From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 13 Jul 2025 07:07:46 +0000 (-0700)
Subject: insert-file-contents unexpected end shrinkage
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=b8f3fcf2b8ef95e2b75958da819731aedb1a1238;p=emacs.git

insert-file-contents unexpected end shrinkage

* src/fileio.c (Finsert_file_contents): If the file unexpectedly
shrinks while reading its tail backwards, give up searching for
the match end.

(cherry picked from commit f4adb56c9adc9b4f4715c656f1f8cfa7305479e5)
---

diff --git a/src/fileio.c b/src/fileio.c
index 221cb175dd8..bd8528af235 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4523,12 +4523,17 @@ by calling `format-decode', which see.  */)
 		report_file_error ("Read error", orig_filename);
 	      else if (nread == 0)
 		{
+		  /* The file unexpectedly shrank.  */
 		  file_size_hint = curpos - trial + total_read;
+		  giveup_match_end = true;
 		  break;
 		}
 	      total_read += nread;
 	    }
 
+	  if (giveup_match_end)
+	    break;
+
 	  /* Scan this bufferful from the end, comparing with
 	     the Emacs buffer.  */
 	  bufpos = total_read;