- Complain and die if --dry-run is used with a batch option.
[rsync/rsync.git] / fileio.c
... / ...
CommitLineData
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
25static char last_byte;
26static int last_sparse;
27extern int sparse_files;
28
29int sparse_end(int f)
30{
31 if (last_sparse) {
32 do_lseek(f,-1,SEEK_CUR);
33 return (write(f,&last_byte,1) == 1 ? 0 : -1);
34 }
35 last_sparse = 0;
36 return 0;
37}
38
39
40static int write_sparse(int f,char *buf,size_t len)
41{
42 size_t l1=0, l2=0;
43 int ret;
44
45 for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
46 for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
47
48 last_byte = buf[len-1];
49
50 if (l1 == len || l2 > 0)
51 last_sparse=1;
52
53 if (l1 > 0) {
54 do_lseek(f,l1,SEEK_CUR);
55 }
56
57 if (l1 == len)
58 return len;
59
60 ret = write(f, buf + l1, len - (l1+l2));
61 if (ret == -1 || ret == 0)
62 return ret;
63 else if (ret != (int) (len - (l1+l2)))
64 return (l1+ret);
65
66 if (l2 > 0)
67 do_lseek(f,l2,SEEK_CUR);
68
69 return len;
70}
71
72
73static char *wf_writeBuf;
74static size_t wf_writeBufSize;
75static size_t wf_writeBufCnt;
76
77int flush_write_file(int f)
78{
79 int ret = 0;
80 char *bp = wf_writeBuf;
81
82 while (wf_writeBufCnt > 0) {
83 if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
84 if (errno == EINTR)
85 continue;
86 return ret;
87 }
88 wf_writeBufCnt -= ret;
89 bp += ret;
90 }
91 return ret;
92}
93
94/*
95 * write_file does not allow incomplete writes. It loops internally
96 * until len bytes are written or errno is set.
97 */
98int write_file(int f,char *buf,size_t len)
99{
100 int ret = 0;
101
102 while (len > 0) {
103 int r1;
104 if (sparse_files) {
105 int len1 = MIN(len, SPARSE_WRITE_SIZE);
106 r1 = write_sparse(f, buf, len1);
107 } else {
108 if (!wf_writeBuf) {
109 wf_writeBufSize = MAX_MAP_SIZE;
110 wf_writeBufCnt = 0;
111 wf_writeBuf = new_array(char, MAX_MAP_SIZE);
112 if (!wf_writeBuf)
113 out_of_memory("write_file");
114 }
115 r1 = MIN(len, wf_writeBufSize - wf_writeBufCnt);
116 if (r1) {
117 memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
118 wf_writeBufCnt += r1;
119 }
120 if (wf_writeBufCnt == wf_writeBufSize) {
121 if (flush_write_file(f) < 0)
122 return -1;
123 if (!r1 && len)
124 continue;
125 }
126 }
127 if (r1 <= 0) {
128 if (ret > 0) return ret;
129 return r1;
130 }
131 len -= r1;
132 buf += r1;
133 ret += r1;
134 }
135 return ret;
136}
137
138
139/* this provides functionality somewhat similar to mmap() but using
140 read(). It gives sliding window access to a file. mmap() is not
141 used because of the possibility of another program (such as a
142 mailer) truncating the file thus giving us a SIGBUS */
143struct map_struct *map_file(int fd,OFF_T len)
144{
145 struct map_struct *map;
146
147 if (!(map = new(struct map_struct)))
148 out_of_memory("map_file");
149
150 memset(map, 0, sizeof map[0]);
151 map->fd = fd;
152 map->file_size = len;
153
154 return map;
155}
156
157/* slide the read window in the file */
158char *map_ptr(struct map_struct *map,OFF_T offset,int len)
159{
160 int nread;
161 OFF_T window_start, read_start;
162 int window_size, read_size, read_offset;
163
164 if (len == 0) {
165 return NULL;
166 }
167
168 /* can't go beyond the end of file */
169 if (len > (map->file_size - offset)) {
170 len = map->file_size - offset;
171 }
172
173 /* in most cases the region will already be available */
174 if (offset >= map->p_offset &&
175 offset+len <= map->p_offset+map->p_len) {
176 return (map->p + (offset - map->p_offset));
177 }
178
179
180 /* nope, we are going to have to do a read. Work out our desired window */
181 if (offset > 2*CHUNK_SIZE) {
182 window_start = offset - 2*CHUNK_SIZE;
183 window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
184 } else {
185 window_start = 0;
186 }
187 window_size = MAX_MAP_SIZE;
188 if (window_start + window_size > map->file_size) {
189 window_size = map->file_size - window_start;
190 }
191 if (offset + len > window_start + window_size) {
192 window_size = (offset+len) - window_start;
193 }
194
195 /* make sure we have allocated enough memory for the window */
196 if (window_size > map->p_size) {
197 map->p = realloc_array(map->p, char, window_size);
198 if (!map->p) out_of_memory("map_ptr");
199 map->p_size = window_size;
200 }
201
202 /* now try to avoid re-reading any bytes by reusing any bytes from the previous
203 buffer. */
204 if (window_start >= map->p_offset &&
205 window_start < map->p_offset + map->p_len &&
206 window_start + window_size >= map->p_offset + map->p_len) {
207 read_start = map->p_offset + map->p_len;
208 read_offset = read_start - window_start;
209 read_size = window_size - read_offset;
210 memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
211 } else {
212 read_start = window_start;
213 read_size = window_size;
214 read_offset = 0;
215 }
216
217 if (read_size <= 0) {
218 rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size);
219 } else {
220 if (map->p_fd_offset != read_start) {
221 if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) {
222 rprintf(FERROR,"lseek failed in map_ptr\n");
223 exit_cleanup(RERR_FILEIO);
224 }
225 map->p_fd_offset = read_start;
226 }
227
228 if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) {
229 if (nread < 0) {
230 nread = 0;
231 if (!map->status)
232 map->status = errno;
233 }
234 /* the best we can do is zero the buffer - the file
235 has changed mid transfer! */
236 memset(map->p+read_offset+nread, 0, read_size - nread);
237 }
238 map->p_fd_offset += nread;
239 }
240
241 map->p_offset = window_start;
242 map->p_len = window_size;
243
244 return map->p + (offset - map->p_offset);
245}
246
247
248int unmap_file(struct map_struct *map)
249{
250 int ret;
251
252 if (map->p) {
253 free(map->p);
254 map->p = NULL;
255 }
256 ret = map->status;
257 memset(map, 0, sizeof map[0]);
258 free(map);
259
260 return ret;
261}
262