123 lines
3.0 KiB
C
123 lines
3.0 KiB
C
/* @(#)fdopendir.c 1.1 13/10/27 Copyright 2011-2013 J. Schilling */
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/*
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* Emulate the behavior of fdopendir(fd)
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*
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* Note that emulation methods that do not use the /proc filesystem are
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* not MT safe. In the non-MT-safe case, we do:
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*
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* savewd()/fchdir()/open(name)/restorewd()
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*
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* Errors may force us to abort the program as our caller is not expected
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* to know that we do more than a simple open() here and that the
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* working directory may be changed by us.
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*
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* Copyright (c) 2011-13 J. Schilling
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*/
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/*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* See the file CDDL.Schily.txt in this distribution for details.
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* A copy of the CDDL is also available via the Internet at
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* http://www.opensource.org/licenses/cddl1.txt
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file CDDL.Schily.txt from this distribution.
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*/
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#include <schily/unistd.h>
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#include <schily/types.h>
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#include <schily/fcntl.h>
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#include <schily/dirent.h>
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#include <schily/maxpath.h>
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#include <schily/errno.h>
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#include <schily/standard.h>
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#include <schily/schily.h>
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#include "at-defs.h"
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#ifndef HAVE_FDOPENDIR
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#ifndef ENAMETOOLONG
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#define ENAMETOOLONG EINVAL
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#endif
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EXPORT DIR *
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fdopendir(fd)
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int fd;
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{
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int n;
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DIR *ret = 0;
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char buf[PATH_MAX];
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char *proc_name;
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struct save_wd save_wd;
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if ((proc_name = proc_fd2name(buf, fd, ".")) != NULL) {
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ret = opendir(proc_name);
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if (ret != (DIR *)NULL) {
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close(fd);
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return (ret);
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}
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if (NON_PROCFS_ERRNO(errno))
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return (ret);
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} else if (geterrno() == ENAMETOOLONG) {
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return ((DIR *)NULL);
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}
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if (savewd(&save_wd) < 0) {
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/*
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* We abort here as the caller may not know that we are forced
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* to savewd/fchdir/restorewd here and misinterpret errno.
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*/
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savewd_abort(geterrno());
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/* NOTREACHED */
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return ((DIR *)NULL);
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}
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if (fd >= 0 && save_wd.fd == fd) {
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/*
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* If we just opened "fd" with the same number in savewd(), fd
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* must have been illegal when calling openat();
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*/
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closewd(&save_wd);
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seterrno(EBADF);
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return ((DIR *)NULL);
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}
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if ((n = fchdir(fd)) < 0) {
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int err = geterrno();
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/*
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* In case that fchdir() is emulated via chdir() and we use a
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* multi hop chdir(), we may be on an undefined intermediate
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* directory. Try to return to last working directory and if
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* this fails, abort for security.
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*/
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if (n == -2 && restorewd(&save_wd) < 0) {
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restorewd_abort(geterrno());
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/* NOTREACHED */
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}
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closewd(&save_wd);
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seterrno(err);
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return ((DIR *)NULL);
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}
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ret = opendir("."); /* The actual call() */
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if (ret != (DIR *)NULL)
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close(fd);
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if (restorewd(&save_wd) < 0) {
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int err = geterrno();
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closedir(ret);
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closewd(&save_wd);
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restorewd_abort(err);
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/* NOTREACHED */
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seterrno(err);
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return ((DIR *)NULL);
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}
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closewd(&save_wd);
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return (ret);
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}
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#endif /* HAVE_FDOPENDIR */
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