c_ksh.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

		if (!tp && !pflag) {
			tp = tsearch(&aliases, id, hash(id));
			if (tp && !(tp->flag & ISSET))
				tp = NULL;
		}
		if (!tp)
			tp = findcom(id, fcflags);
		if (vflag || (tp->type != CALIAS && tp->type != CEXEC
			      && tp->type != CTALIAS))
			shprintf("%s", id);
		switch (tp->type) {
		  case CKEYWD:
			if (vflag)
				shprintf(" is a reserved word");
			break;
		  case CALIAS:
			if (vflag)
				shprintf(" is an %salias for ",
					(tp->flag & EXPORT) ? "exported "
							    : null);
			if (!iam_whence && !vflag)
				shprintf("alias %s=", id);
			print_value_quoted(tp->val.s);
			break;
		  case CFUNC:
			if (vflag) {
				shprintf(" is a");
				if (tp->flag & EXPORT)
					shprintf("n exported");
				if (tp->flag & TRACE)
					shprintf(" traced");
				if (!(tp->flag & ISSET)) {
					shprintf(" undefined");
					if (tp->u.fpath)
						shprintf(" (autoload from %s)",
							tp->u.fpath);
				}
				shprintf(" function");
			}
			break;
		  case CSHELL:
			if (vflag)
				shprintf(" is a%s shell builtin",
				    (tp->flag & SPEC_BI) ? " special" : null);
			break;
		  case CTALIAS:
		  case CEXEC:
			if (tp->flag & ISSET) {
				if (vflag) {
					shprintf(" is ");
					if (tp->type == CTALIAS)
						shprintf(
						    "a tracked %salias for ",
							(tp->flag & EXPORT) ?
								"exported "
							      : null);
				}
				shprintf("%s", tp->val.s);
			} else {
				if (vflag)
					shprintf(" not found");
				ret = 1;
			}
			break;
		  default:
			shprintf("%s is *GOK*", id);
			break;
		}
		if (vflag || !ret)
			shprintf(newline);
	}
	return ret;
}

/* Deal with command -vV - command -p dealt with in comexec() */
int
c_command(wp)
	char **wp;
{
	/* Let c_whence do the work.  Note that c_command() must be
	 * a distinct function from c_whence() (tested in comexec()).
	 */
	return c_whence(wp);
}

/* typeset, export, and readonly */
int
c_typeset(wp)
	char **wp;
{
	struct block *l = e->loc;
	struct tbl *vp, **p;
	Tflag fset = 0, fclr = 0;
	int thing = 0, func = 0, local = 0;
	const char *options = "L#R#UZ#fi#lprtux";	/* see comment below */
	char *fieldstr, *basestr;
	int field, base;
	int optc;
	Tflag flag;
	int pflag = 0;

	switch (**wp) {
 	  case 'e':		/* export */
 		fset |= EXPORT;
		options = "p";
 		break;
 	  case 'r':		/* readonly */
 		fset |= RDONLY;
		options = "p";
 		break;
	  case 's':		/* set */
		/* called with 'typeset -' */
		break;
 	  case 't':		/* typeset */
 		local = 1;
 		break;
 	}
 
	fieldstr = basestr = (char *) 0;
	builtin_opt.flags |= GF_PLUSOPT;
	/* at&t ksh seems to have 0-9 as options, which are multiplied
	 * to get a number that is used with -L, -R, -Z or -i (eg, -1R2
	 * sets right justify in a field of 12).  This allows options
	 * to be grouped in an order (eg, -Lu12), but disallows -i8 -L3 and
	 * does not allow the number to be specified as a separate argument
	 * Here, the number must follow the RLZi option, but is optional
	 * (see the # kludge in ksh_getopt()).
	 */
	while ((optc = ksh_getopt(wp, &builtin_opt, options)) != EOF) {
		flag = 0;
		switch (optc) {
		  case 'L':
			flag = LJUST;
			fieldstr = builtin_opt.optarg;
			break;
		  case 'R':
			flag = RJUST;
			fieldstr = builtin_opt.optarg;
			break;
		  case 'U':
			/* at&t ksh uses u, but this conflicts with
			 * upper/lower case.  If this option is changed,
			 * need to change the -U below as well
			 */
			flag = INT_U;
			break;
		  case 'Z':
			flag = ZEROFIL;
			fieldstr = builtin_opt.optarg;
			break;
		  case 'f':
			func = 1;
			break;
		  case 'i':
			flag = INTEGER;
			basestr = builtin_opt.optarg;
			break;
		  case 'l':
			flag = LCASEV;
			break;
		  case 'p': /* posix export/readonly -p flag.
			     * typset -p is the same as typeset (in pdksh);
			     * here for compatability with ksh93.
			     */
			pflag = 1;
			break;
		  case 'r':
			flag = RDONLY;
			break;
		  case 't':
			flag = TRACE;
			break;
		  case 'u':
			flag = UCASEV_AL;	/* upper case / autoload */
			break;
		  case 'x':
			flag = EXPORT;
			break;
		  case '?':
			return 1;
		}
		if (builtin_opt.info & GI_PLUS) {
			fclr |= flag;
			fset &= ~flag;
			thing = '+';
		} else {
			fset |= flag;
			fclr &= ~flag;
			thing = '-';
		}
	}

	field = 0;
	if (fieldstr && !bi_getn(fieldstr, &field))
		return 1;
	base = 0;
	if (basestr && !bi_getn(basestr, &base))
		return 1;

	if (!(builtin_opt.info & GI_MINUSMINUS) && wp[builtin_opt.optind]
	    && (wp[builtin_opt.optind][0] == '-'
		|| wp[builtin_opt.optind][0] == '+')
	    && wp[builtin_opt.optind][1] == '\0')
	{
		thing = wp[builtin_opt.optind][0];
		builtin_opt.optind++;
	}

	if (func && ((fset|fclr) & ~(TRACE|UCASEV_AL|EXPORT))) {
		bi_errorf("only -t, -u and -x options may be used with -f");
		return 1;
	}
	if (wp[builtin_opt.optind]) {
		/* Take care of exclusions.  
		 * At this point, flags in fset are cleared in fclr and vise
		 * versa.  This property should be preserved.
		 */
		if (fset & LCASEV)	/* LCASEV has priority over UCASEV_AL */
			fset &= ~UCASEV_AL;
		if (fset & LJUST)	/* LJUST has priority over RJUST */
			fset &= ~RJUST;
		if ((fset & (ZEROFIL|LJUST)) == ZEROFIL) { /* -Z implies -ZR */
			fset |= RJUST;
			fclr &= ~RJUST;
		}
		/* Setting these attributes clears the others, unless they
		 * are also set in this command
		 */
		if (fset & (LJUST|RJUST|ZEROFIL|UCASEV_AL|LCASEV|INTEGER
			    |INT_U|INT_L))
			fclr |= ~fset &
				(LJUST|RJUST|ZEROFIL|UCASEV_AL|LCASEV|INTEGER
				 |INT_U|INT_L);
	}

	/* set variables and attributes */
	if (wp[builtin_opt.optind]) {
		int i;
		int rval = 0;
		struct tbl *f;

		if (local && !func)
			fset |= LOCAL;
		for (i = builtin_opt.optind; wp[i]; i++) {
			if (func) {
				f = findfunc(wp[i], hash(wp[i]),
					     (fset&UCASEV_AL) ? TRUE : FALSE);
				if (!f) {
					/* at&t ksh does ++rval: bogus */
					rval = 1;
					continue;
				}
				if (fset | fclr) {
					f->flag |= fset;
					f->flag &= ~fclr;
				} else
					fptreef(shl_stdout, 0,
						f->flag & FKSH ?
						    "function %s %T\n"
						    : "%s() %T\n"
						,
						wp[i], f->val.t);
			} else if (!typeset(wp[i], fset, fclr, field, base)) {
				bi_errorf("%s: not identifier", wp[i]);
				return 1;
			}
		}
		return rval;
	}

	/* list variables and attributes */
	flag = fset | fclr; /* no difference at this point.. */
	if (func) {
	    for (l = e->loc; l; l = l->next) {
		for (p = tsort(&l->funs); (vp = *p++); ) {
		    if (flag && (vp->flag & flag) == 0)
			    continue;
		    if (thing == '-')
			fptreef(shl_stdout, 0, vp->flag & FKSH ?
						    "function %s %T\n"
						    : "%s() %T\n",
				vp->name, vp->val.t);
		    else
			shprintf("%s\n", vp->name);
		}
	    }
	} else {
	    for (l = e->loc; l; l = l->next) {
		for (p = tsort(&l->vars); (vp = *p++); ) {
		    struct tbl *tvp;
		    int any_set = 0;
		    /*
		     * See if the parameter is set (for arrays, if any
		     * element is set).
		     */
		    for (tvp = vp; tvp; tvp = tvp->u.array)
			if (tvp->flag & ISSET) {
			    any_set = 1;
			    break;
			}
		    /*
		     * Check attributes - note that all array elements
		     * have (should have?) the same attributes, so checking
		     * the first is sufficient.
		     *
		     * Report an unset param only if the user has
		     * explicitly given it some attribute (like export);
		     * otherwise, after "echo $FOO", we would report FOO...
		     */
		    if (!any_set && !(vp->flag & USERATTRIB))
			continue;
		    if (flag && (vp->flag & flag) == 0)
			continue;
		    for (; vp; vp = vp->u.array) {
			/* Ignore array elements that aren't set unless there
			 * are no set elements, in which case the first is
			 * reported on
			 */
			if ((vp->flag&ARRAY) && any_set && !(vp->flag & ISSET))
			    continue;
			/* no arguments */
			if (thing == 0 && flag == 0) {
			    /* at&t ksh prints things like export, integer,
			     * leftadj, zerofill, etc., but POSIX says must
			     * be suitable for re-entry...
			     */
			    shprintf("typeset ");
			    if ((vp->flag&INTEGER))
				shprintf("-i ");
			    if ((vp->flag&EXPORT))
				shprintf("-x ");
			    if ((vp->flag&RDONLY))
				shprintf("-r ");
			    if ((vp->flag&TRACE)) 
				shprintf("-t ");
			    if ((vp->flag&LJUST)) 
				shprintf("-L%d ", vp->u2.field);
			    if ((vp->flag&RJUST)) 
				shprintf("-R%d ", vp->u2.field);
			    if ((vp->flag&ZEROFIL)) 
				shprintf("-Z ");
			    if ((vp->flag&LCASEV)) 
				shprintf("-l ");
			    if ((vp->flag&UCASEV_AL)) 
				shprintf("-u ");
			    if ((vp->flag&INT_U)) 
				shprintf("-U ");
			    shprintf("%s\n", vp->name);
			    if (vp->flag&ARRAY)
				break;
			} else {
			    if (pflag)
				shprintf("%s ",
				    (flag & EXPORT) ?  "export" : "readonly");
			    if ((vp->flag&ARRAY) && any_set)
				shprintf("%s[%d]", vp->name, vp->index);
			    else
				shprintf("%s", vp->name);
			    if (thing == '-' && (vp->flag&ISSET)) {
				char *s = str_val(vp);

				shprintf("=");
				/* at&t ksh can't have justified integers.. */
				if ((vp->flag & (INTEGER|LJUST|RJUST))
								== INTEGER)
				    shprintf("%s", s);
				else
				    print_value_quoted(s);
			    }
			    shprintf(newline);
			}
			/* Only report first `element' of an array with
			 * no set elements.
			 */
			if (!any_set)
			    break;
		    }
		}
	    }
	}
	return 0;
}
	
int
c_alias(wp)
	char **wp;
{
	struct table *t = &aliases;
	int rv = 0, rflag = 0, tflag, Uflag = 0, pflag = 0;
	int prefix = 0;
	Tflag xflag = 0;
	int optc;

	builtin_opt.flags |= GF_PLUSOPT;
	while ((optc = ksh_getopt(wp, &builtin_opt, "dprtUx")) != EOF) {
		prefix = builtin_opt.info & GI_PLUS ? '+' : '-';
		switch (optc) {
		  case 'd':
			t = &homedirs;
			break;
		  case 'p':
			pflag = 1;
			break;
		  case 'r':
			rflag = 1;
			break;
		  case 't':
			t = &taliases;
			break;
		  case 'U': /* kludge for tracked alias initialization
			     * (don't do a path search, just make an entry)
			     */
			Uflag = 1;
			break;
		  case 'x':
			xflag = EXPORT;
			break;
		  case '?':
			return 1;
		}
	}
	wp += builtin_opt.optind;

	if (!(builtin_opt.info & GI_MINUSMINUS) && *wp
	    && (wp[0][0] == '-' || wp[0][0] == '+') && wp[0][1] == '\0')
	{
		prefix = wp[0][0];
		wp++;
	}

	tflag = t == &taliases;

	/* "hash -r" means reset all the tracked aliases.. */
	if (rflag) {
		static const char *const args[] = {
			    "unalias", "-ta", (const char *) 0
			};

		if (!tflag || *wp) {
			shprintf(
	    "alias: -r flag can only be used with -t and without arguments\n");
			return 1;
		}
		ksh_getopt_reset(&builtin_opt, GF_ERROR);
		return c_unalias((char **) args);
	}

	
	if (*wp == NULL) {
		struct tbl *ap, **p;

		for (p = tsort(t); (ap = *p++) != NULL; )
			if ((ap->flag & (ISSET|xflag)) == (ISSET|xflag)) {
				if (pflag)
					shf_puts("alias ", shl_stdout);
				shf_puts(ap->name, shl_stdout);
				if (prefix != '+') {
					shf_putc('=', shl_stdout);
					print_value_quoted(ap->val.s);
				}
				shprintf(newline);
			}
	}

	for (; *wp != NULL; wp++) {
		char *alias = *wp;
		char *val = strchr(alias, '=');
		char *newval;
		struct tbl *ap;
		int h;

		if (val)
			alias = str_nsave(alias, val++ - alias, ATEMP);
		h = hash(alias);
		if (val == NULL && !tflag && !xflag) {
			ap = tsearch(t, alias, h);
			if (ap != NULL && (ap->flag&ISSET)) {
				if (pflag)
					shf_puts("alias ", shl_stdout);
				shf_puts(ap->name, shl_stdout);
				if (prefix != '+') {
					shf_putc('=', shl_stdout);
					print_value_quoted(ap->val.s);
				}
				shprintf(newline);
			} else {
				shprintf("%s alias not found\n", alias);
				rv = 1;
			}
			continue;
		}