From: Gerd Moellmann <gerd@gnu.org>
Date: Tue, 15 Feb 2000 10:27:23 +0000 (+0000)
Subject: (send_process) [BROKEN_PTY_READ_AFTER_EAGAIN]:
X-Git-Tag: emacs-pretest-21.0.90~5012
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=3433b6bdab2a6a42228d3515b57e41b16e4c3cb3;p=emacs.git

(send_process) [BROKEN_PTY_READ_AFTER_EAGAIN]:
Workaround for FreeBSD bug.  Flush output queue after EAGAIN in
write(2).
---

diff --git a/src/process.c b/src/process.c
index dab701a9e7f..aa83422f8c1 100644
--- a/src/process.c
+++ b/src/process.c
@@ -3431,6 +3431,32 @@ send_process (proc, buf, len, object)
 		    Lisp_Object zero;
 		    int offset;
 
+#ifdef BROKEN_PTY_READ_AFTER_EAGAIN
+		    /* A gross hack to work around a bug in FreeBSD.
+		       In the following sequence, read(2) returns
+		       bogus data:
+
+		       write(2)	 1022 bytes
+		       write(2)   954 bytes, get EAGAIN
+		       read(2)   1024 bytes in process_read_output
+		       read(2)     11 bytes in process_read_output
+
+		       That is, read(2) returns more bytes than have
+		       ever been written successfully.  The 1033 bytes
+		       read are the 1022 bytes written successfully
+		       after processing (for example with CRs added if
+		       the terminal is set up that way which it is
+		       here).  The same bytes will be seen again in a
+		       later read(2), without the CRs.  */
+		    
+		    if (errno == EAGAIN)
+		      {
+			int flags = FWRITE;
+			ioctl (XINT (XPROCESS (proc)->outfd), TIOCFLUSH,
+			       &flags);
+		      }
+#endif /* BROKEN_PTY_READ_AFTER_EAGAIN */
+		    
 		    /* Running filters might relocate buffers or strings.
 		       Arrange to relocate BUF.  */
 		    if (BUFFERP (object))