# HG changeset patch
# User Henry S. Thompson <ht@inf.ed.ac.uk>
# Date 1773657781 0
# Node ID 6b1137bdbd0da42a3632f5c0f4c508bcd183690b
# Parent  4497f2ad3a6fd1813273c4bc60a397fe4cf358fb
give access to block offsets via callback

diff -r 4497f2ad3a6f -r 6b1137bdbd0d lib/python/gzip_plus.py
--- a/lib/python/gzip_plus.py	Thu Mar 12 18:28:27 2026 +0000
+++ b/lib/python/gzip_plus.py	Mon Mar 16 10:43:01 2026 +0000
@@ -180,7 +180,8 @@
     myfileobj = None
 
     def __init__(self, filename=None, mode=None,
-                 compresslevel=_COMPRESS_LEVEL_BEST, fileobj=None, mtime=None):
+                 compresslevel=_COMPRESS_LEVEL_BEST, fileobj=None, mtime=None,
+                 eob_callback=None):
         """Constructor for the GzipFile class.
 
         At least one of fileobj and filename must be given a
@@ -213,6 +214,7 @@
         If mtime is omitted or None, the current time is used. Use mtime = 0
         to generate a compressed stream that does not depend on creation time.
 
+        The optional eobCallback will be called with block boundaries if provided.
         """
 
         if mode and ('t' in mode or 'U' in mode):
@@ -236,7 +238,7 @@
 
             if mode.startswith('r'):
                 self.mode = READ
-                raw = _GzipReader(fileobj)
+                raw = _GzipReader(fileobj, eob_callback)
                 self._buffer = io.BufferedReader(raw)
                 self.name = filename
 
@@ -522,7 +524,7 @@
 
 
 class _GzipReader(_compression.DecompressReader):
-    def __init__(self, fp):
+    def __init__(self, fp, eob_callback):
         super().__init__(_PaddedFile(fp), zlib._ZlibDecompressor,
                          wbits=-zlib.MAX_WBITS)
         # Set flag indicating start of a new member
@@ -530,6 +532,7 @@
         self._last_mtime = None
         self._cur_block = None
         self._next_block = 0
+        self._eob_callback = eob_callback
 
     def _init_read(self):
         self._crc = zlib.crc32(b"")
@@ -618,6 +621,8 @@
 
         self._cur_block = self._next_block
         self._next_block = self._fp.tell()
+        if self._eob_callback is not None:
+            self._eob_callback(self._cur_block, self._next_block)
 
     def _rewind(self):
         super()._rewind()