+            tarballname = gitsrcname
+            if ud.shallow_revs:
+                tarballname = "%s_%s" % (tarballname, "_".join(sorted(ud.shallow_revs)))
+
+            for name, revision in sorted(ud.revisions.iteritems()):
+                tarballname = "%s_%s" % (tarballname, ud.revisions[name][:7])
+                depth = ud.shallow_depths[name]
+                if depth:
+                    tarballname = "%s-%s" % (tarballname, depth)
+
+            if ud.trim_refs:
+                if not ud.nobranch:
+                    shallow_refs = ud.branches.itervalues()
+                    shallow_refs = itertools.chain(shallow_refs, ud.shallow_extra_refs)
+                    tarballname = "%s_%s" % (tarballname, "_".join(sorted(shallow_refs)))
+                ud.shallowtarball = 'gitshallow_%s.tar.gz' % tarballname
+            else:
+                ud.shallowtarball = 'gitshallowall_%s.tar.gz' % tarballname
+            ud.fullshallow = os.path.join(dl_dir, ud.shallowtarball)
+            ud.mirrortarballs = [ud.shallowtarball, ud.mirrortarball]
+
     def localpath(self, ud, d):
         return ud.clonedir
 

@@ -167,6 +239,8 @@ class Git(FetchMethod):
         for name in ud.names:
             if not self._contains_ref(ud, d, name):
                 return True
+        if ud.shallow and ud.write_shallow_tarballs and not os.path.exists(ud.fullshallow):
+            return True
         if ud.write_tarballs and not os.path.exists(ud.fullmirror):
             return True
         return False

@@ -183,8 +257,16 @@ class Git(FetchMethod):
     def download(self, ud, d):
         """Fetch url"""
 
-        # If the checkout doesn't exist and the mirror tarball does, extract it
-        if not os.path.exists(ud.clonedir) and os.path.exists(ud.fullmirror):
+        no_clone = not os.path.exists(ud.clonedir)
+        need_update = no_clone or self.need_update(ud, d)
+
+        # A current clone is preferred to either tarball, a shallow tarball is
+        # preferred to an out of date clone, and a missing clone will use
+        # either tarball.
+        if ud.shallow and os.path.exists(ud.fullshallow) and need_update:
+            ud.localpath = ud.fullshallow
+            return
+        elif os.path.exists(ud.fullmirror) and no_clone:
             bb.utils.mkdirhier(ud.clonedir)
             os.chdir(ud.clonedir)
             runfetchcmd("tar -xzf %s" % (ud.fullmirror), d)

@@ -231,23 +313,139 @@ class Git(FetchMethod):
                 raise bb.fetch2.FetchError("Unable to find revision %s in branch %s even from upstream" % (ud.revisions[name], ud.branches[name]))
 
     def build_mirror_data(self, ud, d):
-        # Generate a mirror tarball if needed
-        if ud.write_tarballs and not os.path.exists(ud.fullmirror):
-            # it's possible that this symlink points to read-only filesystem with PREMIRROR
+        if ud.shallow and ud.write_shallow_tarballs:
+            if not os.path.exists(ud.fullshallow):
+                if os.path.islink(ud.fullshallow):
+                    os.unlink(ud.fullshallow)
+                tempdir = tempfile.mkdtemp(dir=d.getVar('DL_DIR', True))
+                shallowclone = os.path.join(tempdir, 'git')
+                try:
+                    repourl = self._get_repo_url(ud)
+                    branchinfo = dict((name, (ud.shallow_depths[name], ud.revisions[name], ud.branches[name])) for name in ud.names)
+                    self._populate_shallowclone(repourl, ud.clonedir, shallowclone, ud.basecmd, branchinfo, ud.nobranch, ud.trim_refs, ud.shallow_extra_refs, ud.shallow_revs, ud.bareclone, d)
+
+                    logger.info("Creating tarball of git repository")
+                    runfetchcmd("tar -czf %s %s" % (ud.fullshallow, os.path.join(".")), d)
+                    runfetchcmd("touch %s.done" % ud.fullshallow, d)
+                finally:
+                    bb.utils.remove(tempdir, recurse=True)
+        elif ud.write_tarballs and not os.path.exists(ud.fullmirror):
             if os.path.islink(ud.fullmirror):
                 os.unlink(ud.fullmirror)
-
             os.chdir(ud.clonedir)
             logger.info("Creating tarball of git repository")
-            runfetchcmd("tar -czf %s %s" % (ud.fullmirror, os.path.join(".") ), d)
-            runfetchcmd("touch %s.done" % (ud.fullmirror), d)
+            runfetchcmd("tar -czf %s %s" % (ud.fullmirror, os.path.join(".")), d)
+            runfetchcmd("touch %s.done" % ud.fullmirror, d)
+
+    def _populate_shallowclone(self, repourl, source, dest, gitcmd, branchinfo, nobranch, trim_refs, extra_refs, shallow_revisions, bareclone, d):
+        if shallow_revisions is None:
+            shallow_revisions = []
+
+        # Map depths to revisions
+        to_parse = []
+        for depth, revision, branch in branchinfo.itervalues():
+            if not depth:
+                continue
+
+            to_parse.append('%s~%d^{}' % (revision, depth - 1))
+
+        parsed = runfetchcmd("GIT_DIR='%s' %s rev-parse %s" % (source, gitcmd, " ".join(to_parse)), d)
+        shallow_revisions.extend(parsed.splitlines())
+
+        cloneflags = "-s -n"
+        if bareclone:
+            cloneflags += " --mirror"
+        runfetchcmd("%s clone %s %s %s" % (gitcmd, cloneflags, source, dest), d)
+
+        os.chdir(dest)
+
+        shallow_branches = []
+        shallow_branches.extend(extra_refs)
+        for name, (depth, revision, branch) in branchinfo.iteritems():
+            if nobranch:
+                ref = "refs/shallow/%s" % name
+            else:
+                ref = "refs/remotes/origin/%s" % branch
+
+            if trim_refs:
+                shallow_branches.append(ref)
+            runfetchcmd("%s update-ref %s %s" % (gitcmd, ref, revision), d)
+
+        if trim_refs:
+            self.filter_refs(gitcmd, d, shallow_branches)
+
+        git_dir = runfetchcmd('%s rev-parse --git-dir' % gitcmd, d).rstrip()
+        self._make_repo_shallow(shallow_revisions, git_dir, gitcmd, d, branches=shallow_branches or None)
+
+        alternates_file = os.path.join(git_dir, "objects", "info", "alternates")
+        os.unlink(alternates_file)
+
+    def _make_repo_shallow(self, revisions, git_dir, gitcmd, d, branches=None):
+        if branches is not None:
+            refs = branches
+        else:
+            refs = self.get_all_refs(gitcmd, d, lambda r, t: not t or t == 'commit')
+
+        parsed_revs = runfetchcmd('%s rev-parse %s' % (gitcmd, ' '.join('%s^{}' % i for i in revisions)), d)
+        queue = collections.deque(r.rstrip() for r in parsed_revs.splitlines())
+        seen = set()
+
+        shallow_file = os.path.join(git_dir, 'shallow')
+        try:
+            os.unlink(shallow_file)
+        except OSError as exc:
+            if exc.errno != errno.ENOENT:
+                raise
+
+        for rev in iter_except(queue.popleft, IndexError):
+            if rev in seen:
+                continue
+
+            bb.note("Processing shallow revision: %s" % rev)
+            parent_output = runfetchcmd('%s rev-parse %s^@' % (gitcmd, rev), d)
+            parents = [p.rstrip() for p in parent_output.splitlines()]
+            with open(shallow_file, 'a') as f:
+                f.write(rev + '\n')
+            seen.add(rev)
+
+            for parent in parents:
+                for ref in refs:
+                    try:
+                        merge_base = runfetchcmd('%s merge-base %s %s' % (gitcmd, parent, ref), d).rstrip()
+                    except bb.fetch2.FetchError:
+                        continue
+                    queue.append(merge_base)
+
+        runfetchcmd('%s reflog expire --expire-unreachable=now --all' % gitcmd, d)
+        runfetchcmd('%s repack -ad' % gitcmd, d)
+        runfetchcmd('%s prune --expire now' % gitcmd, d)
+
+    @classmethod
+    def get_all_refs(cls, gitcmd, d, ref_filter=None):
+        """Return all the existing refs in this repository, optionally filtering the refs."""
+        ref_output = runfetchcmd('{} for-each-ref "--format=%(refname)" "%(*objecttype)"'.format(gitcmd), d)
+        ref_split = (tuple(iter_extend(l.rstrip().rsplit('\t', 1), 2)) for l in ref_output.splitlines())
+        if ref_filter:
+            ref_split = (e for e in ref_split if ref_filter(*e))
+        refs = [r for r, _ in ref_split]
+        return refs
+
+    @classmethod
+    def filter_refs(cls, gitcmd, d, refs):
+        """Remove all but the specified refs from the git repository."""
+        all_refs = cls.get_all_refs(gitcmd, d)
+        full_refs = runfetchcmd('%s rev-parse --symbolic-full-name %s' % (gitcmd, ' '.join(refs)), d).splitlines()
+        to_remove = set(all_refs) - set(full_refs)
+        if to_remove:
+            p = bb.process.Popen(['xargs', '-0', '-n', '1', 'git', 'update-ref', '-d', '--no-deref'], stderr=subprocess.PIPE)
+            p.communicate(''.join(l + '\0' for l in to_remove))
 
     def unpack(self, ud, destdir, d):
         """ unpack the downloaded src to destdir"""
 
         subdir = ud.parm.get("subpath", "")
         if subdir != "":
-            readpathspec = ":%s" % (subdir)
+            readpathspec = ":%s" % subdir
             def_destsuffix = "%s/" % os.path.basename(subdir.rstrip('/'))
         else:
             readpathspec = ""

@@ -258,11 +456,33 @@ class Git(FetchMethod):
         if os.path.exists(destdir):
             bb.utils.prunedir(destdir)
 
-        cloneflags = "-s -n"
-        if ud.bareclone:
-            cloneflags += " --mirror"
+        if ud.shallow and (not os.path.exists(ud.clonedir) or self.need_update(ud, d)):
+            bb.utils.mkdirhier(destdir)
+            os.chdir(destdir)
+            runfetchcmd("tar -xzf %s" % ud.fullshallow, d)
+        else:
+            cloneflags = "-s -n"
+            if ud.bareclone:
+                cloneflags += " --mirror"
+
+            # Versions of git prior to 1.7.9.2 have issues where foo.git and foo get confused
+            # and you end up with some horrible union of the two when you attempt to clone it
+            # The least invasive workaround seems to be a symlink to the real directory to
+            # fool git into ignoring any .git version that may also be present.
+            #
+            # The issue is fixed in more recent versions of git so we can drop this hack in future
+            # when that version becomes common enough.
+            clonedir = ud.clonedir
+            if not ud.path.endswith(".git"):
+                indirectiondir = destdir[:-1] + ".indirectionsymlink"
+                if os.path.exists(indirectiondir):
+                    os.remove(indirectiondir)
+                bb.utils.mkdirhier(os.path.dirname(indirectiondir))
+                os.symlink(ud.clonedir, indirectiondir)
+                clonedir = indirectiondir
+
+            runfetchcmd("%s clone %s %s/ %s" % (ud.basecmd, cloneflags, clonedir, destdir), d)
 
-        runfetchcmd("%s clone %s %s/ %s" % (ud.basecmd, cloneflags, ud.clonedir, destdir), d)
         os.chdir(destdir)
         repourl = self._get_repo_url(ud)
         runfetchcmd("%s remote set-url origin %s" % (ud.basecmd, repourl), d)

index 526668b..7e96a2c 100644
@@ -66,9 +66,13 @@ Supported SRC_URI options are:
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+import collections
 import errno
+import itertools
 import os
 import re
+import subprocess
+import tempfile
 import bb
 import errno
 from   bb    import data

@@ -76,6 +80,23 @@ from   bb.fetch2 import FetchMethod
 from   bb.fetch2 import runfetchcmd
 from   bb.fetch2 import logger
 
+
+def iter_except(func, exception, start=None):
+    """Yield a function repeatedly until it raises an exception."""
+    try:
+        if start is not None:
+            yield start()
+        while True:
+            yield func()
+    except exception:
+        pass
+
+
+def iter_extend(iterable, length, obj=None):
+    """Ensure that iterable is the specified length by extending with obj"""
+    return itertools.islice(itertools.chain(iterable, itertools.repeat(obj)), length)
+
+
 class Git(FetchMethod):
     """Class to fetch a module or modules from git repositories"""
     def init(self, d):

@@ -120,15 +141,43 @@ class Git(FetchMethod):
         branches = ud.parm.get("branch", "master").split(',')
         if len(branches) != len(ud.names):
             raise bb.fetch2.ParameterError("The number of name and branch parameters is not balanced", ud.url)
+
+        ud.shallow = d.getVar("BB_GIT_SHALLOW", True) == "1"
+        ud.shallow_revs = (d.getVar("BB_GIT_SHALLOW_REVS", True) or "").split()
+        trim_refs = d.getVar("BB_GIT_SHALLOW_TRIM_REFS", True)
+        ud.trim_refs = not trim_refs or trim_refs == "0"
+        ud.shallow_extra_refs = (d.getVar("BB_GIT_SHALLOW_EXTRA_REFS", True) or "").split()
+
+        depth_default = d.getVar("BB_GIT_SHALLOW_DEPTH", True)
+        if depth_default is not None:
+            try:
+                depth_default = int(depth_default)
+            except ValueError:
+                raise bb.fetch2.FetchError("Invalid depth for BB_GIT_SHALLOW_DEPTH: %s" % depth_default)
+        else:
+            depth_default = 1
+        ud.shallow_depths = collections.defaultdict(lambda: depth_default)
+
         ud.branches = {}
-        for name in ud.names:
-            branch = branches[ud.names.index(name)]
+        for pos, name in enumerate(ud.names):
+            branch = branches[pos]
             ud.branches[name] = branch
             ud.unresolvedrev[name] = branch
 
+            shallow_depth = d.getVar("BB_GIT_SHALLOW_DEPTH_%s" % name, True)
+            if shallow_depth and shallow_depth != "0":
+                try:
+                    shallow_depth = int(shallow_depth)
+                except ValueError:
+                    raise bb.fetch2.FetchError("Invalid depth for BB_GIT_SHALLOW_DEPTH_%s: %s" % (name, shallow_depth))
+                else:
+                    ud.shallow_depths[name] = shallow_depth
+
         ud.basecmd = data.getVar("FETCHCMD_git", d, True) or "git -c core.fsyncobjectfiles=0"
 
-        ud.write_tarballs = ((data.getVar("BB_GENERATE_MIRROR_TARBALLS", d, True) or "0") != "0") or ud.rebaseable
+        write_tarballs = d.getVar("BB_GENERATE_MIRROR_TARBALLS", True) or "0"
+        ud.write_tarballs = write_tarballs != "0" or ud.rebaseable
+        ud.write_shallow_tarballs = (d.getVar("BB_GENERATE_SHALLOW_TARBALLS", True) or write_tarballs) != "0"
 
         ud.setup_revisons(d)
 

@@ -150,13 +199,36 @@ class Git(FetchMethod):
         if ud.rebaseable:
             for name in ud.names:
                 gitsrcname = gitsrcname + '_' + ud.revisions[name]
-        ud.mirrortarball = 'git2_%s.tar.gz' % (gitsrcname)
-        ud.fullmirror = os.path.join(d.getVar("DL_DIR", True), ud.mirrortarball)
-        gitdir = d.getVar("GITDIR", True) or (d.getVar("DL_DIR", True) + "/git2/")
-        ud.clonedir = os.path.join(gitdir, gitsrcname)
 
+        dl_dir = d.getVar("DL_DIR", True)
+        gitdir = d.getVar("GITDIR", True) or (dl_dir + "/git2/")
+        ud.clonedir = os.path.join(gitdir, gitsrcname)
         ud.localfile = ud.clonedir
 
+        ud.mirrortarball = 'git2_%s.tar.gz' % gitsrcname
+        ud.fullmirror = os.path.join(dl_dir, ud.mirrortarball)
+        if ud.shallow:
+            tarballname = gitsrcname
+            if ud.shallow_revs:
+                tarballname = "%s_%s" % (tarballname, "_".join(sorted(ud.shallow_revs)))
+
+            for name, revision in sorted(ud.revisions.iteritems()):
+                tarballname = "%s_%s" % (tarballname, ud.revisions[name][:7])
+                depth = ud.shallow_depths[name]
+                if depth:
+                    tarballname = "%s-%s" % (tarballname, depth)
+
+            if ud.trim_refs:
+                if not ud.nobranch:
+                    shallow_refs = ud.branches.itervalues()
+                    shallow_refs = itertools.chain(shallow_refs, ud.shallow_extra_refs)
+                    tarballname = "%s_%s" % (tarballname, "_".join(sorted(shallow_refs)))
+                ud.shallowtarball = 'gitshallow_%s.tar.gz' % tarballname
+            else:
+                ud.shallowtarball = 'gitshallowall_%s.tar.gz' % tarballname
+            ud.fullshallow = os.path.join(dl_dir, ud.shallowtarball)
+            ud.mirrortarballs = [ud.shallowtarball, ud.mirrortarball]
+
     def localpath(self, ud, d):
         return ud.clonedir
 

@@ -167,6 +239,8 @@ class Git(FetchMethod):
         for name in ud.names:
             if not self._contains_ref(ud, d, name):
                 return True
+        if ud.shallow and ud.write_shallow_tarballs and not os.path.exists(ud.fullshallow):
+            return True
         if ud.write_tarballs and not os.path.exists(ud.fullmirror):
             return True
         return False

@@ -183,8 +257,16 @@ class Git(FetchMethod):
     def download(self, ud, d):
         """Fetch url"""
 
-        # If the checkout doesn't exist and the mirror tarball does, extract it
-        if not os.path.exists(ud.clonedir) and os.path.exists(ud.fullmirror):
+        no_clone = not os.path.exists(ud.clonedir)
+        need_update = no_clone or self.need_update(ud, d)
+
+        # A current clone is preferred to either tarball, a shallow tarball is
+        # preferred to an out of date clone, and a missing clone will use
+        # either tarball.
+        if ud.shallow and os.path.exists(ud.fullshallow) and need_update:
+            ud.localpath = ud.fullshallow
+            return
+        elif os.path.exists(ud.fullmirror) and no_clone:
             bb.utils.mkdirhier(ud.clonedir)
             os.chdir(ud.clonedir)
             runfetchcmd("tar -xzf %s" % (ud.fullmirror), d)

@@ -231,23 +313,139 @@ class Git(FetchMethod):
                 raise bb.fetch2.FetchError("Unable to find revision %s in branch %s even from upstream" % (ud.revisions[name], ud.branches[name]))
 
     def build_mirror_data(self, ud, d):
-        # Generate a mirror tarball if needed
-        if ud.write_tarballs and not os.path.exists(ud.fullmirror):
-            # it's possible that this symlink points to read-only filesystem with PREMIRROR
+        if ud.shallow and ud.write_shallow_tarballs:
+            if not os.path.exists(ud.fullshallow):
+                if os.path.islink(ud.fullshallow):
+                    os.unlink(ud.fullshallow)
+                tempdir = tempfile.mkdtemp(dir=d.getVar('DL_DIR', True))
+                shallowclone = os.path.join(tempdir, 'git')
+                try:
+                    repourl = self._get_repo_url(ud)
+                    branchinfo = dict((name, (ud.shallow_depths[name], ud.revisions[name], ud.branches[name])) for name in ud.names)
+                    self._populate_shallowclone(repourl, ud.clonedir, shallowclone, ud.basecmd, branchinfo, ud.nobranch, ud.trim_refs, ud.shallow_extra_refs, ud.shallow_revs, ud.bareclone, d)
+
+                    logger.info("Creating tarball of git repository")
+                    runfetchcmd("tar -czf %s %s" % (ud.fullshallow, os.path.join(".")), d)
+                    runfetchcmd("touch %s.done" % ud.fullshallow, d)
+                finally:
+                    bb.utils.remove(tempdir, recurse=True)
+        elif ud.write_tarballs and not os.path.exists(ud.fullmirror):
             if os.path.islink(ud.fullmirror):
                 os.unlink(ud.fullmirror)
-
             os.chdir(ud.clonedir)
             logger.info("Creating tarball of git repository")
-            runfetchcmd("tar -czf %s %s" % (ud.fullmirror, os.path.join(".") ), d)
-            runfetchcmd("touch %s.done" % (ud.fullmirror), d)
+            runfetchcmd("tar -czf %s %s" % (ud.fullmirror, os.path.join(".")), d)
+            runfetchcmd("touch %s.done" % ud.fullmirror, d)
+
+    def _populate_shallowclone(self, repourl, source, dest, gitcmd, branchinfo, nobranch, trim_refs, extra_refs, shallow_revisions, bareclone, d):
+        if shallow_revisions is None:
+            shallow_revisions = []
+
+        # Map depths to revisions
+        to_parse = []
+        for depth, revision, branch in branchinfo.itervalues():
+            if not depth:
+                continue
+
+            to_parse.append('%s~%d^{}' % (revision, depth - 1))
+
+        parsed = runfetchcmd("GIT_DIR='%s' %s rev-parse %s" % (source, gitcmd, " ".join(to_parse)), d)
+        shallow_revisions.extend(parsed.splitlines())
+
+        cloneflags = "-s -n"
+        if bareclone:
+            cloneflags += " --mirror"
+        runfetchcmd("%s clone %s %s %s" % (gitcmd, cloneflags, source, dest), d)
+
+        os.chdir(dest)
+
+        shallow_branches = []
+        shallow_branches.extend(extra_refs)
+        for name, (depth, revision, branch) in branchinfo.iteritems():
+            if nobranch:
+                ref = "refs/shallow/%s" % name
+            else:
+                ref = "refs/remotes/origin/%s" % branch
+
+            if trim_refs:
+                shallow_branches.append(ref)
+            runfetchcmd("%s update-ref %s %s" % (gitcmd, ref, revision), d)
+
+        if trim_refs:
+            self.filter_refs(gitcmd, d, shallow_branches)
+
+        git_dir = runfetchcmd('%s rev-parse --git-dir' % gitcmd, d).rstrip()
+        self._make_repo_shallow(shallow_revisions, git_dir, gitcmd, d, branches=shallow_branches or None)
+
+        alternates_file = os.path.join(git_dir, "objects", "info", "alternates")
+        os.unlink(alternates_file)
+
+    def _make_repo_shallow(self, revisions, git_dir, gitcmd, d, branches=None):
+        if branches is not None:
+            refs = branches
+        else:
+            refs = self.get_all_refs(gitcmd, d, lambda r, t: not t or t == 'commit')
+
+        parsed_revs = runfetchcmd('%s rev-parse %s' % (gitcmd, ' '.join('%s^{}' % i for i in revisions)), d)
+        queue = collections.deque(r.rstrip() for r in parsed_revs.splitlines())
+        seen = set()
+
+        shallow_file = os.path.join(git_dir, 'shallow')
+        try:
+            os.unlink(shallow_file)
+        except OSError as exc:
+            if exc.errno != errno.ENOENT:
+                raise
+
+        for rev in iter_except(queue.popleft, IndexError):
+            if rev in seen:
+                continue
+
+            bb.note("Processing shallow revision: %s" % rev)
+            parent_output = runfetchcmd('%s rev-parse %s^@' % (gitcmd, rev), d)
+            parents = [p.rstrip() for p in parent_output.splitlines()]
+            with open(shallow_file, 'a') as f:
+                f.write(rev + '\n')
+            seen.add(rev)
+
+            for parent in parents:
+                for ref in refs:
+                    try:
+                        merge_base = runfetchcmd('%s merge-base %s %s' % (gitcmd, parent, ref), d).rstrip()
+                    except bb.fetch2.FetchError:
+                        continue
+                    queue.append(merge_base)
+
+        runfetchcmd('%s reflog expire --expire-unreachable=now --all' % gitcmd, d)
+        runfetchcmd('%s repack -ad' % gitcmd, d)
+        runfetchcmd('%s prune --expire now' % gitcmd, d)
+
+    @classmethod
+    def get_all_refs(cls, gitcmd, d, ref_filter=None):
+        """Return all the existing refs in this repository, optionally filtering the refs."""
+        ref_output = runfetchcmd('{} for-each-ref "--format=%(refname)" "%(*objecttype)"'.format(gitcmd), d)
+        ref_split = (tuple(iter_extend(l.rstrip().rsplit('\t', 1), 2)) for l in ref_output.splitlines())
+        if ref_filter:
+            ref_split = (e for e in ref_split if ref_filter(*e))
+        refs = [r for r, _ in ref_split]
+        return refs
+
+    @classmethod
+    def filter_refs(cls, gitcmd, d, refs):
+        """Remove all but the specified refs from the git repository."""
+        all_refs = cls.get_all_refs(gitcmd, d)
+        full_refs = runfetchcmd('%s rev-parse --symbolic-full-name %s' % (gitcmd, ' '.join(refs)), d).splitlines()
+        to_remove = set(all_refs) - set(full_refs)
+        if to_remove:
+            p = bb.process.Popen(['xargs', '-0', '-n', '1', 'git', 'update-ref', '-d', '--no-deref'], stderr=subprocess.PIPE)
+            p.communicate(''.join(l + '\0' for l in to_remove))
 
     def unpack(self, ud, destdir, d):
         """ unpack the downloaded src to destdir"""
 
         subdir = ud.parm.get("subpath", "")
         if subdir != "":
-            readpathspec = ":%s" % (subdir)
+            readpathspec = ":%s" % subdir
             def_destsuffix = "%s/" % os.path.basename(subdir.rstrip('/'))
         else:
             readpathspec = ""

@@ -258,11 +456,17 @@ class Git(FetchMethod):
         if os.path.exists(destdir):
             bb.utils.prunedir(destdir)
 
-        cloneflags = "-s -n"
-        if ud.bareclone:
-            cloneflags += " --mirror"
+        if ud.shallow and (not os.path.exists(ud.clonedir) or self.need_update(ud, d)):
+            bb.utils.mkdirhier(destdir)
+            os.chdir(destdir)
+            runfetchcmd("tar -xzf %s" % ud.fullshallow, d)
+        else:
+            cloneflags = "-s -n"
+            if ud.bareclone:
+                cloneflags += " --mirror"
+
+            runfetchcmd("%s clone %s %s/ %s" % (ud.basecmd, cloneflags, ud.clonedir, destdir), d)
 
-        runfetchcmd("%s clone %s %s/ %s" % (ud.basecmd, cloneflags, ud.clonedir, destdir), d)
         os.chdir(destdir)
         repourl = self._get_repo_url(ud)
         runfetchcmd("%s remote set-url origin %s" % (ud.basecmd, repourl), d)

index 526668b..6289fad 100644
@@ -66,9 +66,13 @@ Supported SRC_URI options are:
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+import collections
 import errno
+import itertools
 import os
 import re
+import subprocess
+import tempfile
 import bb
 import errno
 from   bb    import data

@@ -76,6 +80,23 @@ from   bb.fetch2 import FetchMethod
 from   bb.fetch2 import runfetchcmd
 from   bb.fetch2 import logger
 
+
+def iter_except(func, exception, start=None):
+    """Yield a function repeatedly until it raises an exception."""
+    try:
+        if start is not None:
+            yield start()
+        while True:
+            yield func()
+    except exception:
+        pass
+
+
+def iter_extend(iterable, length, obj=None):
+    """Ensure that iterable is the specified length by extending with obj"""
+    return itertools.islice(itertools.chain(iterable, itertools.repeat(obj)), length)
+
+
 class Git(FetchMethod):
     """Class to fetch a module or modules from git repositories"""
     def init(self, d):

@@ -120,15 +141,43 @@ class Git(FetchMethod):
         branches = ud.parm.get("branch", "master").split(',')
         if len(branches) != len(ud.names):
             raise bb.fetch2.ParameterError("The number of name and branch parameters is not balanced", ud.url)
+
+        ud.shallow = d.getVar("BB_GIT_SHALLOW", True) == "1"
+        ud.shallow_revs = (d.getVar("BB_GIT_SHALLOW_REVS", True) or "").split()
+        trim_refs = d.getVar("BB_GIT_SHALLOW_TRIM_REFS", True)
+        ud.trim_refs = not trim_refs or trim_refs == "0"
+        ud.shallow_extra_refs = (d.getVar("BB_GIT_SHALLOW_EXTRA_REFS", True) or "").split()
+
+        depth_default = d.getVar("BB_GIT_SHALLOW_DEPTH", True)
+        if depth_default is not None:
+            try:
+                depth_default = int(depth_default)
+            except ValueError:
+                raise bb.fetch2.FetchError("Invalid depth for BB_GIT_SHALLOW_DEPTH: %s" % depth_default)
+        else:
+            depth_default = 1
+        ud.shallow_depths = collections.defaultdict(lambda: depth_default)
+
         ud.branches = {}
-        for name in ud.names:
-            branch = branches[ud.names.index(name)]
+        for pos, name in enumerate(ud.names):
+            branch = branches[pos]
             ud.branches[name] = branch
             ud.unresolvedrev[name] = branch
 
+            shallow_depth = d.getVar("BB_GIT_SHALLOW_DEPTH_%s" % name, True)
+            if shallow_depth and shallow_depth != "0":
+                try:
+                    shallow_depth = int(shallow_depth)
+                except ValueError:
+                    raise bb.fetch2.FetchError("Invalid depth for BB_GIT_SHALLOW_DEPTH_%s: %s" % (name, shallow_depth))
+                else:
+                    ud.shallow_depths[name] = shallow_depth
+
         ud.basecmd = data.getVar("FETCHCMD_git", d, True) or "git -c core.fsyncobjectfiles=0"
 
-        ud.write_tarballs = ((data.getVar("BB_GENERATE_MIRROR_TARBALLS", d, True) or "0") != "0") or ud.rebaseable
+        write_tarballs = d.getVar("BB_GENERATE_MIRROR_TARBALLS", True) or "0"
+        ud.write_tarballs = write_tarballs != "0" or ud.rebaseable
+        ud.write_shallow_tarballs = (d.getVar("BB_GENERATE_SHALLOW_TARBALLS", True) or write_tarballs) != "0"
 
         ud.setup_revisons(d)
 

@@ -150,13 +199,36 @@ class Git(FetchMethod):
         if ud.rebaseable:
             for name in ud.names:
                 gitsrcname = gitsrcname + '_' + ud.revisions[name]
-        ud.mirrortarball = 'git2_%s.tar.gz' % (gitsrcname)
-        ud.fullmirror = os.path.join(d.getVar("DL_DIR", True), ud.mirrortarball)
-        gitdir = d.getVar("GITDIR", True) or (d.getVar("DL_DIR", True) + "/git2/")
-        ud.clonedir = os.path.join(gitdir, gitsrcname)
 
+        dl_dir = d.getVar("DL_DIR", True)
+        gitdir = d.getVar("GITDIR", True) or (dl_dir + "/git2/")
+        ud.clonedir = os.path.join(gitdir, gitsrcname)
         ud.localfile = ud.clonedir
 
+        ud.mirrortarball = 'git2_%s.tar.gz' % gitsrcname
+        ud.fullmirror = os.path.join(dl_dir, ud.mirrortarball)
+        if ud.shallow:
+            tarballname = gitsrcname
+            if ud.shallow_revs:
+                tarballname = "%s_%s" % (tarballname, "_".join(sorted(ud.shallow_revs)))
+
+            for name, revision in sorted(ud.revisions.iteritems()):
+                tarballname = "%s_%s" % (tarballname, ud.revisions[name][:7])
+                depth = ud.shallow_depths[name]
+                if depth:
+                    tarballname = "%s-%s" % (tarballname, depth)
+
+            if ud.trim_refs:
+                if not ud.nobranch:
+                    shallow_refs = ud.branches.itervalues()
+                    shallow_refs = itertools.chain(shallow_refs, ud.shallow_extra_refs)
+                    tarballname = "%s_%s" % (tarballname, "_".join(sorted(shallow_refs)).replace('/', '.'))
+                ud.shallowtarball = 'gitshallow_%s.tar.gz' % tarballname
+            else:
+                ud.shallowtarball = 'gitshallowall_%s.tar.gz' % tarballname
+            ud.fullshallow = os.path.join(dl_dir, ud.shallowtarball)
+            ud.mirrortarballs = [ud.shallowtarball, ud.mirrortarball]
+
     def localpath(self, ud, d):
         return ud.clonedir
 

@@ -167,6 +239,8 @@ class Git(FetchMethod):
         for name in ud.names:
             if not self._contains_ref(ud, d, name):
                 return True
+        if ud.shallow and ud.write_shallow_tarballs and not os.path.exists(ud.fullshallow):
+            return True
         if ud.write_tarballs and not os.path.exists(ud.fullmirror):
             return True
         return False

@@ -183,8 +257,16 @@ class Git(FetchMethod):
     def download(self, ud, d):
         """Fetch url"""
 
-        # If the checkout doesn't exist and the mirror tarball does, extract it
-        if not os.path.exists(ud.clonedir) and os.path.exists(ud.fullmirror):
+        no_clone = not os.path.exists(ud.clonedir)
+        need_update = no_clone or self.need_update(ud, d)
+
+        # A current clone is preferred to either tarball, a shallow tarball is
+        # preferred to an out of date clone, and a missing clone will use
+        # either tarball.
+        if ud.shallow and os.path.exists(ud.fullshallow) and need_update:
+            ud.localpath = ud.fullshallow
+            return
+        elif os.path.exists(ud.fullmirror) and no_clone:
             bb.utils.mkdirhier(ud.clonedir)
             os.chdir(ud.clonedir)
             runfetchcmd("tar -xzf %s" % (ud.fullmirror), d)

@@ -231,23 +313,139 @@ class Git(FetchMethod):
                 raise bb.fetch2.FetchError("Unable to find revision %s in branch %s even from upstream" % (ud.revisions[name], ud.branches[name]))
 
     def build_mirror_data(self, ud, d):
-        # Generate a mirror tarball if needed
-        if ud.write_tarballs and not os.path.exists(ud.fullmirror):
-            # it's possible that this symlink points to read-only filesystem with PREMIRROR
+        if ud.shallow and ud.write_shallow_tarballs:
+            if not os.path.exists(ud.fullshallow):
+                if os.path.islink(ud.fullshallow):
+                    os.unlink(ud.fullshallow)
+                tempdir = tempfile.mkdtemp(dir=d.getVar('DL_DIR', True))
+                shallowclone = os.path.join(tempdir, 'git')
+                try:
+                    repourl = self._get_repo_url(ud)
+                    branchinfo = dict((name, (ud.shallow_depths[name], ud.revisions[name], ud.branches[name])) for name in ud.names)
+                    self._populate_shallowclone(repourl, ud.clonedir, shallowclone, ud.basecmd, branchinfo, ud.nobranch, ud.trim_refs, ud.shallow_extra_refs, ud.shallow_revs, ud.bareclone, d)
+
+                    logger.info("Creating tarball of git repository")
+                    runfetchcmd("tar -czf %s %s" % (ud.fullshallow, os.path.join(".")), d)
+                    runfetchcmd("touch %s.done" % ud.fullshallow, d)
+                finally:
+                    bb.utils.remove(tempdir, recurse=True)
+        elif ud.write_tarballs and not os.path.exists(ud.fullmirror):
             if os.path.islink(ud.fullmirror):
                 os.unlink(ud.fullmirror)
-
             os.chdir(ud.clonedir)
             logger.info("Creating tarball of git repository")
-            runfetchcmd("tar -czf %s %s" % (ud.fullmirror, os.path.join(".") ), d)
-            runfetchcmd("touch %s.done" % (ud.fullmirror), d)
+            runfetchcmd("tar -czf %s %s" % (ud.fullmirror, os.path.join(".")), d)
+            runfetchcmd("touch %s.done" % ud.fullmirror, d)
+
+    def _populate_shallowclone(self, repourl, source, dest, gitcmd, branchinfo, nobranch, trim_refs, extra_refs, shallow_revisions, bareclone, d):
+        if shallow_revisions is None:
+            shallow_revisions = []
+
+        # Map depths to revisions
+        to_parse = []
+        for depth, revision, branch in branchinfo.itervalues():
+            if not depth:
+                continue
+
+            to_parse.append('%s~%d^{}' % (revision, depth - 1))
+
+        parsed = runfetchcmd("GIT_DIR='%s' %s rev-parse %s" % (source, gitcmd, " ".join(to_parse)), d)
+        shallow_revisions.extend(parsed.splitlines())
+
+        cloneflags = "-s -n"
+        if bareclone:
+            cloneflags += " --mirror"
+        runfetchcmd("%s clone %s %s %s" % (gitcmd, cloneflags, source, dest), d)
+
+        os.chdir(dest)
+
+        shallow_branches = []
+        shallow_branches.extend(extra_refs)
+        for name, (depth, revision, branch) in branchinfo.iteritems():
+            if nobranch:
+                ref = "refs/shallow/%s" % name
+            else:
+                ref = "refs/remotes/origin/%s" % branch
+
+            if trim_refs:
+                shallow_branches.append(ref)
+            runfetchcmd("%s update-ref %s %s" % (gitcmd, ref, revision), d)
+
+        if trim_refs:
+            self.filter_refs(gitcmd, d, shallow_branches)
+
+        git_dir = runfetchcmd('%s rev-parse --git-dir' % gitcmd, d).rstrip()
+        self._make_repo_shallow(shallow_revisions, git_dir, gitcmd, d, branches=shallow_branches or None)
+
+        alternates_file = os.path.join(git_dir, "objects", "info", "alternates")
+        os.unlink(alternates_file)
+
+    def _make_repo_shallow(self, revisions, git_dir, gitcmd, d, branches=None):
+        if branches is not None:
+            refs = branches
+        else:
+            refs = self.get_all_refs(gitcmd, d, lambda r, t: not t or t == 'commit')
+
+        parsed_revs = runfetchcmd('%s rev-parse %s' % (gitcmd, ' '.join('%s^{}' % i for i in revisions)), d)
+        queue = collections.deque(r.rstrip() for r in parsed_revs.splitlines())
+        seen = set()
+
+        shallow_file = os.path.join(git_dir, 'shallow')
+        try:
+            os.unlink(shallow_file)
+        except OSError as exc:
+            if exc.errno != errno.ENOENT:
+                raise
+
+        for rev in iter_except(queue.popleft, IndexError):
+            if rev in seen:
+                continue
+
+            bb.note("Processing shallow revision: %s" % rev)
+            parent_output = runfetchcmd('%s rev-parse %s^@' % (gitcmd, rev), d)
+            parents = [p.rstrip() for p in parent_output.splitlines()]
+            with open(shallow_file, 'a') as f:
+                f.write(rev + '\n')
+            seen.add(rev)
+
+            for parent in parents:
+                for ref in refs:
+                    try:
+                        merge_base = runfetchcmd('%s merge-base %s %s' % (gitcmd, parent, ref), d).rstrip()
+                    except bb.fetch2.FetchError:
+                        continue
+                    queue.append(merge_base)
+
+        runfetchcmd('%s reflog expire --expire-unreachable=now --all' % gitcmd, d)
+        runfetchcmd('%s repack -ad' % gitcmd, d)
+        runfetchcmd('%s prune --expire now' % gitcmd, d)
+
+    @classmethod
+    def get_all_refs(cls, gitcmd, d, ref_filter=None):
+        """Return all the existing refs in this repository, optionally filtering the refs."""
+        ref_output = runfetchcmd('{} for-each-ref "--format=%(refname)" "%(*objecttype)"'.format(gitcmd), d)
+        ref_split = (tuple(iter_extend(l.rstrip().rsplit('\t', 1), 2)) for l in ref_output.splitlines())
+        if ref_filter:
+            ref_split = (e for e in ref_split if ref_filter(*e))
+        refs = [r for r, _ in ref_split]
+        return refs
+
+    @classmethod
+    def filter_refs(cls, gitcmd, d, refs):
+        """Remove all but the specified refs from the git repository."""
+        all_refs = cls.get_all_refs(gitcmd, d)
+        full_refs = runfetchcmd('%s rev-parse --symbolic-full-name %s' % (gitcmd, ' '.join(refs)), d).splitlines()
+        to_remove = set(all_refs) - set(full_refs)
+        if to_remove:
+            p = bb.process.Popen(['xargs', '-0', '-n', '1', 'git', 'update-ref', '-d', '--no-deref'], stderr=subprocess.PIPE)
+            p.communicate(''.join(l + '\0' for l in to_remove))
 
     def unpack(self, ud, destdir, d):
         """ unpack the downloaded src to destdir"""
 
         subdir = ud.parm.get("subpath", "")
         if subdir != "":
-            readpathspec = ":%s" % (subdir)
+            readpathspec = ":%s" % subdir
             def_destsuffix = "%s/" % os.path.basename(subdir.rstrip('/'))
         else:
             readpathspec = ""

@@ -258,11 +456,17 @@ class Git(FetchMethod):
         if os.path.exists(destdir):
             bb.utils.prunedir(destdir)
 
-        cloneflags = "-s -n"
-        if ud.bareclone:
-            cloneflags += " --mirror"
+        if ud.shallow and (not os.path.exists(ud.clonedir) or self.need_update(ud, d)):
+            bb.utils.mkdirhier(destdir)
+            os.chdir(destdir)
+            runfetchcmd("tar -xzf %s" % ud.fullshallow, d)
+        else:
+            cloneflags = "-s -n"
+            if ud.bareclone:
+                cloneflags += " --mirror"
+
+            runfetchcmd("%s clone %s %s/ %s" % (ud.basecmd, cloneflags, ud.clonedir, destdir), d)
 
-        runfetchcmd("%s clone %s %s/ %s" % (ud.basecmd, cloneflags, ud.clonedir, destdir), d)
         os.chdir(destdir)
         repourl = self._get_repo_url(ud)
         runfetchcmd("%s remote set-url origin %s" % (ud.basecmd, repourl), d)