read_key: drop optimization where we read 3 bytes at once

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

2 files changed, 15 insertions, 9 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index a0b1bcf8e..81f6fdeff 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1451,10 +1451,13 @@ static int lineedit_read_key(char *read_key_buffer)
         pfd.events = POLLIN;
         do {
  poll_again:
-                /* Wait for input. Can't just call read_key, it will return
-                 * at once if stdin is in non-blocking mode. */
-                safe_poll(&pfd, 1, -1);
-                /* note: read_key sets errno to 0 on success: */
+                if (read_key_buffer[0] == 0) {
+                        /* Wait for input. Can't just call read_key,
+                         * it returns at once if stdin
+                         * is in non-blocking mode. */
+                        safe_poll(&pfd, 1, -1);
+                }
+                /* Note: read_key sets errno to 0 on success: */
                 ic = read_key(STDIN_FILENO, read_key_buffer);
                 if (ENABLE_FEATURE_EDITING_ASK_TERMINAL
                  && (int32_t)ic == KEYCODE_CURSOR_POS
diff --git a/libbb/read_key.c b/libbb/read_key.c
index 3771045d2..6f6c39e45 100644
--- a/libbb/read_key.c
+++ b/libbb/read_key.c
@@ -69,11 +69,14 @@ int64_t FAST_FUNC read_key(int fd, char *buffer)
         errno = 0;
         n = (unsigned char) *buffer++;
         if (n == 0) {
-                /* If no data, block waiting for input. If we read more
-                 * than the minimal ESC sequence size, the "n=0" below
-                 * would instead have to figure out how much to keep,
-                 * resulting in larger code. */
-                n = safe_read(fd, buffer, 3);
+                /* If no data, block waiting for input.
+                 * 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
+                 * "li" too, and cat was getting wrong input.
+                 */
+                n = safe_read(fd, buffer, 1);
                 if (n <= 0)
                         return -1;
         }