exec.c

来自「Android 一些工具」· C语言 代码 · 共 1,064 行 · 第 1/2 页

		}
		while (stat(fullname, &statb) < 0) {
#ifdef SYSV
			if (errno == EINTR)
				continue;
#endif
			if (errno != ENOENT && errno != ENOTDIR)
				e = errno;
			goto loop;
		}
		e = EACCES;	/* if we fail, this will be the error */
		if (!S_ISREG(statb.st_mode))
			goto loop;
		if (pathopt) {		/* this is a %func directory */
			if (act & DO_NOFUNC)
				goto loop;
			stalloc(strlen(fullname) + 1);
			readcmdfile(fullname);
			if ((cmdp = cmdlookup(name, 0)) == NULL ||
			    cmdp->cmdtype != CMDFUNCTION)
				error("%s not defined in %s", name, fullname);
			stunalloc(fullname);
			goto success;
		}
#ifdef notdef
		/* XXX this code stops root executing stuff, and is buggy
		   if you need a group from the group list. */
		if (statb.st_uid == geteuid()) {
			if ((statb.st_mode & 0100) == 0)
				goto loop;
		} else if (statb.st_gid == getegid()) {
			if ((statb.st_mode & 010) == 0)
				goto loop;
		} else {
			if ((statb.st_mode & 01) == 0)
				goto loop;
		}
#endif
		TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname));
		INTOFF;
		if (act & DO_ALTPATH) {
			stalloc(strlen(fullname) + 1);
			cmdp = &loc_cmd;
		} else
			cmdp = cmdlookup(name, 1);
		cmdp->cmdtype = CMDNORMAL;
		cmdp->param.index = idx;
		INTON;
		goto success;
	}

	/* We failed.  If there was an entry for this command, delete it */
	if (cmdp)
		delete_cmd_entry();
	if (act & DO_ERR)
		outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC));
	entry->cmdtype = CMDUNKNOWN;
	return;

builtin_success:
	INTOFF;
	if (act & DO_ALTPATH)
		cmdp = &loc_cmd;
	else
		cmdp = cmdlookup(name, 1);
	if (cmdp->cmdtype == CMDFUNCTION)
		/* DO_NOFUNC must have been set */
		cmdp = &loc_cmd;
	cmdp->cmdtype = CMDBUILTIN;
	cmdp->param.bltin = bltin;
	INTON;
success:
	cmdp->rehash = 0;
	entry->cmdtype = cmdp->cmdtype;
	entry->u = cmdp->param;
}



/*
 * Search the table of builtin commands.
 */

int
(*find_builtin(name))(int, char **)
	char *name;
{
	const struct builtincmd *bp;

	for (bp = builtincmd ; bp->name ; bp++) {
		if (*bp->name == *name && equal(bp->name, name))
			return bp->builtin;
	}
	return 0;
}

int
(*find_splbltin(name))(int, char **)
	char *name;
{
	const struct builtincmd *bp;

	for (bp = splbltincmd ; bp->name ; bp++) {
		if (*bp->name == *name && equal(bp->name, name))
			return bp->builtin;
	}
	return 0;
}

/*
 * At shell startup put special builtins into hash table.
 * ensures they are executed first (see posix).
 * We stop functions being added with the same name
 * (as they are impossible to call)
 */

void
hash_special_builtins(void)
{
	const struct builtincmd *bp;
	struct tblentry *cmdp;

	for (bp = splbltincmd ; bp->name ; bp++) {
		cmdp = cmdlookup(bp->name, 1);
		cmdp->cmdtype = CMDSPLBLTIN;
		cmdp->param.bltin = bp->builtin;
	}
}



/*
 * Called when a cd is done.  Marks all commands so the next time they
 * are executed they will be rehashed.
 */

void
hashcd(void)
{
	struct tblentry **pp;
	struct tblentry *cmdp;

	for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) {
		for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
			if (cmdp->cmdtype == CMDNORMAL
			 || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))
				cmdp->rehash = 1;
		}
	}
}



/*
 * Fix command hash table when PATH changed.
 * Called before PATH is changed.  The argument is the new value of PATH;
 * pathval() still returns the old value at this point.
 * Called with interrupts off.
 */

void
changepath(const char *newval)
{
	const char *old, *new;
	int idx;
	int firstchange;
	int bltin;

	old = pathval();
	new = newval;
	firstchange = 9999;	/* assume no change */
	idx = 0;
	bltin = -1;
	for (;;) {
		if (*old != *new) {
			firstchange = idx;
			if ((*old == '\0' && *new == ':')
			 || (*old == ':' && *new == '\0'))
				firstchange++;
			old = new;	/* ignore subsequent differences */
		}
		if (*new == '\0')
			break;
		if (*new == '%' && bltin < 0 && prefix("builtin", new + 1))
			bltin = idx;
		if (*new == ':') {
			idx++;
		}
		new++, old++;
	}
	if (builtinloc < 0 && bltin >= 0)
		builtinloc = bltin;		/* zap builtins */
	if (builtinloc >= 0 && bltin < 0)
		firstchange = 0;
	clearcmdentry(firstchange);
	builtinloc = bltin;
}


/*
 * Clear out command entries.  The argument specifies the first entry in
 * PATH which has changed.
 */

STATIC void
clearcmdentry(int firstchange)
{
	struct tblentry **tblp;
	struct tblentry **pp;
	struct tblentry *cmdp;

	INTOFF;
	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
		pp = tblp;
		while ((cmdp = *pp) != NULL) {
			if ((cmdp->cmdtype == CMDNORMAL &&
			     cmdp->param.index >= firstchange)
			 || (cmdp->cmdtype == CMDBUILTIN &&
			     builtinloc >= firstchange)) {
				*pp = cmdp->next;
				ckfree(cmdp);
			} else {
				pp = &cmdp->next;
			}
		}
	}
	INTON;
}


/*
 * Delete all functions.
 */

#ifdef mkinit
MKINIT void deletefuncs(void);
MKINIT void hash_special_builtins(void);

INIT {
	hash_special_builtins();
}

SHELLPROC {
	deletefuncs();
}
#endif

void
deletefuncs(void)
{
	struct tblentry **tblp;
	struct tblentry **pp;
	struct tblentry *cmdp;

	INTOFF;
	for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) {
		pp = tblp;
		while ((cmdp = *pp) != NULL) {
			if (cmdp->cmdtype == CMDFUNCTION) {
				*pp = cmdp->next;
				freefunc(cmdp->param.func);
				ckfree(cmdp);
			} else {
				pp = &cmdp->next;
			}
		}
	}
	INTON;
}



/*
 * Locate a command in the command hash table.  If "add" is nonzero,
 * add the command to the table if it is not already present.  The
 * variable "lastcmdentry" is set to point to the address of the link
 * pointing to the entry, so that delete_cmd_entry can delete the
 * entry.
 */

struct tblentry **lastcmdentry;


STATIC struct tblentry *
cmdlookup(const char *name, int add)
{
	int hashval;
	const char *p;
	struct tblentry *cmdp;
	struct tblentry **pp;

	p = name;
	hashval = *p << 4;
	while (*p)
		hashval += *p++;
	hashval &= 0x7FFF;
	pp = &cmdtable[hashval % CMDTABLESIZE];
	for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) {
		if (equal(cmdp->cmdname, name))
			break;
		pp = &cmdp->next;
	}
	if (add && cmdp == NULL) {
		INTOFF;
		cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB
					+ strlen(name) + 1);
		cmdp->next = NULL;
		cmdp->cmdtype = CMDUNKNOWN;
		cmdp->rehash = 0;
		strcpy(cmdp->cmdname, name);
		INTON;
	}
	lastcmdentry = pp;
	return cmdp;
}

/*
 * Delete the command entry returned on the last lookup.
 */

STATIC void
delete_cmd_entry(void)
{
	struct tblentry *cmdp;

	INTOFF;
	cmdp = *lastcmdentry;
	*lastcmdentry = cmdp->next;
	ckfree(cmdp);
	INTON;
}



#ifdef notdef
void
getcmdentry(char *name, struct cmdentry *entry)
{
	struct tblentry *cmdp = cmdlookup(name, 0);

	if (cmdp) {
		entry->u = cmdp->param;
		entry->cmdtype = cmdp->cmdtype;
	} else {
		entry->cmdtype = CMDUNKNOWN;
		entry->u.index = 0;
	}
}
#endif


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

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

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


/*
 * Define a shell function.
 */

void
defun(char *name, union node *func)
{
	struct cmdentry entry;

	INTOFF;
	entry.cmdtype = CMDFUNCTION;
	entry.u.func = copyfunc(func);
	addcmdentry(name, &entry);
	INTON;
}


/*
 * Delete a function if it exists.
 */

int
unsetfunc(char *name)
{
	struct tblentry *cmdp;

	if ((cmdp = cmdlookup(name, 0)) != NULL &&
	    cmdp->cmdtype == CMDFUNCTION) {
		freefunc(cmdp->param.func);
		delete_cmd_entry();
		return (0);
	}
	return (1);
}

/*
 * Locate and print what a word is...
 * also used for 'command -[v|V]'
 */

int
typecmd(int argc, char **argv)
{
	struct cmdentry entry;
	struct tblentry *cmdp;
	char * const *pp;
	struct alias *ap;
	int err = 0;
	char *arg;
	int c;
	int V_flag = 0;
	int v_flag = 0;
	int p_flag = 0;

	while ((c = nextopt("vVp")) != 0) {
		switch (c) {
		case 'v': v_flag = 1; break;
		case 'V': V_flag = 1; break;
		case 'p': p_flag = 1; break;
		}
	}

	if (p_flag && (v_flag || V_flag))
		error("cannot specify -p with -v or -V");

	while ((arg = *argptr++)) {
		if (!v_flag)
			out1str(arg);
		/* First look at the keywords */
		for (pp = parsekwd; *pp; pp++)
			if (**pp == *arg && equal(*pp, arg))
				break;

		if (*pp) {
			if (v_flag)
				err = 1;
			else
				out1str(" is a shell keyword\n");
			continue;
		}

		/* Then look at the aliases */
		if ((ap = lookupalias(arg, 1)) != NULL) {
			if (!v_flag)
				out1fmt(" is an alias for \n");
			out1fmt("%s\n", ap->val);
			continue;
		}

		/* Then check if it is a tracked alias */
		if ((cmdp = cmdlookup(arg, 0)) != NULL) {
			entry.cmdtype = cmdp->cmdtype;
			entry.u = cmdp->param;
		} else {
			/* Finally use brute force */
			find_command(arg, &entry, DO_ABS, pathval());
		}

		switch (entry.cmdtype) {
		case CMDNORMAL: {
			if (strchr(arg, '/') == NULL) {
				const char *path = pathval();
				char *name;
				int j = entry.u.index;
				do {
					name = padvance(&path, arg);
					stunalloc(name);
				} while (--j >= 0);
				if (!v_flag)
					out1fmt(" is%s ",
					    cmdp ? " a tracked alias for" : "");
				out1fmt("%s\n", name);
			} else {
				if (access(arg, X_OK) == 0) {
					if (!v_flag)
						out1fmt(" is ");
					out1fmt("%s\n", arg);
				} else {
					if (!v_flag)
						out1fmt(": %s\n",
						    strerror(errno));
					else
						err = 126;
				}
			}
 			break;
		}
		case CMDFUNCTION:
			if (!v_flag)
				out1str(" is a shell function\n");
			else
				out1fmt("%s\n", arg);
			break;

		case CMDBUILTIN:
			if (!v_flag)
				out1str(" is a shell builtin\n");
			else
				out1fmt("%s\n", arg);
			break;

		case CMDSPLBLTIN:
			if (!v_flag)
				out1str(" is a special shell builtin\n");
			else
				out1fmt("%s\n", arg);
			break;

		default:
			if (!v_flag)
				out1str(": not found\n");
			err = 127;
			break;
		}
	}
	return err;
}