less: move "retry-on-EAGAIN" logic closer to read ops

This makes "G" (goto end of input) command work as well as
/search_for_nonexistent_string: both will read to EOF now
even from somewhat slow input (such as kernel's "git log").

function                                             old     new   delta
ndelay_on                                             35      43      +8
ndelay_off                                            35      43      +8
read_lines                                           695     691      -4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 16/-4)              Total: 12 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index 23f27516f..f25ce9446 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -25,20 +25,22 @@
 #include "libbb.h"
 
 /* Turn on nonblocking I/O on a fd */
-void FAST_FUNC ndelay_on(int fd)
+int FAST_FUNC ndelay_on(int fd)
 {
         int flags = fcntl(fd, F_GETFL);
         if (flags & O_NONBLOCK)
-                return;
+                return flags;
         fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+        return flags;
 }
 
-void FAST_FUNC ndelay_off(int fd)
+int FAST_FUNC ndelay_off(int fd)
 {
         int flags = fcntl(fd, F_GETFL);
         if (!(flags & O_NONBLOCK))
-                return;
+                return flags;
         fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
+        return flags;
 }
 
 void FAST_FUNC close_on_exec_on(int fd)