master ab3cfa4a17 1/2: Don’t hang when copying FIFOs

[Paul Eggert]

branch: master
commit ab3cfa4a17663cf479f286149a2289974dd67240
Author: Paul Eggert <eggert@cs.ucla.edu>
Commit: Paul Eggert <eggert@cs.ucla.edu>

    Don’t hang when copying FIFOs
    
    * src/fileio.c (Fcopy_file): Open the input file with O_NONBLOCK.
    This prevents a hang if the input file is a FIFO.
    If it’s a regular file O_NONBLOCK has no effect;
    otherwise the file is soon rejected anyway.
---
 src/fileio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/fileio.c b/src/fileio.c
index 92335b639c..a50f8d67c1 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2219,7 +2219,7 @@ permissions.  */)
       report_file_error ("Copying permissions to", newname);
     }
 #else /* not WINDOWSNT */
-  ifd = emacs_open (SSDATA (encoded_file), O_RDONLY, 0);
+  ifd = emacs_open (SSDATA (encoded_file), O_RDONLY | O_NONBLOCK, 0);
 
   if (ifd < 0)
     report_file_error ("Opening input file", file);