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Revision 1.13, Wed Feb 15 15:58:46 2017 UTC (4 years ago) by schwarze
Branch: MAIN
Changes since 1.12: +7 -8 lines

Style improvement, no functional change.

As reported by Yuri Pankov, some versions of GCC whine that "tmp"
might be used uninitialized in fts_open(3).  Clearly, that cannot
actually happen, but explicitly setting it to NULL is safer anyway.
While here, rename the badly named variable "tmp" and make the
inner "if" easier to understand.

Feedback and OK guenther@

#include "config.h"

#if HAVE_FTS

int dummy;

#else

/*	$Id: compat_fts.c,v 1.13 2017/02/15 15:58:46 schwarze Exp $	*/
/*	$OpenBSD: fts.c,v 1.56 2016/09/21 04:38:56 guenther Exp $	*/

/*-
 * Copyright (c) 1990, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/stat.h>
#include <sys/types.h>

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "compat_fts.h"

#define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))

static FTSENT	*fts_alloc(FTS *, const char *, size_t);
static FTSENT	*fts_build(FTS *);
static void	 fts_lfree(FTSENT *);
static void	 fts_load(FTS *, FTSENT *);
static size_t	 fts_maxarglen(char * const *);
static void	 fts_padjust(FTS *, FTSENT *);
static int	 fts_palloc(FTS *, size_t);
static FTSENT	*fts_sort(FTS *, FTSENT *, int);
static unsigned short	 fts_stat(FTS *, FTSENT *);

#define	ISDOT(a)	(a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))
#ifndef	O_DIRECTORY
#define	O_DIRECTORY	0
#endif
#ifndef	O_CLOEXEC
#define	O_CLOEXEC	0
#endif
#ifndef	PATH_MAX
#define	PATH_MAX	4096
#endif

#define	CLR(opt)	(sp->fts_options &= ~(opt))
#define	ISSET(opt)	(sp->fts_options & (opt))
#define	SET(opt)	(sp->fts_options |= (opt))

FTS *
fts_open(char * const *argv, int options,
    int (*compar)(const FTSENT **, const FTSENT **))
{
	FTS *sp;
	FTSENT *p, *root;
	int nitems;
	FTSENT *parent, *prev;

	/* Options check. */
	if (options & ~FTS_OPTIONMASK) {
		errno = EINVAL;
		return (NULL);
	}

	/* At least one path must be specified. */
	if (*argv == NULL) {
		errno = EINVAL;
		return (NULL);
	}

	/* Allocate/initialize the stream */
	if ((sp = calloc(1, sizeof(FTS))) == NULL)
		return (NULL);
	sp->fts_compar = compar;
	sp->fts_options = options;

	/*
	 * Start out with 1K of path space, and enough, in any case,
	 * to hold the user's paths.
	 */
	if (fts_palloc(sp, MAXIMUM(fts_maxarglen(argv), PATH_MAX)))
		goto mem1;

	/* Allocate/initialize root's parent. */
	if ((parent = fts_alloc(sp, "", 0)) == NULL)
		goto mem2;
	parent->fts_level = FTS_ROOTPARENTLEVEL;

	/* Allocate/initialize root(s). */
	for (root = prev = NULL, nitems = 0; *argv; ++argv, ++nitems) {
		if ((p = fts_alloc(sp, *argv, strlen(*argv))) == NULL)
			goto mem3;
		p->fts_level = FTS_ROOTLEVEL;
		p->fts_parent = parent;
		p->fts_accpath = p->fts_name;
		p->fts_info = fts_stat(sp, p);

		/* Command-line "." and ".." are real directories. */
		if (p->fts_info == FTS_DOT)
			p->fts_info = FTS_D;

		/*
		 * If comparison routine supplied, traverse in sorted
		 * order; otherwise traverse in the order specified.
		 */
		if (compar) {
			p->fts_link = root;
			root = p;
		} else {
			p->fts_link = NULL;
			if (root == NULL)
				root = p;
			else
				prev->fts_link = p;
			prev = p;
		}
	}
	if (compar && nitems > 1)
		root = fts_sort(sp, root, nitems);

	/*
	 * Allocate a dummy pointer and make fts_read think that we've just
	 * finished the node before the root(s); set p->fts_info to FTS_INIT
	 * so that everything about the "current" node is ignored.
	 */
	if ((sp->fts_cur = fts_alloc(sp, "", 0)) == NULL)
		goto mem3;
	sp->fts_cur->fts_link = root;
	sp->fts_cur->fts_info = FTS_INIT;

	if (nitems == 0)
		free(parent);

	return (sp);

mem3:	fts_lfree(root);
	free(parent);
mem2:	free(sp->fts_path);
mem1:	free(sp);
	return (NULL);
}

static void
fts_load(FTS *sp, FTSENT *p)
{
	size_t len;
	char *cp;

	/*
	 * Load the stream structure for the next traversal.  Since we don't
	 * actually enter the directory until after the preorder visit, set
	 * the fts_accpath field specially so the chdir gets done to the right
	 * place and the user can access the first node.  From fts_open it's
	 * known that the path will fit.
	 */
	len = p->fts_pathlen = p->fts_namelen;
	memmove(sp->fts_path, p->fts_name, len + 1);
	if ((cp = strrchr(p->fts_name, '/')) && (cp != p->fts_name || cp[1])) {
		len = strlen(++cp);
		memmove(p->fts_name, cp, len + 1);
		p->fts_namelen = len;
	}
	p->fts_accpath = p->fts_path = sp->fts_path;
	sp->fts_dev = p->fts_dev;
}

int
fts_close(FTS *sp)
{
	FTSENT *freep, *p;

	/*
	 * This still works if we haven't read anything -- the dummy structure
	 * points to the root list, so we step through to the end of the root
	 * list which has a valid parent pointer.
	 */
	if (sp->fts_cur) {
		for (p = sp->fts_cur; p->fts_level >= FTS_ROOTLEVEL;) {
			freep = p;
			p = p->fts_link ? p->fts_link : p->fts_parent;
			free(freep);
		}
		free(p);
	}

	/* Free up child linked list, sort array, path buffer, stream ptr.*/
	if (sp->fts_child)
		fts_lfree(sp->fts_child);
	free(sp->fts_array);
	free(sp->fts_path);
	free(sp);

	return (0);
}

/*
 * Special case of "/" at the end of the path so that slashes aren't
 * appended which would cause paths to be written as "....//foo".
 */
#define	NAPPEND(p)							\
	(p->fts_path[p->fts_pathlen - 1] == '/'				\
	    ? p->fts_pathlen - 1 : p->fts_pathlen)

FTSENT *
fts_read(FTS *sp)
{
	FTSENT *p, *tmp;
	int instr;
	char *t;

	/* If finished or unrecoverable error, return NULL. */
	if (sp->fts_cur == NULL || ISSET(FTS_STOP))
		return (NULL);

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

	/* Save and zero out user instructions. */
	instr = p->fts_instr;
	p->fts_instr = FTS_NOINSTR;

	/* Directory in pre-order. */
	if (p->fts_info == FTS_D) {
		/* If skipped or crossed mount point, do post-order visit. */
		if (instr == FTS_SKIP ||
		    (ISSET(FTS_XDEV) && p->fts_dev != sp->fts_dev)) {
			if (sp->fts_child) {
				fts_lfree(sp->fts_child);
				sp->fts_child = NULL;
			}
			p->fts_info = FTS_DP;
			return (p);
		}

		/*
		 * If haven't read do so.  If the read fails, fts_build sets
		 * FTS_STOP or the fts_info field of the node.
		 */
		if (sp->fts_child) {
			/* nothing */
		} else if ((sp->fts_child = fts_build(sp)) == NULL) {
			if (ISSET(FTS_STOP))
				return (NULL);
			return (p);
		}
		p = sp->fts_child;
		sp->fts_child = NULL;
		goto name;
	}

	/* Move to the next node on this level. */
next:	tmp = p;
	if ((p = p->fts_link)) {
		free(tmp);

		/*
		 * If reached the top, return to the original directory (or
		 * the root of the tree), and load the paths for the next root.
		 */
		if (p->fts_level == FTS_ROOTLEVEL) {
			fts_load(sp, p);
			return (sp->fts_cur = p);
		}

		/*
		 * User may have called fts_set on the node.  If skipped,
		 * ignore.  If followed, get a file descriptor so we can
		 * get back if necessary.
		 */
		if (p->fts_instr == FTS_SKIP)
			goto next;

name:		t = sp->fts_path + NAPPEND(p->fts_parent);
		*t++ = '/';
		memmove(t, p->fts_name, p->fts_namelen + 1);
		return (sp->fts_cur = p);
	}

	/* Move up to the parent node. */
	p = tmp->fts_parent;
	free(tmp);

	if (p->fts_level == FTS_ROOTPARENTLEVEL) {
		/*
		 * Done; free everything up and set errno to 0 so the user
		 * can distinguish between error and EOF.
		 */
		free(p);
		errno = 0;
		return (sp->fts_cur = NULL);
	}

	/* NUL terminate the pathname. */
	sp->fts_path[p->fts_pathlen] = '\0';

	p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
	return (sp->fts_cur = p);
}

/*
 * Fts_set takes the stream as an argument although it's not used in this
 * implementation; it would be necessary if anyone wanted to add global
 * semantics to fts using fts_set.  An error return is allowed for similar
 * reasons.
 */
int
fts_set(FTS *sp, FTSENT *p, int instr)
{
	if (instr && instr != FTS_NOINSTR && instr != FTS_SKIP) {
		errno = EINVAL;
		return (1);
	}
	p->fts_instr = instr;
	return (0);
}

/*
 * 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(FTS *sp)
{
	struct dirent *dp;
	FTSENT *p, *head;
	FTSENT *cur, *tail;
	DIR *dirp;
	void *oldaddr;
	size_t dlen, len, maxlen;
	int nitems, level, doadjust;
	int saved_errno;
	char *cp;

	/* 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.
	 */
	if ((dirp = opendir(cur->fts_accpath)) == NULL) {
		cur->fts_info = FTS_DNR;
		cur->fts_errno = errno;
		return (NULL);
	}

	/*
	 * 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.
	 */
	len = NAPPEND(cur);
	cp = sp->fts_path + len;
	*cp++ = '/';
	len++;
	maxlen = sp->fts_pathlen - len;

	/*
	 * fts_level is signed so we must prevent it from wrapping
	 * around to FTS_ROOTLEVEL and FTS_ROOTPARENTLEVEL.
	 */
	level = cur->fts_level;
	if (level < FTS_MAXLEVEL)
	    level++;

	/* Read the directory, attaching each entry to the `link' pointer. */
	doadjust = 0;
	for (head = tail = NULL, nitems = 0; dirp && (dp = readdir(dirp));) {
		if (ISDOT(dp->d_name))
			continue;

#if HAVE_DIRENT_NAMLEN
		dlen = dp->d_namlen;
#else
		dlen = strlen(dp->d_name);
#endif

		if (!(p = fts_alloc(sp, dp->d_name, dlen)))
			goto mem1;
		if (dlen >= maxlen) {	/* include space for NUL */
			oldaddr = sp->fts_path;
			if (fts_palloc(sp, dlen + len + 1)) {
				/*
				 * No more memory for path or structures.  Save
				 * errno, free up the current structure and the
				 * structures already allocated.
				 */
mem1:				saved_errno = errno;
				free(p);
				fts_lfree(head);
				(void)closedir(dirp);
				cur->fts_info = FTS_ERR;
				SET(FTS_STOP);
				errno = saved_errno;
				return (NULL);
			}
			/* Did realloc() change the pointer? */
			if (oldaddr != sp->fts_path) {
				doadjust = 1;
				cp = sp->fts_path + len;
			}
			maxlen = sp->fts_pathlen - len;
		}

		p->fts_level = level;
		p->fts_parent = sp->fts_cur;
		p->fts_pathlen = len + dlen;
		if (p->fts_pathlen < len) {
			/*
			 * If we wrap, free up the current structure and
			 * the structures already allocated, then error
			 * out with ENAMETOOLONG.
			 */
			free(p);
			fts_lfree(head);
			(void)closedir(dirp);
			cur->fts_info = FTS_ERR;
			SET(FTS_STOP);
			errno = ENAMETOOLONG;
			return (NULL);
		}

		/* Build a file name for fts_stat to stat. */
		p->fts_accpath = p->fts_path;
		memmove(cp, p->fts_name, p->fts_namelen + 1);
		/* Stat it. */
		p->fts_info = fts_stat(sp, p);

		/* 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;
	}
	if (dirp)
		(void)closedir(dirp);

	/*
	 * If realloc() changed the address of the path, adjust the
	 * addresses for the rest of the tree and the dir list.
	 */
	if (doadjust)
		fts_padjust(sp, head);

	/*
	 * If not changing directories, reset the path back to original
	 * state.
	 */
	if (len == sp->fts_pathlen || nitems == 0)
		--cp;
	*cp = '\0';

	/* If didn't find anything, return NULL. */
	if (!nitems) {
		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 unsigned short
fts_stat(FTS *sp, FTSENT *p)
{
	FTSENT *t;
	dev_t dev;
	ino_t ino;
	struct stat *sbp;

	/* If user needs stat info, stat buffer already allocated. */
	sbp = p->fts_statp;

	if (lstat(p->fts_accpath, sbp)) {
		p->fts_errno = errno;
		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(FTS *sp, FTSENT *head, int nitems)
{
	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) {
		struct _ftsent **a;

		sp->fts_nitems = nitems + 40;
		if ((a = reallocarray(sp->fts_array,
		    sp->fts_nitems, sizeof(FTSENT *))) == NULL) {
			free(sp->fts_array);
			sp->fts_array = NULL;
			sp->fts_nitems = 0;
			return (head);
		}
		sp->fts_array = a;
	}
	for (ap = sp->fts_array, p = head; p; p = p->fts_link)
		*ap++ = p;
	qsort(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(FTS *sp, const char *name, size_t namelen)
{
	FTSENT *p;
	size_t len;

	len = sizeof(FTSENT) + namelen;
	if ((p = calloc(1, len)) == NULL)
		return (NULL);

	p->fts_path = sp->fts_path;
	p->fts_namelen = namelen;
	p->fts_instr = FTS_NOINSTR;
	p->fts_statp = malloc(sizeof(struct stat));
	if (p->fts_statp == NULL) {
		free(p);
		return (NULL);
	}
	memcpy(p->fts_name, name, namelen);

	return (p);
}

static void
fts_lfree(FTSENT *head)
{
	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 PATH_MAX, 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(FTS *sp, size_t more)
{
	char *p;

	/*
	 * Check for possible wraparound.
	 */
	more += 256;
	if (sp->fts_pathlen + more < sp->fts_pathlen) {
		free(sp->fts_path);
		sp->fts_path = NULL;
		errno = ENAMETOOLONG;
		return (1);
	}
	sp->fts_pathlen += more;
	p = realloc(sp->fts_path, sp->fts_pathlen);
	if (p == NULL) {
		free(sp->fts_path);
		sp->fts_path = NULL;
		return (1);
	}
	sp->fts_path = p;
	return (0);
}

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

#define	ADJUST(p) {							\
	if ((p)->fts_accpath != (p)->fts_name) {			\
		(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, including the current level. */
	for (p = head; p->fts_level >= FTS_ROOTLEVEL;) {
		ADJUST(p);
		p = p->fts_link ? p->fts_link : p->fts_parent;
	}
}

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

	for (max = 0; *argv; ++argv)
		if ((len = strlen(*argv)) > max)
			max = len;
	return (max + 1);
}

#endif