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shell.c
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shell.c
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/*
* Copyright (C) 2009, 2020 Freie Universität Berlin
* Copyright (C) 2013, INRIA.
* Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup sys_shell
* @{
*
* @file
* @brief Implementation of a simple command interpreter.
* For each command (i.e. "echo"), a handler can be specified.
* If the first word of a user-entered command line matches the
* name of a handler, the handler will be called with the remaining
* arguments passed in a manner similar to `main()`'s argc/argv
* parameters.
*
* @author Kaspar Schleiser <kaspar@schleiser.de>
* @author René Kijewski <rene.kijewski@fu-berlin.de>
* @author Juan Carrano <j.carrano@fu-berlin.de>
* @author Hendrik van Essen <hendrik.ve@fu-berlin.de>
*
* @}
*/
#include <string.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include <errno.h>
#include "kernel_defines.h"
#include "xfa.h"
#include "shell.h"
#include "shell_lock.h"
#ifdef MODULE_VFS
#include <fcntl.h>
#include "vfs.h"
#endif
/* define shell command cross file array */
XFA_INIT_CONST(shell_command_xfa_t*, shell_commands_xfa);
#define ETX '\x03' /** ASCII "End-of-Text", or Ctrl-C */
#define EOT '\x04' /** ASCII "End-of-Transmission", or Ctrl-D */
#define BS '\x08' /** ASCII "Backspace" */
#define DEL '\x7f' /** ASCII "Delete" */
#if defined(MODULE_NEWLIB) || defined(MODULE_PICOLIBC)
#define flush_if_needed() fflush(stdout)
#else
#define flush_if_needed()
#endif /* MODULE_NEWLIB || MODULE_PICOLIBC */
#define SQUOTE '\''
#define DQUOTE '"'
#define ESCAPECHAR '\\'
#define SPACE ' '
#define TAB '\t'
#define PARSE_ESCAPE_MASK 0x4;
extern void shell_lock_checkpoint(char *line_buf, int len);
extern bool shell_lock_is_locked(void);
extern void shell_lock_auto_lock_refresh(void);
enum parse_state {
PARSE_BLANK = 0x0,
PARSE_UNQUOTED = 0x1,
PARSE_SINGLEQUOTE = 0x2,
PARSE_DOUBLEQUOTE = 0x3,
PARSE_UNQUOTED_ESC = 0x5,
PARSE_SINGLEQUOTE_ESC = 0x6,
PARSE_DOUBLEQUOTE_ESC = 0x7,
};
static enum parse_state escape_toggle(enum parse_state s)
{
return s ^ PARSE_ESCAPE_MASK;
}
static shell_command_handler_t search_commands(const shell_command_t *entry,
char *command)
{
for (; entry->name != NULL; entry++) {
if (strcmp(entry->name, command) == 0) {
return entry->handler;
}
}
return NULL;
}
static shell_command_handler_t search_commands_xfa(char *command)
{
unsigned n = XFA_LEN(shell_command_t*, shell_commands_xfa);
for (unsigned i = 0; i < n; i++) {
const volatile shell_command_xfa_t *entry = shell_commands_xfa[i];
if (flash_strcmp(command, entry->name) == 0) {
return entry->handler;
}
}
return NULL;
}
static shell_command_handler_t find_handler(
const shell_command_t *command_list, char *command)
{
shell_command_handler_t handler = NULL;
if (command_list != NULL) {
handler = search_commands(command_list, command);
}
if (handler == NULL) {
handler = search_commands_xfa(command);
}
return handler;
}
static void print_commands(const shell_command_t *entry)
{
for (; entry->name != NULL; entry++) {
printf("%-20s %s\n", entry->name, entry->desc);
}
}
static void print_commands_xfa(void)
{
unsigned n = XFA_LEN(shell_command_xfa_t*, shell_commands_xfa);
for (unsigned i = 0; i < n; i++) {
const volatile shell_command_xfa_t *entry = shell_commands_xfa[i];
printf("%-20" PRIsflash " %" PRIsflash "\n",
entry->name, entry->desc);
}
}
static void print_help(const shell_command_t *command_list)
{
printf("Command Description\n"
"---------------------------------------\n");
if (command_list != NULL) {
print_commands(command_list);
}
print_commands_xfa();
}
/**
* Break input line into words, create argv and call the command handler.
*
* Words are broken up at spaces. A backslash escapes the character that comes
* after (meaning if it is taken literally and if it is a space it does not break
* the word). Spaces can also be protected by quoting with double or single
* quotes.
*
* There are two unquoted states (PARSE_BLANK and PARSE_UNQUOTED) and two quoted
* states (PARSE_SINGLEQUOTE and PARSE_DOUBLEQUOTE). In addition, every state
* (except PARSE_BLANK) has an escaped pair state (e.g PARSE_SINGLEQUOTE and
* PARSE_SINGLEQUOTE_ESC).
*
* For the following let's define some things
* - Function transit(character, state) to change to 'state' after
* 'character' was read. The order of a list of transit-functions matters.
* - A BLANK is either SPACE or TAB
* - '*' means any character
*
* PARSE_BLANK
* transit(SQUOTE, PARSE_SINGLEQUOTE)
* transit(DQUOTE, PARSE_DOUBLEQUOTE)
* transit(ESCAPECHAR, PARSE_UNQUOTED_ESC)
* transit(BLANK, PARSE_BLANK)
* transit(*, PARSE_UNQUOTED) -> store character
*
* PARSE_UNQUOTED
* transit(SQUOTE, PARSE_SINGLEQUOTE)
* transit(DQUOTE, PARSE_DOUBLEQUOTE)
* transit(BLANK, PARSE_BLANK)
* transit(ESCAPECHAR, PARSE_UNQUOTED_ESC)
* transit(*, PARSE_UNQUOTED) -> store character
*
* PARSE_UNQUOTED_ESC
* transit(*, PARSE_UNQUOTED) -> store character
*
* PARSE_SINGLEQUOTE
* transit(SQUOTE, PARSE_UNQUOTED)
* transit(ESCAPECHAR, PARSE_SINGLEQUOTE_ESC)
* transit(*, PARSE_SINGLEQUOTE) -> store character
*
* PARSE_SINGLEQUOTE_ESC
* transit(*, PARSE_SINGLEQUOTE) -> store character
*
* PARSE_DOUBLEQUOTE
* transit(DQUOTE, PARSE_UNQUOTED)
* transit(ESCAPECHAR, PARSE_DOUBLEQUOTE_ESC)
* transit(*, PARSE_DOUBLEQUOTE) -> store character
*
* PARSE_DOUBLEQUOTE_ESC
* transit(*, PARSE_DOUBLEQUOTE) -> store character
*
*
*/
int shell_handle_input_line(const shell_command_t *command_list, char *line)
{
/* first we need to calculate the number of arguments */
int argc = 0;
char *readpos = line;
char *writepos = readpos;
uint8_t pstate = PARSE_BLANK;
if (IS_USED(MODULE_SHELL_HOOKS)) {
shell_post_readline_hook();
}
for (; *readpos != '\0'; readpos++) {
char wordbreak = SPACE;
bool is_wordbreak = false;
switch (pstate) {
case PARSE_BLANK:
if (*readpos != SPACE && *readpos != TAB) {
argc++;
}
if (*readpos == SQUOTE) {
pstate = PARSE_SINGLEQUOTE;
}
else if (*readpos == DQUOTE) {
pstate = PARSE_DOUBLEQUOTE;
}
else if (*readpos == ESCAPECHAR) {
pstate = PARSE_UNQUOTED_ESC;
}
else if (*readpos != SPACE && *readpos != TAB) {
pstate = PARSE_UNQUOTED;
*writepos++ = *readpos;
}
break;
case PARSE_UNQUOTED:
if (*readpos == SQUOTE) {
pstate = PARSE_SINGLEQUOTE;
}
else if (*readpos == DQUOTE) {
pstate = PARSE_DOUBLEQUOTE;
}
else if (*readpos == ESCAPECHAR) {
pstate = escape_toggle(pstate);
}
else if (*readpos == SPACE || *readpos == TAB) {
pstate = PARSE_BLANK;
*writepos++ = '\0';
}
else {
*writepos++ = *readpos;
}
break;
case PARSE_SINGLEQUOTE:
wordbreak = SQUOTE;
is_wordbreak = true;
break;
case PARSE_DOUBLEQUOTE:
wordbreak = DQUOTE;
is_wordbreak = true;
break;
default: /* QUOTED state */
pstate = escape_toggle(pstate);
*writepos++ = *readpos;
break;
}
if (is_wordbreak) {
if (*readpos == wordbreak) {
if (wordbreak == SQUOTE || wordbreak == DQUOTE) {
pstate = PARSE_UNQUOTED;
}
}
else if (*readpos == ESCAPECHAR) {
pstate = escape_toggle(pstate);
}
else {
*writepos++ = *readpos;
}
}
}
*writepos = '\0';
if (pstate != PARSE_BLANK && pstate != PARSE_UNQUOTED) {
printf("shell: incorrect quoting\n");
return -EINVAL;
}
if (argc == 0) {
return 0;
}
/* then we fill the argv array */
int collected;
/* allocate argv on the stack leaving space for NULL termination */
char *argv[argc + 1];
readpos = line;
for (collected = 0; collected < argc; collected++) {
argv[collected] = readpos;
readpos += strlen(readpos) + 1;
}
/* NULL terminate argv. See `shell_command_handler_t` doc in shell.h for
rationale. */
argv[argc] = NULL;
/* then we call the appropriate handler */
shell_command_handler_t handler = find_handler(command_list, argv[0]);
if (handler != NULL) {
if (IS_USED(MODULE_SHELL_HOOKS)) {
shell_pre_command_hook(argc, argv);
int res = handler(argc, argv);
shell_post_command_hook(res, argc, argv);
return res;
}
else {
return handler(argc, argv);
}
}
else {
if (strcmp("help", argv[0]) == 0) {
print_help(command_list);
return 0;
}
else {
printf("shell: command not found: %s\n", argv[0]);
}
}
return -ENOEXEC;
}
__attribute__((weak)) void shell_post_readline_hook(void)
{
}
__attribute__((weak)) void shell_pre_command_hook(int argc, char **argv)
{
(void)argv;
(void)argc;
}
__attribute__((weak)) void shell_post_command_hook(int ret, int argc,
char **argv)
{
(void)ret;
(void)argv;
(void)argc;
}
static inline void print_prompt(void)
{
if (!IS_ACTIVE(CONFIG_SHELL_NO_PROMPT) && !IS_ACTIVE(SHELL_NO_PROMPT)) {
putchar('>');
putchar(' ');
}
flush_if_needed();
}
static inline void echo_char(char c)
{
if (!IS_ACTIVE(CONFIG_SHELL_NO_ECHO) && !IS_ACTIVE(SHELL_NO_ECHO)) {
putchar(c);
}
}
static inline void white_tape(void)
{
if (!IS_ACTIVE(CONFIG_SHELL_NO_ECHO) && !IS_ACTIVE(SHELL_NO_ECHO)) {
putchar('\b');
putchar(' ');
putchar('\b');
}
}
static inline void new_line(void)
{
if (!IS_ACTIVE(CONFIG_SHELL_NO_ECHO) && !IS_ACTIVE(SHELL_NO_ECHO)) {
putchar('\r');
putchar('\n');
}
}
/**
* @brief Read a single line from standard input into a buffer.
*
* In addition to copying characters, this routine echoes the line back to
* stdout and also supports primitive line editing.
*
* If the input line is too long, the input will still be consumed until the end
* to prevent the next line from containing garbage.
*
* We allow Unix (\n), DOS (\r\n), and Mac linebreaks (\r).
* QEMU transmits only a single '\r' == 13 on hitting enter ("-serial stdio").
* DOS newlines are handled like hitting enter twice.
*
* @param buf Buffer where the input will be placed.
* @param size Size of the buffer. The maximum line length will be one less
* than size, to accommodate for the null terminator.
* The minimum buffer size is 1.
*
* @return length of the read line, excluding the terminator, if reading was
* successful.
* @return EOF, if the end of the input stream was reached.
* @return -ENOBUFS if the buffer size was exceeded.
*/
int readline(char *buf, size_t size) /* needed externally by module shell_lock */
{
int curr_pos = 0;
bool length_exceeded = false;
assert((size_t) size > 0);
while (1) {
assert((size_t) curr_pos < size);
int c = getchar();
switch (c) {
case EOT:
/* Ctrl-D terminates the current shell instance. */
/* fall-thru */
case EOF:
return EOF;
case ETX:
/* Ctrl-C cancels the current line. */
curr_pos = 0;
length_exceeded = false;
/* fall-thru */
case '\r':
/* fall-thru */
case '\n':
buf[curr_pos] = '\0';
new_line();
return (length_exceeded) ? -ENOBUFS : curr_pos;
/* check for backspace: */
case BS: /* 0x08 (BS) for most terminals */
/* fall-thru */
case DEL: /* 0x7f (DEL) when using QEMU */
if (curr_pos > 0) {
curr_pos--;
if ((size_t) curr_pos < size) {
buf[curr_pos] = '\0';
length_exceeded = false;
}
white_tape();
}
break;
default:
/* Always consume characters, but do not not always store them */
if ((size_t) curr_pos < size - 1) {
buf[curr_pos++] = c;
}
else {
length_exceeded = true;
}
echo_char(c);
break;
}
flush_if_needed();
}
}
void shell_run_once(const shell_command_t *shell_commands,
char *line_buf, int len)
{
if (IS_USED(MODULE_SHELL_LOCK)) {
shell_lock_checkpoint(line_buf, len);
}
print_prompt();
while (1) {
int res = readline(line_buf, len);
if (IS_USED(MODULE_SHELL_LOCK)) {
if (shell_lock_is_locked()) {
break;
}
}
if (IS_USED(MODULE_SHELL_LOCK_AUTO_LOCKING)) {
/* reset lock countdown in case of new input */
shell_lock_auto_lock_refresh();
}
switch (res) {
case EOF:
if (IS_USED(MODULE_SHELL_LOCK)) {
shell_lock_do_lock();
}
return;
case -ENOBUFS:
printf("shell: maximum line length exceeded\n");
break;
default:
shell_handle_input_line(shell_commands, line_buf);
break;
}
print_prompt();
}
}
#ifdef MODULE_VFS
int shell_parse_file(const shell_command_t *shell_commands,
const char *filename, unsigned *line_nr)
{
char buffer[SHELL_DEFAULT_BUFSIZE];
if (line_nr) {
*line_nr = 0;
}
int res, fd = vfs_open(filename, O_RDONLY, 0);
if (fd < 0) {
printf("Can't open %s\n", filename);
return fd;
}
while (1) {
res = vfs_readline(fd, buffer, sizeof(buffer));
if (line_nr) {
*line_nr += 1;
}
/* error reading line */
if (res < 0) {
break;
}
/* skip comment and empty lines */
if (buffer[0] == '#') {
continue;
}
res = shell_handle_input_line(shell_commands, buffer);
if (res) {
break;
}
}
vfs_close(fd);
return res;
}
#endif