From cacdb54953dbc81eecf4c3a55c132836e7849098 Mon Sep 17 00:00:00 2001
From: Ronan Desplanques <ronan.desplanques@gmail.com>
Date: Mon, 23 May 2022 09:57:10 +0200
Subject: Fix integer underflow in flExtension

Before this patch, the expression `Res - File.length()` that was
used as the length underflowed. It was very unlikely to cause any
problem given the saturating behavior of the std::string
constructor that's used.

Replacing `Res - File.length()` with `File.length() - Res` would
have worked, but omitting the last argument altogether invokes an
std::string constructor which does the right thing.
---
 apt-pkg/contrib/fileutl.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index eb5dc859d..10c656301 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -691,7 +691,7 @@ string flExtension(string File)
    if (Res == string::npos)
       return File;
    Res++;
-   return string(File,Res,Res - File.length());
+   return string(File,Res);
 }
 									/*}}}*/
 // flNoLink - If file is a symlink then deref it			/*{{{*/
-- 
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