cli_hush.c

/*
 * sh.c -- a prototype Bourne shell grammar parser
 *      Intended to follow the original Thompson and Ritchie
 *      "small and simple is beautiful" philosophy, which
 *      incidentally is a good match to today's BusyBox.
 *
 * Copyright (C) 2000,2001  Larry Doolittle  <larry@doolittle.boa.org>
 *
 * Credits:
 *      The parser routines proper are all original material, first
 *      written Dec 2000 and Jan 2001 by Larry Doolittle.
 *      The execution engine, the builtins, and much of the underlying
 *      support has been adapted from busybox-0.49pre's lash,
 *      which is Copyright (C) 2000 by Lineo, Inc., and
 *      written by Erik Andersen <andersen@lineo.com>, <andersee@debian.org>.
 *      That, in turn, is based in part on ladsh.c, by Michael K. Johnson and
 *      Erik W. Troan, which they placed in the public domain.  I don't know
 *      how much of the Johnson/Troan code has survived the repeated rewrites.
 * Other credits:
 *      b_addchr() derived from similar w_addchar function in glibc-2.2
 *      setup_redirect(), redirect_opt_num(), and big chunks of main()
 *        and many builtins derived from contributions by Erik Andersen
 *      miscellaneous bugfixes from Matt Kraai
 *
 * There are two big (and related) architecture differences between
 * this parser and the lash parser.  One is that this version is
 * actually designed from the ground up to understand nearly all
 * of the Bourne grammar.  The second, consequential change is that
 * the parser and input reader have been turned inside out.  Now,
 * the parser is in control, and asks for input as needed.  The old
 * way had the input reader in control, and it asked for parsing to
 * take place as needed.  The new way makes it much easier to properly
 * handle the recursion implicit in the various substitutions, especially
 * across continuation lines.
 *
 * Bash grammar not implemented: (how many of these were in original sh?)
 *      $@ (those sure look like weird quoting rules)
 *      $_
 *      ! negation operator for pipes
 *      &> and >& redirection of stdout+stderr
 *      Brace Expansion
 *      Tilde Expansion
 *      fancy forms of Parameter Expansion
 *      aliases
 *      Arithmetic Expansion
 *      <(list) and >(list) Process Substitution
 *      reserved words: case, esac, select, function
 *      Here Documents ( << word )
 *      Functions
 * Major bugs:
 *      job handling woefully incomplete and buggy
 *      reserved word execution woefully incomplete and buggy
 * to-do:
 *      port selected bugfixes from post-0.49 busybox lash - done?
 *      finish implementing reserved words: for, while, until, do, done
 *      change { and } from special chars to reserved words
 *      builtins: break, continue, eval, return, set, trap, ulimit
 *      test magic exec
 *      handle children going into background
 *      clean up recognition of null pipes
 *      check setting of global_argc and global_argv
 *      control-C handling, probably with longjmp
 *      follow IFS rules more precisely, including update semantics
 *      figure out what to do with backslash-newline
 *      explain why we use signal instead of sigaction
 *      propagate syntax errors, die on resource errors?
 *      continuation lines, both explicit and implicit - done?
 *      memory leak finding and plugging - done?
 *      more testing, especially quoting rules and redirection
 *      document how quoting rules not precisely followed for variable assignments
 *      maybe change map[] to use 2-bit entries
 *      (eventually) remove all the printf's
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#define __U_BOOT__
#ifdef __U_BOOT__
#include <malloc.h>         /* malloc, free, realloc*/
#include <linux/ctype.h>    /* isalpha, isdigit */
#include <common.h>        /* readline */
#include <bootretry.h>
#include <cli.h>
#include <cli_hush.h>
#include <command.h>        /* find_cmd */
#ifndef CONFIG_SYS_PROMPT_HUSH_PS2
#define CONFIG_SYS_PROMPT_HUSH_PS2	"> "
#endif
#endif
#ifndef __U_BOOT__
#include <ctype.h>     /* isalpha, isdigit */
#include <unistd.h>    /* getpid */
#include <stdlib.h>    /* getenv, atoi */
#include <string.h>    /* strchr */
#include <stdio.h>     /* popen etc. */
#include <glob.h>      /* glob, of course */
#include <stdarg.h>    /* va_list */
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>    /* should be pretty obvious */

#include <sys/stat.h>  /* ulimit */
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

/* #include <dmalloc.h> */

#if 1
#include "busybox.h"
#include "cmdedit.h"
#else
#define applet_name "hush"
#include "standalone.h"
#define hush_main main
#undef CONFIG_FEATURE_SH_FANCY_PROMPT
#define BB_BANNER
#endif
#endif
#define SPECIAL_VAR_SYMBOL 03
#define SUBSTED_VAR_SYMBOL 04
#ifndef __U_BOOT__
#define FLAG_EXIT_FROM_LOOP 1
#define FLAG_PARSE_SEMICOLON (1 << 1)		/* symbol ';' is special for parser */
#define FLAG_REPARSING       (1 << 2)		/* >= 2nd pass */

#endif

#ifdef __U_BOOT__
DECLARE_GLOBAL_DATA_PTR;

#define EXIT_SUCCESS 0
#define EOF -1
#define syntax() syntax_err()
#define xstrdup strdup
#define error_msg printf
#else
typedef enum {
	REDIRECT_INPUT     = 1,
	REDIRECT_OVERWRITE = 2,
	REDIRECT_APPEND    = 3,
	REDIRECT_HEREIS    = 4,
	REDIRECT_IO        = 5
} redir_type;

/* The descrip member of this structure is only used to make debugging
 * output pretty */
struct {int mode; int default_fd; char *descrip;} redir_table[] = {
	{ 0,                         0, "()" },
	{ O_RDONLY,                  0, "<"  },
	{ O_CREAT|O_TRUNC|O_WRONLY,  1, ">"  },
	{ O_CREAT|O_APPEND|O_WRONLY, 1, ">>" },
	{ O_RDONLY,                 -1, "<<" },
	{ O_RDWR,                    1, "<>" }
};
#endif

typedef enum {
	PIPE_SEQ = 1,
	PIPE_AND = 2,
	PIPE_OR  = 3,
	PIPE_BG  = 4,
} pipe_style;

/* might eventually control execution */
typedef enum {
	RES_NONE  = 0,
	RES_IF    = 1,
	RES_THEN  = 2,
	RES_ELIF  = 3,
	RES_ELSE  = 4,
	RES_FI    = 5,
	RES_FOR   = 6,
	RES_WHILE = 7,
	RES_UNTIL = 8,
	RES_DO    = 9,
	RES_DONE  = 10,
	RES_XXXX  = 11,
	RES_IN    = 12,
	RES_SNTX  = 13
} reserved_style;
#define FLAG_END   (1<<RES_NONE)
#define FLAG_IF    (1<<RES_IF)
#define FLAG_THEN  (1<<RES_THEN)
#define FLAG_ELIF  (1<<RES_ELIF)
#define FLAG_ELSE  (1<<RES_ELSE)
#define FLAG_FI    (1<<RES_FI)
#define FLAG_FOR   (1<<RES_FOR)
#define FLAG_WHILE (1<<RES_WHILE)
#define FLAG_UNTIL (1<<RES_UNTIL)
#define FLAG_DO    (1<<RES_DO)
#define FLAG_DONE  (1<<RES_DONE)
#define FLAG_IN    (1<<RES_IN)
#define FLAG_START (1<<RES_XXXX)

/* This holds pointers to the various results of parsing */
struct p_context {
	struct child_prog *child;
	struct pipe *list_head;
	struct pipe *pipe;