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;
 	}