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 25 systems using getdirentries 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 41 getdirentries() always leaving the file descriptor at a seek offset 42 that is a multiple of DIR_BUF_SIZE. If the code detects that this 43 doesn't happen then it will abort(). It also does not handle 44 directories 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 "replace.h" 51#include <stdlib.h> 52#include <sys/stat.h> 53#include <unistd.h> 54#include <sys/types.h> 55#include <errno.h> 56#include <fcntl.h> 57#include <dirent.h> 58 59#define DIR_BUF_BITS 9 60#define DIR_BUF_SIZE (1<<DIR_BUF_BITS) 61 62struct dir_buf { 63 int fd; 64 int nbytes, ofs; 65 off_t seekpos; 66 char buf[DIR_BUF_SIZE]; 67}; 68 69DIR *opendir(const char *dname) 70{ 71 struct dir_buf *d; 72 struct stat sb; 73 d = malloc(sizeof(*d)); 74 if (d == NULL) { 75 errno = ENOMEM; 76 return NULL; 77 } 78 d->fd = open(dname, O_RDONLY); 79 if (d->fd == -1) { 80 free(d); 81 return NULL; 82 } 83 if (fstat(d->fd, &sb) < 0) { 84 close(d->fd); 85 free(d); 86 return NULL; 87 } 88 if (!S_ISDIR(sb.st_mode)) { 89 close(d->fd); 90 free(d); 91 errno = ENOTDIR; 92 return NULL; 93 } 94 d->ofs = 0; 95 d->seekpos = 0; 96 d->nbytes = 0; 97 return (DIR *)d; 98} 99 100struct dirent *readdir(DIR *dir) 101{ 102 struct dir_buf *d = (struct dir_buf *)dir; 103 struct dirent *de; 104 105 if (d->ofs >= d->nbytes) { 106 long pos; 107 d->nbytes = getdirentries(d->fd, d->buf, DIR_BUF_SIZE, &pos); 108 d->seekpos = pos; 109 d->ofs = 0; 110 } 111 if (d->ofs >= d->nbytes) { 112 return NULL; 113 } 114 de = (struct dirent *)&d->buf[d->ofs]; 115 d->ofs += de->d_reclen; 116 return de; 117} 118 119#ifdef TELLDIR_TAKES_CONST_DIR 120long telldir(const DIR *dir) 121#else 122long telldir(DIR *dir) 123#endif 124{ 125 struct dir_buf *d = (struct dir_buf *)dir; 126 if (d->ofs >= d->nbytes) { 127 d->seekpos = lseek(d->fd, 0, SEEK_CUR); 128 d->ofs = 0; 129 d->nbytes = 0; 130 } 131 /* this relies on seekpos always being a multiple of 132 DIR_BUF_SIZE. Is that always true on BSD systems? */ 133 if (d->seekpos & (DIR_BUF_SIZE-1)) { 134 abort(); 135 } 136 return d->seekpos + d->ofs; 137} 138 139#ifdef SEEKDIR_RETURNS_INT 140int seekdir(DIR *dir, long ofs) 141#else 142void seekdir(DIR *dir, long ofs) 143#endif 144{ 145 struct dir_buf *d = (struct dir_buf *)dir; 146 long pos; 147 d->seekpos = lseek(d->fd, ofs & ~(DIR_BUF_SIZE-1), SEEK_SET); 148 d->nbytes = getdirentries(d->fd, d->buf, DIR_BUF_SIZE, &pos); 149 d->ofs = 0; 150 while (d->ofs < (ofs & (DIR_BUF_SIZE-1))) { 151 if (readdir(dir) == NULL) break; 152 } 153#ifdef SEEKDIR_RETURNS_INT 154 return -1; 155#endif 156} 157 158void rewinddir(DIR *dir) 159{ 160 seekdir(dir, 0); 161} 162 163int closedir(DIR *dir) 164{ 165 struct dir_buf *d = (struct dir_buf *)dir; 166 int r = close(d->fd); 167 if (r != 0) { 168 return r; 169 } 170 free(d); 171 return 0; 172} 173 174#ifndef dirfd 175/* darn, this is a macro on some systems. */ 176int dirfd(DIR *dir) 177{ 178 struct dir_buf *d = (struct dir_buf *)dir; 179 return d->fd; 180} 181#endif 182 183 184