[src/trunk]: src/lib/libc/gen add fts_safe_changedir() function and use it ev...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/eabbaff288a3
branches:  trunk
changeset: 512326:eabbaff288a3
user:      christos <christos%NetBSD.org@localhost>
date:      Mon Jul 09 21:33:03 2001 +0000

description:
add fts_safe_changedir() function and use it everywhere.
Idea from Todd Miller <millert%openbsd.org@localhost>

diffstat:

 lib/libc/gen/__fts13.c |  86 +++++++++++++++++++++++++++++--------------------
 1 files changed, 51 insertions(+), 35 deletions(-)

diffs (139 lines):

diff -r e847c1575783 -r eabbaff288a3 lib/libc/gen/__fts13.c
--- a/lib/libc/gen/__fts13.c    Mon Jul 09 21:01:31 2001 +0000
+++ b/lib/libc/gen/__fts13.c    Mon Jul 09 21:33:03 2001 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: __fts13.c,v 1.34 2001/06/06 14:10:46 christos Exp $    */
+/*     $NetBSD: __fts13.c,v 1.35 2001/07/09 21:33:03 christos Exp $    */
 
 /*-
  * Copyright (c) 1990, 1993, 1994
@@ -38,7 +38,7 @@
 #if 0
 static char sccsid[] = "@(#)fts.c      8.6 (Berkeley) 8/14/94";
 #else
-__RCSID("$NetBSD: __fts13.c,v 1.34 2001/06/06 14:10:46 christos Exp $");
+__RCSID("$NetBSD: __fts13.c,v 1.35 2001/07/09 21:33:03 christos Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -99,6 +99,8 @@
 static void     fts_padjust __P((FTS *, FTSENT *));
 static FTSENT  *fts_sort __P((FTS *, FTSENT *, size_t));
 static u_short  fts_stat __P((FTS *, FTSENT *, int));
+static int      fts_safe_changedir __P((const FTS *, const FTSENT *, int,
+    const char *));
 
 #define        ISDOT(a)        (a[0] == '.' && (!a[1] || (a[1] == '.' && !a[2])))
 
@@ -397,7 +399,7 @@
                 * FTS_STOP or the fts_info field of the node.
                 */
                if (sp->fts_child) {
-                       if (CHDIR(sp, p->fts_accpath)) {
+                       if (fts_safe_changedir(sp, p, -1, p->fts_accpath)) {
                                p->fts_errno = errno;
                                p->fts_flags |= FTS_DONTCHDIR;
                                for (p = sp->fts_child; p; p = p->fts_link)
@@ -495,36 +497,9 @@
                }
                (void)close(p->fts_symfd);
        } else if (!(p->fts_flags & FTS_DONTCHDIR) &&
-               !ISSET(FTS_NOCHDIR)) {
-               int fd;
-               struct STAT sb;
-
-               if ((fd = open("..", O_RDONLY)) == -1) {
-                       SET(FTS_STOP);
-                       return (NULL);
-               }
-               if (fstat(fd, &sb) == -1) {
-                       saved_errno = errno;
-                       (void)close(fd);
-                       errno = saved_errno;
-                       SET(FTS_STOP);
-                       return (NULL);
-               }
-               if (sb.st_ino != p->fts_parent->fts_ino ||
-                   sb.st_dev != p->fts_parent->fts_dev) {
-                       (void)close(fd);
-                       errno = ENOENT;
-                       SET(FTS_STOP);
-                       return (NULL);
-               }
-               if (fchdir(fd) == -1) {
-                       saved_errno = errno;
-                       (void)close(fd);
-                       errno = saved_errno;
-                       SET(FTS_STOP);
-                       return (NULL);
-               }
-               (void)close(fd);
+           fts_safe_changedir(sp, p->fts_parent, -1, "..")) {
+               SET(FTS_STOP);
+               return (NULL);
        }
        p->fts_info = p->fts_errno ? FTS_ERR : FTS_DP;
        return (sp->fts_cur = p);
@@ -722,7 +697,7 @@
         */
        cderrno = 0;
        if (nlinks || type == BREAD) {
-               if (FCHDIR(sp, dirfd(dirp))) {
+               if (fts_safe_changedir(sp, cur, dirfd(dirp), NULL)) {
                        if (nlinks && type == BREAD)
                                cur->fts_errno = errno;
                        cur->fts_flags |= FTS_DONTCHDIR;
@@ -871,7 +846,8 @@
         */
        if (descend && (type == BCHILD || !nitems) &&
            (cur->fts_level == FTS_ROOTLEVEL ?
-           FCHDIR(sp, sp->fts_rfd) : CHDIR(sp, ".."))) {
+           FCHDIR(sp, sp->fts_rfd) :
+           fts_safe_changedir(sp, cur->fts_parent, -1, ".."))) {
                cur->fts_info = FTS_ERR;
                SET(FTS_STOP);
                return (NULL);
@@ -1169,3 +1145,43 @@
                        max = len;
        return (max + 1);
 }
+
+/*
+ * Change to dir specified by fd or p->fts_accpath without getting
+ * tricked by someone changing the world out from underneath us.
+ * Assumes p->fts_dev and p->fts_ino are filled in.
+ */
+static int
+fts_safe_changedir(sp, p, fd, path)
+       const FTS *sp;
+       const FTSENT *p;
+       int fd;
+       const char *path;
+{
+       int oldfd = fd, ret = -1;
+       struct STAT sb;
+
+       if (ISSET(FTS_NOCHDIR))
+               return 0;
+
+       if (fd < 0 && (fd = open(path, O_RDONLY)) == -1)
+               return -1;
+
+       if (fstat(fd, &sb) == -1)
+               goto bail;
+
+       if (sb.st_ino != p->fts_ino || sb.st_dev != p->fts_dev) {
+               errno = ENOENT;
+               goto bail;
+       }
+
+       ret = fchdir(fd);
+
+bail:
+       if (oldfd < 0) {
+               int save_errno = errno;
+               (void)close(fd);
+               errno = save_errno;
+       }
+       return ret;
+}