| 1 | /* |
| 2 | Copyright (C) Andrew Tridgell 1998 |
| 3 | Copyright (C) 2002 by Martin Pool |
| 4 | |
| 5 | This program is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 2 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program; if not, write to the Free Software |
| 17 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 18 | */ |
| 19 | |
| 20 | /* |
| 21 | File IO utilities used in rsync |
| 22 | */ |
| 23 | #include "rsync.h" |
| 24 | |
| 25 | extern int sparse_files; |
| 26 | |
| 27 | static char last_byte; |
| 28 | static int last_sparse; |
| 29 | |
| 30 | int sparse_end(int f) |
| 31 | { |
| 32 | if (last_sparse) { |
| 33 | do_lseek(f,-1,SEEK_CUR); |
| 34 | return (write(f,&last_byte,1) == 1 ? 0 : -1); |
| 35 | } |
| 36 | last_sparse = 0; |
| 37 | return 0; |
| 38 | } |
| 39 | |
| 40 | |
| 41 | static int write_sparse(int f,char *buf,size_t len) |
| 42 | { |
| 43 | size_t l1=0, l2=0; |
| 44 | int ret; |
| 45 | |
| 46 | for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {} |
| 47 | for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {} |
| 48 | |
| 49 | last_byte = buf[len-1]; |
| 50 | |
| 51 | if (l1 == len || l2 > 0) |
| 52 | last_sparse=1; |
| 53 | |
| 54 | if (l1 > 0) { |
| 55 | do_lseek(f,l1,SEEK_CUR); |
| 56 | } |
| 57 | |
| 58 | if (l1 == len) |
| 59 | return len; |
| 60 | |
| 61 | ret = write(f, buf + l1, len - (l1+l2)); |
| 62 | if (ret == -1 || ret == 0) |
| 63 | return ret; |
| 64 | else if (ret != (int) (len - (l1+l2))) |
| 65 | return (l1+ret); |
| 66 | |
| 67 | if (l2 > 0) |
| 68 | do_lseek(f,l2,SEEK_CUR); |
| 69 | |
| 70 | return len; |
| 71 | } |
| 72 | |
| 73 | |
| 74 | static char *wf_writeBuf; |
| 75 | static size_t wf_writeBufSize; |
| 76 | static size_t wf_writeBufCnt; |
| 77 | |
| 78 | int flush_write_file(int f) |
| 79 | { |
| 80 | int ret = 0; |
| 81 | char *bp = wf_writeBuf; |
| 82 | |
| 83 | while (wf_writeBufCnt > 0) { |
| 84 | if ((ret = write(f, bp, wf_writeBufCnt)) < 0) { |
| 85 | if (errno == EINTR) |
| 86 | continue; |
| 87 | return ret; |
| 88 | } |
| 89 | wf_writeBufCnt -= ret; |
| 90 | bp += ret; |
| 91 | } |
| 92 | return ret; |
| 93 | } |
| 94 | |
| 95 | |
| 96 | /* |
| 97 | * write_file does not allow incomplete writes. It loops internally |
| 98 | * until len bytes are written or errno is set. |
| 99 | */ |
| 100 | int write_file(int f,char *buf,size_t len) |
| 101 | { |
| 102 | int ret = 0; |
| 103 | |
| 104 | while (len > 0) { |
| 105 | int r1; |
| 106 | if (sparse_files) { |
| 107 | int len1 = MIN(len, SPARSE_WRITE_SIZE); |
| 108 | r1 = write_sparse(f, buf, len1); |
| 109 | } else { |
| 110 | if (!wf_writeBuf) { |
| 111 | wf_writeBufSize = WRITE_SIZE * 8; |
| 112 | wf_writeBufCnt = 0; |
| 113 | wf_writeBuf = new_array(char, wf_writeBufSize); |
| 114 | if (!wf_writeBuf) |
| 115 | out_of_memory("write_file"); |
| 116 | } |
| 117 | r1 = MIN(len, wf_writeBufSize - wf_writeBufCnt); |
| 118 | if (r1) { |
| 119 | memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1); |
| 120 | wf_writeBufCnt += r1; |
| 121 | } |
| 122 | if (wf_writeBufCnt == wf_writeBufSize) { |
| 123 | if (flush_write_file(f) < 0) |
| 124 | return -1; |
| 125 | if (!r1 && len) |
| 126 | continue; |
| 127 | } |
| 128 | } |
| 129 | if (r1 <= 0) { |
| 130 | if (ret > 0) |
| 131 | return ret; |
| 132 | return r1; |
| 133 | } |
| 134 | len -= r1; |
| 135 | buf += r1; |
| 136 | ret += r1; |
| 137 | } |
| 138 | return ret; |
| 139 | } |
| 140 | |
| 141 | |
| 142 | /* This provides functionality somewhat similar to mmap() but using read(). |
| 143 | * It gives sliding window access to a file. mmap() is not used because of |
| 144 | * the possibility of another program (such as a mailer) truncating the |
| 145 | * file thus giving us a SIGBUS. */ |
| 146 | struct map_struct *map_file(int fd, OFF_T len, OFF_T map_size, |
| 147 | size_t block_size) |
| 148 | { |
| 149 | struct map_struct *map; |
| 150 | |
| 151 | if (!(map = new(struct map_struct))) |
| 152 | out_of_memory("map_file"); |
| 153 | |
| 154 | if (block_size && (map_size % block_size)) |
| 155 | map_size += block_size - (map_size % block_size); |
| 156 | |
| 157 | memset(map, 0, sizeof map[0]); |
| 158 | map->fd = fd; |
| 159 | map->file_size = len; |
| 160 | map->def_window_size = map_size; |
| 161 | |
| 162 | return map; |
| 163 | } |
| 164 | |
| 165 | |
| 166 | /* slide the read window in the file */ |
| 167 | char *map_ptr(struct map_struct *map,OFF_T offset,int len) |
| 168 | { |
| 169 | int nread; |
| 170 | OFF_T window_start, read_start; |
| 171 | int window_size, read_size, read_offset; |
| 172 | |
| 173 | if (len == 0) |
| 174 | return NULL; |
| 175 | |
| 176 | /* can't go beyond the end of file */ |
| 177 | if (len > (map->file_size - offset)) { |
| 178 | len = map->file_size - offset; |
| 179 | } |
| 180 | |
| 181 | /* in most cases the region will already be available */ |
| 182 | if (offset >= map->p_offset && |
| 183 | offset+len <= map->p_offset+map->p_len) { |
| 184 | return (map->p + (offset - map->p_offset)); |
| 185 | } |
| 186 | |
| 187 | /* nope, we are going to have to do a read. Work out our desired window */ |
| 188 | window_start = offset; |
| 189 | window_size = map->def_window_size; |
| 190 | if (window_start + window_size > map->file_size) { |
| 191 | window_size = map->file_size - window_start; |
| 192 | } |
| 193 | if (offset + len > window_start + window_size) { |
| 194 | window_size = (offset+len) - window_start; |
| 195 | } |
| 196 | |
| 197 | /* make sure we have allocated enough memory for the window */ |
| 198 | if (window_size > map->p_size) { |
| 199 | map->p = realloc_array(map->p, char, window_size); |
| 200 | if (!map->p) |
| 201 | out_of_memory("map_ptr"); |
| 202 | map->p_size = window_size; |
| 203 | } |
| 204 | |
| 205 | /* now try to avoid re-reading any bytes by reusing any bytes from the previous |
| 206 | buffer. */ |
| 207 | if (window_start >= map->p_offset && |
| 208 | window_start < map->p_offset + map->p_len && |
| 209 | window_start + window_size >= map->p_offset + map->p_len) { |
| 210 | read_start = map->p_offset + map->p_len; |
| 211 | read_offset = read_start - window_start; |
| 212 | read_size = window_size - read_offset; |
| 213 | memmove(map->p, map->p + (map->p_len - read_offset), read_offset); |
| 214 | } else { |
| 215 | read_start = window_start; |
| 216 | read_size = window_size; |
| 217 | read_offset = 0; |
| 218 | } |
| 219 | |
| 220 | if (read_size <= 0) { |
| 221 | rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size); |
| 222 | } else { |
| 223 | if (map->p_fd_offset != read_start) { |
| 224 | if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) { |
| 225 | rprintf(FERROR,"lseek failed in map_ptr\n"); |
| 226 | exit_cleanup(RERR_FILEIO); |
| 227 | } |
| 228 | map->p_fd_offset = read_start; |
| 229 | } |
| 230 | |
| 231 | if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) { |
| 232 | if (nread < 0) { |
| 233 | nread = 0; |
| 234 | if (!map->status) |
| 235 | map->status = errno; |
| 236 | } |
| 237 | /* the best we can do is zero the buffer - the file |
| 238 | has changed mid transfer! */ |
| 239 | memset(map->p+read_offset+nread, 0, read_size - nread); |
| 240 | } |
| 241 | map->p_fd_offset += nread; |
| 242 | } |
| 243 | |
| 244 | map->p_offset = window_start; |
| 245 | map->p_len = window_size; |
| 246 | |
| 247 | return map->p + (offset - map->p_offset); |
| 248 | } |
| 249 | |
| 250 | |
| 251 | int unmap_file(struct map_struct *map) |
| 252 | { |
| 253 | int ret; |
| 254 | |
| 255 | if (map->p) { |
| 256 | free(map->p); |
| 257 | map->p = NULL; |
| 258 | } |
| 259 | ret = map->status; |
| 260 | memset(map, 0, sizeof map[0]); |
| 261 | free(map); |
| 262 | |
| 263 | return ret; |
| 264 | } |