[PATCH v2 02/25] cli: Move readline character-processing to a state machine
Simon Glass
sjg at chromium.org
Fri Nov 4 23:48:20 CET 2022
The current cread_line() function is very long. It handles the escape
processing inline. The menu command does similar processing but at the
character level, so there is some duplication.
Split the character processing into a new function cli_ch_process() which
processes individual characters and returns the resulting input character,
taking account of escape sequences. It requires the caller to set up and
maintain its state.
Update cread_line() to use this new function.
The only intended functional change is that an invalid escape sequence
does not add invalid/control characters into the input buffer, but instead
discards these.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
(no changes since v1)
common/Makefile | 6 +-
common/cli_getch.c | 204 ++++++++++++++++++++++++++++++++++++++++++
common/cli_readline.c | 150 +++++--------------------------
include/cli.h | 72 +++++++++++++++
4 files changed, 301 insertions(+), 131 deletions(-)
create mode 100644 common/cli_getch.c
diff --git a/common/Makefile b/common/Makefile
index 20addfb244c..67485e77a04 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -38,7 +38,7 @@ obj-$(CONFIG_SPLASH_SOURCE) += splash_source.o
obj-$(CONFIG_MENU) += menu.o
obj-$(CONFIG_UPDATE_COMMON) += update.o
obj-$(CONFIG_USB_KEYBOARD) += usb_kbd.o
-obj-$(CONFIG_CMDLINE) += cli_readline.o cli_simple.o
+obj-$(CONFIG_CMDLINE) += cli_getch.o cli_readline.o cli_simple.o
endif # !CONFIG_SPL_BUILD
@@ -93,8 +93,8 @@ obj-y += eeprom/eeprom_field.o eeprom/eeprom_layout.o
endif
obj-y += cli.o
-obj-$(CONFIG_FSL_DDR_INTERACTIVE) += cli_simple.o cli_readline.o
-obj-$(CONFIG_STM32MP1_DDR_INTERACTIVE) += cli_simple.o cli_readline.o
+obj-$(CONFIG_FSL_DDR_INTERACTIVE) += cli_getch.o cli_simple.o cli_readline.o
+obj-$(CONFIG_STM32MP1_DDR_INTERACTIVE) += cli_getch.o cli_simple.o cli_readline.o
obj-$(CONFIG_DFU_OVER_USB) += dfu.o
obj-y += command.o
obj-$(CONFIG_$(SPL_TPL_)LOG) += log.o
diff --git a/common/cli_getch.c b/common/cli_getch.c
new file mode 100644
index 00000000000..9eeea7fef29
--- /dev/null
+++ b/common/cli_getch.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2000
+ * Wolfgang Denk, DENX Software Engineering, wd at denx.de.
+ *
+ * Copyright 2022 Google LLC
+ */
+
+#include <common.h>
+#include <cli.h>
+
+/**
+ * enum cli_esc_state_t - indicates what to do with an escape character
+ *
+ * @ESC_REJECT: Invalid escape sequence, so the esc_save[] characters are
+ * returned from each subsequent call to cli_ch_esc()
+ * @ESC_SAVE: Character should be saved in esc_save until we have another one
+ * @ESC_CONVERTED: Escape sequence has been completed and the resulting
+ * character is available
+ */
+enum cli_esc_state_t {
+ ESC_REJECT,
+ ESC_SAVE,
+ ESC_CONVERTED
+};
+
+void cli_ch_init(struct cli_ch_state *cch)
+{
+ memset(cch, '\0', sizeof(*cch));
+}
+
+/**
+ * cli_ch_esc() - Process a character in an ongoing escape sequence
+ *
+ * @cch: State information
+ * @ichar: Character to process
+ * @actp: Returns the action to take
+ * Returns: Output character if *actp is ESC_CONVERTED, else 0
+ */
+static int cli_ch_esc(struct cli_ch_state *cch, int ichar,
+ enum cli_esc_state_t *actp)
+{
+ enum cli_esc_state_t act = ESC_REJECT;
+
+ switch (cch->esc_len) {
+ case 1:
+ if (ichar == '[' || ichar == 'O')
+ act = ESC_SAVE;
+ break;
+ case 2:
+ switch (ichar) {
+ case 'D': /* <- key */
+ ichar = CTL_CH('b');
+ act = ESC_CONVERTED;
+ break; /* pass off to ^B handler */
+ case 'C': /* -> key */
+ ichar = CTL_CH('f');
+ act = ESC_CONVERTED;
+ break; /* pass off to ^F handler */
+ case 'H': /* Home key */
+ ichar = CTL_CH('a');
+ act = ESC_CONVERTED;
+ break; /* pass off to ^A handler */
+ case 'F': /* End key */
+ ichar = CTL_CH('e');
+ act = ESC_CONVERTED;
+ break; /* pass off to ^E handler */
+ case 'A': /* up arrow */
+ ichar = CTL_CH('p');
+ act = ESC_CONVERTED;
+ break; /* pass off to ^P handler */
+ case 'B': /* down arrow */
+ ichar = CTL_CH('n');
+ act = ESC_CONVERTED;
+ break; /* pass off to ^N handler */
+ case '1':
+ case '2':
+ case '3':
+ case '4':
+ case '7':
+ case '8':
+ if (cch->esc_save[1] == '[') {
+ /* see if next character is ~ */
+ act = ESC_SAVE;
+ }
+ break;
+ }
+ break;
+ case 3:
+ switch (ichar) {
+ case '~':
+ switch (cch->esc_save[2]) {
+ case '3': /* Delete key */
+ ichar = CTL_CH('d');
+ act = ESC_CONVERTED;
+ break; /* pass to ^D handler */
+ case '1': /* Home key */
+ case '7':
+ ichar = CTL_CH('a');
+ act = ESC_CONVERTED;
+ break; /* pass to ^A handler */
+ case '4': /* End key */
+ case '8':
+ ichar = CTL_CH('e');
+ act = ESC_CONVERTED;
+ break; /* pass to ^E handler */
+ }
+ break;
+ case '0':
+ if (cch->esc_save[2] == '2')
+ act = ESC_SAVE;
+ break;
+ }
+ break;
+ case 4:
+ switch (ichar) {
+ case '0':
+ case '1':
+ act = ESC_SAVE;
+ break; /* bracketed paste */
+ }
+ break;
+ case 5:
+ if (ichar == '~') { /* bracketed paste */
+ ichar = 0;
+ act = ESC_CONVERTED;
+ }
+ }
+
+ *actp = act;
+
+ return act == ESC_CONVERTED ? ichar : 0;
+}
+
+int cli_ch_process(struct cli_ch_state *cch, int ichar)
+{
+ /*
+ * ichar=0x0 when error occurs in U-Boot getchar() or when the caller
+ * wants to check if there are more characters saved in the escape
+ * sequence
+ */
+ if (!ichar) {
+ if (cch->emit_upto) {
+ if (cch->emit_upto < cch->esc_len)
+ return cch->esc_save[cch->emit_upto++];
+ cch->emit_upto = 0;
+ }
+ return 0;
+ } else if (ichar == -ETIMEDOUT) {
+ /*
+ * If we are in an escape sequence but nothing has followed the
+ * Escape character, then the user probably just pressed the
+ * Escape key. Return it and clear the sequence.
+ */
+ if (cch->esc_len) {
+ cch->esc_len = 0;
+ return '\e';
+ }
+
+ /* Otherwise there is nothing to return */
+ return 0;
+ }
+
+ if (ichar == '\n' || ichar == '\r')
+ return '\n';
+
+ /* handle standard linux xterm esc sequences for arrow key, etc. */
+ if (cch->esc_len != 0) {
+ enum cli_esc_state_t act;
+
+ ichar = cli_ch_esc(cch, ichar, &act);
+
+ switch (act) {
+ case ESC_SAVE:
+ /* save this character and return nothing */
+ cch->esc_save[cch->esc_len++] = ichar;
+ return 0;
+ case ESC_REJECT:
+ /*
+ * invalid escape sequence, start returning the
+ * characters in it
+ */
+ cch->esc_save[cch->esc_len++] = ichar;
+ return cch->esc_save[cch->emit_upto++];
+ case ESC_CONVERTED:
+ /* valid escape sequence, return the resulting char */
+ cch->esc_len = 0;
+ return ichar;
+ }
+ }
+
+ if (ichar == '\e') {
+ if (!cch->esc_len) {
+ cch->esc_save[cch->esc_len] = ichar;
+ cch->esc_len = 1;
+ } else {
+ puts("impossible condition #876\n");
+ cch->esc_len = 0;
+ }
+ return 0;
+ }
+
+ return ichar;
+}
diff --git a/common/cli_readline.c b/common/cli_readline.c
index f6e2bcdeceb..7eb469227ac 100644
--- a/common/cli_readline.c
+++ b/common/cli_readline.c
@@ -62,7 +62,6 @@ static char *delete_char (char *buffer, char *p, int *colp, int *np, int plen)
#define putnstr(str, n) printf("%.*s", (int)n, str)
-#define CTL_CH(c) ((c) - 'a' + 1)
#define CTL_BACKSPACE ('\b')
#define DEL ((char)255)
#define DEL7 ((char)127)
@@ -252,156 +251,53 @@ static void cread_add_str(char *str, int strsize, int insert,
static int cread_line(const char *const prompt, char *buf, unsigned int *len,
int timeout)
{
+ struct cli_ch_state s_cch, *cch = &s_cch;
unsigned long num = 0;
unsigned long eol_num = 0;
unsigned long wlen;
char ichar;
int insert = 1;
- int esc_len = 0;
- char esc_save[8];
int init_len = strlen(buf);
int first = 1;
+ cli_ch_init(cch);
+
if (init_len)
cread_add_str(buf, init_len, 1, &num, &eol_num, buf, *len);
while (1) {
- if (bootretry_tstc_timeout())
- return -2; /* timed out */
- if (first && timeout) {
- uint64_t etime = endtick(timeout);
-
- while (!tstc()) { /* while no incoming data */
- if (get_ticks() >= etime)
- return -2; /* timed out */
- schedule();
+ /* Check for saved characters */
+ ichar = cli_ch_process(cch, 0);
+
+ if (!ichar) {
+ if (bootretry_tstc_timeout())
+ return -2; /* timed out */
+ if (first && timeout) {
+ u64 etime = endtick(timeout);
+
+ while (!tstc()) { /* while no incoming data */
+ if (get_ticks() >= etime)
+ return -2; /* timed out */
+ schedule();
+ }
+ first = 0;
}
- first = 0;
+
+ ichar = getcmd_getch();
}
- ichar = getcmd_getch();
+ ichar = cli_ch_process(cch, ichar);
/* ichar=0x0 when error occurs in U-Boot getc */
if (!ichar)
continue;
- if ((ichar == '\n') || (ichar == '\r')) {
+ if (ichar == '\n') {
putc('\n');
break;
}
- /*
- * handle standard linux xterm esc sequences for arrow key, etc.
- */
- if (esc_len != 0) {
- enum { ESC_REJECT, ESC_SAVE, ESC_CONVERTED } act = ESC_REJECT;
-
- if (esc_len == 1) {
- if (ichar == '[' || ichar == 'O')
- act = ESC_SAVE;
- } else if (esc_len == 2) {
- switch (ichar) {
- case 'D': /* <- key */
- ichar = CTL_CH('b');
- act = ESC_CONVERTED;
- break; /* pass off to ^B handler */
- case 'C': /* -> key */
- ichar = CTL_CH('f');
- act = ESC_CONVERTED;
- break; /* pass off to ^F handler */
- case 'H': /* Home key */
- ichar = CTL_CH('a');
- act = ESC_CONVERTED;
- break; /* pass off to ^A handler */
- case 'F': /* End key */
- ichar = CTL_CH('e');
- act = ESC_CONVERTED;
- break; /* pass off to ^E handler */
- case 'A': /* up arrow */
- ichar = CTL_CH('p');
- act = ESC_CONVERTED;
- break; /* pass off to ^P handler */
- case 'B': /* down arrow */
- ichar = CTL_CH('n');
- act = ESC_CONVERTED;
- break; /* pass off to ^N handler */
- case '1':
- case '2':
- case '3':
- case '4':
- case '7':
- case '8':
- if (esc_save[1] == '[') {
- /* see if next character is ~ */
- act = ESC_SAVE;
- }
- break;
- }
- } else if (esc_len == 3) {
- switch (ichar) {
- case '~':
- switch (esc_save[2]) {
- case '3': /* Delete key */
- ichar = CTL_CH('d');
- act = ESC_CONVERTED;
- break; /* pass to ^D handler */
- case '1': /* Home key */
- case '7':
- ichar = CTL_CH('a');
- act = ESC_CONVERTED;
- break; /* pass to ^A handler */
- case '4': /* End key */
- case '8':
- ichar = CTL_CH('e');
- act = ESC_CONVERTED;
- break; /* pass to ^E handler */
- }
- break;
- case '0':
- if (esc_save[2] == '2')
- act = ESC_SAVE;
- break;
- }
- } else if (esc_len == 4) {
- switch (ichar) {
- case '0':
- case '1':
- act = ESC_SAVE;
- break; /* bracketed paste */
- }
- } else if (esc_len == 5) {
- if (ichar == '~') { /* bracketed paste */
- ichar = 0;
- act = ESC_CONVERTED;
- }
- }
- switch (act) {
- case ESC_SAVE:
- esc_save[esc_len++] = ichar;
- continue;
- case ESC_REJECT:
- esc_save[esc_len++] = ichar;
- cread_add_str(esc_save, esc_len, insert,
- &num, &eol_num, buf, *len);
- esc_len = 0;
- continue;
- case ESC_CONVERTED:
- esc_len = 0;
- break;
- }
- }
-
switch (ichar) {
- case 0x1b:
- if (esc_len == 0) {
- esc_save[esc_len] = ichar;
- esc_len = 1;
- } else {
- puts("impossible condition #876\n");
- esc_len = 0;
- }
- break;
-
case CTL_CH('a'):
BEGINNING_OF_LINE();
break;
@@ -470,8 +366,6 @@ static int cread_line(const char *const prompt, char *buf, unsigned int *len,
{
char *hline;
- esc_len = 0;
-
if (ichar == CTL_CH('p'))
hline = hist_prev();
else
diff --git a/include/cli.h b/include/cli.h
index ba5b8ebd36e..863519e4b13 100644
--- a/include/cli.h
+++ b/include/cli.h
@@ -7,6 +7,21 @@
#ifndef __CLI_H
#define __CLI_H
+#include <stdbool.h>
+
+/**
+ * struct cli_ch_state - state information for reading cmdline characters
+ *
+ * @esc_len: Number of escape characters read so far
+ * @esc_save: Escape characters collected so far
+ * @emit_upto: Next character to emit from esc_save (0 if not emitting)
+ */
+struct cli_ch_state {
+ int esc_len;
+ char esc_save[8];
+ int emit_upto;
+};
+
/**
* Go into the command loop
*
@@ -154,5 +169,62 @@ void cli_loop(void);
void cli_init(void);
#define endtick(seconds) (get_ticks() + (uint64_t)(seconds) * get_tbclk())
+#define CTL_CH(c) ((c) - 'a' + 1)
+
+/**
+ * cli_ch_init() - Set up the initial state to process input characters
+ *
+ * @cch: State to set up
+ */
+void cli_ch_init(struct cli_ch_state *cch);
+
+/**
+ * cli_ch_process() - Process an input character
+ *
+ * When @ichar is 0, this function returns any characters from an invalid escape
+ * sequence which are still pending in the buffer
+ *
+ * Otherwise it processes the input character. If it is an escape character,
+ * then an escape sequence is started and the function returns 0. If we are in
+ * the middle of an escape sequence, the character is processed and may result
+ * in returning 0 (if more characters are needed) or a valid character (if
+ * @ichar finishes the sequence).
+ *
+ * If @ichar is a valid character and there is no escape sequence in progress,
+ * then it is returned as is.
+ *
+ * If the Enter key is pressed, '\n' is returned.
+ *
+ * Usage should be like this::
+ *
+ * struct cli_ch_state cch;
+ *
+ * cli_ch_init(cch);
+ * do
+ * {
+ * int ichar, ch;
+ *
+ * ichar = cli_ch_process(cch, 0);
+ * if (!ichar) {
+ * ch = getchar();
+ * ichar = cli_ch_process(cch, ch);
+ * }
+ * (handle the ichar character)
+ * } while (!done)
+ *
+ * If tstc() is used to look for keypresses, this function can be called with
+ * @ichar set to -ETIMEDOUT if there is no character after 5-10ms. This allows
+ * the ambgiuity between the Escape key and the arrow keys (which generate an
+ * escape character followed by other characters) to be resolved.
+ *
+ * @cch: Current state
+ * @ichar: Input character to process, or 0 if none, or -ETIMEDOUT if no
+ * character has been received within a small number of milliseconds (this
+ * cancels any existing escape sequence and allows pressing the Escape key to
+ * work)
+ * Returns: Resulting input character after processing, 0 if none, '\e' if
+ * an existing escape sequence was cancelled
+ */
+int cli_ch_process(struct cli_ch_state *cch, int ichar);
#endif
--
2.38.1.431.g37b22c650d-goog
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