hush.c

uboot详细解读可用启动引导LINUX2.6内核

/*   job management: */
static int checkjobs(struct pipe* fg_pipe);
static void insert_bg_job(struct pipe *pi);
static void remove_bg_job(struct pipe *pi);
#endif
/*     local variable support */
static char **make_list_in(char **inp, char *name);
static char *insert_var_value(char *inp);
static char *get_local_var(const char *var);
#ifndef __U_BOOT__
static void  unset_local_var(const char *name);
#endif
static int set_local_var(const char *s, int flg_export);

#ifndef __U_BOOT__
/* Table of built-in functions.  They can be forked or not, depending on
 * context: within pipes, they fork.  As simple commands, they do not.
 * When used in non-forking context, they can change global variables
 * in the parent shell process.  If forked, of course they can not.
 * For example, 'unset foo | whatever' will parse and run, but foo will
 * still be set at the end. */
static struct built_in_command bltins[] = {
	{"bg", "Resume a job in the background", builtin_fg_bg},
	{"break", "Exit for, while or until loop", builtin_not_written},
	{"cd", "Change working directory", builtin_cd},
	{"continue", "Continue for, while or until loop", builtin_not_written},
	{"env", "Print all environment variables", builtin_env},
	{"eval", "Construct and run shell command", builtin_eval},
	{"exec", "Exec command, replacing this shell with the exec'd process",
		builtin_exec},
	{"exit", "Exit from shell()", builtin_exit},
	{"export", "Set environment variable", builtin_export},
	{"fg", "Bring job into the foreground", builtin_fg_bg},
	{"jobs", "Lists the active jobs", builtin_jobs},
	{"pwd", "Print current directory", builtin_pwd},
	{"read", "Input environment variable", builtin_read},
	{"return", "Return from a function", builtin_not_written},
	{"set", "Set/unset shell local variables", builtin_set},
	{"shift", "Shift positional parameters", builtin_shift},
	{"trap", "Trap signals", builtin_not_written},
	{"ulimit","Controls resource limits", builtin_not_written},
	{"umask","Sets file creation mask", builtin_umask},
	{"unset", "Unset environment variable", builtin_unset},
	{".", "Source-in and run commands in a file", builtin_source},
	{"help", "List shell built-in commands", builtin_help},
	{NULL, NULL, NULL}
};

static const char *set_cwd(void)
{
	if(cwd==unknown)
		cwd = NULL;     /* xgetcwd(arg) called free(arg) */
	cwd = xgetcwd((char *)cwd);
	if (!cwd)
		cwd = unknown;
	return cwd;
}

/* built-in 'eval' handler */
static int builtin_eval(struct child_prog *child)
{
	char *str = NULL;
	int rcode = EXIT_SUCCESS;

	if (child->argv[1]) {
		str = make_string(child->argv + 1);
		parse_string_outer(str, FLAG_EXIT_FROM_LOOP |
					FLAG_PARSE_SEMICOLON);
		free(str);
		rcode = last_return_code;
	}
	return rcode;
}

/* built-in 'cd <path>' handler */
static int builtin_cd(struct child_prog *child)
{
	char *newdir;
	if (child->argv[1] == NULL)
		newdir = getenv("HOME");
	else
		newdir = child->argv[1];
	if (chdir(newdir)) {
		printf("cd: %s: %s\n", newdir, strerror(errno));
		return EXIT_FAILURE;
	}
	set_cwd();
	return EXIT_SUCCESS;
}

/* built-in 'env' handler */
static int builtin_env(struct child_prog *dummy)
{
	char **e = environ;
	if (e == NULL) return EXIT_FAILURE;
	for (; *e; e++) {
		puts(*e);
	}
	return EXIT_SUCCESS;
}

/* built-in 'exec' handler */
static int builtin_exec(struct child_prog *child)
{
	if (child->argv[1] == NULL)
		return EXIT_SUCCESS;   /* Really? */
	child->argv++;
	pseudo_exec(child);
	/* never returns */
}

/* built-in 'exit' handler */
static int builtin_exit(struct child_prog *child)
{
	if (child->argv[1] == NULL)
		exit(last_return_code);
	exit (atoi(child->argv[1]));
}

/* built-in 'export VAR=value' handler */
static int builtin_export(struct child_prog *child)
{
	int res = 0;
	char *name = child->argv[1];

	if (name == NULL) {
		return (builtin_env(child));
	}

	name = strdup(name);

	if(name) {
		char *value = strchr(name, '=');

		if (!value) {
			char *tmp;
			/* They are exporting something without an =VALUE */

			value = get_local_var(name);
			if (value) {
				size_t ln = strlen(name);

				tmp = realloc(name, ln+strlen(value)+2);
				if(tmp==NULL)
					res = -1;
				else {
					sprintf(tmp+ln, "=%s", value);
					name = tmp;
				}
			} else {
				/* bash does not return an error when trying to export
				 * an undefined variable.  Do likewise. */
				res = 1;
			}
		}
	}
	if (res<0)
		perror_msg("export");
	else if(res==0)
		res = set_local_var(name, 1);
	else
		res = 0;
	free(name);
	return res;
}

/* built-in 'fg' and 'bg' handler */
static int builtin_fg_bg(struct child_prog *child)
{
	int i, jobnum;
	struct pipe *pi=NULL;

	if (!interactive)
		return EXIT_FAILURE;
	/* If they gave us no args, assume they want the last backgrounded task */
	if (!child->argv[1]) {
		for (pi = job_list; pi; pi = pi->next) {
			if (pi->jobid == last_jobid) {
				break;
			}
		}
		if (!pi) {
			error_msg("%s: no current job", child->argv[0]);
			return EXIT_FAILURE;
		}
	} else {
		if (sscanf(child->argv[1], "%%%d", &jobnum) != 1) {
			error_msg("%s: bad argument '%s'", child->argv[0], child->argv[1]);
			return EXIT_FAILURE;
		}
		for (pi = job_list; pi; pi = pi->next) {
			if (pi->jobid == jobnum) {
				break;
			}
		}
		if (!pi) {
			error_msg("%s: %d: no such job", child->argv[0], jobnum);
			return EXIT_FAILURE;
		}
	}

	if (*child->argv[0] == 'f') {
		/* Put the job into the foreground.  */
		tcsetpgrp(shell_terminal, pi->pgrp);
	}

	/* Restart the processes in the job */
	for (i = 0; i < pi->num_progs; i++)
		pi->progs[i].is_stopped = 0;

	if ( (i=kill(- pi->pgrp, SIGCONT)) < 0) {
		if (i == ESRCH) {
			remove_bg_job(pi);
		} else {
			perror_msg("kill (SIGCONT)");
		}
	}

	pi->stopped_progs = 0;
	return EXIT_SUCCESS;
}

/* built-in 'help' handler */
static int builtin_help(struct child_prog *dummy)
{
	struct built_in_command *x;

	printf("\nBuilt-in commands:\n");
	printf("-------------------\n");
	for (x = bltins; x->cmd; x++) {
		if (x->descr==NULL)
			continue;
		printf("%s\t%s\n", x->cmd, x->descr);
	}
	printf("\n\n");
	return EXIT_SUCCESS;
}

/* built-in 'jobs' handler */
static int builtin_jobs(struct child_prog *child)
{
	struct pipe *job;
	char *status_string;

	for (job = job_list; job; job = job->next) {
		if (job->running_progs == job->stopped_progs)
			status_string = "Stopped";
		else
			status_string = "Running";

		printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
	}
	return EXIT_SUCCESS;
}


/* built-in 'pwd' handler */
static int builtin_pwd(struct child_prog *dummy)
{
	puts(set_cwd());
	return EXIT_SUCCESS;
}

/* built-in 'read VAR' handler */
static int builtin_read(struct child_prog *child)
{
	int res;

	if (child->argv[1]) {
		char string[BUFSIZ];
		char *var = 0;

		string[0] = 0;  /* In case stdin has only EOF */
		/* read string */
		fgets(string, sizeof(string), stdin);
		chomp(string);
		var = malloc(strlen(child->argv[1])+strlen(string)+2);
		if(var) {
			sprintf(var, "%s=%s", child->argv[1], string);
			res = set_local_var(var, 0);
		} else
			res = -1;
		if (res)
			fprintf(stderr, "read: %m\n");
		free(var);      /* So not move up to avoid breaking errno */
		return res;
	} else {
		do res=getchar(); while(res!='\n' && res!=EOF);
		return 0;
	}
}

/* built-in 'set VAR=value' handler */
static int builtin_set(struct child_prog *child)
{
	char *temp = child->argv[1];
	struct variables *e;

	if (temp == NULL)
		for(e = top_vars; e; e=e->next)
			printf("%s=%s\n", e->name, e->value);
	else
		set_local_var(temp, 0);

		return EXIT_SUCCESS;
}


/* Built-in 'shift' handler */
static int builtin_shift(struct child_prog *child)
{
	int n=1;
	if (child->argv[1]) {
		n=atoi(child->argv[1]);
	}
	if (n>=0 && n<global_argc) {
		/* XXX This probably breaks $0 */
		global_argc -= n;
		global_argv += n;
		return EXIT_SUCCESS;
	} else {
		return EXIT_FAILURE;
	}
}

/* Built-in '.' handler (read-in and execute commands from file) */
static int builtin_source(struct child_prog *child)
{
	FILE *input;
	int status;

	if (child->argv[1] == NULL)
		return EXIT_FAILURE;

	/* XXX search through $PATH is missing */
	input = fopen(child->argv[1], "r");
	if (!input) {
		error_msg("Couldn't open file '%s'", child->argv[1]);
		return EXIT_FAILURE;
	}

	/* Now run the file */
	/* XXX argv and argc are broken; need to save old global_argv
	 * (pointer only is OK!) on this stack frame,
	 * set global_argv=child->argv+1, recurse, and restore. */
	mark_open(fileno(input));
	status = parse_file_outer(input);
	mark_closed(fileno(input));
	fclose(input);
	return (status);
}

static int builtin_umask(struct child_prog *child)
{
	mode_t new_umask;
	const char *arg = child->argv[1];
	char *end;
	if (arg) {
		new_umask=strtoul(arg, &end, 8);
		if (*end!='\0' || end == arg) {
			return EXIT_FAILURE;
		}
	} else {
		printf("%.3o\n", (unsigned int) (new_umask=umask(0)));
	}
	umask(new_umask);
	return EXIT_SUCCESS;
}

/* built-in 'unset VAR' handler */
static int builtin_unset(struct child_prog *child)
{
	/* bash returned already true */
	unset_local_var(child->argv[1]);
	return EXIT_SUCCESS;
}

static int builtin_not_written(struct child_prog *child)
{
	printf("builtin_%s not written\n",child->argv[0]);
	return EXIT_FAILURE;
}
#endif

static int b_check_space(o_string *o, int len)
{
	/* It would be easy to drop a more restrictive policy
	 * in here, such as setting a maximum string length */
	if (o->length + len > o->maxlen) {
		char *old_data = o->data;
		/* assert (data == NULL || o->maxlen != 0); */
		o->maxlen += max(2*len, B_CHUNK);
		o->data = realloc(o->data, 1 + o->maxlen);
		if (o->data == NULL) {
			free(old_data);
		}
	}
	return o->data == NULL;
}

static int b_addchr(o_string *o, int ch)
{
	debug_printf("b_addchr: %c %d %p\n", ch, o->length, o);
	if (b_check_space(o, 1)) return B_NOSPAC;
	o->data[o->length] = ch;
	o->length++;
	o->data[o->length] = '\0';
	return 0;
}

static void b_reset(o_string *o)
{
	o->length = 0;
	o->nonnull = 0;
	if (o->data != NULL) *o->data = '\0';
}

static void b_free(o_string *o)
{
	b_reset(o);
	free(o->data);
	o->data = NULL;
	o->maxlen = 0;
}

/* My analysis of quoting semantics tells me that state information
 * is associated with a destination, not a source.
 */
static int b_addqchr(o_string *o, int ch, int quote)
{
	if (quote && strchr("*?[\\",ch)) {
		int rc;
		rc = b_addchr(o, '\\');
		if (rc) return rc;
	}
	return b_addchr(o, ch);
}

/* belongs in utility.c */
char *simple_itoa(unsigned int i)
{
	/* 21 digits plus null terminator, good for 64-bit or smaller ints */
	static char local[22];
	char *p = &local[21];
	*p-- = '\0';
	do {
		*p-- = '0' + i % 10;
		i /= 10;
	} while (i > 0);
	return p + 1;
}

#ifndef __U_BOOT__
static int b_adduint(o_string *o, unsigned int i)
{
	int r;
	char *p = simple_itoa(i);
	/* no escape checking necessary */
	do r=b_addchr(o, *p++); while (r==0 && *p);
	return r;
}
#endif

static int static_get(struct in_str *i)
{
	int ch = *i->p++;
	if (ch=='\0') return EOF;
	return ch;
}

static int static_peek(struct in_str *i)
{
	return *i->p;
}

#ifndef __U_BOOT__
static inline void cmdedit_set_initial_prompt(void)
{
#ifndef CONFIG_FEATURE_SH_FANCY_PROMPT
	PS1 = NULL;
#else
	PS1 = getenv("PS1");
	if(PS1==0)
		PS1 = "\\w \\$ ";
#endif
}

static inline void setup_prompt_string(int promptmode, char **prompt_str)
{
	debug_printf("setup_prompt_string %d ",promptmode);