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

/*
 * built-in Korn commands: c_*
 */

#include "sh.h"
#include "ksh_stat.h"
#include <ctype.h>

#ifdef __CYGWIN__
#include <sys/cygwin.h>
#endif /* __CYGWIN__ */

int
c_cd(wp)
	char	**wp;
{
	int optc;
	int physical = Flag(FPHYSICAL);
	int cdnode;			/* was a node from cdpath added in? */
	int printpath = 0;		/* print where we cd'd? */
	int rval;
	struct tbl *pwd_s, *oldpwd_s;
	XString xs;
	char *xp;
	char *dir, *try, *pwd;
	int phys_path;
	char *cdpath;

	while ((optc = ksh_getopt(wp, &builtin_opt, "LP")) != EOF)
		switch (optc) {
		case 'L':
			physical = 0;
			break;
		case 'P':
			physical = 1;
			break;
		case '?':
			return 1;
		}
	wp += builtin_opt.optind;

	if (Flag(FRESTRICTED)) {
		bi_errorf("restricted shell - can't cd");
		return 1;
	}

	pwd_s = global("PWD");
	oldpwd_s = global("OLDPWD");

	if (!wp[0]) {
		/* No arguments - go home */
		if ((dir = str_val(global("HOME"))) == null) {
			bi_errorf("no home directory (HOME not set)");
			return 1;
		}
	} else if (!wp[1]) {
		/* One argument: - or dir */
		dir = wp[0];
		if (strcmp(dir, "-") == 0) {
			dir = str_val(oldpwd_s);
			if (dir == null) {
				bi_errorf("no OLDPWD");
				return 1;
			}
			printpath++;
		}
	} else if (!wp[2]) {
		/* Two arguments - substitute arg1 in PWD for arg2 */
		int ilen, olen, nlen, elen;
		char *cp;

		if (!current_wd[0]) {
			bi_errorf("don't know current directory");
			return 1;
		}
		/* substitue arg1 for arg2 in current path.
		 * if the first substitution fails because the cd fails
		 * we could try to find another substitution. For now
		 * we don't
		 */
		if ((cp = strstr(current_wd, wp[0])) == (char *) 0) {
			bi_errorf("bad substitution");
			return 1;
		}
		ilen = cp - current_wd;
		olen = strlen(wp[0]);
		nlen = strlen(wp[1]);
		elen = strlen(current_wd + ilen + olen) + 1;
		dir = alloc(ilen + nlen + elen, ATEMP);
		memcpy(dir, current_wd, ilen);
		memcpy(dir + ilen, wp[1], nlen);
		memcpy(dir + ilen + nlen, current_wd + ilen + olen, elen);
		printpath++;
	} else {
		bi_errorf("too many arguments");
		return 1;
	}

	Xinit(xs, xp, PATH, ATEMP);
	/* xp will have a bogus value after make_path() - set it to 0
	 * so that if it's used, it will cause a dump
	 */
	xp = (char *) 0;

	cdpath = str_val(global("CDPATH"));
	do {
		cdnode = make_path(current_wd, dir, &cdpath, &xs, &phys_path);
#ifdef S_ISLNK
		if (physical)
			rval = chdir(try = Xstring(xs, xp) + phys_path);
		else
#endif /* S_ISLNK */
		{
			simplify_path(Xstring(xs, xp));
			rval = chdir(try = Xstring(xs, xp));
		}
	} while (rval < 0 && cdpath != (char *) 0);

	if (rval < 0) {
		if (cdnode)
			bi_errorf("%s: bad directory", dir);
		else
			bi_errorf("%s - %s", try, strerror(errno));
		return 1;
	}

	/* Clear out tracked aliases with relative paths */
	flushcom(0);

	/* Set OLDPWD (note: unsetting OLDPWD does not disable this
	 * setting in at&t ksh)
	 */
	if (current_wd[0])
		/* Ignore failure (happens if readonly or integer) */
		setstr(oldpwd_s, current_wd, KSH_RETURN_ERROR);

	if (!ISABSPATH(Xstring(xs, xp))) {
#ifdef OS2
		/* simplify_path() doesn't know about os/2's drive contexts,
		 * so it can't set current_wd when changing to a:foo.
		 * Handle this by calling getcwd()...
		 */
		pwd = ksh_get_wd((char *) 0, 0);
#else /* OS2 */
		pwd = (char *) 0;
#endif /* OS2 */
	} else
#ifdef S_ISLNK
	if (!physical || !(pwd = get_phys_path(Xstring(xs, xp))))
#endif /* S_ISLNK */
		pwd = Xstring(xs, xp);

	/* Set PWD */
	if (pwd) {
#ifdef __CYGWIN__
		char ptmp[PATH];  /* larger than MAX_PATH */
		cygwin_conv_to_full_posix_path(pwd, ptmp);
#else /* __CYGWIN__ */
		char *ptmp = pwd;
#endif /* __CYGWIN__ */
		set_current_wd(ptmp);
		/* Ignore failure (happens if readonly or integer) */
		setstr(pwd_s, ptmp, KSH_RETURN_ERROR);
	} else {
		set_current_wd(null);
		pwd = Xstring(xs, xp);
		/* XXX unset $PWD? */
	}
	if (printpath || cdnode)
		shprintf("%s\n", pwd);

	return 0;
}

int
c_pwd(wp)
	char	**wp;
{
	int optc;
	int physical = Flag(FPHYSICAL);
	char *p;

	while ((optc = ksh_getopt(wp, &builtin_opt, "LP")) != EOF)
		switch (optc) {
		case 'L':
			physical = 0;
			break;
		case 'P':
			physical = 1;
			break;
		case '?':
			return 1;
		}
	wp += builtin_opt.optind;

	if (wp[0]) {
		bi_errorf("too many arguments");
		return 1;
	}
#ifdef S_ISLNK
	p = current_wd[0] ? (physical ? get_phys_path(current_wd) : current_wd)
			  : (char *) 0;
#else /* S_ISLNK */
	p = current_wd[0] ? current_wd : (char *) 0;
#endif /* S_ISLNK */
	if (p && eaccess(p, R_OK) < 0)
		p = (char *) 0;
	if (!p) {
		p = ksh_get_wd((char *) 0, 0);
		if (!p) {
			bi_errorf("can't get current directory - %s",
				strerror(errno));
			return 1;
		}
	}
	shprintf("%s\n", p);
	return 0;
}

int
c_print(wp)
	char **wp;
{
#define PO_NL		BIT(0)	/* print newline */
#define PO_EXPAND	BIT(1)	/* expand backslash sequences */
#define PO_PMINUSMINUS	BIT(2)	/* print a -- argument */
#define PO_HIST		BIT(3)	/* print to history instead of stdout */
#define PO_COPROC	BIT(4)	/* printing to coprocess: block SIGPIPE */
#define PO_FSLASH	BIT(5)  /* swap slash for backslash (for os2 ) */
	int fd = 1;
	int flags = PO_EXPAND|PO_NL;
	char *s;
	const char *emsg;
	XString xs;
	char *xp;

	if (wp[0][0] == 'e') {	/* echo command */
		int nflags = flags;

		/* A compromise between sysV and BSD echo commands:
		 * escape sequences are enabled by default, and
		 * -n, -e and -E are recognized if they appear
		 * in arguments with no illegal options (ie, echo -nq
		 * will print -nq).
		 * Different from sysV echo since options are recognized,
		 * different from BSD echo since escape sequences are enabled
		 * by default.
		 */
		wp += 1;
		while ((s = *wp) && *s == '-' && s[1]) {
			while (*++s)
				if (*s == 'n')
					nflags &= ~PO_NL;
				else if (*s == 'e')
					nflags |= PO_EXPAND;
				else if (*s == 'E')
					nflags &= ~PO_EXPAND;
				else
					/* bad option: don't use nflags, print
					 * argument
					 */
					break;
			if (*s)
				break;
			wp++;
			flags = nflags;
		}
	} else {
		int optc;
#if OS2
		const char *options = "Rnpfrsu,"; /* added f flag */
#else
		const char *options = "Rnprsu,";
#endif
		while ((optc = ksh_getopt(wp, &builtin_opt, options)) != EOF)
			switch (optc) {
			  case 'R': /* fake BSD echo command */
				flags |= PO_PMINUSMINUS;
				flags &= ~PO_EXPAND;
				options = "ne";
				break;
			  case 'e':
				flags |= PO_EXPAND;
				break;
#ifdef OS2
			  case 'f':
				flags |= PO_FSLASH;
				break;
#endif
			  case 'n':
				flags &= ~PO_NL;
				break;
#ifdef KSH
			  case 'p':
				if ((fd = coproc_getfd(W_OK, &emsg)) < 0) {
					bi_errorf("-p: %s", emsg);
					return 1;
				}
				break;
#endif /* KSH */
			  case 'r':
				flags &= ~PO_EXPAND;
				break;
			  case 's':
				flags |= PO_HIST;
				break;
			  case 'u':
				if (!*(s = builtin_opt.optarg))
					fd = 0;
				else if ((fd = check_fd(s, W_OK, &emsg)) < 0) {
					bi_errorf("-u: %s: %s", s, emsg);
					return 1;
				}
				break;
			  case '?':
				return 1;
			}
		if (!(builtin_opt.info & GI_MINUSMINUS)) {
			/* treat a lone - like -- */
			if (wp[builtin_opt.optind]
			    && strcmp(wp[builtin_opt.optind], "-") == 0)
				builtin_opt.optind++;
		} else if (flags & PO_PMINUSMINUS)
			builtin_opt.optind--;
		wp += builtin_opt.optind;
	}

	Xinit(xs, xp, 128, ATEMP);

	while (*wp != NULL) {
		register int c;
		s = *wp;
		while ((c = *s++) != '\0') {
			Xcheck(xs, xp);
#ifdef OS2
			if ((flags & PO_FSLASH) && c == '\\') 
				if (*s == '\\')
					*s++;
				else
					c = '/';
#endif /* OS2 */
			if ((flags & PO_EXPAND) && c == '\\') {
				int i;

				switch ((c = *s++)) {
				/* Oddly enough, \007 seems more portable than
				 * \a (due to HP-UX cc, Ultrix cc, old pcc's,
				 * etc.).
				 */
				case 'a': c = '\007'; break;
				case 'b': c = '\b'; break;
				case 'c': flags &= ~PO_NL;
					  continue; /* AT&T brain damage */
				case 'f': c = '\f'; break;
				case 'n': c = '\n'; break;
				case 'r': c = '\r'; break;
				case 't': c = '\t'; break;
				case 'v': c = 0x0B; break;
				case '0':
					/* Look for an octal number: can have
					 * three digits (not counting the
					 * leading 0).  Truely burnt.
					 */
					c = 0;
					for (i = 0; i < 3; i++) {
						if (*s >= '0' && *s <= '7')
							c = c*8 + *s++ - '0';
						else
							break;
					}
					break;
				case '\0': s--; c = '\\'; break;
				case '\\': break;
				default:
					Xput(xs, xp, '\\');
				}
			}
			Xput(xs, xp, c);
		}
		if (*++wp != NULL)
			Xput(xs, xp, ' ');
	}
	if (flags & PO_NL)
		Xput(xs, xp, '\n');

	if (flags & PO_HIST) {
		Xput(xs, xp, '\0');
		source->line++;
		histsave(source->line, Xstring(xs, xp), 1);
		Xfree(xs, xp);
	} else {
		int n, len = Xlength(xs, xp);
#ifdef KSH
		int UNINITIALIZED(opipe);

		/* Ensure we aren't killed by a SIGPIPE while writing to
		 * a coprocess.  at&t ksh doesn't seem to do this (seems
		 * to just check that the co-process is alive, which is
		 * not enough).
		 */
		if (coproc.write >= 0 && coproc.write == fd) {
			flags |= PO_COPROC;
			opipe = block_pipe();
		}
#endif /* KSH */
		for (s = Xstring(xs, xp); len > 0; ) {
			n = write(fd, s, len);
			if (n < 0) {
#ifdef KSH
				if (flags & PO_COPROC)
					restore_pipe(opipe);
#endif /* KSH */
				if (errno == EINTR) {
					/* allow user to ^C out */
					intrcheck();
#ifdef KSH
					if (flags & PO_COPROC)
						opipe = block_pipe();
#endif /* KSH */
					continue;
				}
#ifdef KSH
				/* This doesn't really make sense - could
				 * break scripts (print -p generates
				 * error message).
				*if (errno == EPIPE)
				*	coproc_write_close(fd);
				 */
#endif /* KSH */
				return 1;
			}
			s += n;
			len -= n;
		}
#ifdef KSH
		if (flags & PO_COPROC)
			restore_pipe(opipe);
#endif /* KSH */
	}

	return 0;
}

int
c_whence(wp)
	char **wp;
{
	struct tbl *tp;
	char *id;
	int pflag = 0, vflag = 0, Vflag = 0;
	int ret = 0;
	int optc;
	int iam_whence = wp[0][0] == 'w';
	int fcflags;
	const char *options = iam_whence ? "pv" : "pvV";

	while ((optc = ksh_getopt(wp, &builtin_opt, options)) != EOF)
		switch (optc) {
		case 'p':
			pflag = 1;
			break;
		case 'v':
			vflag = 1;
			break;
		case 'V':
			Vflag = 1;
			break;
		case '?':
			return 1;
		}
	wp += builtin_opt.optind;


	fcflags = FC_BI | FC_PATH | FC_FUNC;
	if (!iam_whence) {
		/* Note that -p on its own is deal with in comexec() */
		if (pflag)
			fcflags |= FC_DEFPATH;
		/* Convert command options to whence options - note that
		 * command -pV uses a different path search than whence -v
		 * or whence -pv.  This should be considered a feature.
		 */
		vflag = Vflag;
	}
	if (pflag)
		fcflags &= ~(FC_BI | FC_FUNC);

	while ((vflag || ret == 0) && (id = *wp++) != NULL) {
		tp = NULL;
		if ((iam_whence || vflag) && !pflag)
			tp = tsearch(&keywords, id, hash(id));