backup: replace simple max size with rule-based system

Now individual files or patterns can have their own maximum sizes.

backup.py

@@ -29,38 +29,25 @@ def pstr(path: bytes) -> str:
 def format_size(n: int) -> str:
     return humanfriendly.format_size(n, keep_width=True, binary=True)
 
+# Type corresponding to patterns that are generated by
+# wcmatch.translate: two lists of compiled REs (a,b).  A path matches
+# if it matches at least one regex in "a" and none in "b".
+MatchPatterns = typing.Tuple[typing.List[re.Pattern], typing.List[re.Pattern]]
+
 class Config:
     roots: typing.List[bytes]
-    max_file_size: typing.Optional[int]
     one_file_system: bool
     exclude_caches: bool
-    exclude: typing.List[bytes]
-    force_include: typing.List[bytes]
+    exclude: MatchPatterns
+    unexclude: MatchPatterns
+    max_size_rules: typing.List[typing.Tuple[int, MatchPatterns]]
     notify_email: typing.Optional[str]
 
     def __init__(self, configfile: str):
-        # Read config
-        with open(configfile, 'r') as f:
-            config = yaml.safe_load(f)
-            self.one_file_system = config.get('one-file-system', False)
-            self.exclude_caches = config.get('exclude-caches', False)
 
-            if 'max-file-size' in config:
-                self.max_file_size = humanfriendly.parse_size(
-                    config['max-file-size'])
-            else:
-                self.max_file_size = None
-
-            raw = config.get('roots', '').encode().split(b'\n')
-            self.roots = []
-            for x in raw:
-                if not len(x):
-                    continue
-                self.roots.append(x)
-            self.roots.sort(key=len)
-
-            def process_match_list(config_name):
-                raw = config.get(config_name, '').encode().split(b'\n')
+        # Helper to process lists of patterns into regexes
+        def process_match_list(config_entry):
+                raw = config_entry.encode().split(b'\n')
                 pats = []
                 # Prepend '**/' to any relative patterns
                 for x in raw:
@@ -70,39 +57,49 @@ class Config:
                         pats.append(x)
                     else:
                         pats.append(b'**/' + x)
-                return pats
 
-            self.exclude = process_match_list('exclude')
-            self.force_include = process_match_list('force-include')
+                # Compile patterns.
+                (a, b) = wcmatch.glob.translate(
+                    pats, flags=(wcmatch.glob.GLOBSTAR |
+                                 wcmatch.glob.DOTGLOB |
+                                 wcmatch.glob.NODOTDIR |
+                                 wcmatch.glob.EXTGLOB |
+                                 wcmatch.glob.BRACE))
+                return ([ re.compile(x) for x in a ],
+                        [ re.compile(x) for x in b ])
+
+        # Read config
+        with open(configfile, 'r') as f:
+            config = yaml.safe_load(f)
+            self.one_file_system = config.get('one-file-system', False)
+            self.exclude_caches = config.get('exclude-caches', False)
+
+            raw = config.get('roots', '').encode().split(b'\n')
+            self.roots = []
+            for x in raw:
+                if not len(x):
+                    continue
+                self.roots.append(x)
+            self.roots.sort(key=len)
+
+            self.exclude = process_match_list(config.get('exclude', ''))
+            self.unexclude = process_match_list(config.get('unexclude', ''))
+
+            self.max_size_rules = []
+            rules = { humanfriendly.parse_size(k): v
+                      for k, v in config.get('max-size-rules', {}).items() }
+            for size in reversed(sorted(rules)):
+                self.max_size_rules.append(
+                    (size, process_match_list(rules[size])))
 
             self.notify_email = config.get('notify-email', None)
 
-        # Compile patterns
-        flags = (wcmatch.glob.GLOBSTAR |
-                 wcmatch.glob.DOTGLOB |
-                 wcmatch.glob.NODOTDIR |
-                 wcmatch.glob.EXTGLOB |
-                 wcmatch.glob.BRACE)
-
-        # Path matches if it matches at least one regex in "a" and no
-        # regex in "b"
-        (a, b) = wcmatch.glob.translate(self.exclude, flags=flags)
-        self.exclude_re = ([ re.compile(x) for x in a ],
-                           [ re.compile(x) for x in b ])
-
-        (a, b) = wcmatch.glob.translate(self.force_include, flags=flags)
-        self.force_include_re = ([ re.compile(x) for x in a ],
-                                 [ re.compile(x) for x in b ])
-
-    def match_re(self,
-                 re: typing.Tuple[typing.List[typing.Pattern],
-                                  typing.List[typing.Pattern]],
-                 path: bytes):
+    def match_re(self, r: MatchPatterns, path: bytes):
         # Path matches if it matches at least one regex in
-        # re[0] and no regex in re[1].
-        for a in re[0]:
+        # r[0] and no regex in r[1].
+        for a in r[0]:
             if a.match(path):
-                for b in re[1]:
+                for b in r[1]:
                     if b.match(path):
                         return False
                 return True
@@ -166,7 +163,7 @@ class Backup:
             # See if there's a reason to exclude it
             exclude_reason = None
 
-            if self.config.match_re(self.config.exclude_re, decorated_path):
+            if self.config.match_re(self.config.exclude, decorated_path):
                 # Config file says to exclude
                 exclude_reason = ('I', f"skipping, excluded by config file")
 
@@ -178,17 +175,24 @@ class Backup:
                 exclude_reason = ('I', "skipping, on different filesystem")
 
             elif (is_reg
-                  and self.config.max_file_size
-                  and size > self.config.max_file_size):
-                # Too big
-                a = format_size(size)
-                b = format_size(self.config.max_file_size)
-                exclude_reason = ('W', f"file size {a} exceeds limit {b}")
+                  and len(self.config.max_size_rules)
+                  and size > self.config.max_size_rules[-1][0]):
+                # Check file sizes against our list.
+                # Only need to check if the size is bigger than the smallest
+                # entry on the list; then, we need to check it against all rules
+                # to see which one applies.
+                for (max_size, patterns) in self.config.max_size_rules:
+                    if self.config.match_re(patterns, decorated_path):
+                        if size > max_size:
+                            a = format_size(size)
+                            b = format_size(max_size)
+                            exclude_reason = (
+                                'W', f"file size {a} exceeds limit {b}")
+                        break
 
             # If we have a reason to exclude it, stop now unless it's
             # force-included
-            force = self.config.match_re(self.config.force_include_re,
-                                         decorated_path)
+            force = self.config.match_re(self.config.unexclude, decorated_path)
             if exclude_reason and not force:
                 self.log(exclude_reason[0],
                          f"{exclude_reason[1]}: {pstr(path)}")

config.yaml

@@ -10,12 +10,6 @@ roots: |
 one-file-system: true
 exclude-caches: true
 
-# Files larger than this are excluded.  If a large file isn't
-# explicitly mentioned in "excludes" below, it also generates a
-# warning.  Note that this counts used blocks, so files with large
-# holes will still be considered small (since they'll compress easily)
-max-file-size: 500MiB
-
 # Files/dirs to exclude from backup.
 # Relative paths are treated as if starting with **/
 # Paths ending in / will only match directories.
@@ -27,10 +21,21 @@ exclude: |
   Steam/ubuntu*/
   .cache/
 
+# Rules to exclude files based on file size.
+# This is a dict of sizes, each with a list of rules.
+# For a given path, the largest size with a matching rule applies.
+# Matching follows the same behavior as the "exclude" list.
+# Size is calculated as used blocks (think "du", not "du --apparent-size").
+max-size-rules:
+  500 MiB: |
+    *
+#  1.0 GiB: |
+#    *.mp4
+
 # Files that are always included, even if they would have been
 # excluded due to file size or the "exclude" list.
-# Matching rules are the same as above.
-force-include: |
+# Matching follows the same behavior as the "exclude" list.
+unexclude: |
   .git/objects/pack/*.pack
 
 # Email address for notification at end of backup