lash.c

shell-HHARM9200.rar 华恒 AT91rm9200 中Busybox shell的源代码

/* vi: set sw=4 ts=4: */
/*
 * lash -- the BusyBox Lame-Ass SHell
 *
 * Copyright (C) 1999-2004 by Erik Andersen <[e-mail]>
 *
 * Based in part on ladsh.c by Michael K. Johnson and Erik W. Troan, which is
 * under the following liberal license: "We have placed this source code in the
 * public domain. Use it in any project, free or commercial."
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/* This shell's parsing engine is officially at a dead-end.  Future
 * work shell work should be done using hush, msh, or ash.  This is
 * still a very useful, small shell -- it just don't need any more
 * features beyond what it already has...
 */

//For debugging/development on the shell only...
//#define DEBUG_SHELL


#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <unistd.h>
#include <getopt.h>
#include <termios.h>
#include "busybox.h"
#include "cmdedit.h"

#ifdef CONFIG_LOCALE_SUPPORT
#include <locale.h>
#endif

#include <glob.h>
#define expand_t	glob_t

/* Always enable for the moment... */
#define CONFIG_LASH_PIPE_N_REDIRECTS
#define CONFIG_LASH_JOB_CONTROL

static const int MAX_READ = 128;	/* size of input buffer for `read' builtin */
#define JOB_STATUS_FORMAT "[%d] %-22s %.40s\n"


#ifdef CONFIG_LASH_PIPE_N_REDIRECTS
enum redir_type { REDIRECT_INPUT, REDIRECT_OVERWRITE,
	REDIRECT_APPEND
};
#endif

static const unsigned int DEFAULT_CONTEXT=0x1;
static const unsigned int IF_TRUE_CONTEXT=0x2;
static const unsigned int IF_FALSE_CONTEXT=0x4;
static const unsigned int THEN_EXP_CONTEXT=0x8;
static const unsigned int ELSE_EXP_CONTEXT=0x10;

#ifdef CONFIG_LASH_PIPE_N_REDIRECTS
struct redir_struct {
	enum redir_type type;	/* type of redirection */
	int fd;						/* file descriptor being redirected */
	char *filename;				/* file to redirect fd to */
};
#endif

struct child_prog {
	pid_t pid;					/* 0 if exited */
	char **argv;				/* program name and arguments */
	int num_redirects;			/* elements in redirection array */
	int is_stopped;				/* is the program currently running? */
	struct job *family;			/* pointer back to the child's parent job */
#ifdef CONFIG_LASH_PIPE_N_REDIRECTS
	struct redir_struct *redirects;	/* I/O redirects */
#endif
};

struct jobset {
	struct job *head;			/* head of list of running jobs */
	struct job *fg;				/* current foreground job */
};

struct job {
	int jobid;					/* job number */
	int num_progs;				/* total number of programs in job */
	int running_progs;			/* number of programs running */
	char *text;					/* name of job */
	char *cmdbuf;				/* buffer various argv's point into */
	pid_t pgrp;					/* process group ID for the job */
	struct child_prog *progs;	/* array of programs in job */
	struct job *next;			/* to track background commands */
	int stopped_progs;			/* number of programs alive, but stopped */
	unsigned int job_context;	/* bitmask defining current context */
	struct jobset *job_list;
};

struct built_in_command {
	char *cmd;					/* name */
	char *descr;				/* description */
	int (*function) (struct child_prog *);	/* function ptr */
};

struct close_me {
	int fd;
	struct close_me *next;
};

/* function prototypes for builtins */
static int builtin_cd(struct child_prog *cmd);
static int builtin_exec(struct child_prog *cmd);
static int builtin_exit(struct child_prog *cmd);
static int builtin_fg_bg(struct child_prog *cmd);
static int builtin_help(struct child_prog *cmd);
static int builtin_jobs(struct child_prog *dummy);
static int builtin_pwd(struct child_prog *dummy);
static int builtin_export(struct child_prog *cmd);
static int builtin_source(struct child_prog *cmd);
static int builtin_unset(struct child_prog *cmd);
static int builtin_read(struct child_prog *cmd);


/* function prototypes for shell stuff */
static void mark_open(int fd);
static void mark_closed(int fd);
static void close_all(void);
static void checkjobs(struct jobset *job_list);
static void remove_job(struct jobset *j_list, struct job *job);
static int get_command(FILE * source, char *command);
static int parse_command(char **command_ptr, struct job *job, int *inbg);
static int run_command(struct job *newjob, int inbg, int outpipe[2]);
static int pseudo_exec(struct child_prog *cmd) __attribute__ ((noreturn));
static int busy_loop(FILE * input);


/* Table of built-in functions (these are non-forking builtins, meaning they
 * can change global variables in the parent shell process but they will not
 * work with pipes and redirects; 'unset foo | whatever' will not work) */
static struct built_in_command bltins[] = {
	{"bg", "Resume a job in the background", builtin_fg_bg},
	{"cd", "Change working directory", builtin_cd},
	{"exec", "Exec command, replacing this shell with the exec'd process", builtin_exec},
	{"exit", "Exit from shell()", builtin_exit},
	{"fg", "Bring job into the foreground", builtin_fg_bg},
	{"jobs", "Lists the active jobs", builtin_jobs},
	{"export", "Set environment variable", builtin_export},
	{"unset", "Unset environment variable", builtin_unset},
	{"read", "Input environment variable", builtin_read},
	{".", "Source-in and run commands in a file", builtin_source},
	/* to do: add ulimit */
	{NULL, NULL, NULL}
};

/* Table of forking built-in functions (things that fork cannot change global
 * variables in the parent process, such as the current working directory) */
static struct built_in_command bltins_forking[] = {
	{"pwd", "Print current directory", builtin_pwd},
	{"help", "List shell built-in commands", builtin_help},
	{NULL, NULL, NULL}
};


static int shell_context;  /* Type prompt trigger (PS1 or PS2) */


/* Globals that are static to this file */
static const char *cwd;
static char *local_pending_command = NULL;
static struct jobset job_list = { NULL, NULL };
static int argc;
static char **argv;
static struct close_me *close_me_head;
static int last_return_code;
static int last_bg_pid;
static unsigned int last_jobid;
static int shell_terminal;
static char *PS1;
static char *PS2 = "> ";


#ifdef DEBUG_SHELL
static inline void debug_printf(const char *format, ...)
{
	va_list args;
	va_start(args, format);
	vfprintf(stderr, format, args);
	va_end(args);
}
#else
static inline void debug_printf(const char *format, ...) { }
#endif

/*
	Most builtins need access to the struct child_prog that has
	their arguments, previously coded as cmd->progs[0].  That coding
	can exhibit a bug, if the builtin is not the first command in
	a pipeline: "echo foo | exec sort" will attempt to exec foo.

builtin   previous use      notes
------ -----------------  ---------
cd      cmd->progs[0]
exec    cmd->progs[0]  squashed bug: didn't look for applets or forking builtins
exit    cmd->progs[0]
fg_bg   cmd->progs[0], job_list->head, job_list->fg
help    0
jobs    job_list->head
pwd     0
export  cmd->progs[0]
source  cmd->progs[0]
unset   cmd->progs[0]
read    cmd->progs[0]

I added "struct job *family;" to struct child_prog,
and switched API to builtin_foo(struct child_prog *child);
So   cmd->text        becomes  child->family->text
     cmd->job_context  becomes  child->family->job_context
     cmd->progs[0]    becomes  *child
     job_list          becomes  child->family->job_list
 */

/* 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: %m\n", newdir);
		return EXIT_FAILURE;
	}
	cwd = xgetcwd((char *)cwd);
	if (!cwd)
		cwd = bb_msg_unknown;
	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++;
	close_all();
	pseudo_exec(child);
	/* never returns */
}

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

	exit (atoi(child->argv[1]));
}

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

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

		child->family->job_list->fg = job;
	}

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

	job->stopped_progs = 0;

	if ( (i=kill(- job->pgrp, SIGCONT)) < 0) {
		if (i == ESRCH) {
			remove_job(&job_list, job);
		} else {
			bb_perror_msg("kill (SIGCONT)");
		}
	}

	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);
	}
	for (x = bltins_forking; 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 job *job;
	char *status_string;

	for (job = child->family->job_list->head; 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)
{
	cwd = xgetcwd((char *)cwd);
	if (!cwd)
		cwd = bb_msg_unknown;
	puts(cwd);
	return EXIT_SUCCESS;
}

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

	if (v == NULL) {
		char **e;
		for (e = environ; *e; e++) {
			puts(*e);
		}
		return 0;
	}
	res = putenv(v);
	if (res)
		fprintf(stderr, "export: %m\n");
#ifdef CONFIG_FEATURE_SH_FANCY_PROMPT
	if (strncmp(v, "PS1=", 4)==0)
		PS1 = getenv("PS1");
#endif

#ifdef CONFIG_LOCALE_SUPPORT
	if(strncmp(v, "LC_ALL=", 7)==0)
		setlocale(LC_ALL, getenv("LC_ALL"));
	if(strncmp(v, "LC_CTYPE=", 9)==0)
		setlocale(LC_CTYPE, getenv("LC_CTYPE"));
#endif

	return (res);
}

/* built-in 'read VAR' handler */
static int builtin_read(struct child_prog *child)
{
	int res = 0, len, newlen;
	char *s;
	char string[MAX_READ];

	if (child->argv[1]) {
		/* argument (VAR) given: put "VAR=" into buffer */
		safe_strncpy(string, child->argv[1], MAX_READ-1);
		len = strlen(string);
		string[len++] = '=';
		string[len]   = '\0';
		fgets(&string[len], sizeof(string) - len, stdin);	/* read string */
		newlen = strlen(string);
		if(newlen > len)
			string[--newlen] = '\0';	/* chomp trailing newline */
		/*
		** string should now contain "VAR=<value>"
		** copy it (putenv() won't do that, so we must make sure
		** the string resides in a static buffer!)
		*/
		res = -1;
		if((s = strdup(string)))
			res = putenv(s);
		if (res)
			fprintf(stderr, "read: %m\n");
	}
	else
		fgets(string, sizeof(string), stdin);

	return (res);
}

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

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

	input = fopen(child->argv[1], "r");
	if (!input) {
		printf( "Couldn't open file '%s'\n", child->argv[1]);
		return EXIT_FAILURE;
	}

	fd=fileno(input);
	mark_open(fd);
	/* Now run the file */
	status = busy_loop(input);
	fclose(input);
	mark_closed(fd);
	return (status);
}

/* built-in 'unset VAR' handler */
static int builtin_unset(struct child_prog *child)
{
	if (child->argv[1] == NULL) {
		printf( "unset: parameter required.\n");
		return EXIT_FAILURE;
	}
	unsetenv(child->argv[1]);
	return EXIT_SUCCESS;
}

static void mark_open(int fd)
{
	struct close_me *new = xmalloc(sizeof(struct close_me));
	new->fd = fd;
	new->next = close_me_head;
	close_me_head = new;
}

static void mark_closed(int fd)
{
	struct close_me *tmp;
	if (close_me_head == NULL || close_me_head->fd != fd)
		bb_error_msg_and_die("corrupt close_me");
	tmp = close_me_head;
	close_me_head = close_me_head->next;
	free(tmp);
}

static void close_all()
{
	struct close_me *c, *tmp;
	for (c=close_me_head; c; c=tmp) {
		close(c->fd);
		tmp=c->next;
		free(c);
	}
	close_me_head = NULL;
}


#ifdef CONFIG_LASH_JOB_CONTROL
/* free up all memory from a job */
static void free_job(struct job *cmd)
{
	int i;
	struct jobset *keep;

	for (i = 0; i < cmd->num_progs; i++) {
		free(cmd->progs[i].argv);
#ifdef CONFIG_LASH_PIPE_N_REDIRECTS
		if (cmd->progs[i].redirects)
			free(cmd->progs[i].redirects);
#endif
	}
	free(cmd->progs);
	free(cmd->text);
	free(cmd->cmdbuf);
	keep = cmd->job_list;
	memset(cmd, 0, sizeof(struct job));
	cmd->job_list = keep;
}

/* remove a job from a jobset */
static void remove_job(struct jobset *j_list, struct job *job)
{
	struct job *prevjob;

	free_job(job);
	if (job == j_list->head) {
		j_list->head = job->next;
	} else {
		prevjob = j_list->head;
		while (prevjob->next != job)
			prevjob = prevjob->next;
		prevjob->next = job->next;
	}

	if (j_list->head)
		last_jobid = j_list->head->jobid;
	else
		last_jobid = 0;

	free(job);
}

/* Checks to see if any background processes have exited -- if they
   have, figure out why and see if a job has completed */
static void checkjobs(struct jobset *j_list)
{
	struct job *job;
	pid_t childpid;