Release 3.0.6

[pinch] / pinch.py

diff --git a/pinch.py b/pinch.py
index 8fe7df16c10958ccaa6c0edfd8c7a834d444faa4..f95323f68edc611ead3c3e85de9ec814dc785e09 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -1,4 +1,3 @@
-from abc import ABC, abstractmethod

 import argparse
 import configparser
 import filecmp
 import argparse
 import configparser
 import filecmp


@@ -12,6 +11,7 @@ import shlex
 import shutil
 import subprocess
 import sys
 import shutil
 import subprocess
 import sys

+import tarfile

 import tempfile
 import types
 import urllib.parse
 import tempfile
 import types
 import urllib.parse


@@ -19,6 +19,7 @@ import urllib.request
 import xml.dom.minidom
 
 from typing import (
 import xml.dom.minidom
 
 from typing import (

+    Callable,

     Dict,
     Iterable,
     List,
     Dict,
     Iterable,
     List,


@@ -26,11 +27,15 @@ from typing import (
     NamedTuple,
     NewType,
     Optional,
     NamedTuple,
     NewType,
     Optional,

+    Set,

     Tuple,
     Type,
     Tuple,
     Type,

+    TypeVar,

     Union,
 )
 
     Union,
 )
 

+import git_cache
+

 # Use xdg module when it's less painful to have as a dependency
 
 
 # Use xdg module when it's less painful to have as a dependency
 
 


@@ -95,6 +100,12 @@ class AliasPin(NamedTuple):
     pass
 
 
     pass
 
 

+class SymlinkPin(NamedTuple):
+    @property
+    def release_name(self) -> str:
+        return 'link'
+
+

 class GitPin(NamedTuple):
     git_revision: str
     release_name: str
 class GitPin(NamedTuple):
     git_revision: str
     release_name: str


@@ -107,90 +118,103 @@ class ChannelPin(NamedTuple):
     tarball_sha256: str
 
 
     tarball_sha256: str
 
 

-Pin = Union[AliasPin, GitPin, ChannelPin]
+Pin = Union[AliasPin, SymlinkPin, GitPin, ChannelPin]

 
 
 
 

-class SearchPath(types.SimpleNamespace, ABC):
+def copy_to_nix_store(v: Verification, filename: str) -> str:
+    v.status('Putting tarball in Nix store')
+    process = subprocess.run(
+        ['nix-store', '--add', filename], stdout=subprocess.PIPE)
+    v.result(process.returncode == 0)
+    return process.stdout.decode().strip()  # type: ignore  # (for old mypy)

 
 

-    @abstractmethod
-    def pin(self, v: Verification) -> Pin:
-        pass

 
 

+def symlink_archive(v: Verification, path: str) -> str:
+    with tempfile.TemporaryDirectory() as td:
+        archive_filename = os.path.join(td, 'link.tar.gz')
+        os.symlink(path, os.path.join(td, 'link'))
+        with tarfile.open(archive_filename, mode='x:gz') as t:
+            t.add(os.path.join(td, 'link'), arcname='link')
+        return copy_to_nix_store(v, archive_filename)

 
 

-class AliasSearchPath(SearchPath):
+
+class AliasSearchPath(NamedTuple):

     alias_of: str
 
     alias_of: str
 

-    def pin(self, v: Verification) -> AliasPin:
-        assert not hasattr(self, 'git_repo')
+    # pylint: disable=no-self-use
+    def pin(self, _: Verification, __: Optional[Pin]) -> AliasPin:

         return AliasPin()
 
 
         return AliasPin()
 
 

-# (This lint-disable is for pylint bug https://github.com/PyCQA/pylint/issues/179
-# which is fixed in pylint 2.5.)
-class TarrableSearchPath(SearchPath, ABC):  # pylint: disable=abstract-method
-    channel_html: bytes
-    channel_url: str
-    forwarded_url: str
-    git_ref: str
-    git_repo: str
-    table: Dict[str, ChannelTableEntry]
+class SymlinkSearchPath(NamedTuple):
+    path: str
+
+    # pylint: disable=no-self-use
+    def pin(self, _: Verification, __: Optional[Pin]) -> SymlinkPin:
+        return SymlinkPin()

 
 

+    def fetch(self, v: Verification, _: Pin) -> str:
+        return symlink_archive(v, self.path)

 
 

-class GitSearchPath(TarrableSearchPath):
-    def pin(self, v: Verification) -> GitPin:
-        old_revision = (
-            self.git_revision if hasattr(self, 'git_revision') else None)
-        if hasattr(self, 'git_revision'):
-            del self.git_revision

 
 

-        new_revision = git_fetch(v, self, None, old_revision)
+class GitSearchPath(NamedTuple):
+    git_ref: str
+    git_repo: str
+
+    def pin(self, v: Verification, old_pin: Optional[Pin]) -> GitPin:
+        _, new_revision = git_cache.fetch(self.git_repo, self.git_ref)
+        if old_pin is not None:
+            assert isinstance(old_pin, GitPin)
+            verify_git_ancestry(v, self, old_pin.git_revision, new_revision)

         return GitPin(release_name=git_revision_name(v, self, new_revision),
                       git_revision=new_revision)
 
         return GitPin(release_name=git_revision_name(v, self, new_revision),
                       git_revision=new_revision)
 

-    def fetch(self, v: Verification, section: str,
-              conf: configparser.SectionProxy) -> str:
-        if 'git_revision' not in conf or 'release_name' not in conf:
-            raise Exception(
-                'Cannot update unpinned channel "%s" (Run "pin" before "update")' %
-                section)
-        the_pin = GitPin(
-            release_name=conf['release_name'],
-            git_revision=conf['git_revision'])
-
-        ensure_git_rev_available(v, self, the_pin, None)
-        return git_get_tarball(v, self, the_pin)
-
-
-class ChannelSearchPath(TarrableSearchPath):
-    def pin(self, v: Verification) -> ChannelPin:
-        old_revision = (
-            self.git_revision if hasattr(self, 'git_revision') else None)
-        if hasattr(self, 'git_revision'):
-            del self.git_revision
-
-        fetch(v, self)
-        new_gitpin = parse_channel(v, self)
-        fetch_resources(v, self, new_gitpin)
-        ensure_git_rev_available(v, self, new_gitpin, old_revision)
-        check_channel_contents(v, self, new_gitpin)
+    def fetch(self, v: Verification, pin: Pin) -> str:
+        assert isinstance(pin, GitPin)
+        git_cache.ensure_rev_available(
+            self.git_repo, self.git_ref, pin.git_revision)
+        return git_get_tarball(v, self, pin)
+
+
+class ChannelSearchPath(NamedTuple):
+    channel_url: str
+    git_ref: str
+    git_repo: str
+
+    def pin(self, v: Verification, old_pin: Optional[Pin]) -> ChannelPin:
+        if old_pin is not None:
+            assert isinstance(old_pin, ChannelPin)
+
+        channel_html, forwarded_url = fetch_channel(v, self)
+        table, new_gitpin = parse_channel(v, channel_html)
+        if old_pin is not None and old_pin.git_revision == new_gitpin.git_revision:
+            return old_pin
+        fetch_resources(v, new_gitpin, forwarded_url, table)
+        git_cache.ensure_rev_available(
+            self.git_repo, self.git_ref, new_gitpin.git_revision)
+        if old_pin is not None:
+            verify_git_ancestry(
+                v, self, old_pin.git_revision, new_gitpin.git_revision)
+        check_channel_contents(v, self, table, new_gitpin)

         return ChannelPin(
             release_name=new_gitpin.release_name,
         return ChannelPin(
             release_name=new_gitpin.release_name,

-            tarball_url=self.table['nixexprs.tar.xz'].absolute_url,
-            tarball_sha256=self.table['nixexprs.tar.xz'].digest,
+            tarball_url=table['nixexprs.tar.xz'].absolute_url,
+            tarball_sha256=table['nixexprs.tar.xz'].digest,

             git_revision=new_gitpin.git_revision)
 
             git_revision=new_gitpin.git_revision)
 

-    # Lint TODO: Put tarball_url and tarball_sha256 in ChannelSearchPath

     # pylint: disable=no-self-use
     # pylint: disable=no-self-use

-    def fetch(self, v: Verification, section: str,
-              conf: configparser.SectionProxy) -> str:
-        if 'git_repo' not in conf or 'release_name' not in conf:
-            raise Exception(
-                'Cannot update unpinned channel "%s" (Run "pin" before "update")' %
-                section)
+    def fetch(self, v: Verification, pin: Pin) -> str:
+        assert isinstance(pin, ChannelPin)

 
         return fetch_with_nix_prefetch_url(
 
         return fetch_with_nix_prefetch_url(

-            v, conf['tarball_url'], Digest16(
-                conf['tarball_sha256']))
+            v, pin.tarball_url, Digest16(pin.tarball_sha256))
+
+
+SearchPath = Union[AliasSearchPath,
+                   SymlinkSearchPath,
+                   GitSearchPath,
+                   ChannelSearchPath]
+TarrableSearchPath = Union[GitSearchPath, ChannelSearchPath]

 
 
 def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:
 
 
 def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:


@@ -221,18 +245,21 @@ def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:
     return filecmp.cmpfiles(a, b, files, shallow=False)
 
 
     return filecmp.cmpfiles(a, b, files, shallow=False)
 
 

-def fetch(v: Verification, channel: TarrableSearchPath) -> None:
-    v.status('Fetching channel')
+def fetch_channel(
+        v: Verification, channel: ChannelSearchPath) -> Tuple[str, str]:
+    v.status('Fetching channel from %s' % channel.channel_url)

     request = urllib.request.urlopen(channel.channel_url, timeout=10)
     request = urllib.request.urlopen(channel.channel_url, timeout=10)

-    channel.channel_html = request.read()
-    channel.forwarded_url = request.geturl()
+    channel_html = request.read().decode()
+    forwarded_url = request.geturl()

     v.result(request.status == 200)  # type: ignore  # (for old mypy)
     v.result(request.status == 200)  # type: ignore  # (for old mypy)

-    v.check('Got forwarded', channel.channel_url != channel.forwarded_url)
+    v.check('Got forwarded', channel.channel_url != forwarded_url)
+    return channel_html, forwarded_url

 
 
 
 

-def parse_channel(v: Verification, channel: TarrableSearchPath) -> GitPin:
+def parse_channel(v: Verification, channel_html: str) \
+        -> Tuple[Dict[str, ChannelTableEntry], GitPin]:

     v.status('Parsing channel description as XML')
     v.status('Parsing channel description as XML')

-    d = xml.dom.minidom.parseString(channel.channel_html)
+    d = xml.dom.minidom.parseString(channel_html)

     v.ok()
 
     v.status('Extracting release name:')
     v.ok()
 
     v.status('Extracting release name:')


@@ -251,16 +278,15 @@ def parse_channel(v: Verification, channel: TarrableSearchPath) -> GitPin:
     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 
     v.status('Parsing table')
     v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ')
 
     v.status('Parsing table')

-    channel.table = {}
+    table: Dict[str, ChannelTableEntry] = {}

     for row in d.getElementsByTagName('tr')[1:]:
         name = row.childNodes[0].firstChild.firstChild.nodeValue
         url = row.childNodes[0].firstChild.getAttribute('href')
         size = int(row.childNodes[1].firstChild.nodeValue)
         digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)
     for row in d.getElementsByTagName('tr')[1:]:
         name = row.childNodes[0].firstChild.firstChild.nodeValue
         url = row.childNodes[0].firstChild.getAttribute('href')
         size = int(row.childNodes[1].firstChild.nodeValue)
         digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue)

-        channel.table[name] = ChannelTableEntry(
-            url=url, digest=digest, size=size)
+        table[name] = ChannelTableEntry(url=url, digest=digest, size=size)

     v.ok()
     v.ok()

-    return GitPin(release_name=title_name, git_revision=git_revision)
+    return table, GitPin(release_name=title_name, git_revision=git_revision)

 
 
 def digest_string(s: bytes) -> Digest16:
 
 
 def digest_string(s: bytes) -> Digest16:


@@ -276,18 +302,39 @@ def digest_file(filename: str) -> Digest16:
     return Digest16(hasher.hexdigest())
 
 
     return Digest16(hasher.hexdigest())
 
 

+@functools.lru_cache
+def _experimental_flag_needed(v: Verification) -> bool:
+    v.status('Checking Nix version')
+    process = subprocess.run(['nix', '--help'], stdout=subprocess.PIPE)
+    v.result(process.returncode == 0)
+    return b'--experimental-features' in process.stdout
+
+
+def _nix_command(v: Verification) -> List[str]:
+    return ['nix', '--experimental-features',
+            'nix-command'] if _experimental_flag_needed(v) else ['nix']
+
+

 def to_Digest16(v: Verification, digest32: Digest32) -> Digest16:
     v.status('Converting digest to base16')
 def to_Digest16(v: Verification, digest32: Digest32) -> Digest16:
     v.status('Converting digest to base16')

-    process = subprocess.run(
-        ['nix', 'to-base16', '--type', 'sha256', digest32], stdout=subprocess.PIPE)
+    process = subprocess.run(_nix_command(v) + [
+        'to-base16',
+        '--type',
+        'sha256',
+        digest32],
+        stdout=subprocess.PIPE)

     v.result(process.returncode == 0)
     return Digest16(process.stdout.decode().strip())
 
 
 def to_Digest32(v: Verification, digest16: Digest16) -> Digest32:
     v.status('Converting digest to base32')
     v.result(process.returncode == 0)
     return Digest16(process.stdout.decode().strip())
 
 
 def to_Digest32(v: Verification, digest16: Digest16) -> Digest32:
     v.status('Converting digest to base32')

-    process = subprocess.run(
-        ['nix', 'to-base32', '--type', 'sha256', digest16], stdout=subprocess.PIPE)
+    process = subprocess.run(_nix_command(v) + [
+        'to-base32',
+        '--type',
+        'sha256',
+        digest16],
+        stdout=subprocess.PIPE)

     v.result(process.returncode == 0)
     return Digest32(process.stdout.decode().strip())
 
     v.result(process.returncode == 0)
     return Digest32(process.stdout.decode().strip())
 


@@ -304,7 +351,7 @@ def fetch_with_nix_prefetch_url(
     assert empty == ''
     v.check("Verifying nix-prefetch-url's digest",
             to_Digest16(v, Digest32(prefetch_digest)) == digest)
     assert empty == ''
     v.check("Verifying nix-prefetch-url's digest",
             to_Digest16(v, Digest32(prefetch_digest)) == digest)

-    v.status("Verifying file digest")
+    v.status("Verifying digest of %s" % path)

     file_digest = digest_file(path)
     v.result(file_digest == digest)
     return path  # type: ignore  # (for old mypy)
     file_digest = digest_file(path)
     v.result(file_digest == digest)
     return path  # type: ignore  # (for old mypy)


@@ -312,25 +359,16 @@ def fetch_with_nix_prefetch_url(
 
 def fetch_resources(
         v: Verification,
 
 def fetch_resources(
         v: Verification,

-        channel: ChannelSearchPath,
-        pin: GitPin) -> None:
+        pin: GitPin,
+        forwarded_url: str,
+        table: Dict[str, ChannelTableEntry]) -> None:

     for resource in ['git-revision', 'nixexprs.tar.xz']:
     for resource in ['git-revision', 'nixexprs.tar.xz']:

-        fields = channel.table[resource]
-        fields.absolute_url = urllib.parse.urljoin(
-            channel.forwarded_url, fields.url)
+        fields = table[resource]
+        fields.absolute_url = urllib.parse.urljoin(forwarded_url, fields.url)

         fields.file = fetch_with_nix_prefetch_url(
             v, fields.absolute_url, fields.digest)
     v.status('Verifying git commit on main page matches git commit in table')
         fields.file = fetch_with_nix_prefetch_url(
             v, fields.absolute_url, fields.digest)
     v.status('Verifying git commit on main page matches git commit in table')

-    v.result(
-        open(
-            channel.table['git-revision'].file).read(999) == pin.git_revision)
-
-
-def git_cachedir(git_repo: str) -> str:
-    return os.path.join(
-        xdg.XDG_CACHE_HOME,
-        'pinch/git',
-        digest_string(git_repo.encode()))
+    v.result(open(table['git-revision'].file).read(999) == pin.git_revision)

 
 
 def tarball_cache_file(channel: TarrableSearchPath, pin: GitPin) -> str:
 
 
 def tarball_cache_file(channel: TarrableSearchPath, pin: GitPin) -> str:


@@ -346,101 +384,19 @@ def tarball_cache_file(channel: TarrableSearchPath, pin: GitPin) -> str:
 def verify_git_ancestry(
         v: Verification,
         channel: TarrableSearchPath,
 def verify_git_ancestry(
         v: Verification,
         channel: TarrableSearchPath,

-        new_revision: str,
-        old_revision: Optional[str]) -> None:
-    cachedir = git_cachedir(channel.git_repo)
-    v.status('Verifying rev is an ancestor of ref')
+        old_revision: str,
+        new_revision: str) -> None:
+    cachedir = git_cache.git_cachedir(channel.git_repo)
+    v.status('Verifying rev is an ancestor of previous rev %s' % old_revision)

     process = subprocess.run(['git',
                               '-C',
                               cachedir,
                               'merge-base',
                               '--is-ancestor',
     process = subprocess.run(['git',
                               '-C',
                               cachedir,
                               'merge-base',
                               '--is-ancestor',

-                              new_revision,
-                              channel.git_ref])
-    v.result(process.returncode == 0)
-
-    if old_revision is not None:
-        v.status(
-            'Verifying rev is an ancestor of previous rev %s' %
-            old_revision)
-        process = subprocess.run(['git',
-                                  '-C',
-                                  cachedir,
-                                  'merge-base',
-                                  '--is-ancestor',
-                                  old_revision,
-                                  new_revision])
-        v.result(process.returncode == 0)
-
-
-def git_fetch(
-        v: Verification,
-        channel: TarrableSearchPath,
-        desired_revision: Optional[str],
-        old_revision: Optional[str]) -> str:
-    # It would be nice if we could share the nix git cache, but as of the time
-    # of writing it is transitioning from gitv2 (deprecated) to gitv3 (not ready
-    # yet), and trying to straddle them both is too far into nix implementation
-    # details for my comfort.  So we re-implement here half of nix.fetchGit.
-    # :(
-
-    cachedir = git_cachedir(channel.git_repo)
-    if not os.path.exists(cachedir):
-        v.status("Initializing git repo")
-        process = subprocess.run(
-            ['git', 'init', '--bare', cachedir])
-        v.result(process.returncode == 0)
-
-    v.status('Fetching ref "%s" from %s' % (channel.git_ref, channel.git_repo))
-    # We don't use --force here because we want to abort and freak out if forced
-    # updates are happening.
-    process = subprocess.run(['git',
-                              '-C',
-                              cachedir,
-                              'fetch',
-                              channel.git_repo,
-                              '%s:%s' % (channel.git_ref,
-                                         channel.git_ref)])
+                              old_revision,
+                              new_revision])

     v.result(process.returncode == 0)
 
     v.result(process.returncode == 0)
 

-    if desired_revision is not None:
-        v.status('Verifying that fetch retrieved this rev')
-        process = subprocess.run(
-            ['git', '-C', cachedir, 'cat-file', '-e', desired_revision])
-        v.result(process.returncode == 0)
-
-    new_revision = open(
-        os.path.join(
-            cachedir,
-            'refs',
-            'heads',
-            channel.git_ref)).read(999).strip()
-
-    verify_git_ancestry(v, channel, new_revision, old_revision)
-
-    return new_revision
-
-
-def ensure_git_rev_available(
-        v: Verification,
-        channel: TarrableSearchPath,
-        pin: GitPin,
-        old_revision: Optional[str]) -> None:
-    cachedir = git_cachedir(channel.git_repo)
-    if os.path.exists(cachedir):
-        v.status('Checking if we already have this rev:')
-        process = subprocess.run(
-            ['git', '-C', cachedir, 'cat-file', '-e', pin.git_revision])
-        if process.returncode == 0:
-            v.status('yes')
-        if process.returncode == 1:
-            v.status('no')
-        v.result(process.returncode == 0 or process.returncode == 1)
-        if process.returncode == 0:
-            verify_git_ancestry(v, channel, pin.git_revision, old_revision)
-            return
-    git_fetch(v, channel, pin.git_revision, old_revision)
-

 
 def compare_tarball_and_git(
         v: Verification,
 
 def compare_tarball_and_git(
         v: Verification,


@@ -477,13 +433,10 @@ def compare_tarball_and_git(
 
 def extract_tarball(
         v: Verification,
 
 def extract_tarball(
         v: Verification,

-        channel: TarrableSearchPath,
+        table: Dict[str, ChannelTableEntry],

         dest: str) -> None:
         dest: str) -> None:

-    v.status('Extracting tarball %s' %
-             channel.table['nixexprs.tar.xz'].file)
-    shutil.unpack_archive(
-        channel.table['nixexprs.tar.xz'].file,
-        dest)
+    v.status('Extracting tarball %s' % table['nixexprs.tar.xz'].file)
+    shutil.unpack_archive(table['nixexprs.tar.xz'].file, dest)

     v.ok()
 
 
     v.ok()
 
 


@@ -495,7 +448,7 @@ def git_checkout(
     v.status('Checking out corresponding git revision')
     git = subprocess.Popen(['git',
                             '-C',
     v.status('Checking out corresponding git revision')
     git = subprocess.Popen(['git',
                             '-C',

-                            git_cachedir(channel.git_repo),
+                            git_cache.git_cachedir(channel.git_repo),

                             'archive',
                             pin.git_revision],
                            stdout=subprocess.PIPE)
                             'archive',
                             pin.git_revision],
                            stdout=subprocess.PIPE)


@@ -527,7 +480,7 @@ def git_get_tarball(
                 pin.git_revision)
             git = subprocess.Popen(['git',
                                     '-C',
                 pin.git_revision)
             git = subprocess.Popen(['git',
                                     '-C',

-                                    git_cachedir(channel.git_repo),
+                                    git_cache.git_cachedir(channel.git_repo),

                                     'archive',
                                     '--prefix=%s/' % pin.release_name,
                                     pin.git_revision],
                                     'archive',
                                     '--prefix=%s/' % pin.release_name,
                                     pin.git_revision],


@@ -537,11 +490,7 @@ def git_get_tarball(
             git.wait()
             v.result(git.returncode == 0 and xz.returncode == 0)
 
             git.wait()
             v.result(git.returncode == 0 and xz.returncode == 0)
 

-        v.status('Putting tarball in Nix store')
-        process = subprocess.run(
-            ['nix-store', '--add', output_filename], stdout=subprocess.PIPE)
-        v.result(process.returncode == 0)
-        store_tarball = process.stdout.decode().strip()
+        store_tarball = copy_to_nix_store(v, output_filename)

 
         os.makedirs(os.path.dirname(cache_file), exist_ok=True)
         open(cache_file, 'w').write(store_tarball)
 
         os.makedirs(os.path.dirname(cache_file), exist_ok=True)
         open(cache_file, 'w').write(store_tarball)


@@ -575,11 +524,12 @@ def check_channel_metadata(
 def check_channel_contents(
         v: Verification,
         channel: TarrableSearchPath,
 def check_channel_contents(
         v: Verification,
         channel: TarrableSearchPath,

+        table: Dict[str, ChannelTableEntry],

         pin: GitPin) -> None:
     with tempfile.TemporaryDirectory() as channel_contents, \
             tempfile.TemporaryDirectory() as git_contents:
 
         pin: GitPin) -> None:
     with tempfile.TemporaryDirectory() as channel_contents, \
             tempfile.TemporaryDirectory() as git_contents:
 

-        extract_tarball(v, channel, channel_contents)
+        extract_tarball(v, table, channel_contents)

         check_channel_metadata(v, pin, channel_contents)
 
         git_checkout(v, channel, pin, git_contents)
         check_channel_metadata(v, pin, channel_contents)
 
         git_checkout(v, channel, pin, git_contents)


@@ -597,7 +547,7 @@ def git_revision_name(
     v.status('Getting commit date')
     process = subprocess.run(['git',
                               '-C',
     v.status('Getting commit date')
     process = subprocess.run(['git',
                               '-C',

-                              git_cachedir(channel.git_repo),
+                              git_cache.git_cachedir(channel.git_repo),

                               'log',
                               '-n1',
                               '--format=%ct-%h',
                               'log',
                               '-n1',
                               '--format=%ct-%h',


@@ -610,13 +560,52 @@ def git_revision_name(
                       process.stdout.decode().strip())
 
 
                       process.stdout.decode().strip())
 
 

-def read_search_path(conf: configparser.SectionProxy) -> SearchPath:
-    mapping: Mapping[str, Type[SearchPath]] = {
-        'alias': AliasSearchPath,
-        'channel': ChannelSearchPath,
-        'git': GitSearchPath,
+K = TypeVar('K')
+V = TypeVar('V')
+
+
+def partition_dict(pred: Callable[[K, V], bool],
+                   d: Dict[K, V]) -> Tuple[Dict[K, V], Dict[K, V]]:
+    selected: Dict[K, V] = {}
+    remaining: Dict[K, V] = {}
+    for k, v in d.items():
+        if pred(k, v):
+            selected[k] = v
+        else:
+            remaining[k] = v
+    return selected, remaining
+
+
+def filter_dict(d: Dict[K, V], fields: Set[K]
+                ) -> Tuple[Dict[K, V], Dict[K, V]]:
+    return partition_dict(lambda k, v: k in fields, d)
+
+
+def read_config_section(
+        conf: configparser.SectionProxy) -> Tuple[SearchPath, Optional[Pin]]:
+    mapping: Mapping[str, Tuple[Type[SearchPath], Type[Pin]]] = {
+        'alias': (AliasSearchPath, AliasPin),
+        'channel': (ChannelSearchPath, ChannelPin),
+        'git': (GitSearchPath, GitPin),
+        'symlink': (SymlinkSearchPath, SymlinkPin),

     }
     }

-    return mapping[conf['type']](**dict(conf.items()))
+    SP, P = mapping[conf['type']]
+    _, all_fields = filter_dict(dict(conf.items()), set(['type']))
+    pin_fields, remaining_fields = filter_dict(all_fields, set(P._fields))
+    # Error suppression works around https://github.com/python/mypy/issues/9007
+    pin_present = pin_fields != {} or P._fields == ()
+    pin = P(**pin_fields) if pin_present else None  # type: ignore
+    return SP(**remaining_fields), pin
+
+
+def read_pinned_config_section(
+        section: str, conf: configparser.SectionProxy) -> Tuple[SearchPath, Pin]:
+    sp, pin = read_config_section(conf)
+    if pin is None:
+        raise Exception(
+            'Cannot update unpinned channel "%s" (Run "pin" before "update")' %
+            section)
+    return sp, pin

 
 
 def read_config(filename: str) -> configparser.ConfigParser:
 
 
 def read_config(filename: str) -> configparser.ConfigParser:


@@ -644,9 +633,9 @@ def pinCommand(args: argparse.Namespace) -> None:
         if args.channels and section not in args.channels:
             continue
 
         if args.channels and section not in args.channels:
             continue
 

-        sp = read_search_path(config[section])
+        sp, old_pin = read_config_section(config[section])

 
 

-        config[section].update(sp.pin(v)._asdict())
+        config[section].update(sp.pin(v, old_pin)._asdict())

 
     with open(args.channels_file, 'w') as configfile:
         config.write(configfile)
 
     with open(args.channels_file, 'w') as configfile:
         config.write(configfile)


@@ -655,31 +644,42 @@ def pinCommand(args: argparse.Namespace) -> None:
 def updateCommand(args: argparse.Namespace) -> None:
     v = Verification()
     exprs: Dict[str, str] = {}
 def updateCommand(args: argparse.Namespace) -> None:
     v = Verification()
     exprs: Dict[str, str] = {}

-    config = read_config_files(args.channels_file)
-    for section in config:
-        sp = read_search_path(config[section])
-        if isinstance(sp, AliasSearchPath):
-            assert 'git_repo' not in config[section]
-            continue
-        tarball = sp.fetch(v, section, config[section])
+    profile_manifest = os.path.join(args.profile, "manifest.nix")
+    search_paths: List[str] = [
+        "-I", "pinch_profile=" + args.profile,
+        "-I", "pinch_profile_manifest=" + os.readlink(profile_manifest)
+    ] if os.path.exists(profile_manifest) else []
+    config = {
+        section: read_pinned_config_section(section, conf) for section,
+        conf in read_config_files(
+            args.channels_file).items()}
+    alias, nonalias = partition_dict(
+        lambda k, v: isinstance(v[0], AliasSearchPath), config)
+
+    for section, (sp, pin) in sorted(nonalias.items()):
+        assert not isinstance(sp, AliasSearchPath)  # mypy can't see through
+        assert not isinstance(pin, AliasPin)        # partition_dict()
+        tarball = sp.fetch(v, pin)
+        search_paths.extend(["-I", "pinch_tarball_for_%s=%s" %
+                            (pin.release_name, tarball)])

         exprs[section] = (
             'f: f { name = "%s"; channelName = "%%s"; src = builtins.storePath "%s"; }' %
         exprs[section] = (
             'f: f { name = "%s"; channelName = "%%s"; src = builtins.storePath "%s"; }' %

-            (config[section]['release_name'], tarball))
+            (pin.release_name, tarball))

 
 

-    for section in config:
-        if 'alias_of' in config[section]:
-            exprs[section] = exprs[str(config[section]['alias_of'])]
+    for section, (sp, pin) in alias.items():
+        assert isinstance(sp, AliasSearchPath)  # For mypy
+        exprs[section] = exprs[sp.alias_of]

 
     command = [
         'nix-env',
         '--profile',
 
     command = [
         'nix-env',
         '--profile',

-        '/nix/var/nix/profiles/per-user/%s/channels' %
-        getpass.getuser(),
+        args.profile,

         '--show-trace',
         '--file',
         '<nix/unpack-channel.nix>',
         '--install',
         '--show-trace',
         '--file',
         '<nix/unpack-channel.nix>',
         '--install',

-        '--from-expression'] + [exprs[name] % name for name in sorted(exprs.keys())]
+    ] + search_paths + ['--from-expression'] + [
+        exprs[name] % name for name in sorted(exprs.keys())]

     if args.dry_run:
         print(' '.join(map(shlex.quote, command)))
     else:
     if args.dry_run:
         print(' '.join(map(shlex.quote, command)))
     else:


@@ -697,6 +697,8 @@ def main() -> None:
     parser_pin.set_defaults(func=pinCommand)
     parser_update = subparsers.add_parser('update')
     parser_update.add_argument('--dry-run', action='store_true')
     parser_pin.set_defaults(func=pinCommand)
     parser_update = subparsers.add_parser('update')
     parser_update.add_argument('--dry-run', action='store_true')

+    parser_update.add_argument('--profile', default=(
+        '/nix/var/nix/profiles/per-user/%s/channels' % getpass.getuser()))

     parser_update.add_argument('channels_file', type=str, nargs='+')
     parser_update.set_defaults(func=updateCommand)
     args = parser.parse_args()
     parser_update.add_argument('channels_file', type=str, nargs='+')
     parser_update.set_defaults(func=updateCommand)
     args = parser.parse_args()