2 * File IO utilities used in rsync.
4 * Copyright (C) 1998 Andrew Tridgell
5 * Copyright (C) 2002 Martin Pool
6 * Copyright (C) 2004-2009 Wayne Davison
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 3 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, visit the http://fsf.org website.
26 #define ENODATA EAGAIN
29 extern int sparse_files;
31 static OFF_T sparse_seek = 0;
33 int sparse_end(int f, OFF_T size)
41 ret = do_ftruncate(f, size);
43 if (do_lseek(f, sparse_seek-1, SEEK_CUR) != size-1)
47 ret = write(f, "", 1);
48 } while (ret < 0 && errno == EINTR);
50 ret = ret <= 0 ? -1 : 0;
60 static int write_sparse(int f, char *buf, int len)
65 for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
66 for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
74 do_lseek(f, sparse_seek, SEEK_CUR);
77 while ((ret = write(f, buf + l1, len - (l1+l2))) <= 0) {
78 if (ret < 0 && errno == EINTR)
83 if (ret != (int)(len - (l1+l2)))
90 static char *wf_writeBuf;
91 static size_t wf_writeBufSize;
92 static size_t wf_writeBufCnt;
94 int flush_write_file(int f)
97 char *bp = wf_writeBuf;
99 while (wf_writeBufCnt > 0) {
100 if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
105 wf_writeBufCnt -= ret;
113 * write_file does not allow incomplete writes. It loops internally
114 * until len bytes are written or errno is set.
116 int write_file(int f, char *buf, int len)
122 if (sparse_files > 0) {
123 int len1 = MIN(len, SPARSE_WRITE_SIZE);
124 r1 = write_sparse(f, buf, len1);
127 wf_writeBufSize = WRITE_SIZE * 8;
129 wf_writeBuf = new_array(char, wf_writeBufSize);
131 out_of_memory("write_file");
133 r1 = (int)MIN((size_t)len, wf_writeBufSize - wf_writeBufCnt);
135 memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
136 wf_writeBufCnt += r1;
138 if (wf_writeBufCnt == wf_writeBufSize) {
139 if (flush_write_file(f) < 0)
158 /* This provides functionality somewhat similar to mmap() but using read().
159 * It gives sliding window access to a file. mmap() is not used because of
160 * the possibility of another program (such as a mailer) truncating the
161 * file thus giving us a SIGBUS. */
162 struct map_struct *map_file(int fd, OFF_T len, int32 read_size,
165 struct map_struct *map;
167 if (!(map = new0(struct map_struct)))
168 out_of_memory("map_file");
170 if (blk_size && (read_size % blk_size))
171 read_size += blk_size - (read_size % blk_size);
174 map->file_size = len;
175 map->def_window_size = read_size;
181 /* slide the read window in the file */
182 char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
185 OFF_T window_start, read_start;
186 int32 window_size, read_size, read_offset;
191 rprintf(FERROR, "invalid len passed to map_ptr: %ld\n",
193 exit_cleanup(RERR_FILEIO);
196 /* in most cases the region will already be available */
197 if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
198 return map->p + (offset - map->p_offset);
200 /* nope, we are going to have to do a read. Work out our desired window */
201 window_start = offset;
202 window_size = map->def_window_size;
203 if (window_start + window_size > map->file_size)
204 window_size = (int32)(map->file_size - window_start);
205 if (len > window_size)
208 /* make sure we have allocated enough memory for the window */
209 if (window_size > map->p_size) {
210 map->p = realloc_array(map->p, char, window_size);
212 out_of_memory("map_ptr");
213 map->p_size = window_size;
216 /* Now try to avoid re-reading any bytes by reusing any bytes
217 * from the previous buffer. */
218 if (window_start >= map->p_offset &&
219 window_start < map->p_offset + map->p_len &&
220 window_start + window_size >= map->p_offset + map->p_len) {
221 read_start = map->p_offset + map->p_len;
222 read_offset = (int32)(read_start - window_start);
223 read_size = window_size - read_offset;
224 memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
226 read_start = window_start;
227 read_size = window_size;
231 if (read_size <= 0) {
232 rprintf(FERROR, "invalid read_size of %ld in map_ptr\n",
234 exit_cleanup(RERR_FILEIO);
237 if (map->p_fd_offset != read_start) {
238 OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET);
239 if (ret != read_start) {
240 rsyserr(FERROR, errno, "lseek returned %s, not %s",
241 big_num(ret), big_num(read_start));
242 exit_cleanup(RERR_FILEIO);
244 map->p_fd_offset = read_start;
246 map->p_offset = window_start;
247 map->p_len = window_size;
249 while (read_size > 0) {
250 nread = read(map->fd, map->p + read_offset, read_size);
253 map->status = nread ? errno : ENODATA;
254 /* The best we can do is zero the buffer -- the file
255 * has changed mid transfer! */
256 memset(map->p + read_offset, 0, read_size);
259 map->p_fd_offset += nread;
260 read_offset += nread;
268 int unmap_file(struct map_struct *map)
277 memset(map, 0, sizeof map[0]);