read_key: drop optimization where we read 3 bytes at once

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

4 files changed, 65 insertions, 59 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 788140d..963e2af 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -933,54 +933,6 @@ void bb_displayroutes(int noresolve, int netstatfmt) FAST_FUNC;
 #endif
 
 
-/* "Keycodes" that report an escape sequence.
- * We use something which fits into signed char,
- * yet doesn't represent any valid Unicode characher.
- * Also, -1 is reserved for error indication and we don't use it. */
-enum {
-	KEYCODE_UP       =  -2,
-	KEYCODE_DOWN     =  -3,
-	KEYCODE_RIGHT    =  -4,
-	KEYCODE_LEFT     =  -5,
-	KEYCODE_HOME     =  -6,
-	KEYCODE_END      =  -7,
-	KEYCODE_INSERT   =  -8,
-	KEYCODE_DELETE   =  -9,
-	KEYCODE_PAGEUP   = -10,
-	KEYCODE_PAGEDOWN = -11,
-#if 0
-	KEYCODE_FUN1     = -12,
-	KEYCODE_FUN2     = -13,
-	KEYCODE_FUN3     = -14,
-	KEYCODE_FUN4     = -15,
-	KEYCODE_FUN5     = -16,
-	KEYCODE_FUN6     = -17,
-	KEYCODE_FUN7     = -18,
-	KEYCODE_FUN8     = -19,
-	KEYCODE_FUN9     = -20,
-	KEYCODE_FUN10    = -21,
-	KEYCODE_FUN11    = -22,
-	KEYCODE_FUN12    = -23,
-#endif
-	KEYCODE_CURSOR_POS = -0x100,
-	/* How long is the longest ESC sequence we know?
-	 * We want it big enough to be able to contain
-	 * cursor position sequence "ESC [ 9999 ; 9999 R"
-	 */
-	KEYCODE_BUFFER_SIZE = 16
-};
-/* Note: fd may be in blocking or non-blocking mode, both make sense.
- * For one, less uses non-blocking mode.
- * Only the first read syscall inside read_key may block indefinitely
- * (unless fd is in non-blocking mode),
- * subsequent reads will time out after a few milliseconds.
- * Return of -1 means EOF or error (errno == 0 on EOF).
- * buffer[0] is used as a counter of buffered chars and must be 0
- * on first call.
- */
-int64_t read_key(int fd, char *buffer) FAST_FUNC;
-
-
 /* Networking */
 int create_icmp_socket(void) FAST_FUNC;
 int create_icmp6_socket(void) FAST_FUNC;
@@ -1209,6 +1161,54 @@ unsigned long long bb_makedev(unsigned int major, unsigned int minor) FAST_FUNC;
 #endif
 
 
+/* "Keycodes" that report an escape sequence.
+ * We use something which fits into signed char,
+ * yet doesn't represent any valid Unicode characher.
+ * Also, -1 is reserved for error indication and we don't use it. */
+enum {
+	KEYCODE_UP       =  -2,
+	KEYCODE_DOWN     =  -3,
+	KEYCODE_RIGHT    =  -4,
+	KEYCODE_LEFT     =  -5,
+	KEYCODE_HOME     =  -6,
+	KEYCODE_END      =  -7,
+	KEYCODE_INSERT   =  -8,
+	KEYCODE_DELETE   =  -9,
+	KEYCODE_PAGEUP   = -10,
+	KEYCODE_PAGEDOWN = -11,
+#if 0
+	KEYCODE_FUN1     = -12,
+	KEYCODE_FUN2     = -13,
+	KEYCODE_FUN3     = -14,
+	KEYCODE_FUN4     = -15,
+	KEYCODE_FUN5     = -16,
+	KEYCODE_FUN6     = -17,
+	KEYCODE_FUN7     = -18,
+	KEYCODE_FUN8     = -19,
+	KEYCODE_FUN9     = -20,
+	KEYCODE_FUN10    = -21,
+	KEYCODE_FUN11    = -22,
+	KEYCODE_FUN12    = -23,
+#endif
+	KEYCODE_CURSOR_POS = -0x100,
+	/* How long is the longest ESC sequence we know?
+	 * We want it big enough to be able to contain
+	 * cursor position sequence "ESC [ 9999 ; 9999 R"
+	 */
+	KEYCODE_BUFFER_SIZE = 16
+};
+/* Note: fd may be in blocking or non-blocking mode, both make sense.
+ * For one, less uses non-blocking mode.
+ * Only the first read syscall inside read_key may block indefinitely
+ * (unless fd is in non-blocking mode),
+ * subsequent reads will time out after a few milliseconds.
+ * Return of -1 means EOF or error (errno == 0 on EOF).
+ * buffer[0] is used as a counter of buffered chars and must be 0
+ * on first call.
+ */
+int64_t read_key(int fd, char *buffer) FAST_FUNC;
+
+
 #if ENABLE_FEATURE_EDITING
 /* It's NOT just ENABLEd or disabled. It's a number: */
 # ifdef CONFIG_FEATURE_EDITING_HISTORY
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index a0b1bcf..81f6fde 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 3771045..6f6c39e 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;
 	}
diff --git a/shell/hush.c b/shell/hush.c
index add40eb..5fa693b 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1006,7 +1006,7 @@ static void restore_G_args(save_arg_t *sv, char **argv)
  * Commands run in command substitution ("`cmd`")
  * have SIGTTIN, SIGTTOU, SIGTSTP set to SIG_IGN.
  *
- * Ordinary commands have signals set to SIG_IGN/DFL set as inherited
+ * Ordinary commands have signals set to SIG_IGN/DFL as inherited
  * by the shell from its parent.
  *
  * Siganls which differ from SIG_DFL action
@@ -1285,7 +1285,7 @@ static int set_local_var(char *str, int flg_export, int flg_read_only)
 		if (strncmp(cur->varstr, str, name_len) != 0) {
 			if (!cur->next) {
 				/* Bail out. Note that now cur points
-				 * to last var in linked list */
+				 * to the last var in the linked list */
 				break;
 			}
 			cur = cur->next;