bug#70415: 30.0.50; [Cygwin] `lock-file' creates a symlink with funny name

[Eli Zaretskii]

> Date: Sat, 4 May 2024 18:01:25 -0400
> From: Ken Brown <kbrown@cornell.edu>
> Cc: yamaoka@jpl.org, 70415@debbugs.gnu.org
> 
> > Not only was the system's page file deemed to be a directory, but it was 
> > deemed to have a negative modification time.  I think that's where the 
> > dash came from.  But I don't know why that prevented the lock file from 
> > being deleted.
> 
> I found the answer: filelock.c:current_lock_owner returns an error if 
> the colon exists and is not followed by a digit.  See filelock.c:421.

Right.  Does the below look like the right change to support such
weird cases?

diff --git a/src/filelock.c b/src/filelock.c
index 01d35c4..86c6eeb 100644
--- a/src/filelock.c
+++ b/src/filelock.c
@@ -419,7 +419,9 @@ current_lock_owner (lock_info_type *owner, Lisp_Object 
lfname)
       boot += 2;
       FALLTHROUGH;
     case ':':
-      if (! c_isdigit (boot[0]))
+      if (! c_isdigit (boot[0])
+         /* A negative number.  */
+         || (boot[0] == '-' && c_isdigit (boot[1])))
        return EINVAL;
       boot_time = strtoimax (boot, &lfinfo_end, 10);
       break;