polymorphic fetch()

[pinch] / pinch.py

diff --git a/pinch.py b/pinch.py
index 7049b69134f7ac114c58d815662c221817972c37..58f7a3290cc507760303858cd90ba351f118d0e0 100644 (file)
--- a/pinch.py
+++ b/pinch.py
@@ -1,3 +1,4 @@
+from abc import ABC, abstractmethod

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


@@ -85,12 +86,24 @@ class ChannelTableEntry(types.SimpleNamespace):
     url: str
 
 
     url: str
 
 

-class SearchPath(types.SimpleNamespace):
+class SearchPath(types.SimpleNamespace, ABC):

     release_name: str
 
     release_name: str
 

+    @abstractmethod
+    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
+        pass
+

 
 

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

     alias_of: str
     alias_of: str

+
+    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
+        assert not hasattr(self, 'git_repo')
+
+
+# (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
     channel_html: bytes
     channel_url: str
     forwarded_url: str


@@ -100,23 +113,15 @@ class Channel(SearchPath):
     old_git_revision: str
     table: Dict[str, ChannelTableEntry]
 
     old_git_revision: str
     table: Dict[str, ChannelTableEntry]
 

-    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
-        if hasattr(self, 'alias_of'):
-            assert not hasattr(self, 'git_repo')
-            return

 
 

+class GitSearchPath(TarrableSearchPath):
+    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:

         if hasattr(self, 'git_revision'):
             self.old_git_revision = self.git_revision
             del self.git_revision
 
         if hasattr(self, 'git_revision'):
             self.old_git_revision = self.git_revision
             del self.git_revision
 

-        if 'channel_url' in conf:
-            pin_channel(v, self)
-            conf['release_name'] = self.release_name
-            conf['tarball_url'] = self.table['nixexprs.tar.xz'].absolute_url
-            conf['tarball_sha256'] = self.table['nixexprs.tar.xz'].digest
-        else:
-            git_fetch(v, self)
-            conf['release_name'] = git_revision_name(v, self)
+        git_fetch(v, self)
+        conf['release_name'] = git_revision_name(v, self)

         conf['git_revision'] = self.git_revision
 
     def fetch(self, v: Verification, section: str,
         conf['git_revision'] = self.git_revision
 
     def fetch(self, v: Verification, section: str,


@@ -126,15 +131,36 @@ class Channel(SearchPath):
                 'Cannot update unpinned channel "%s" (Run "pin" before "update")' %
                 section)
 
                 'Cannot update unpinned channel "%s" (Run "pin" before "update")' %
                 section)
 

-        if 'channel_url' in conf:
-            return fetch_with_nix_prefetch_url(
-                v, conf['tarball_url'], Digest16(
-                    conf['tarball_sha256']))
-

         ensure_git_rev_available(v, self)
         return git_get_tarball(v, self)
 
 
         ensure_git_rev_available(v, self)
         return git_get_tarball(v, self)
 
 

+class ChannelSearchPath(TarrableSearchPath):
+    def pin(self, v: Verification, conf: configparser.SectionProxy) -> None:
+        if hasattr(self, 'git_revision'):
+            self.old_git_revision = self.git_revision
+            del self.git_revision
+
+        pin_channel(v, self)
+        conf['release_name'] = self.release_name
+        conf['tarball_url'] = self.table['nixexprs.tar.xz'].absolute_url
+        conf['tarball_sha256'] = self.table['nixexprs.tar.xz'].digest
+        conf['git_revision'] = self.git_revision
+
+    # Lint TODO: Put tarball_url and tarball_sha256 in ChannelSearchPath
+    # 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)
+
+        return fetch_with_nix_prefetch_url(
+            v, conf['tarball_url'], Digest16(
+                conf['tarball_sha256']))
+
+

 def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:
 
     def throw(error: OSError) -> None:
 def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]:
 
     def throw(error: OSError) -> None:


@@ -163,7 +189,7 @@ 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: Channel) -> None:
+def fetch(v: Verification, channel: TarrableSearchPath) -> None:

     v.status('Fetching channel')
     request = urllib.request.urlopen(channel.channel_url, timeout=10)
     channel.channel_html = request.read()
     v.status('Fetching channel')
     request = urllib.request.urlopen(channel.channel_url, timeout=10)
     channel.channel_html = request.read()


@@ -172,7 +198,7 @@ def fetch(v: Verification, channel: Channel) -> None:
     v.check('Got forwarded', channel.channel_url != channel.forwarded_url)
 
 
     v.check('Got forwarded', channel.channel_url != channel.forwarded_url)
 
 

-def parse_channel(v: Verification, channel: Channel) -> None:
+def parse_channel(v: Verification, channel: TarrableSearchPath) -> None:

     v.status('Parsing channel description as XML')
     d = xml.dom.minidom.parseString(channel.channel_html)
     v.ok()
     v.status('Parsing channel description as XML')
     d = xml.dom.minidom.parseString(channel.channel_html)
     v.ok()


@@ -252,7 +278,7 @@ def fetch_with_nix_prefetch_url(
     return path  # type: ignore  # (for old mypy)
 
 
     return path  # type: ignore  # (for old mypy)
 
 

-def fetch_resources(v: Verification, channel: Channel) -> None:
+def fetch_resources(v: Verification, channel: TarrableSearchPath) -> None:

     for resource in ['git-revision', 'nixexprs.tar.xz']:
         fields = channel.table[resource]
         fields.absolute_url = urllib.parse.urljoin(
     for resource in ['git-revision', 'nixexprs.tar.xz']:
         fields = channel.table[resource]
         fields.absolute_url = urllib.parse.urljoin(


@@ -272,7 +298,7 @@ def git_cachedir(git_repo: str) -> str:
         digest_string(git_repo.encode()))
 
 
         digest_string(git_repo.encode()))
 
 

-def tarball_cache_file(channel: Channel) -> str:
+def tarball_cache_file(channel: TarrableSearchPath) -> str:

     return os.path.join(
         xdg.XDG_CACHE_HOME,
         'pinch/git-tarball',
     return os.path.join(
         xdg.XDG_CACHE_HOME,
         'pinch/git-tarball',


@@ -282,7 +308,7 @@ def tarball_cache_file(channel: Channel) -> str:
          channel.release_name))
 
 
          channel.release_name))
 
 

-def verify_git_ancestry(v: Verification, channel: Channel) -> None:
+def verify_git_ancestry(v: Verification, channel: TarrableSearchPath) -> None:

     cachedir = git_cachedir(channel.git_repo)
     v.status('Verifying rev is an ancestor of ref')
     process = subprocess.run(['git',
     cachedir = git_cachedir(channel.git_repo)
     v.status('Verifying rev is an ancestor of ref')
     process = subprocess.run(['git',


@@ -308,7 +334,7 @@ def verify_git_ancestry(v: Verification, channel: Channel) -> None:
         v.result(process.returncode == 0)
 
 
         v.result(process.returncode == 0)
 
 

-def git_fetch(v: Verification, channel: Channel) -> None:
+def git_fetch(v: Verification, channel: TarrableSearchPath) -> None:

     # 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
     # 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


@@ -350,7 +376,9 @@ def git_fetch(v: Verification, channel: Channel) -> None:
     verify_git_ancestry(v, channel)
 
 
     verify_git_ancestry(v, channel)
 
 

-def ensure_git_rev_available(v: Verification, channel: Channel) -> None:
+def ensure_git_rev_available(
+        v: Verification,
+        channel: TarrableSearchPath) -> None:

     cachedir = git_cachedir(channel.git_repo)
     if os.path.exists(cachedir):
         v.status('Checking if we already have this rev:')
     cachedir = git_cachedir(channel.git_repo)
     if os.path.exists(cachedir):
         v.status('Checking if we already have this rev:')


@@ -369,7 +397,7 @@ def ensure_git_rev_available(v: Verification, channel: Channel) -> None:
 
 def compare_tarball_and_git(
         v: Verification,
 
 def compare_tarball_and_git(
         v: Verification,

-        channel: Channel,
+        channel: TarrableSearchPath,

         channel_contents: str,
         git_contents: str) -> None:
     v.status('Comparing channel tarball with git checkout')
         channel_contents: str,
         git_contents: str) -> None:
     v.status('Comparing channel tarball with git checkout')


@@ -400,7 +428,10 @@ def compare_tarball_and_git(
         len(benign_errors) == len(expected_errors))
 
 
         len(benign_errors) == len(expected_errors))
 
 

-def extract_tarball(v: Verification, channel: Channel, dest: str) -> None:
+def extract_tarball(
+        v: Verification,
+        channel: TarrableSearchPath,
+        dest: str) -> None:

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


@@ -409,7 +440,10 @@ def extract_tarball(v: Verification, channel: Channel, dest: str) -> None:
     v.ok()
 
 
     v.ok()
 
 

-def git_checkout(v: Verification, channel: Channel, dest: str) -> None:
+def git_checkout(
+        v: Verification,
+        channel: TarrableSearchPath,
+        dest: str) -> None:

     v.status('Checking out corresponding git revision')
     git = subprocess.Popen(['git',
                             '-C',
     v.status('Checking out corresponding git revision')
     git = subprocess.Popen(['git',
                             '-C',


@@ -426,7 +460,7 @@ def git_checkout(v: Verification, channel: Channel, dest: str) -> None:
     v.result(git.returncode == 0 and tar.returncode == 0)
 
 
     v.result(git.returncode == 0 and tar.returncode == 0)
 
 

-def git_get_tarball(v: Verification, channel: Channel) -> str:
+def git_get_tarball(v: Verification, channel: TarrableSearchPath) -> str:

     cache_file = tarball_cache_file(channel)
     if os.path.exists(cache_file):
         cached_tarball = open(cache_file).read(9999)
     cache_file = tarball_cache_file(channel)
     if os.path.exists(cache_file):
         cached_tarball = open(cache_file).read(9999)


@@ -465,7 +499,7 @@ def git_get_tarball(v: Verification, channel: Channel) -> str:
 
 def check_channel_metadata(
         v: Verification,
 
 def check_channel_metadata(
         v: Verification,

-        channel: Channel,
+        channel: TarrableSearchPath,

         channel_contents: str) -> None:
     v.status('Verifying git commit in channel tarball')
     v.result(
         channel_contents: str) -> None:
     v.status('Verifying git commit in channel tarball')
     v.result(


@@ -487,7 +521,9 @@ def check_channel_metadata(
     v.result(channel.release_name.endswith(version_suffix))
 
 
     v.result(channel.release_name.endswith(version_suffix))
 
 

-def check_channel_contents(v: Verification, channel: Channel) -> None:
+def check_channel_contents(
+        v: Verification,
+        channel: TarrableSearchPath) -> None:

     with tempfile.TemporaryDirectory() as channel_contents, \
             tempfile.TemporaryDirectory() as git_contents:
 
     with tempfile.TemporaryDirectory() as channel_contents, \
             tempfile.TemporaryDirectory() as git_contents:
 


@@ -502,7 +538,7 @@ def check_channel_contents(v: Verification, channel: Channel) -> None:
     v.ok()
 
 
     v.ok()
 
 

-def pin_channel(v: Verification, channel: Channel) -> None:
+def pin_channel(v: Verification, channel: TarrableSearchPath) -> None:

     fetch(v, channel)
     parse_channel(v, channel)
     fetch_resources(v, channel)
     fetch(v, channel)
     parse_channel(v, channel)
     fetch_resources(v, channel)


@@ -510,7 +546,7 @@ def pin_channel(v: Verification, channel: Channel) -> None:
     check_channel_contents(v, channel)
 
 
     check_channel_contents(v, channel)
 
 

-def git_revision_name(v: Verification, channel: Channel) -> str:
+def git_revision_name(v: Verification, channel: TarrableSearchPath) -> str:

     v.status('Getting commit date')
     process = subprocess.run(['git',
                               '-C',
     v.status('Getting commit date')
     process = subprocess.run(['git',
                               '-C',


@@ -528,7 +564,11 @@ def git_revision_name(v: Verification, channel: Channel) -> str:
 
 
 def read_search_path(conf: configparser.SectionProxy) -> SearchPath:
 
 
 def read_search_path(conf: configparser.SectionProxy) -> SearchPath:

-    return Channel(**dict(conf.items()))
+    if 'alias_of' in conf:
+        return AliasSearchPath(**dict(conf.items()))
+    if 'channel_url' in conf:
+        return ChannelSearchPath(**dict(conf.items()))
+    return GitSearchPath(**dict(conf.items()))

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


@@ -537,6 +577,18 @@ def read_config(filename: str) -> configparser.ConfigParser:
     return config
 
 
     return config
 
 

+def read_config_files(
+        filenames: Iterable[str]) -> Dict[str, configparser.SectionProxy]:
+    merged_config: Dict[str, configparser.SectionProxy] = {}
+    for file in filenames:
+        config = read_config(file)
+        for section in config.sections():
+            if section in merged_config:
+                raise Exception('Duplicate channel "%s"' % section)
+            merged_config[section] = config[section]
+    return merged_config
+
+

 def pin(args: argparse.Namespace) -> None:
     v = Verification()
     config = read_config(args.channels_file)
 def pin(args: argparse.Namespace) -> None:
     v = Verification()
     config = read_config(args.channels_file)


@@ -554,28 +606,21 @@ def pin(args: argparse.Namespace) -> None:
 
 def update(args: argparse.Namespace) -> None:
     v = Verification()
 
 def update(args: argparse.Namespace) -> None:
     v = Verification()

-    config = configparser.ConfigParser()

     exprs: Dict[str, str] = {}
     exprs: Dict[str, str] = {}

-    configs = [read_config(filename) for filename in args.channels_file]
-    for config in configs:
-        for section in config.sections():
-            if 'alias_of' in config[section]:
-                assert 'git_repo' not in config[section]
-                continue
-            sp = read_search_path(config[section])
-            tarball = sp.fetch(v, section, config[section])
-            if section in exprs:
-                raise Exception('Duplicate channel "%s"' % section)
-            exprs[section] = (
-                'f: f { name = "%s"; channelName = "%%s"; src = builtins.storePath "%s"; }' %
-                (config[section]['release_name'], tarball))
-
-    for config in configs:
-        for section in config.sections():
-            if 'alias_of' in config[section]:
-                if section in exprs:
-                    raise Exception('Duplicate channel "%s"' % section)
-                exprs[section] = exprs[str(config[section]['alias_of'])]
+    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])
+        exprs[section] = (
+            'f: f { name = "%s"; channelName = "%%s"; src = builtins.storePath "%s"; }' %
+            (config[section]['release_name'], tarball))
+
+    for section in config:
+        if 'alias_of' in config[section]:
+            exprs[section] = exprs[str(config[section]['alias_of'])]

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