eval.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。

	  case '%':		/* shortest match at end */
		for (p = end; p >= str; p--) {
			if (gmatch(p, pat, FALSE))
				return str_nsave(str, p - str, ATEMP);
		}
		break;
	  case '%'|0x80:	/* longest match at end */
		for (p = str; p <= end; p++) {
			if (gmatch(p, pat, FALSE))
				return str_nsave(str, p - str, ATEMP);
		}
		break;
	}

	return str;		/* no match, return string */
}

/*
 * glob
 * Name derived from V6's /etc/glob, the program that expanded filenames.
 */

/* XXX cp not const 'cause slashes are temporarily replaced with nulls... */
static void
glob(cp, wp, markdirs)
	char *cp;
	register XPtrV *wp;
	int markdirs;
{
	int oldsize = XPsize(*wp);

	if (glob_str(cp, wp, markdirs) == 0)
		XPput(*wp, debunk(cp, cp));
	else
		qsortp(XPptrv(*wp) + oldsize, (size_t)(XPsize(*wp) - oldsize),
			xstrcmp);
}

#define GF_NONE		0
#define GF_EXCHECK	BIT(0)		/* do existance check on file */
#define GF_GLOBBED	BIT(1)		/* some globbing has been done */
#define GF_MARKDIR	BIT(2)		/* add trailing / to directories */

/* Apply file globbing to cp and store the matching files in wp.  Returns
 * the number of matches found.
 */
int
glob_str(cp, wp, markdirs)
	char *cp;
	XPtrV *wp;
	int markdirs;
{
	int oldsize = XPsize(*wp);
	XString xs;
	char *xp;

	Xinit(xs, xp, 256, ATEMP);
	globit(&xs, &xp, cp, wp, markdirs ? GF_MARKDIR : GF_NONE);
	Xfree(xs, xp);

	return XPsize(*wp) - oldsize;
}

static void
globit(xs, xpp, sp, wp, check)
	XString *xs;		/* dest string */
	char **xpp;		/* ptr to dest end */
	char *sp;		/* source path */
	register XPtrV *wp;	/* output list */
	int check;		/* GF_* flags */
{
	register char *np;	/* next source component */
	char *xp = *xpp;
	char *se;
	char odirsep;

	/* This to allow long expansions to be interrupted */
	intrcheck();

	if (sp == NULL) {	/* end of source path */
		/* We only need to check if the file exists if a pattern
		 * is followed by a non-pattern (eg, foo*x/bar; no check
		 * is needed for foo* since the match must exist) or if
		 * any patterns were expanded and the markdirs option is set.
		 * Symlinks make things a bit tricky...
		 */
		if ((check & GF_EXCHECK)
		    || ((check & GF_MARKDIR) && (check & GF_GLOBBED)))
		{
#define stat_check()	(stat_done ? stat_done : \
			    (stat_done = stat(Xstring(*xs, xp), &statb) < 0 \
				? -1 : 1))
			struct stat lstatb, statb;
			int stat_done = 0;	 /* -1: failed, 1 ok */

			if (lstat(Xstring(*xs, xp), &lstatb) < 0)
				return;
			/* special case for systems which strip trailing
			 * slashes from regular files (eg, /etc/passwd/).
			 * SunOS 4.1.3 does this...
			 */
			if ((check & GF_EXCHECK) && xp > Xstring(*xs, xp)
			    && ISDIRSEP(xp[-1]) && !S_ISDIR(lstatb.st_mode)
#ifdef S_ISLNK
			    && (!S_ISLNK(lstatb.st_mode)
				|| stat_check() < 0
				|| !S_ISDIR(statb.st_mode))
#endif /* S_ISLNK */
				)
				return;
			/* Possibly tack on a trailing / if there isn't already
			 * one and if the file is a directory or a symlink to a
			 * directory
			 */
			if (((check & GF_MARKDIR) && (check & GF_GLOBBED))
			    && xp > Xstring(*xs, xp) && !ISDIRSEP(xp[-1])
			    && (S_ISDIR(lstatb.st_mode)
#ifdef S_ISLNK
				|| (S_ISLNK(lstatb.st_mode)
				    && stat_check() > 0
				    && S_ISDIR(statb.st_mode))
#endif /* S_ISLNK */
				    ))
			{
				*xp++ = DIRSEP;
				*xp = '\0';
			}
		}
#ifdef OS2 /* Done this way to avoid bug in gcc 2.7.2... */
    /* Ugly kludge required for command
     * completion - see how search_access()
     * is implemented for OS/2...
     */
# define KLUDGE_VAL	4
#else /* OS2 */
# define KLUDGE_VAL	0
#endif /* OS2 */
		XPput(*wp, str_nsave(Xstring(*xs, xp), Xlength(*xs, xp)
			+ KLUDGE_VAL, ATEMP));
		return;
	}

	if (xp > Xstring(*xs, xp))
		*xp++ = DIRSEP;
	while (ISDIRSEP(*sp)) {
		Xcheck(*xs, xp);
		*xp++ = *sp++;
	}
	np = ksh_strchr_dirsep(sp);
	if (np != NULL) {
		se = np;
		odirsep = *np;	/* don't assume DIRSEP, can be multiple kinds */
		*np++ = '\0';
	} else {
		odirsep = '\0'; /* keep gcc quiet */
		se = sp + strlen(sp);
	}


	/* Check if sp needs globbing - done to avoid pattern checks for strings
	 * containing MAGIC characters, open ['s without the matching close ],
	 * etc. (otherwise opendir() will be called which may fail because the
	 * directory isn't readable - if no globbing is needed, only execute
	 * permission should be required (as per POSIX)).
	 */
	if (!has_globbing(sp, se)) {
		XcheckN(*xs, xp, se - sp + 1);
		debunk(xp, sp);
		xp += strlen(xp);
		*xpp = xp;
		globit(xs, xpp, np, wp, check);
	} else {
		DIR *dirp;
		struct dirent *d;
		char *name;
		int len;
		int prefix_len;

		/* xp = *xpp;	   copy_non_glob() may have re-alloc'd xs */
		*xp = '\0';
		prefix_len = Xlength(*xs, xp);
		dirp = ksh_opendir(prefix_len ? Xstring(*xs, xp) : ".");
		if (dirp == NULL)
			goto Nodir;
		while ((d = readdir(dirp)) != NULL) {
			name = d->d_name;
			if (name[0] == '.' &&
			    (name[1] == 0 || (name[1] == '.' && name[2] == 0)))
				continue; /* always ignore . and .. */
			if ((*name == '.' && *sp != '.')
			    || !gmatch(name, sp, TRUE))
				continue;

			len = NLENGTH(d) + 1;
			XcheckN(*xs, xp, len);
			memcpy(xp, name, len);
			*xpp = xp + len - 1;
			globit(xs, xpp, np, wp,
				(check & GF_MARKDIR) | GF_GLOBBED
				| (np ? GF_EXCHECK : GF_NONE));
			xp = Xstring(*xs, xp) + prefix_len;
		}
		closedir(dirp);
	  Nodir:;
	}

	if (np != NULL)
		*--np = odirsep;
}

#if 0
/* Check if p contains something that needs globbing; if it does, 0 is
 * returned; if not, p is copied into xs/xp after stripping any MAGICs
 */
static int	copy_non_glob ARGS((XString *xs, char **xpp, char *p));
static int
copy_non_glob(xs, xpp, p)
	XString *xs;
	char **xpp;
	char *p;
{
	char *xp;
	int len = strlen(p);

	XcheckN(*xs, *xpp, len);
	xp = *xpp;
	for (; *p; p++) {
		if (ISMAGIC(*p)) {
			int c = *++p;

			if (c == '*' || c == '?')
				return 0;
			if (*p == '[') {
				char *q = p + 1;

				if (ISMAGIC(*q) && q[1] == NOT)
					q += 2;
				if (ISMAGIC(*q) && q[1] == ']')
					q += 2;
				for (; *q; q++)
					if (ISMAGIC(*q) && *++q == ']')
						return 0;
				/* pass a literal [ through */
			}
			/* must be a MAGIC-MAGIC, or MAGIC-!, MAGIC--, etc. */
		}
		*xp++ = *p;
	}
	*xp = '\0';
	*xpp = xp;
	return 1;
}
#endif /* 0 */

/* remove MAGIC from string */
char *
debunk(dp, sp)
	char *dp;
	const char *sp;
{
	char *d, *s;

	if ((s = strchr(sp, MAGIC))) {
		memcpy(dp, sp, s - sp);
		for (d = dp + (s - sp); *s; s++)
			if (!ISMAGIC(*s) || !(*++s & 0x80)
			    || !strchr("*+?@! ", *s & 0x7f))
				*d++ = *s;
			else {
				/* extended pattern operators: *+?@! */
				if ((*s & 0x7f) != ' ')
					*d++ = *s & 0x7f;
				*d++ = '(';
			}
		*d = '\0';
	} else if (dp != sp)
		strcpy(dp, sp);
	return dp;
}

/* Check if p is an unquoted name, possibly followed by a / or :.  If so
 * puts the expanded version in *dcp,dp and returns a pointer in p just
 * past the name, otherwise returns 0.
 */
static char *
maybe_expand_tilde(p, dsp, dpp, isassign)
	char *p;
	XString *dsp;
	char **dpp;
	int isassign;
{
	XString ts;
	char *dp = *dpp;
	char *tp, *r;

	Xinit(ts, tp, 16, ATEMP);
	/* : only for DOASNTILDE form */
	while (p[0] == CHAR && !ISDIRSEP(p[1])
	       && (!isassign || p[1] != PATHSEP))
	{
		Xcheck(ts, tp);
		*tp++ = p[1];
		p += 2;
	}
	*tp = '\0';
	r = (p[0] == EOS || p[0] == CHAR || p[0] == CSUBST) ? tilde(Xstring(ts, tp)) : (char *) 0;
	Xfree(ts, tp);
	if (r) {
		while (*r) {
			Xcheck(*dsp, dp);
			if (ISMAGIC(*r))
				*dp++ = MAGIC;
			*dp++ = *r++;
		}
		*dpp = dp;
		r = p;
	}
	return r;
}

/*
 * tilde expansion
 *
 * based on a version by Arnold Robbins
 */

static char *
tilde(cp)
	char *cp;
{
	char *dp;

	if (cp[0] == '\0')
		dp = str_val(global("HOME"));
	else if (cp[0] == '+' && cp[1] == '\0')
		dp = str_val(global("PWD"));
	else if (cp[0] == '-' && cp[1] == '\0')
		dp = str_val(global("OLDPWD"));
	else
		dp = homedir(cp);
	/* If HOME, PWD or OLDPWD are not set, don't expand ~ */
	if (dp == null)
		dp = (char *) 0;
	return dp;
}

/*
 * map userid to user's home directory.
 * note that 4.3's getpw adds more than 6K to the shell,
 * and the YP version probably adds much more.
 * we might consider our own version of getpwnam() to keep the size down.
 */

static char *
homedir(name)
	char *name;
{
	register struct tbl *ap;

	ap = tenter(&homedirs, name, hash(name));
	if (!(ap->flag & ISSET)) {
#ifdef OS2
		/* No usernames in OS2 - punt */
		return NULL;
#else /* OS2 */
		struct passwd *pw;

		pw = getpwnam(name);
		if (pw == NULL)
			return NULL;
		ap->val.s = str_save(pw->pw_dir, APERM);
		ap->flag |= DEFINED|ISSET|ALLOC;
#endif /* OS2 */
	}
	return ap->val.s;
}

#ifdef BRACE_EXPAND
static void
alt_expand(wp, start, exp_start, end, fdo)
	XPtrV *wp;
	char *start, *exp_start;
	char *end;
	int fdo;
{
	int UNINITIALIZED(count);
	char *brace_start, *brace_end, *UNINITIALIZED(comma);
	char *field_start;
	char *p;

	/* search for open brace */
	for (p = exp_start; (p = strchr(p, MAGIC)) && p[1] != OBRACE; p += 2)
		;
	brace_start = p;

	/* find matching close brace, if any */
	if (p) {
		comma = (char *) 0;
		count = 1;
		for (p += 2; *p && count; p++) {
			if (ISMAGIC(*p)) {
				if (*++p == OBRACE)
					count++;
				else if (*p == CBRACE)
					--count;
				else if (*p == ',' && count == 1)
					comma = p;
			}
		}
	}
	/* no valid expansions... */
	if (!p || count != 0) {
		/* Note that given a{{b,c} we do not expand anything (this is
		 * what at&t ksh does.  This may be changed to do the {b,c}
		 * expansion. }
		 */
		if (fdo & DOGLOB)
			glob(start, wp, fdo & DOMARKDIRS);
		else
			XPput(*wp, debunk(start, start));
		return;
	}
	brace_end = p;
	if (!comma) {
		alt_expand(wp, start, brace_end, end, fdo);
		return;
	}

	/* expand expression */
	field_start = brace_start + 2;
	count = 1;
	for (p = brace_start + 2; p != brace_end; p++) {
		if (ISMAGIC(*p)) {
			if (*++p == OBRACE)
				count++;
			else if ((*p == CBRACE && --count == 0)
				 || (*p == ',' && count == 1))
			{
				char *new;
				int l1, l2, l3;

				l1 = brace_start - start;
				l2 = (p - 1) - field_start;
				l3 = end - brace_end;
				new = (char *) alloc(l1 + l2 + l3 + 1, ATEMP);
				memcpy(new, start, l1);
				memcpy(new + l1, field_start, l2);
				memcpy(new + l1 + l2, brace_end, l3);
				new[l1 + l2 + l3] = '\0';
				alt_expand(wp, new, new + l1,
					   new + l1 + l2 + l3, fdo);
				field_start = p + 1;
			}
		}
	}
	return;
}
#endif /* BRACE_EXPAND */