| 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 | #ifndef ENODATA |
| 26 | #define ENODATA EAGAIN |
| 27 | #endif |
| 28 | |
| 29 | extern int sparse_files; |
| 30 | |
| 31 | static char last_byte; |
| 32 | static int last_sparse; |
| 33 | |
| 34 | int sparse_end(int f) |
| 35 | { |
| 36 | if (last_sparse) { |
| 37 | do_lseek(f,-1,SEEK_CUR); |
| 38 | return (write(f,&last_byte,1) == 1 ? 0 : -1); |
| 39 | } |
| 40 | last_sparse = 0; |
| 41 | return 0; |
| 42 | } |
| 43 | |
| 44 | |
| 45 | static int write_sparse(int f,char *buf,size_t len) |
| 46 | { |
| 47 | size_t l1=0, l2=0; |
| 48 | int ret; |
| 49 | |
| 50 | for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {} |
| 51 | for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {} |
| 52 | |
| 53 | last_byte = buf[len-1]; |
| 54 | |
| 55 | if (l1 == len || l2 > 0) |
| 56 | last_sparse=1; |
| 57 | |
| 58 | if (l1 > 0) { |
| 59 | do_lseek(f,l1,SEEK_CUR); |
| 60 | } |
| 61 | |
| 62 | if (l1 == len) |
| 63 | return len; |
| 64 | |
| 65 | ret = write(f, buf + l1, len - (l1+l2)); |
| 66 | if (ret == -1 || ret == 0) |
| 67 | return ret; |
| 68 | else if (ret != (int) (len - (l1+l2))) |
| 69 | return (l1+ret); |
| 70 | |
| 71 | if (l2 > 0) |
| 72 | do_lseek(f,l2,SEEK_CUR); |
| 73 | |
| 74 | return len; |
| 75 | } |
| 76 | |
| 77 | |
| 78 | static char *wf_writeBuf; |
| 79 | static size_t wf_writeBufSize; |
| 80 | static size_t wf_writeBufCnt; |
| 81 | |
| 82 | int flush_write_file(int f) |
| 83 | { |
| 84 | int ret = 0; |
| 85 | char *bp = wf_writeBuf; |
| 86 | |
| 87 | while (wf_writeBufCnt > 0) { |
| 88 | if ((ret = write(f, bp, wf_writeBufCnt)) < 0) { |
| 89 | if (errno == EINTR) |
| 90 | continue; |
| 91 | return ret; |
| 92 | } |
| 93 | wf_writeBufCnt -= ret; |
| 94 | bp += ret; |
| 95 | } |
| 96 | return ret; |
| 97 | } |
| 98 | |
| 99 | |
| 100 | /* |
| 101 | * write_file does not allow incomplete writes. It loops internally |
| 102 | * until len bytes are written or errno is set. |
| 103 | */ |
| 104 | int write_file(int f,char *buf,size_t len) |
| 105 | { |
| 106 | int ret = 0; |
| 107 | |
| 108 | while (len > 0) { |
| 109 | int r1; |
| 110 | if (sparse_files) { |
| 111 | int len1 = MIN(len, SPARSE_WRITE_SIZE); |
| 112 | r1 = write_sparse(f, buf, len1); |
| 113 | } else { |
| 114 | if (!wf_writeBuf) { |
| 115 | wf_writeBufSize = WRITE_SIZE * 8; |
| 116 | wf_writeBufCnt = 0; |
| 117 | wf_writeBuf = new_array(char, wf_writeBufSize); |
| 118 | if (!wf_writeBuf) |
| 119 | out_of_memory("write_file"); |
| 120 | } |
| 121 | r1 = MIN(len, wf_writeBufSize - wf_writeBufCnt); |
| 122 | if (r1) { |
| 123 | memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1); |
| 124 | wf_writeBufCnt += r1; |
| 125 | } |
| 126 | if (wf_writeBufCnt == wf_writeBufSize) { |
| 127 | if (flush_write_file(f) < 0) |
| 128 | return -1; |
| 129 | if (!r1 && len) |
| 130 | continue; |
| 131 | } |
| 132 | } |
| 133 | if (r1 <= 0) { |
| 134 | if (ret > 0) |
| 135 | return ret; |
| 136 | return r1; |
| 137 | } |
| 138 | len -= r1; |
| 139 | buf += r1; |
| 140 | ret += r1; |
| 141 | } |
| 142 | return ret; |
| 143 | } |
| 144 | |
| 145 | |
| 146 | /* This provides functionality somewhat similar to mmap() but using read(). |
| 147 | * It gives sliding window access to a file. mmap() is not used because of |
| 148 | * the possibility of another program (such as a mailer) truncating the |
| 149 | * file thus giving us a SIGBUS. */ |
| 150 | struct map_struct *map_file(int fd, OFF_T len, int32 read_size, |
| 151 | int32 blk_size) |
| 152 | { |
| 153 | struct map_struct *map; |
| 154 | |
| 155 | if (!(map = new(struct map_struct))) |
| 156 | out_of_memory("map_file"); |
| 157 | |
| 158 | if (blk_size && (read_size % blk_size)) |
| 159 | read_size += blk_size - (read_size % blk_size); |
| 160 | |
| 161 | memset(map, 0, sizeof map[0]); |
| 162 | map->fd = fd; |
| 163 | map->file_size = len; |
| 164 | map->def_window_size = read_size; |
| 165 | |
| 166 | return map; |
| 167 | } |
| 168 | |
| 169 | |
| 170 | /* slide the read window in the file */ |
| 171 | char *map_ptr(struct map_struct *map, OFF_T offset, int32 len) |
| 172 | { |
| 173 | int32 nread; |
| 174 | OFF_T window_start, read_start; |
| 175 | int32 window_size, read_size, read_offset; |
| 176 | |
| 177 | if (len == 0) |
| 178 | return NULL; |
| 179 | if (len < 0) { |
| 180 | rprintf(FERROR, "invalid len passed to map_ptr: %ld\n", |
| 181 | (long)len); |
| 182 | exit_cleanup(RERR_FILEIO); |
| 183 | } |
| 184 | |
| 185 | /* in most cases the region will already be available */ |
| 186 | if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len) |
| 187 | return map->p + (offset - map->p_offset); |
| 188 | |
| 189 | /* nope, we are going to have to do a read. Work out our desired window */ |
| 190 | window_start = offset; |
| 191 | window_size = map->def_window_size; |
| 192 | if (window_start + window_size > map->file_size) |
| 193 | window_size = map->file_size - window_start; |
| 194 | if (len > window_size) |
| 195 | window_size = len; |
| 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 |
| 206 | * from the previous 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(FERROR, "invalid read_size of %ld in map_ptr\n", |
| 222 | (long)read_size); |
| 223 | exit_cleanup(RERR_FILEIO); |
| 224 | } |
| 225 | |
| 226 | if (map->p_fd_offset != read_start) { |
| 227 | OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET); |
| 228 | if (ret != read_start) { |
| 229 | rsyserr(FERROR, errno, "lseek returned %.0f, not %.0f", |
| 230 | (double)ret, (double)read_start); |
| 231 | exit_cleanup(RERR_FILEIO); |
| 232 | } |
| 233 | map->p_fd_offset = read_start; |
| 234 | } |
| 235 | map->p_fd_offset += read_size; |
| 236 | map->p_offset = window_start; |
| 237 | map->p_len = window_size; |
| 238 | |
| 239 | while (read_size > 0) { |
| 240 | nread = read(map->fd, map->p + read_offset, read_size); |
| 241 | if (nread <= 0) { |
| 242 | if (!map->status) |
| 243 | map->status = nread ? errno : ENODATA; |
| 244 | /* The best we can do is zero the buffer -- the file |
| 245 | * has changed mid transfer! */ |
| 246 | memset(map->p + read_offset, 0, read_size); |
| 247 | break; |
| 248 | } |
| 249 | read_offset += nread; |
| 250 | read_size -= nread; |
| 251 | } |
| 252 | |
| 253 | return map->p; |
| 254 | } |
| 255 | |
| 256 | |
| 257 | int unmap_file(struct map_struct *map) |
| 258 | { |
| 259 | int ret; |
| 260 | |
| 261 | if (map->p) { |
| 262 | free(map->p); |
| 263 | map->p = NULL; |
| 264 | } |
| 265 | ret = map->status; |
| 266 | memset(map, 0, sizeof map[0]); |
| 267 | free(map); |
| 268 | |
| 269 | return ret; |
| 270 | } |