ash.c

手机嵌入式Linux下可用的busybox源码

	{EINTR, ALL},
	{EACCES, ALL},
	{EIO, ALL},
	{ENOENT, E_OPEN},
	{ENOENT, E_CREAT},
	{ENOENT, E_EXEC},
	{ENOTDIR, E_OPEN},
	{ENOTDIR, E_CREAT},
	{ENOTDIR, E_EXEC},
	{EISDIR, ALL},
	{EEXIST, E_CREAT},
#ifdef EMFILE
	{EMFILE, ALL},
#endif
	{ENFILE, ALL},
	{ENOSPC, ALL},
#ifdef EDQUOT
	{EDQUOT, ALL},
#endif
#ifdef ENOSR
	{ENOSR, ALL},
#endif
	{ENXIO, ALL},
	{EROFS, ALL},
	{ETXTBSY, ALL},
#ifdef EAGAIN
	{EAGAIN, E_EXEC},
#endif
	{ENOMEM, ALL},
#ifdef ENOLINK
	{ENOLINK, ALL},
#endif
#ifdef EMULTIHOP
	{EMULTIHOP, ALL},
#endif
#ifdef ECOMM
	{ECOMM, ALL},
#endif
#ifdef ESTALE
	{ESTALE, ALL},
#endif
#ifdef ETIMEDOUT
	{ETIMEDOUT, ALL},
#endif
#ifdef ELOOP
	{ELOOP, ALL},
#endif
	{E2BIG, E_EXEC},
#ifdef ELIBACC
	{ELIBACC, E_EXEC},
#endif
};

#define ERRNAME_SIZE (sizeof(errormsg)/sizeof(struct errname))

/*
 * Return a string describing an error.  The returned string may be a
 * pointer to a static buffer that will be overwritten on the next call.
 * Action describes the operation that got the error.
 */

static const char *errmsg(int e, int action)
{
	struct errname const *ep;
	static char buf[12];

	for (ep = errormsg; ep < errormsg + ERRNAME_SIZE; ep++) {
		if (ep->errcode == e && (ep->action & action) != 0)
			return strerror(e);
	}

	snprintf(buf, sizeof buf, "error %d", e);
	return buf;
}


#ifdef CONFIG_ASH_OPTIMIZE_FOR_SIZE
static void __inton()
{
	if (--suppressint == 0 && intpending) {
		onint();
	}
}
static void forceinton(void)
{
	suppressint = 0;
	if (intpending)
		onint();
}
#endif

/* flags in argument to evaltree */
#define EV_EXIT 01		/* exit after evaluating tree */
#define EV_TESTED 02	/* exit status is checked; ignore -e flag */
#define EV_BACKCMD 04	/* command executing within back quotes */

static int evalskip;	/* set if we are skipping commands */
static int skipcount;	/* number of levels to skip */
static int loopnest;	/* current loop nesting level */
static int funcnest;	/* depth of function calls */


static struct strlist *cmdenviron;	/* environment for builtin command */
static int exitstatus;	/* exit status of last command */
static int oexitstatus;	/* saved exit status */

static void evalsubshell(const union node *, int);
static void expredir(union node *);
static void prehash(union node *);
static void eprintlist(struct strlist *);

static union node *parsecmd(int);

/*
 * Called to reset things after an exception.
 */

/*
 * The eval commmand.
 */
static void evalstring(char *, int);

static int evalcmd(int argc, char **argv)
{
	char *p;
	char *concat;
	char **ap;

	if (argc > 1) {
		p = argv[1];
		if (argc > 2) {
			STARTSTACKSTR(concat);
			ap = argv + 2;
			for (;;) {
				while (*p)
					STPUTC(*p++, concat);
				if ((p = *ap++) == NULL)
					break;
				STPUTC(' ', concat);
			}
			STPUTC('\0', concat);
			p = grabstackstr(concat);
		}
		evalstring(p, EV_TESTED);
	}
	return exitstatus;
}

/*
 * Execute a command or commands contained in a string.
 */

static void evaltree(union node *, int);
static void setinputstring(char *);
static void popfile(void);
static void setstackmark(struct stackmark *mark);
static void popstackmark(struct stackmark *mark);


static void evalstring(char *s, int flag)
{
	union node *n;
	struct stackmark smark;

	setstackmark(&smark);
	setinputstring(s);
	while ((n = parsecmd(0)) != NEOF) {
		evaltree(n, flag);
		popstackmark(&smark);
	}
	popfile();
	popstackmark(&smark);
}

static struct builtincmd *find_builtin(const char *);
static void expandarg(union node *, struct arglist *, int);
static void calcsize(const union node *);
static union node *copynode(const union node *);

/*
 * Make a copy of a parse tree.
 */

static int funcblocksize;	/* size of structures in function */
static int funcstringsize;	/* size of strings in node */
static pointer funcblock;	/* block to allocate function from */
static char *funcstring;	/* block to allocate strings from */


static inline union node *copyfunc(union node *n)
{
	if (n == NULL)
		return NULL;
	funcblocksize = 0;
	funcstringsize = 0;
	calcsize(n);
	funcblock = xmalloc(funcblocksize + funcstringsize);
	funcstring = (char *) funcblock + funcblocksize;
	return copynode(n);
}

/*
 * Add a new command entry, replacing any existing command entry for
 * the same name.
 */

static inline void addcmdentry(char *name, struct cmdentry *entry)
{
	struct tblentry *cmdp;

	INTOFF;
	cmdp = cmdlookup(name, 1);
	if (cmdp->cmdtype == CMDFUNCTION) {
		free(cmdp->param.func);
	}
	cmdp->cmdtype = entry->cmdtype;
	cmdp->param = entry->u;
	INTON;
}

static inline void evalloop(const union node *n, int flags)
{
	int status;

	loopnest++;
	status = 0;
	flags &= EV_TESTED;
	for (;;) {
		evaltree(n->nbinary.ch1, EV_TESTED);
		if (evalskip) {
		  skipping:if (evalskip == SKIPCONT && --skipcount <= 0) {
				evalskip = 0;
				continue;
			}
			if (evalskip == SKIPBREAK && --skipcount <= 0)
				evalskip = 0;
			break;
		}
		if (n->type == NWHILE) {
			if (exitstatus != 0)
				break;
		} else {
			if (exitstatus == 0)
				break;
		}
		evaltree(n->nbinary.ch2, flags);
		status = exitstatus;
		if (evalskip)
			goto skipping;
	}
	loopnest--;
	exitstatus = status;
}

static void evalfor(const union node *n, int flags)
{
	struct arglist arglist;
	union node *argp;
	struct strlist *sp;
	struct stackmark smark;

	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	for (argp = n->nfor.args; argp; argp = argp->narg.next) {
		oexitstatus = exitstatus;
		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE | EXP_RECORD);
		if (evalskip)
			goto out;
	}
	*arglist.lastp = NULL;

	exitstatus = 0;
	loopnest++;
	flags &= EV_TESTED;
	for (sp = arglist.list; sp; sp = sp->next) {
		setvar(n->nfor.var, sp->text, 0);
		evaltree(n->nfor.body, flags);
		if (evalskip) {
			if (evalskip == SKIPCONT && --skipcount <= 0) {
				evalskip = 0;
				continue;
			}
			if (evalskip == SKIPBREAK && --skipcount <= 0)
				evalskip = 0;
			break;
		}
	}
	loopnest--;
  out:
	popstackmark(&smark);
}

static inline void evalcase(const union node *n, int flags)
{
	union node *cp;
	union node *patp;
	struct arglist arglist;
	struct stackmark smark;

	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	oexitstatus = exitstatus;
	expandarg(n->ncase.expr, &arglist, EXP_TILDE);
	for (cp = n->ncase.cases; cp && evalskip == 0; cp = cp->nclist.next) {
		for (patp = cp->nclist.pattern; patp; patp = patp->narg.next) {
			if (casematch(patp, arglist.list->text)) {
				if (evalskip == 0) {
					evaltree(cp->nclist.body, flags);
				}
				goto out;
			}
		}
	}
  out:
	popstackmark(&smark);
}

/*
 * Evaluate a pipeline.  All the processes in the pipeline are children
 * of the process creating the pipeline.  (This differs from some versions
 * of the shell, which make the last process in a pipeline the parent
 * of all the rest.)
 */

static inline void evalpipe(union node *n, int flags)
{
	struct job *jp;
	struct nodelist *lp;
	int pipelen;
	int prevfd;
	int pip[2];

	TRACE(("evalpipe(0x%lx) called\n", (long) n));
	pipelen = 0;
	for (lp = n->npipe.cmdlist; lp; lp = lp->next)
		pipelen++;
	flags |= EV_EXIT;
	INTOFF;
	jp = makejob(n, pipelen);
	prevfd = -1;
	for (lp = n->npipe.cmdlist; lp; lp = lp->next) {
		prehash(lp->n);
		pip[1] = -1;
		if (lp->next) {
			if (pipe(pip) < 0) {
				close(prevfd);
				error("Pipe call failed");
			}
		}
		if (forkshell(jp, lp->n, n->npipe.backgnd) == 0) {
			INTON;
			if (pip[1] >= 0) {
				close(pip[0]);
			}
			if (prevfd > 0) {
				dup2(prevfd, 0);
				close(prevfd);
			}
			if (pip[1] > 1) {
				dup2(pip[1], 1);
				close(pip[1]);
			}
			evaltree(lp->n, flags);
		}
		if (prevfd >= 0)
			close(prevfd);
		prevfd = pip[0];
		close(pip[1]);
	}
	if (n->npipe.backgnd == 0) {
		exitstatus = waitforjob(jp);
		TRACE(("evalpipe:  job done exit status %d\n", exitstatus));
	}
	INTON;
}

static void find_command(const char *, struct cmdentry *, int, const char *);

static int isassignment(const char *word)
{
	if (!is_name(*word)) {
		return 0;
	}
	do {
		word++;
	} while (is_in_name(*word));
	return *word == '=';
}


static void evalcommand(union node *cmd, int flags)
{
	struct stackmark smark;
	union node *argp;
	struct arglist arglist;
	struct arglist varlist;
	char **argv;
	int argc;
	char **envp;
	struct strlist *sp;
	int mode;
	struct cmdentry cmdentry;
	struct job *jp;
	char *volatile savecmdname;
	volatile struct shparam saveparam;
	struct localvar *volatile savelocalvars;
	volatile int e;
	char *lastarg;
	const char *path;
	int spclbltin;
	struct jmploc *volatile savehandler;
	struct jmploc jmploc;

#if __GNUC__
	/* Avoid longjmp clobbering */
	(void) &argv;
	(void) &argc;
	(void) &lastarg;
	(void) &flags;
	(void) &spclbltin;
#endif

	/* First expand the arguments. */
	TRACE(("evalcommand(0x%lx, %d) called\n", (long) cmd, flags));
	setstackmark(&smark);
	arglist.lastp = &arglist.list;
	varlist.lastp = &varlist.list;
	arglist.list = 0;
	oexitstatus = exitstatus;
	exitstatus = 0;
	path = pathval();
	for (argp = cmd->ncmd.assign; argp; argp = argp->narg.next) {
		expandarg(argp, &varlist, EXP_VARTILDE);
	}
	for (argp = cmd->ncmd.args; argp && !arglist.list; argp = argp->narg.next) {
		expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
	}
	if (argp) {
		struct builtincmd *bcmd;
		int pseudovarflag;

		bcmd = find_builtin(arglist.list->text);
		pseudovarflag = bcmd && IS_BUILTIN_ASSIGN(bcmd);
		for (; argp; argp = argp->narg.next) {
			if (pseudovarflag && isassignment(argp->narg.text)) {
				expandarg(argp, &arglist, EXP_VARTILDE);
				continue;
			}
			expandarg(argp, &arglist, EXP_FULL | EXP_TILDE);
		}
	}
	*arglist.lastp = NULL;
	*varlist.lastp = NULL;
	expredir(cmd->ncmd.redirect);
	argc = 0;
	for (sp = arglist.list; sp; sp = sp->next)
		argc++;
	argv = stalloc(sizeof(char *) * (argc + 1));

	for (sp = arglist.list; sp; sp = sp->next) {
		TRACE(("evalcommand arg: %s\n", sp->text));
		*argv++ = sp->text;
	}
	*argv = NULL;
	lastarg = NULL;
	if (iflag && funcnest == 0 && argc > 0)
		lastarg = argv[-1];
	argv -= argc;

	/* Print the command if xflag is set. */
	if (xflag) {
		out2c('+');
		eprintlist(varlist.list);
		eprintlist(arglist.list);
		out2c('\n');
	}

	/* Now locate the command. */
	if (argc == 0) {
		cmdentry.cmdtype = CMDBUILTIN;
		cmdentry.u.cmd = BLTINCMD;
		spclbltin = 1;
	} else {
		const char *oldpath;
		int findflag = DO_ERR;
		int oldfindflag;

		/*
		 * Modify the command lookup path, if a PATH= assignment
		 * is present
		 */
		for (sp = varlist.list; sp; sp = sp->next)
			if (varequal(sp->text, defpathvar)) {
				path = sp->text + 5;
				findflag |= DO_BRUTE;
			}
		oldpath = path;
		oldfindflag = findflag;
		spclbltin = -1;
		for (;;) {
			find_command(argv[0], &cmdentry, findflag, path);
			if (cmdentry.cmdtype == CMD