2 * File IO utilities used in rsync.
4 * Copyright (C) 1998 Andrew Tridgell
5 * Copyright (C) 2002 Martin Pool
6 * Copyright (C) 2004-2015 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 /* We want all reads to be aligned on 1K boundries. */
30 #define ALIGN_BOUNDRY 1024
31 /* How far past the boundary is an offset? */
32 #define ALIGNED_OVERSHOOT(oft) ((oft) & (ALIGN_BOUNDRY-1))
33 /* Round up a length to the next boundary */
34 #define ALIGNED_LENGTH(len) ((((len) - 1) | (ALIGN_BOUNDRY-1)) + 1)
36 extern int sparse_files;
38 static OFF_T sparse_seek = 0;
40 int sparse_end(int f, OFF_T size)
48 ret = do_ftruncate(f, size);
50 if (do_lseek(f, sparse_seek-1, SEEK_CUR) != size-1)
54 ret = write(f, "", 1);
55 } while (ret < 0 && errno == EINTR);
57 ret = ret <= 0 ? -1 : 0;
67 static int write_sparse(int f, char *buf, int len)
72 for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
73 for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
81 do_lseek(f, sparse_seek, SEEK_CUR);
84 while ((ret = write(f, buf + l1, len - (l1+l2))) <= 0) {
85 if (ret < 0 && errno == EINTR)
91 if (ret != (int)(len - (l1+l2))) {
100 static char *wf_writeBuf;
101 static size_t wf_writeBufSize;
102 static size_t wf_writeBufCnt;
104 int flush_write_file(int f)
107 char *bp = wf_writeBuf;
109 while (wf_writeBufCnt > 0) {
110 if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
115 wf_writeBufCnt -= ret;
123 * write_file does not allow incomplete writes. It loops internally
124 * until len bytes are written or errno is set.
126 int write_file(int f, char *buf, int len)
132 if (sparse_files > 0) {
133 int len1 = MIN(len, SPARSE_WRITE_SIZE);
134 r1 = write_sparse(f, buf, len1);
137 wf_writeBufSize = WRITE_SIZE * 8;
139 wf_writeBuf = new_array(char, wf_writeBufSize);
141 out_of_memory("write_file");
143 r1 = (int)MIN((size_t)len, wf_writeBufSize - wf_writeBufCnt);
145 memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
146 wf_writeBufCnt += r1;
148 if (wf_writeBufCnt == wf_writeBufSize) {
149 if (flush_write_file(f) < 0)
168 /* This provides functionality somewhat similar to mmap() but using read().
169 * It gives sliding window access to a file. mmap() is not used because of
170 * the possibility of another program (such as a mailer) truncating the
171 * file thus giving us a SIGBUS. */
172 struct map_struct *map_file(int fd, OFF_T len, int32 read_size, int32 blk_size)
174 struct map_struct *map;
176 if (!(map = new0(struct map_struct)))
177 out_of_memory("map_file");
179 if (blk_size && (read_size % blk_size))
180 read_size += blk_size - (read_size % blk_size);
183 map->file_size = len;
184 map->def_window_size = ALIGNED_LENGTH(read_size);
190 /* slide the read window in the file */
191 char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
193 OFF_T window_start, read_start;
194 int32 window_size, read_size, read_offset, align_fudge;
199 rprintf(FERROR, "invalid len passed to map_ptr: %ld\n",
201 exit_cleanup(RERR_FILEIO);
204 /* in most cases the region will already be available */
205 if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
206 return map->p + (offset - map->p_offset);
208 /* nope, we are going to have to do a read. Work out our desired window */
209 align_fudge = (int32)ALIGNED_OVERSHOOT(offset);
210 window_start = offset - align_fudge;
211 window_size = map->def_window_size;
212 if (window_start + window_size > map->file_size)
213 window_size = (int32)(map->file_size - window_start);
214 if (window_size < len + align_fudge)
215 window_size = ALIGNED_LENGTH(len + align_fudge);
217 /* make sure we have allocated enough memory for the window */
218 if (window_size > map->p_size) {
219 map->p = realloc_array(map->p, char, window_size);
221 out_of_memory("map_ptr");
222 map->p_size = window_size;
225 /* Now try to avoid re-reading any bytes by reusing any bytes from the previous buffer. */
226 if (window_start >= map->p_offset && window_start < map->p_offset + map->p_len
227 && window_start + window_size >= map->p_offset + map->p_len) {
228 read_start = map->p_offset + map->p_len;
229 read_offset = (int32)(read_start - window_start);
230 read_size = window_size - read_offset;
231 memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
233 read_start = window_start;
234 read_size = window_size;
238 if (read_size <= 0) {
239 rprintf(FERROR, "invalid read_size of %ld in map_ptr\n",
241 exit_cleanup(RERR_FILEIO);
244 if (map->p_fd_offset != read_start) {
245 OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET);
246 if (ret != read_start) {
247 rsyserr(FERROR, errno, "lseek returned %s, not %s",
248 big_num(ret), big_num(read_start));
249 exit_cleanup(RERR_FILEIO);
251 map->p_fd_offset = read_start;
253 map->p_offset = window_start;
254 map->p_len = window_size;
256 while (read_size > 0) {
257 int32 nread = read(map->fd, map->p + read_offset, read_size);
260 map->status = nread ? errno : ENODATA;
261 /* The best we can do is zero the buffer -- the file
262 * has changed mid transfer! */
263 memset(map->p + read_offset, 0, read_size);
266 map->p_fd_offset += nread;
267 read_offset += nread;
271 return map->p + align_fudge;
275 int unmap_file(struct map_struct *map)
284 memset(map, 0, sizeof map[0]);