1 /* $OpenBSD: opendir.c,v 1.23 2011/07/18 17:29:49 matthew Exp $ */ 2 /* 3 * Copyright (c) 1983, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/types.h> 32 #include <sys/stat.h> 33 34 #include <dirent.h> 35 #include <errno.h> 36 #include <fcntl.h> 37 #include <stdlib.h> 38 #include <unistd.h> 39 40 #include "telldir.h" 41 42 static DIR *__fdopendir(int fd, off_t offset); 43 44 /* 45 * Open a directory specified by name. 46 */ 47 DIR * 48 opendir(const char *name) 49 { 50 DIR *dirp; 51 int fd; 52 53 if ((fd = open(name, O_RDONLY | O_DIRECTORY | O_CLOEXEC)) == -1) 54 return (NULL); 55 dirp = __fdopendir(fd, 0); 56 if (dirp == NULL) 57 close(fd); 58 return (dirp); 59 } 60 61 /* 62 * Open a directory specified by file descriptor. 63 */ 64 DIR * 65 fdopendir(int fd) 66 { 67 DIR *dirp; 68 int flags; 69 off_t offset; 70 71 if ((flags = fcntl(fd, F_GETFL)) == -1) 72 return (NULL); 73 if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) { 74 errno = EBADF; 75 return (NULL); 76 } 77 if ((offset = lseek(fd, 0, SEEK_CUR)) == -1) 78 return (NULL); 79 dirp = __fdopendir(fd, offset); 80 if (dirp != NULL) { 81 /* 82 * POSIX doesn't require fdopendir() to set 83 * FD_CLOEXEC, so it's okay for this to fail. 84 */ 85 (void)fcntl(fd, F_SETFD, FD_CLOEXEC); 86 } 87 return (dirp); 88 } 89 90 static DIR * 91 __fdopendir(int fd, off_t offset) 92 { 93 DIR *dirp; 94 struct stat sb; 95 int pageoffset; 96 97 if (fstat(fd, &sb)) 98 return (NULL); 99 if (!S_ISDIR(sb.st_mode)) { 100 errno = ENOTDIR; 101 return (NULL); 102 } 103 if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL) 104 return (NULL); 105 106 /* 107 * Use a buffer that is page aligned. 108 * Hopefully this can be a big win someday by allowing page trades 109 * to user space to be done by getdirentries() 110 */ 111 pageoffset = getpagesize() - 1; 112 dirp->dd_len = ((int)sb.st_blksize + pageoffset) & ~pageoffset; 113 dirp->dd_buf = malloc((size_t)dirp->dd_len); 114 if (dirp->dd_buf == NULL) { 115 free(dirp); 116 return (NULL); 117 } 118 119 dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR)); 120 dirp->dd_td->td_locs = NULL; 121 dirp->dd_td->td_sz = 0; 122 dirp->dd_td->td_loccnt = 0; 123 dirp->dd_td->td_last = 0; 124 125 dirp->dd_seek = 0; 126 dirp->dd_loc = 0; 127 dirp->dd_fd = fd; 128 dirp->dd_unused = 0; 129 dirp->dd_lock = NULL; 130 131 /* 132 * Set up seek point for rewinddir. 133 */ 134 dirp->dd_rewind = telldir(dirp); 135 136 /* 137 * Store our actual seek offset. Must do this *after* setting 138 * dd_rewind = telldir() so that rewinddir() works correctly. 139 */ 140 dirp->dd_seek = offset; 141 142 return (dirp); 143 } 144