Fix inconsistent handling of EINTR in ser-*.c backends

- If serial->write_prim returns EINTR, ser_bas_write returns it to the
  caller.  This just looks wrong to me -- part of the output may have
  already been sent, and there's no way for the caller to know that,
  and thus no way for a caller to handle a partial write correctly.

- While ser-unix.c:ser_unix_read_prim retries on EINTR,
  ser-tcp.c:net_read_prim does not.

This commit moves EINTR handling to the ser_base_write and
ser_base_readchar level, so all serial backends (at least those that
use it) end up handling EINTR consistently.

gdb/ChangeLog:
2016-04-12  Pedro Alves  <palves@redhat.com>

	* ser-base.c (fd_event): Retry read_prim on EINTR.
	(do_ser_base_readchar): Retry read_prim on EINTR.
	(ser_base_write): Retry write_prim on EINTR.
	* ser-unix.c (ser_unix_read_prim): Don't retry on EINTR here.
	(ser_unix_write_prim): Remove comment.

1 files changed, 1 insertions, 11 deletions

diff --git a/gdb/ser-unix.c b/gdb/ser-unix.c
index c54b2e1..562e98b 100644
--- a/gdb/ser-unix.c
+++ b/gdb/ser-unix.c
@@ -1002,21 +1002,11 @@ when debugging using remote targets."),
 int
 ser_unix_read_prim (struct serial *scb, size_t count)
 {
-  int status;
-
-  while (1)
-    {
-      status = read (scb->fd, scb->buf, count);
-      if (status != -1 || errno != EINTR)
-	break;
-    }
-  return status;
+  return read (scb->fd, scb->buf, count);
 }
 
 int
 ser_unix_write_prim (struct serial *scb, const void *buf, size_t len)
 {
-  /* ??? Historically, GDB has not retried calls to "write" that
-     result in EINTR.  */
   return write (scb->fd, buf, len);
 }