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-rw-r--r--linuxnamespaces/__init__.py35
1 files changed, 35 insertions, 0 deletions
diff --git a/linuxnamespaces/__init__.py b/linuxnamespaces/__init__.py
index b50f113..a39ab1d 100644
--- a/linuxnamespaces/__init__.py
+++ b/linuxnamespaces/__init__.py
@@ -136,6 +136,41 @@ class IDAllocation:
"""
return IDMapping(target, self.allocate(count), count)
+ def reserve(self, start: int, count: int) -> None:
+ """Reserve (and remove) the given range from this allocation. If the
+ range is not fully contained in this allocation, a ValueError is
+ raised.
+ """
+ if count < 0:
+ raise ValueError("nagative count")
+ index = bisect.bisect_right(self.ranges, (start, float("inf"))) - 1
+ if index < 0:
+ raise ValueError("range to reserve not found")
+ cur_start, cur_count = self.ranges[index]
+ assert cur_start <= start
+ if cur_start == start:
+ # Requested range starts at range boundary
+ if cur_count < count:
+ raise ValueError("range to reserve not found")
+ if cur_count == count:
+ # Requested range matches a range exactly
+ del self.ranges[index]
+ else:
+ # Requested range is a head of the matched range
+ self.ranges[index] = (start + count, cur_count - count)
+ elif cur_start + cur_count >= start + count:
+ # Requested range fits into a matched range
+ self.ranges[index] = (cur_start, start - cur_start)
+ if cur_start + cur_count > start + count:
+ # Requested range punches a hole into a matched range
+ self.ranges.insert(
+ index + 1,
+ (start + count, cur_start + cur_count - (start + count))
+ )
+ # else: Requested range is a tail of a matched range
+ else:
+ raise ValueError("range to reserve not found")
+
def newidmap(
kind: typing.Literal["uid", "gid"],