From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 13 Feb 2023 16:51:45 +0000 (-0800)
Subject: Don’t scan text twice to guess coding system
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=ccc092115172f15c9135771f90d0000f8bf21614;p=emacs.git

Don’t scan text twice to guess coding system

* src/fileio.c (Finsert_file_contents): If the file shrank
below 4 KiB, don’t read duplicate text into READ_BUF.
This also removes a use of SEEK_END, which Linux /proc
file systems do not support (not that we should get here
with /proc).
---

diff --git a/src/fileio.c b/src/fileio.c
index 751b8ec573c..47177be0f4d 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -4119,7 +4119,7 @@ by calling `format-decode', which see.  */)
 		  if (nread == 1024)
 		    {
 		      int ntail;
-		      if (lseek (fd, - (1024 * 3), SEEK_END) < 0)
+		      if (lseek (fd, st.st_size - 1024 * 3, SEEK_CUR) < 0)
 			report_file_error ("Setting file position",
 					   orig_filename);
 		      ntail = emacs_read_quit (fd, read_buf + nread, 1024 * 3);