2 Copyright (C) Andrew Tridgell 1998
3 Copyright (C) 2002 by Martin Pool
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.
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.
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.
21 File IO utilities used in rsync
25 extern int sparse_files;
27 static char last_byte;
28 static int last_sparse;
33 do_lseek(f,-1,SEEK_CUR);
34 return (write(f,&last_byte,1) == 1 ? 0 : -1);
41 static int write_sparse(int f,char *buf,size_t len)
46 for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
47 for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
49 last_byte = buf[len-1];
51 if (l1 == len || l2 > 0)
55 do_lseek(f,l1,SEEK_CUR);
61 ret = write(f, buf + l1, len - (l1+l2));
62 if (ret == -1 || ret == 0)
64 else if (ret != (int) (len - (l1+l2)))
68 do_lseek(f,l2,SEEK_CUR);
74 static char *wf_writeBuf;
75 static size_t wf_writeBufSize;
76 static size_t wf_writeBufCnt;
78 int flush_write_file(int f)
81 char *bp = wf_writeBuf;
83 while (wf_writeBufCnt > 0) {
84 if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
89 wf_writeBufCnt -= ret;
97 * write_file does not allow incomplete writes. It loops internally
98 * until len bytes are written or errno is set.
100 int write_file(int f,char *buf,size_t len)
107 int len1 = MIN(len, SPARSE_WRITE_SIZE);
108 r1 = write_sparse(f, buf, len1);
111 wf_writeBufSize = WRITE_SIZE * 8;
113 wf_writeBuf = new_array(char, wf_writeBufSize);
115 out_of_memory("write_file");
117 r1 = MIN(len, wf_writeBufSize - wf_writeBufCnt);
119 memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
120 wf_writeBufCnt += r1;
122 if (wf_writeBufCnt == wf_writeBufSize) {
123 if (flush_write_file(f) < 0)
142 /* this provides functionality somewhat similar to mmap() but using
143 read(). It gives sliding window access to a file. mmap() is not
144 used because of the possibility of another program (such as a
145 mailer) truncating the file thus giving us a SIGBUS */
146 struct map_struct *map_file(int fd, OFF_T len, size_t block_size)
148 struct map_struct *map;
150 if (!(map = new(struct map_struct)))
151 out_of_memory("map_file");
153 memset(map, 0, sizeof map[0]);
155 map->file_size = len;
156 map->def_window_size = MAX(MAX_MAP_SIZE, block_size * 32);
162 /* slide the read window in the file */
163 char *map_ptr(struct map_struct *map,OFF_T offset,int len)
166 OFF_T window_start, read_start;
167 int window_size, read_size, read_offset;
172 /* can't go beyond the end of file */
173 if (len > (map->file_size - offset)) {
174 len = map->file_size - offset;
177 /* in most cases the region will already be available */
178 if (offset >= map->p_offset &&
179 offset+len <= map->p_offset+map->p_len) {
180 return (map->p + (offset - map->p_offset));
183 /* nope, we are going to have to do a read. Work out our desired window */
184 if (offset > 2*CHUNK_SIZE) {
185 window_start = offset - 2*CHUNK_SIZE;
186 window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
190 window_size = map->def_window_size;
191 if (window_start + window_size > map->file_size) {
192 window_size = map->file_size - window_start;
194 if (offset + len > window_start + window_size) {
195 window_size = (offset+len) - window_start;
198 /* make sure we have allocated enough memory for the window */
199 if (window_size > map->p_size) {
200 map->p = realloc_array(map->p, char, window_size);
202 out_of_memory("map_ptr");
203 map->p_size = window_size;
206 /* now try to avoid re-reading any bytes by reusing any bytes from the previous
208 if (window_start >= map->p_offset &&
209 window_start < map->p_offset + map->p_len &&
210 window_start + window_size >= map->p_offset + map->p_len) {
211 read_start = map->p_offset + map->p_len;
212 read_offset = read_start - window_start;
213 read_size = window_size - read_offset;
214 memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
216 read_start = window_start;
217 read_size = window_size;
221 if (read_size <= 0) {
222 rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size);
224 if (map->p_fd_offset != read_start) {
225 if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) {
226 rprintf(FERROR,"lseek failed in map_ptr\n");
227 exit_cleanup(RERR_FILEIO);
229 map->p_fd_offset = read_start;
232 if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) {
238 /* the best we can do is zero the buffer - the file
239 has changed mid transfer! */
240 memset(map->p+read_offset+nread, 0, read_size - nread);
242 map->p_fd_offset += nread;
245 map->p_offset = window_start;
246 map->p_len = window_size;
248 return map->p + (offset - map->p_offset);
252 int unmap_file(struct map_struct *map)
261 memset(map, 0, sizeof map[0]);