1 files changed, 16 insertions, 5 deletions

diff --git a/libbb/read_key.c b/libbb/read_key.c
index 98b3131de..0faa12c97 100644
--- a/libbb/read_key.c
+++ b/libbb/read_key.c
@@ -9,7 +9,7 @@
  */
 #include "libbb.h"
 
-int64_t FAST_FUNC read_key(int fd, char *buffer)
+int64_t FAST_FUNC read_key(int fd, char *buffer, int timeout)
 {
         struct pollfd pfd;
         const char *seq;
@@ -90,14 +90,27 @@ int64_t FAST_FUNC read_key(int fd, char *buffer)
                 /* ESC [ Z - Shift-Tab */
         };
 
+        pfd.fd = fd;
+        pfd.events = POLLIN;
+
         buffer++; /* saved chars counter is in buffer[-1] now */
 
  start_over:
         errno = 0;
         n = (unsigned char)buffer[-1];
         if (n == 0) {
-                /* If no data, block waiting for input.
-                 * It is tempting to read more than one byte here,
+                /* If no data, wait for input.
+                 * If requested, wait TIMEOUT ms. TIMEOUT = -1 is useful
+                 * if fd can be in non-blocking mode.
+                 */
+                if (timeout >= -1) {
+                        if (safe_poll(&pfd, 1, timeout) == 0) {
+                                /* Timed out */
+                                errno = EAGAIN;
+                                return -1;
+                        }
+                }
+                /* It is tempting to read more than one byte here,
                  * but it breaks pasting. Example: at shell prompt,
                  * user presses "c","a","t" and then pastes "\nline\n".
                  * When we were reading 3 bytes here, we were eating
@@ -121,8 +134,6 @@ int64_t FAST_FUNC read_key(int fd, char *buffer)
         }
 
         /* Loop through known ESC sequences */
-        pfd.fd = fd;
-        pfd.events = POLLIN;
         seq = esccmds;
         while (*seq != '\0') {
                 /* n - position in sequence we did not read yet */