add PathFullPattern

not really a pattern (as in potentially having any variable parts) - it just does a full,
precise match, after the usual normalizations.

the reason for adding this is mainly for later optimizations, e.g. via set membership check,
so that a lot of such PathFullPatterns can be "matched" within O(1) time.

src/borg/helpers.py

@@ -518,6 +518,17 @@ class PatternBase:
         raise NotImplementedError
 
 
+class PathFullPattern(PatternBase):
+    """Full match of a path."""
+    PREFIX = "pf"
+
+    def _prepare(self, pattern):
+        self.pattern = os.path.normpath(pattern)
+
+    def _match(self, path):
+        return path == self.pattern
+
+
 # For PathPrefixPattern, FnmatchPattern and ShellPattern, we require that the pattern either match the whole path
 # or an initial segment of the path up to but not including a path separator. To unify the two cases, we add a path
 # separator to the end of the path before matching.
@@ -600,6 +611,7 @@ class RegexPattern(PatternBase):
 
 _PATTERN_STYLES = set([
     FnmatchPattern,
+    PathFullPattern,
     PathPrefixPattern,
     RegexPattern,
     ShellPattern,

src/borg/testsuite/helpers.py

@@ -25,7 +25,8 @@ from ..helpers import parse_timestamp, ChunkIteratorFileWrapper, ChunkerParams,
 from ..helpers import ProgressIndicatorPercent, ProgressIndicatorEndless
 from ..helpers import load_exclude_file, load_pattern_file
 from ..helpers import CompressionSpec, ComprSpec, CompressionDecider1, CompressionDecider2
-from ..helpers import parse_pattern, PatternMatcher, RegexPattern, PathPrefixPattern, FnmatchPattern, ShellPattern
+from ..helpers import parse_pattern, PatternMatcher
+from ..helpers import PathFullPattern, PathPrefixPattern, FnmatchPattern, ShellPattern, RegexPattern
 from ..helpers import swidth_slice
 from ..helpers import chunkit
 from ..helpers import safe_ns, safe_s
@@ -254,6 +255,35 @@ def check_patterns(files, pattern, expected):
     assert matched == (files if expected is None else expected)
 
 
+@pytest.mark.parametrize("pattern, expected", [
+    # "None" means all files, i.e. all match the given pattern
+    ("/", []),
+    ("/home", ["/home"]),
+    ("/home///", ["/home"]),
+    ("/./home", ["/home"]),
+    ("/home/user", ["/home/user"]),
+    ("/home/user2", ["/home/user2"]),
+    ("/home/user/.bashrc", ["/home/user/.bashrc"]),
+    ])
+def test_patterns_full(pattern, expected):
+    files = ["/home", "/home/user", "/home/user2", "/home/user/.bashrc", ]
+
+    check_patterns(files, PathFullPattern(pattern), expected)
+
+
+@pytest.mark.parametrize("pattern, expected", [
+    # "None" means all files, i.e. all match the given pattern
+    ("", []),
+    ("relative", []),
+    ("relative/path/", ["relative/path"]),
+    ("relative/path", ["relative/path"]),
+    ])
+def test_patterns_full_relative(pattern, expected):
+    files = ["relative/path", "relative/path2", ]
+
+    check_patterns(files, PathFullPattern(pattern), expected)
+
+
 @pytest.mark.parametrize("pattern, expected", [
     # "None" means all files, i.e. all match the given pattern
     ("/", None),