1/* 2 Unix SMB/CIFS implementation. 3 4 Copyright (C) Andrew Tridgell 2005 5 6 ** NOTE! The following LGPL license applies to the replace 7 ** library. This does NOT imply that all of Samba is released 8 ** under the LGPL 9 10 This library is free software; you can redistribute it and/or 11 modify it under the terms of the GNU Lesser General Public 12 License as published by the Free Software Foundation; either 13 version 3 of the License, or (at your option) any later version. 14 15 This library is distributed in the hope that it will be useful, 16 but WITHOUT ANY WARRANTY; without even the implied warranty of 17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 18 Lesser General Public License for more details. 19 20 You should have received a copy of the GNU Lesser General Public 21 License along with this library; if not, see <http://www.gnu.org/licenses/>. 22*/ 23/* 24 a replacement for opendir/readdir/telldir/seekdir/closedir for BSD systems 25 26 This is needed because the existing directory handling in FreeBSD 27 and OpenBSD (and possibly NetBSD) doesn't correctly handle unlink() 28 on files in a directory where telldir() has been used. On a block 29 boundary it will occasionally miss a file when seekdir() is used to 30 return to a position previously recorded with telldir(). 31 32 This also fixes a severe performance and memory usage problem with 33 telldir() on BSD systems. Each call to telldir() in BSD adds an 34 entry to a linked list, and those entries are cleaned up on 35 closedir(). This means with a large directory closedir() can take an 36 arbitrary amount of time, causing network timeouts as millions of 37 telldir() entries are freed 38 39 Note! This replacement code is not portable. It relies on getdents() 40 always leaving the file descriptor at a seek offset that is a 41 multiple of DIR_BUF_SIZE. If the code detects that this doesn't 42 happen then it will abort(). It also does not handle directories 43 with offsets larger than can be stored in a long, 44 45 This code is available under other free software licenses as 46 well. Contact the author. 47*/ 48 49#include <stdlib.h> 50#include <sys/stat.h> 51#include <unistd.h> 52#include <sys/types.h> 53#include <errno.h> 54#include <fcntl.h> 55#include <dirent.h> 56 57#define DIR_BUF_BITS 9 58#define DIR_BUF_SIZE (1<<DIR_BUF_BITS) 59 60struct dir_buf { 61 int fd; 62 int nbytes, ofs; 63 off_t seekpos; 64 char buf[DIR_BUF_SIZE]; 65}; 66 67DIR *opendir(const char *dname) 68{ 69 struct dir_buf *d; 70 struct stat sb; 71 d = malloc(sizeof(*d)); 72 if (d == NULL) { 73 errno = ENOMEM; 74 return NULL; 75 } 76 d->fd = open(dname, O_RDONLY); 77 if (d->fd == -1) { 78 free(d); 79 return NULL; 80 } 81 if (fstat(d->fd, &sb) < 0) { 82 close(d->fd); 83 free(d); 84 return NULL; 85 } 86 if (!S_ISDIR(sb.st_mode)) { 87 close(d->fd); 88 free(d); 89 errno = ENOTDIR; 90 return NULL; 91 } 92 d->ofs = 0; 93 d->seekpos = 0; 94 d->nbytes = 0; 95 return (DIR *)d; 96} 97 98struct dirent *readdir(DIR *dir) 99{ 100 struct dir_buf *d = (struct dir_buf *)dir; 101 struct dirent *de; 102 103 if (d->ofs >= d->nbytes) { 104 d->seekpos = lseek(d->fd, 0, SEEK_CUR); 105 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE); 106 d->ofs = 0; 107 } 108 if (d->ofs >= d->nbytes) { 109 return NULL; 110 } 111 de = (struct dirent *)&d->buf[d->ofs]; 112 d->ofs += de->d_reclen; 113 return de; 114} 115 116long telldir(DIR *dir) 117{ 118 struct dir_buf *d = (struct dir_buf *)dir; 119 if (d->ofs >= d->nbytes) { 120 d->seekpos = lseek(d->fd, 0, SEEK_CUR); 121 d->ofs = 0; 122 d->nbytes = 0; 123 } 124 /* this relies on seekpos always being a multiple of 125 DIR_BUF_SIZE. Is that always true on BSD systems? */ 126 if (d->seekpos & (DIR_BUF_SIZE-1)) { 127 abort(); 128 } 129 return d->seekpos + d->ofs; 130} 131 132void seekdir(DIR *dir, long ofs) 133{ 134 struct dir_buf *d = (struct dir_buf *)dir; 135 d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET); 136 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE); 137 d->ofs = 0; 138 while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) { 139 if (readdir(dir) == NULL) break; 140 } 141} 142 143void rewinddir(DIR *dir) 144{ 145 seekdir(dir, 0); 146} 147 148int closedir(DIR *dir) 149{ 150 struct dir_buf *d = (struct dir_buf *)dir; 151 int r = close(d->fd); 152 if (r != 0) { 153 return r; 154 } 155 free(d); 156 return 0; 157} 158 159#ifndef dirfd 160/* darn, this is a macro on some systems. */ 161int dirfd(DIR *dir) 162{ 163 struct dir_buf *d = (struct dir_buf *)dir; 164 return d->fd; 165} 166#endif 167