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 2 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, write to the Free Software 22 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 23*/ 24/* 25 a replacement for opendir/readdir/telldir/seekdir/closedir for BSD systems 26 27 This is needed because the existing directory handling in FreeBSD 28 and OpenBSD (and possibly NetBSD) doesn't correctly handle unlink() 29 on files in a directory where telldir() has been used. On a block 30 boundary it will occasionally miss a file when seekdir() is used to 31 return to a position previously recorded with telldir(). 32 33 This also fixes a severe performance and memory usage problem with 34 telldir() on BSD systems. Each call to telldir() in BSD adds an 35 entry to a linked list, and those entries are cleaned up on 36 closedir(). This means with a large directory closedir() can take an 37 arbitrary amount of time, causing network timeouts as millions of 38 telldir() entries are freed 39 40 Note! This replacement code is not portable. It relies on getdents() 41 always leaving the file descriptor at a seek offset that is a 42 multiple of DIR_BUF_SIZE. If the code detects that this doesn't 43 happen then it will abort(). It also does not handle directories 44 with offsets larger than can be stored in a long, 45 46 This code is available under other free software licenses as 47 well. Contact the author. 48*/ 49 50#include <stdlib.h> 51#include <sys/stat.h> 52#include <unistd.h> 53#include <sys/types.h> 54#include <errno.h> 55#include <fcntl.h> 56#include <dirent.h> 57 58#define DIR_BUF_BITS 9 59#define DIR_BUF_SIZE (1<<DIR_BUF_BITS) 60 61struct dir_buf { 62 int fd; 63 int nbytes, ofs; 64 off_t seekpos; 65 char buf[DIR_BUF_SIZE]; 66}; 67 68DIR *opendir(const char *dname) 69{ 70 struct dir_buf *d; 71 struct stat sb; 72 d = malloc(sizeof(*d)); 73 if (d == NULL) { 74 errno = ENOMEM; 75 return NULL; 76 } 77 d->fd = open(dname, O_RDONLY); 78 if (d->fd == -1) { 79 free(d); 80 return NULL; 81 } 82 if (fstat(d->fd, &sb) < 0) { 83 close(d->fd); 84 free(d); 85 return NULL; 86 } 87 if (!S_ISDIR(sb.st_mode)) { 88 close(d->fd); 89 free(d); 90 errno = ENOTDIR; 91 return NULL; 92 } 93 d->ofs = 0; 94 d->seekpos = 0; 95 d->nbytes = 0; 96 return (DIR *)d; 97} 98 99struct dirent *readdir(DIR *dir) 100{ 101 struct dir_buf *d = (struct dir_buf *)dir; 102 struct dirent *de; 103 104 if (d->ofs >= d->nbytes) { 105 d->seekpos = lseek(d->fd, 0, SEEK_CUR); 106 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE); 107 d->ofs = 0; 108 } 109 if (d->ofs >= d->nbytes) { 110 return NULL; 111 } 112 de = (struct dirent *)&d->buf[d->ofs]; 113 d->ofs += de->d_reclen; 114 return de; 115} 116 117long telldir(DIR *dir) 118{ 119 struct dir_buf *d = (struct dir_buf *)dir; 120 if (d->ofs >= d->nbytes) { 121 d->seekpos = lseek(d->fd, 0, SEEK_CUR); 122 d->ofs = 0; 123 d->nbytes = 0; 124 } 125 /* this relies on seekpos always being a multiple of 126 DIR_BUF_SIZE. Is that always true on BSD systems? */ 127 if (d->seekpos & (DIR_BUF_SIZE-1)) { 128 abort(); 129 } 130 return d->seekpos + d->ofs; 131} 132 133void seekdir(DIR *dir, long ofs) 134{ 135 struct dir_buf *d = (struct dir_buf *)dir; 136 d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET); 137 d->nbytes = getdents(d->fd, d->buf, DIR_BUF_SIZE); 138 d->ofs = 0; 139 while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) { 140 if (readdir(dir) == NULL) break; 141 } 142} 143 144void rewinddir(DIR *dir) 145{ 146 seekdir(dir, 0); 147} 148 149int closedir(DIR *dir) 150{ 151 struct dir_buf *d = (struct dir_buf *)dir; 152 int r = close(d->fd); 153 if (r != 0) { 154 return r; 155 } 156 free(d); 157 return 0; 158} 159 160#ifndef dirfd 161/* darn, this is a macro on some systems. */ 162int dirfd(DIR *dir) 163{ 164 struct dir_buf *d = (struct dir_buf *)dir; 165 return d->fd; 166} 167#endif 168