Commit 1963a2e0 authored by Paul Eggert's avatar Paul Eggert
Browse files

* sysdep.c (MAX_RW_COUNT): New macro, to work around kernel bugs.

(emacs_read, emacs_write): Use it.
parent 086e8c47
2011-04-13 Paul Eggert <eggert@cs.ucla.edu>
* sysdep.c (MAX_RW_COUNT): New macro, to work around kernel bugs.
(emacs_read, emacs_write): Use it.
* process.c (send_process): Count partial writes as successes.
See http://lists.gnu.org/archive/html/emacs-devel/2011-04/msg00483.html
......
......@@ -1825,6 +1825,17 @@ emacs_close (int fd)
return rtnval;
}
/* Maximum number of bytes to read or write in a single system call.
This works around a serious bug in Linux kernels before 2.6.16; see
<https://bugzilla.redhat.com/show_bug.cgi?format=multiple&id=612839>.
It's likely to work around similar bugs in other operating systems, so do it
on all platforms. Round INT_MAX down to a page size, with the conservative
assumption that page sizes are at most 2**18 bytes (any kernel with a
page size larger than that shouldn't have the bug). */
#ifndef MAX_RW_COUNT
#define MAX_RW_COUNT (INT_MAX >> 18 << 18)
#endif
/* Read from FILEDESC to a buffer BUF with size NBYTE, retrying if interrupted.
Return the number of bytes read, which might be less than NBYTE.
On error, set errno and return -1. */
......@@ -1833,7 +1844,7 @@ emacs_read (int fildes, char *buf, size_t nbyte)
{
register ssize_t rtnval;
while ((rtnval = read (fildes, buf, nbyte)) == -1
while ((rtnval = read (fildes, buf, min (nbyte, MAX_RW_COUNT))) == -1
&& (errno == EINTR))
QUIT;
return (rtnval);
......@@ -1852,7 +1863,7 @@ emacs_write (int fildes, const char *buf, size_t nbyte)
while (nbyte > 0)
{
rtnval = write (fildes, buf, nbyte);
rtnval = write (fildes, buf, min (nbyte, MAX_RW_COUNT));
if (rtnval < 0)
{
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment