From: Paul Eggert <eggert@cs.ucla.edu>
Date: Thu, 31 Oct 2019 01:15:14 +0000 (-0700)
Subject: Fix bug with lock file on nonstandard filesystem
X-Git-Tag: emacs-27.0.90~804
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=e65be8cc5b623385ebe31aa0a1089e0de2b075b5;p=emacs.git

Fix bug with lock file on nonstandard filesystem

* src/filelock.c (create_lock_file):
Don’t disable user write access to the lock file (Bug#37884).
---

diff --git a/src/filelock.c b/src/filelock.c
index ff25d6475de..2077287345c 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -402,9 +402,15 @@ create_lock_file (char *lfname, char *lock_info_str, bool force)
 	  ptrdiff_t lock_info_len;
 	  lock_info_len = strlen (lock_info_str);
 	  err = 0;
+
+	  /* Make the lock file readable to others, so that others' sessions
+	     can read it.  Even though nobody should write to the lock file,
+	     keep it user-writable to work around problems on nonstandard file
+	     systems that prohibit unlinking readonly files (Bug#37884).  */
 	  if (emacs_write (fd, lock_info_str, lock_info_len) != lock_info_len
-	      || fchmod (fd, S_IRUSR | S_IRGRP | S_IROTH) != 0)
+	      || fchmod (fd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) != 0)
 	    err = errno;
+
 	  /* There is no need to call fsync here, as the contents of
 	     the lock file need not survive system crashes.  */
 	  if (emacs_close (fd) != 0)