fts.c

压缩包中包含LINUX下多个命令的源码

	/* Fatal errors stop here. */
	if (ISSET(FTS_STOP))
		return (NULL);

	/* Return logical hierarchy of user's arguments. */
	if (p->fts_info == FTS_INIT)
		return (p->fts_link);

	/*
	 * If not a directory being visited in pre-order, stop here.  Could
	 * allow FTS_DNR, assuming the user has fixed the problem, but the
	 * same effect is available with FTS_AGAIN.
	 */
	if (p->fts_info != FTS_D /* && p->fts_info != FTS_DNR */)
		return (NULL);

	/* Free up any previous child list. */
	if (sp->fts_child)
		fts_lfree(sp->fts_child);

	if (instr == FTS_NAMEONLY) {
		sp->fts_options |= FTS_NAMEONLY;
		instr = BNAMES;
	} else
		instr = BCHILD;

	/*
	 * If using chdir on a relative path and called BEFORE fts_read does
	 * its chdir to the root of a traversal, we can lose -- we need to
	 * chdir into the subdirectory, and we don't know where the current
	 * directory is, so we can't get back so that the upcoming chdir by
	 * fts_read will work.
	 */
	if (p->fts_level != FTS_ROOTLEVEL || p->fts_accpath[0] == '/' ||
	    ISSET(FTS_NOCHDIR))
		return (sp->fts_child = fts_build(sp, instr));

	if ((fd = open(".", O_RDONLY, 0)) < 0)
		return (NULL);
	sp->fts_child = fts_build(sp, instr);
	if (fchdir(fd))
		return (NULL);
	(void)close(fd);
	return (sp->fts_child);
}

/*
 * This is the tricky part -- do not casually change *anything* in here.  The
 * idea is to build the linked list of entries that are used by fts_children
 * and fts_read.  There are lots of special cases.
 *
 * The real slowdown in walking the tree is the stat calls.  If FTS_NOSTAT is
 * set and it's a physical walk (so that symbolic links can't be directories),
 * we can do things quickly.  First, if it's a 4.4BSD file system, the type
 * of the file is in the directory entry.  Otherwise, we assume that the number
 * of subdirectories in a node is equal to the number of links to the parent.
 * The former skips all stat calls.  The latter skips stat calls in any leaf
 * directories and for any files after the subdirectories in the directory have
 * been found, cutting the stat calls by about 2/3.
 */
static FTSENT *
fts_build(sp, type)
	register FTS *sp;
	int type;
{
	struct dirent *dp;
	register FTSENT *p, *head;
	register int nitems;
	FTSENT *cur, *tail;
	DIR *dirp;
	void *adjaddr;
	int cderrno, descend, len, level, maxlen, nlinks, saved_errno;
	char *cp=NULL;
#ifdef DTF_HIDEW
	int oflag;
#endif

	/* Set current node pointer. */
	cur = sp->fts_cur;

	/*
	 * Open the directory for reading.  If this fails, we're done.
	 * If being called from fts_read, set the fts_info field.
	 */
#ifdef DTF_HIDEW
	if (ISSET (FTS_WHITEOUT))
		oflag = DTF_NODUP|DTF_REWIND;
	else
		oflag = DTF_HIDEW|DTF_NODUP|DTF_REWIND;
#else
# define opendir2(path, flag) opendir(path)
#endif
       if ((dirp = opendir2 (cur->fts_accpath, oflag)) == NULL) {
		if (type == BREAD) {
			cur->fts_info = FTS_DNR;
			cur->fts_errno = errno;
		}
		return (NULL);
	}

	/*
	 * Nlinks is the number of possible entries of type directory in the
	 * directory if we're cheating on stat calls, 0 if we're not doing
	 * any stat calls at all, -1 if we're doing stats on everything.
	 */
	if (type == BNAMES)
		nlinks = 0;
	else if (ISSET(FTS_NOSTAT) && ISSET(FTS_PHYSICAL))
		nlinks = cur->fts_nlink - (ISSET(FTS_SEEDOT) ? 0 : 2);
	else
		nlinks = -1;

#ifdef notdef
	(void)printf("nlinks == %d (cur: %d)\n", nlinks, cur->fts_nlink);
	(void)printf("NOSTAT %d PHYSICAL %d SEEDOT %d\n",
	    ISSET(FTS_NOSTAT), ISSET(FTS_PHYSICAL), ISSET(FTS_SEEDOT));
#endif
	/*
	 * If we're going to need to stat anything or we want to descend
	 * and stay in the directory, chdir.  If this fails we keep going,
	 * but set a flag so we don't chdir after the post-order visit.
	 * We won't be able to stat anything, but we can still return the
	 * names themselves.  Note, that since fts_read won't be able to
	 * chdir into the directory, it will have to return different path
	 * names than before, i.e. "a/b" instead of "b".  Since the node
	 * has already been visited in pre-order, have to wait until the
	 * post-order visit to return the error.  There is a special case
	 * here, if there was nothing to stat then it's not an error to
	 * not be able to stat.  This is all fairly nasty.  If a program
	 * needed sorted entries or stat information, they had better be
	 * checking FTS_NS on the returned nodes.
	 */
	cderrno = 0;
	if (nlinks || type == BREAD) {
		if (FCHDIR(sp, dirfd(dirp))) {
			if (nlinks && type == BREAD)
				cur->fts_errno = errno;
			cur->fts_flags |= FTS_DONTCHDIR;
			descend = 0;
			cderrno = errno;
		} else
			descend = 1;
	} else
		descend = 0;

	/*
	 * Figure out the max file name length that can be stored in the
	 * current path -- the inner loop allocates more path as necessary.
	 * We really wouldn't have to do the maxlen calculations here, we
	 * could do them in fts_read before returning the path, but it's a
	 * lot easier here since the length is part of the dirent structure.
	 *
	 * If not changing directories set a pointer so that can just append
	 * each new name into the path.
	 */
	maxlen = sp->fts_pathlen - cur->fts_pathlen - 1;
	len = NAPPEND(cur);
	if (ISSET(FTS_NOCHDIR)) {
		cp = sp->fts_path + len;
		*cp++ = '/';
	}

	level = cur->fts_level + 1;

	/* Read the directory, attaching each entry to the `link' pointer. */
	adjaddr = NULL;
	head = tail = NULL;
	nitems = 0;
	while((dp = readdir(dirp))) {
		int namlen;

		if (!ISSET(FTS_SEEDOT) && ISDOT(dp->d_name))
			continue;

		namlen = _D_EXACT_NAMLEN (dp);
		if ((p = fts_alloc(sp, dp->d_name, namlen)) == NULL)
			goto mem1;
		if (namlen > maxlen) {
			if (fts_palloc(sp, (size_t)namlen)) {
				/*
				 * No more memory for path or structures.  Save
				 * errno, free up the current structure and the
				 * structures already allocated.
				 */
mem1:				saved_errno = errno;
				if (p)
					free(p);
				fts_lfree(head);
				(void)closedir(dirp);
				errno = saved_errno;
				cur->fts_info = FTS_ERR;
				SET(FTS_STOP);
				return (NULL);
			}
			adjaddr = sp->fts_path;
			maxlen = sp->fts_pathlen - sp->fts_cur->fts_pathlen - 1;
		}

		p->fts_pathlen = len + namlen + 1;
		p->fts_parent = sp->fts_cur;
		p->fts_level = level;

		if (cderrno) {
			if (nlinks) {
				p->fts_info = FTS_NS;
				p->fts_errno = cderrno;
			} else
				p->fts_info = FTS_NSOK;
			p->fts_accpath = cur->fts_accpath;
		} else if (nlinks == 0
#if defined DT_DIR && defined _DIRENT_HAVE_D_TYPE
		    || (nlinks > 0 &&
			dp->d_type != DT_DIR && dp->d_type != DT_UNKNOWN)
#endif
		    ) {
			p->fts_accpath =
			    ISSET(FTS_NOCHDIR) ? p->fts_path : p->fts_name;
			p->fts_info = FTS_NSOK;
		} else {
			/* Build a file name for fts_stat to stat. */
			if (ISSET(FTS_NOCHDIR)) {
				p->fts_accpath = p->fts_path;
				memmove(p->fts_name, cp, p->fts_namelen + 1);
			} else
				p->fts_accpath = p->fts_name;
			/* Stat it. */
			p->fts_info = fts_stat(sp, dp, p, 0);

			/* Decrement link count if applicable. */
			if (nlinks > 0 && (p->fts_info == FTS_D ||
			    p->fts_info == FTS_DC || p->fts_info == FTS_DOT))
				--nlinks;
		}

		/* We walk in directory order so "ls -f" doesn't get upset. */
		p->fts_link = NULL;
		if (head == NULL)
			head = tail = p;
		else {
			tail->fts_link = p;
			tail = p;
		}
		++nitems;
	}
	(void)closedir(dirp);

	/*
	 * If had to realloc the path, adjust the addresses for the rest
	 * of the tree.
	 */
	if (adjaddr)
		fts_padjust(sp, adjaddr);

	/*
	 * If not changing directories, reset the path back to original
	 * state.
	 */
	if (ISSET(FTS_NOCHDIR)) {
		if (cp - 1 > sp->fts_path)
			--cp;
		*cp = '\0';
	}

	/*
	 * If descended after called from fts_children or after called from
	 * fts_read and nothing found, get back.  At the root level we use
	 * the saved fd; if one of fts_open()'s arguments is a relative path
	 * to an empty directory, we wind up here with no other way back.  If
	 * can't get back, we're done.
	 */
	if (descend && (type == BCHILD || !nitems) &&
	    (cur->fts_level == FTS_ROOTLEVEL ?
	     FCHDIR (sp, sp->fts_rfd) : CHDIR (sp, ".."))) {
		cur->fts_info = FTS_ERR;
		SET(FTS_STOP);
		return (NULL);
	}

	/* If didn't find anything, return NULL. */
	if (!nitems) {
		if (type == BREAD)
			cur->fts_info = FTS_DP;
		return (NULL);
	}

	/* Sort the entries. */
	if (sp->fts_compar && nitems > 1)
		head = fts_sort(sp, head, nitems);
	return (head);
}

static u_short
fts_stat(sp, dp, p, follow)
	FTS *sp;
	register FTSENT *p;
	struct dirent *dp;
	int follow;
{
	register FTSENT *t;
	register dev_t dev;
	register ino_t ino;
	struct stat *sbp, sb;
	int saved_errno;

	/* If user needs stat info, stat buffer already allocated. */
	sbp = ISSET(FTS_NOSTAT) ? &sb : p->fts_statp;

#if defined(DT_WHT) && defined(S_IFWHT)
	/*
	 * Whited-out files don't really exist.  However, there's stat(2) file
	 * mask for them, so we set it so that programs (i.e., find) don't have
	 * to test FTS_W separately from other file types.
	 */
	if (dp != NULL && dp->d_type == DT_WHT) {
		memset(sbp, 0, sizeof(struct stat));
		sbp->st_mode = S_IFWHT;
		return (FTS_W);
       }
#endif

	/*
	 * If doing a logical walk, or application requested FTS_FOLLOW, do
	 * a stat(2).  If that fails, check for a non-existent symlink.  If
	 * fail, set the errno from the stat call.
	 */
	if (ISSET(FTS_LOGICAL) || follow) {
		if (stat(p->fts_accpath, sbp)) {
			saved_errno = errno;
			if (!lstat(p->fts_accpath, sbp)) {
				errno = 0;
				return (FTS_SLNONE);
			}
			p->fts_errno = saved_errno;
			goto err;
		}
	} else if (lstat(p->fts_accpath, sbp)) {
		p->fts_errno = errno;
err:		memset(sbp, 0, sizeof(struct stat));
		return (FTS_NS);
	}

	if (S_ISDIR(sbp->st_mode)) {
		/*
		 * Set the device/inode.  Used to find cycles and check for
		 * crossing mount points.  Also remember the link count, used
		 * in fts_build to limit the number of stat calls.  It is
		 * understood that these fields are only referenced if fts_info
		 * is set to FTS_D.
		 */
		dev = p->fts_dev = sbp->st_dev;
		ino = p->fts_ino = sbp->st_ino;
		p->fts_nlink = sbp->st_nlink;

		if (ISDOT(p->fts_name))
			return (FTS_DOT);

		/*
		 * Cycle detection is done by brute force when the directory
		 * is first encountered.  If the tree gets deep enough or the
		 * number of symbolic links to directories is high enough,
		 * something faster might be worthwhile.
		 */
		for (t = p->fts_parent;
		    t->fts_level >= FTS_ROOTLEVEL; t = t->fts_parent)
			if (ino == t->fts_ino && dev == t->fts_dev) {
				p->fts_cycle = t;
				return (FTS_DC);
			}
		return (FTS_D);
	}
	if (S_ISLNK(sbp->st_mode))
		return (FTS_SL);
	if (S_ISREG(sbp->st_mode))
		return (FTS_F);
	return (FTS_DEFAULT);
}

static FTSENT *
fts_sort(sp, head, nitems)
	FTS *sp;
	FTSENT *head;
	register int nitems;
{
	register FTSENT **ap, *p;

	/*
	 * Construct an array of pointers to the structures and call qsort(3).
	 * Reassemble the array in the order returned by qsort.  If unable to
	 * sort for memory reasons, return the directory entries in their
	 * current order.  Allocate enough space for the current needs plus
	 * 40 so don't realloc one entry at a time.
	 */
	if (nitems > sp->fts_nitems) {
		sp->fts_nitems = nitems + 40;
		if ((sp->fts_array = realloc(sp->fts_array,
		    (size_t)(sp->fts_nitems * sizeof(FTSENT *)))) == NULL) {
			sp->fts_nitems = 0;
			return (head);
		}
	}
	for (ap = sp->fts_array, p = head; p; p = p->fts_link)
		*ap++ = p;
	qsort((void *)sp->fts_array, nitems, sizeof(FTSENT *), sp->fts_compar);
	for (head = *(ap = sp->fts_array); --nitems; ++ap)
		ap[0]->fts_link = ap[1];
	ap[0]->fts_link = NULL;
	return (head);
}

static FTSENT *
fts_alloc(sp, name, namelen)
	FTS *sp;
	const char *name;
	register int namelen;
{
	register FTSENT *p;
	size_t len;

	/*
	 * The file name is a variable length array and no stat structure is
	 * necessary if the user has set the nostat bit.  Allocate the FTSENT
	 * structure, the file name and the stat structure in one chunk, but
	 * be careful that the stat structure is reasonably aligned.  Since the
	 * fts_name field is declared to be of size 1, the fts_name pointer is
	 * namelen + 2 before the first possible address of the stat structure.
	 */
	len = sizeof(FTSENT) + namelen;
	if (!ISSET(FTS_NOSTAT))
		len += sizeof(struct stat);
	if ((p = malloc(len)) == NULL)
		return (NULL);

	/* Copy the name plus the trailing NULL. */
	memmove(p->fts_name, name, namelen + 1);

	if (!ISSET(FTS_NOSTAT))
		p->fts_statp = (struct stat *)(p->fts_name + namelen + 2);
	p->fts_namelen = namelen;
	p->fts_path = sp->fts_path;
	p->fts_errno = 0;
	p->fts_flags = 0;
	p->fts_instr = FTS_NOINSTR;
	p->fts_number = 0;
	p->fts_pointer = NULL;
	return (p);
}

static void
fts_lfree(head)
	register FTSENT *head;
{
	register FTSENT *p;

	/* Free a linked list of structures. */
	while ((p = head)) {
		head = head->fts_link;
		free(p);
	}
}

/*
 * Allow essentially unlimited paths; find, rm, ls should all work on any tree.
 * Most systems will allow creation of paths much longer than MAXPATHLEN, even
 * though the kernel won't resolve them.  Add the size (not just what's needed)
 * plus 256 bytes so don't realloc the path 2 bytes at a time.
 */
static int
fts_palloc(sp, more)
	FTS *sp;
	size_t more;
{
	sp->fts_pathlen += more + 256;
	sp->fts_path = realloc(sp->fts_path, (size_t)sp->fts_pathlen);
	return (sp->fts_path == NULL);
}

/*
 * When the path is realloc'd, have to fix all of the pointers in structures
 * already returned.
 */
static void
fts_padjust(sp, addr)
	FTS *sp;
	void *addr;
{
	FTSENT *p;

#define	ADJUST(p) {							\
	(p)->fts_accpath =						\
	    (char *)addr + ((p)->fts_accpath - (p)->fts_path);		\
	(p)->fts_path = addr;						\
}
	/* Adjust the current set of children. */
	for (p = sp->fts_child; p; p = p->fts_link)
		ADJUST(p);

	/* Adjust the rest of the tree. */
	for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {
		ADJUST(p);
		p = p->fts_link ? p->fts_link : p->fts_parent;
	}
}

static size_t
fts_maxarglen(argv)
	char * const *argv;
{
	size_t len, max;

	for (max = 0; *argv; ++argv)
		if ((len = strlen(*argv)) > max)
			max = len;
	return (max);
}