--- a/mercurial/debugcommands.py	Mon May 30 11:30:48 2022 +0200
+++ b/mercurial/debugcommands.py	Mon May 30 23:24:14 2022 +0200
@@ -105,6 +105,7 @@
 
 from .revlogutils import (
     constants as revlog_constants,
+    debug as revlog_debug,
     deltas as deltautil,
     nodemap,
     rewrite,
@@ -1874,36 +1875,16 @@
     opts = pycompat.byteskwargs(opts)
     store = cmdutil.openstorage(repo, b'debugindex', file_, opts)
 
-    if ui.debugflag:
-        shortfn = hex
-    else:
-        shortfn = short
-
-    idlen = 12
-    for i in store:
-        idlen = len(shortfn(store.node(i)))
-        break
-
     fm = ui.formatter(b'debugindex', opts)
-    fm.plain(
-        b'   rev linkrev %s %s p2\n'
-        % (b'nodeid'.ljust(idlen), b'p1'.ljust(idlen))
+
+    return revlog_debug.debug_index(
+        ui,
+        repo,
+        formatter=fm,
+        revlog=store,
+        full_node=ui.debugflag,
     )
 
-    for rev in store:
-        node = store.node(rev)
-        parents = store.parents(node)
-
-        fm.startitem()
-        fm.write(b'rev', b'%6d ', rev)
-        fm.write(b'linkrev', b'%7d ', store.linkrev(rev))
-        fm.write(b'node', b'%s ', shortfn(node))
-        fm.write(b'p1', b'%s ', shortfn(parents[0]))
-        fm.write(b'p2', b'%s', shortfn(parents[1]))
-        fm.plain(b'\n')
-
-    fm.end()
-
 
 @command(
     b'debugindexdot',

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/revlogutils/debug.py	Mon May 30 23:24:14 2022 +0200
@@ -0,0 +1,51 @@
+# revlogutils/debug.py - utility used for revlog debuging
+#
+# Copyright 2005-2007 Olivia Mackall <olivia@selenic.com>
+# Copyright 2022 Octobus <contact@octobus.net>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+
+from .. import (
+    node as nodemod,
+)
+
+
+def debug_index(
+    ui,
+    repo,
+    formatter,
+    revlog,
+    full_node,
+):
+    """display index data for a revlog"""
+    if full_node:
+        hexfn = nodemod.hex
+    else:
+        hexfn = nodemod.short
+
+    idlen = 12
+    for i in revlog:
+        idlen = len(hexfn(revlog.node(i)))
+        break
+
+    fm = formatter
+
+    fm.plain(
+        b'   rev linkrev %s %s p2\n'
+        % (b'nodeid'.ljust(idlen), b'p1'.ljust(idlen))
+    )
+
+    for rev in revlog:
+        node = revlog.node(rev)
+        parents = revlog.parents(node)
+
+        fm.startitem()
+        fm.write(b'rev', b'%6d ', rev)
+        fm.write(b'linkrev', b'%7d ', revlog.linkrev(rev))
+        fm.write(b'node', b'%s ', hexfn(node))
+        fm.write(b'p1', b'%s ', hexfn(parents[0]))
+        fm.write(b'p2', b'%s', hexfn(parents[1]))
+        fm.plain(b'\n')
+
+    fm.end()