c_sh.c

一个开放源代码的 AT&T 的 Korn Shell 的复制品, 支持大多数 ksh89 的特性。

/*
 * built-in Bourne commands
 */

#include "sh.h"
#include "ksh_stat.h" 	/* umask() */
#include "ksh_time.h"
#include "ksh_times.h"

static	char *clocktos ARGS((clock_t t));


/* :, false and true */
int
c_label(wp)
	char **wp;
{
	return wp[0][0] == 'f' ? 1 : 0;
}

int
c_shift(wp)
	char **wp;
{
	register struct block *l = e->loc;
	register int n;
	long val;
	char *arg;

	if (ksh_getopt(wp, &builtin_opt, null) == '?')
		return 1;
	arg = wp[builtin_opt.optind];

	if (arg) {
		evaluate(arg, &val, KSH_UNWIND_ERROR);
		n = val;
	} else
		n = 1;
	if (n < 0) {
		bi_errorf("%s: bad number", arg);
		return (1);
	}
	if (l->argc < n) {
		bi_errorf("nothing to shift");
		return (1);
	}
	l->argv[n] = l->argv[0];
	l->argv += n;
	l->argc -= n;
	return 0;
}

int
c_umask(wp)
	char **wp;
{
	register int i;
	register char *cp;
	int symbolic = 0;
	int old_umask;
	int optc;

	while ((optc = ksh_getopt(wp, &builtin_opt, "S")) != EOF)
		switch (optc) {
		  case 'S':
			symbolic = 1;
			break;
		  case '?':
			return 1;
		}
	cp = wp[builtin_opt.optind];
	if (cp == NULL) {
		old_umask = umask(0);
		umask(old_umask);
		if (symbolic) {
			char buf[18];
			int j;

			old_umask = ~old_umask;
			cp = buf;
			for (i = 0; i < 3; i++) {
				*cp++ = "ugo"[i];
				*cp++ = '=';
				for (j = 0; j < 3; j++)
					if (old_umask & (1 << (8 - (3*i + j))))
						*cp++ = "rwx"[j];
				*cp++ = ',';
			}
			cp[-1] = '\0';
			shprintf("%s\n", buf);
		} else
			shprintf("%#3.3o\n", old_umask);
	} else {
		int new_umask;

		if (digit(*cp)) {
			for (new_umask = 0; *cp >= '0' && *cp <= '7'; cp++)
				new_umask = new_umask * 8 + (*cp - '0');
			if (*cp) {
				bi_errorf("bad number");
				return 1;
			}
		} else {
			/* symbolic format */
			int positions, new_val;
			char op;

			old_umask = umask(0);
			umask(old_umask); /* in case of error */
			old_umask = ~old_umask;
			new_umask = old_umask;
			positions = 0;
			while (*cp) {
				while (*cp && strchr("augo", *cp))
					switch (*cp++) {
					case 'a': positions |= 0111; break;
					case 'u': positions |= 0100; break;
					case 'g': positions |= 0010; break;
					case 'o': positions |= 0001; break;
					}
				if (!positions)
					positions = 0111; /* default is a */
				if (!strchr("=+-", op = *cp))
					break;
				cp++;
				new_val = 0;
				while (*cp && strchr("rwxugoXs", *cp))
					switch (*cp++) {
					case 'r': new_val |= 04; break;
					case 'w': new_val |= 02; break;
					case 'x': new_val |= 01; break;
					case 'u': new_val |= old_umask >> 6;
						  break;
					case 'g': new_val |= old_umask >> 3;
						  break;
					case 'o': new_val |= old_umask >> 0;
						  break;
					case 'X': if (old_umask & 0111)
							new_val |= 01;
						  break;
					case 's': /* ignored */
						  break;
					}
				new_val = (new_val & 07) * positions;
				switch (op) {
				case '-':
					new_umask &= ~new_val;
					break;
				case '=':
					new_umask = new_val
					    | (new_umask & ~(positions * 07));
					break;
				case '+':
					new_umask |= new_val;
				}
				if (*cp == ',') {
					positions = 0;
					cp++;
				} else if (!strchr("=+-", *cp))
					break;
			}
			if (*cp) {
				bi_errorf("bad mask");
				return 1;
			}
			new_umask = ~new_umask;
		}
		umask(new_umask);
	}
	return 0;
}

int
c_dot(wp)
	char **wp;
{
	char *file, *cp;
	char **argv;
	int argc;
	int i;
	int err;

	if (ksh_getopt(wp, &builtin_opt, null) == '?')
		return 1;

	if ((cp = wp[builtin_opt.optind]) == NULL)
		return 0;
	file = search(cp, path, R_OK, &err);
	if (file == NULL) {
		bi_errorf("%s: %s", cp, err ? strerror(err) : "not found");
		return 1;
	}

	/* Set positional parameters? */
	if (wp[builtin_opt.optind + 1]) {
		argv = wp + builtin_opt.optind;
		argv[0] = e->loc->argv[0]; /* preserve $0 */
		for (argc = 0; argv[argc + 1]; argc++)
			;
	} else {
		argc = 0;
		argv = (char **) 0;
	}
	i = include(file, argc, argv, 0);
	if (i < 0) { /* should not happen */
		bi_errorf("%s: %s", cp, strerror(errno));
		return 1;
	}
	return i;
}

int
c_wait(wp)
	char **wp;
{
	int UNINITIALIZED(rv);
	int sig;

	if (ksh_getopt(wp, &builtin_opt, null) == '?')
		return 1;
	wp += builtin_opt.optind;
	if (*wp == (char *) 0) {
		while (waitfor((char *) 0, &sig) >= 0)
			;
		rv = sig;
	} else {
		for (; *wp; wp++)
			rv = waitfor(*wp, &sig);
		if (rv < 0)
			rv = sig ? sig : 127; /* magic exit code: bad job-id */
	}
	return rv;
}

int
c_read(wp)
	char **wp;
{
	register int c = 0;
	int expand = 1, history = 0;
	int expanding;
	int ecode = 0;
	register char *cp;
	int fd = 0;
	struct shf *shf;
	int optc;
	const char *emsg;
	XString cs, xs;
	struct tbl *vp;
	char UNINITIALIZED(*xp);

	while ((optc = ksh_getopt(wp, &builtin_opt, "prsu,")) != EOF)
		switch (optc) {
#ifdef KSH
		  case 'p':
			if ((fd = coproc_getfd(R_OK, &emsg)) < 0) {
				bi_errorf("-p: %s", emsg);
				return 1;
			}
			break;
#endif /* KSH */
		  case 'r':
			expand = 0;
			break;
		  case 's':
			history = 1;
			break;
		  case 'u':
			if (!*(cp = builtin_opt.optarg))
				fd = 0;
			else if ((fd = check_fd(cp, R_OK, &emsg)) < 0) {
				bi_errorf("-u: %s: %s", cp, emsg);
				return 1;
			}
			break;
		  case '?':
			return 1;
		}
	wp += builtin_opt.optind;

	if (*wp == NULL)
		*--wp = "REPLY";

	/* Since we can't necessarily seek backwards on non-regular files,
	 * don't buffer them so we can't read too much.
	 */
	shf = shf_reopen(fd, SHF_RD | SHF_INTERRUPT | can_seek(fd), shl_spare);

	if ((cp = strchr(*wp, '?')) != NULL) {
		*cp = 0;
		if (isatty(fd)) {
			/* at&t ksh says it prints prompt on fd if it's open
			 * for writing and is a tty, but it doesn't do it
			 * (it also doesn't check the interactive flag,
			 * as is indicated in the Kornshell book).
			 */
			shellf("%s", cp+1);
		}
	}

#ifdef KSH
	/* If we are reading from the co-process for the first time,
	 * make sure the other side of the pipe is closed first.  This allows
	 * the detection of eof.
	 *
	 * This is not compatiable with at&t ksh... the fd is kept so another
	 * coproc can be started with same ouput, however, this means eof
	 * can't be detected...  This is why it is closed here.
	 * If this call is removed, remove the eof check below, too.
	* coproc_readw_close(fd);
	 */
#endif /* KSH */

	if (history)
		Xinit(xs, xp, 128, ATEMP);
	expanding = 0;
	Xinit(cs, cp, 128, ATEMP);
	for (; *wp != NULL; wp++) {
		for (cp = Xstring(cs, cp); ; ) {
			if (c == '\n' || c == EOF)
				break;
			while (1) {
				c = shf_getc(shf);
				if (c == '\0'
#ifdef OS2
				    || c == '\r'
#endif /* OS2 */
				    )
					continue;
				if (c == EOF && shf_error(shf)
				    && shf_errno(shf) == EINTR)
				{
					/* Was the offending signal one that
					 * would normally kill a process?
					 * If so, pretend the read was killed.
					 */
					ecode = fatal_trap_check();

					/* non fatal (eg, CHLD), carry on */
					if (!ecode) {
						shf_clearerr(shf);
						continue;
					}
				}
				break;
			}
			if (history) {
				Xcheck(xs, xp);
				Xput(xs, xp, c);
			}
			Xcheck(cs, cp);
			if (expanding) {
				expanding = 0;
				if (c == '\n') {
					c = 0;
					if (Flag(FTALKING_I) && isatty(fd)) {
						/* set prompt in case this is
						 * called from .profile or $ENV
						 */
						set_prompt(PS2, (Source *) 0);
						pprompt(prompt, 0);
					}
				} else if (c != EOF)
					Xput(cs, cp, c);
				continue;
			}
			if (expand && c == '\\') {
				expanding = 1;
				continue;
			}
			if (c == '\n' || c == EOF)
				break;
			if (ctype(c, C_IFS)) {
				if (Xlength(cs, cp) == 0 && ctype(c, C_IFSWS))
					continue;
				if (wp[1])
					break;
			}
			Xput(cs, cp, c);
		}
		/* strip trailing IFS white space from last variable */
		if (!wp[1])
			while (Xlength(cs, cp) && ctype(cp[-1], C_IFS)
			       && ctype(cp[-1], C_IFSWS))
				cp--;
		Xput(cs, cp, '\0');
		vp = global(*wp);
		/* Must be done before setting export. */
		if (vp->flag & RDONLY) {
			shf_flush(shf);
			bi_errorf("%s is read only", *wp);
			return 1;
		}
		if (Flag(FEXPORT))
			typeset(*wp, EXPORT, 0, 0, 0);
		if (!setstr(vp, Xstring(cs, cp), KSH_RETURN_ERROR)) {
		    shf_flush(shf);
		    return 1;
		}
	}

	shf_flush(shf);
	if (history) {
		Xput(xs, xp, '\0');
		source->line++;
		histsave(source->line, Xstring(xs, xp), 1);
		Xfree(xs, xp);
	}
#ifdef KSH
	/* if this is the co-process fd, close the file descriptor
	 * (can get eof if and only if all processes are have died, ie,
	 * coproc.njobs is 0 and the pipe is closed).
	 */
	if (c == EOF && !ecode)
		coproc_read_close(fd);
#endif /* KSH */

	return ecode ? ecode : c == EOF;
}

int
c_eval(wp)
	char **wp;
{
	register struct source *s;

	if (ksh_getopt(wp, &builtin_opt, null) == '?')
		return 1;
	s = pushs(SWORDS, ATEMP);
	s->u.strv = wp + builtin_opt.optind;
	if (!Flag(FPOSIX)) {
		/*
		 * Handle case where the command is empty due to failed
		 * command substitution, eg, eval "$(false)".
		 * In this case, shell() will not set/change exstat (because
		 * compiled tree is empty), so will use this value.
		 * subst_exstat is cleared in execute(), so should be 0 if
		 * there were no substitutions.
		 *
		 * A strict reading of POSIX says we don't do this (though
		 * it is traditionally done). [from 1003.2-1992]
		 *    3.9.1: Simple Commands
		 *	... If there is a command name, execution shall
		 *	continue as described in 3.9.1.1.  If there
		 *	is no command name, but the command contained a command
		 *	substitution, the command shall complete with the exit
		 *	status of the last command substitution
		 *    3.9.1.1: Command Search and Execution
		 *	...(1)...(a) If the command name matches the name of
		 *	a special built-in utility, that special built-in
		 *	utility shall be invoked.
		 * 3.14.5: Eval
		 *	... If there are no arguments, or only null arguments,