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 static char last_byte;
26 static int last_sparse;
27 extern int sparse_files;
32 do_lseek(f,-1,SEEK_CUR);
33 return (write(f,&last_byte,1) == 1 ? 0 : -1);
40 static int write_sparse(int f,char *buf,size_t len)
45 for (l1=0;l1<len && buf[l1]==0;l1++) ;
46 for (l2=0;l2<(len-l1) && buf[len-(l2+1)]==0;l2++) ;
48 last_byte = buf[len-1];
50 if (l1 == len || l2 > 0)
54 do_lseek(f,l1,SEEK_CUR);
60 ret = write(f, buf + l1, len - (l1+l2));
61 if (ret == -1 || ret == 0)
63 else if (ret != (int) (len - (l1+l2)))
67 do_lseek(f,l2,SEEK_CUR);
74 int write_file(int f,char *buf,size_t len)
79 return write(f,buf,len);
83 int len1 = MIN(len, SPARSE_WRITE_SIZE);
84 int r1 = write_sparse(f, buf, len1);
86 if (ret > 0) return ret;
98 /* this provides functionality somewhat similar to mmap() but using
99 read(). It gives sliding window access to a file. mmap() is not
100 used because of the possibility of another program (such as a
101 mailer) truncating the file thus giving us a SIGBUS */
102 struct map_struct *map_file(int fd,OFF_T len)
104 struct map_struct *map;
105 map = (struct map_struct *)malloc(sizeof(*map));
106 if (!map) out_of_memory("map_file");
109 map->file_size = len;
113 map->p_fd_offset = 0;
119 /* slide the read window in the file */
120 char *map_ptr(struct map_struct *map,OFF_T offset,int len)
123 OFF_T window_start, read_start;
124 int window_size, read_size, read_offset;
130 /* can't go beyond the end of file */
131 if (len > (map->file_size - offset)) {
132 len = map->file_size - offset;
135 /* in most cases the region will already be available */
136 if (offset >= map->p_offset &&
137 offset+len <= map->p_offset+map->p_len) {
138 return (map->p + (offset - map->p_offset));
142 /* nope, we are going to have to do a read. Work out our desired window */
143 if (offset > 2*CHUNK_SIZE) {
144 window_start = offset - 2*CHUNK_SIZE;
145 window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
149 window_size = MAX_MAP_SIZE;
150 if (window_start + window_size > map->file_size) {
151 window_size = map->file_size - window_start;
153 if (offset + len > window_start + window_size) {
154 window_size = (offset+len) - window_start;
157 /* make sure we have allocated enough memory for the window */
158 if (window_size > map->p_size) {
159 map->p = (char *)Realloc(map->p, window_size);
160 if (!map->p) out_of_memory("map_ptr");
161 map->p_size = window_size;
164 /* now try to avoid re-reading any bytes by reusing any bytes from the previous
166 if (window_start >= map->p_offset &&
167 window_start < map->p_offset + map->p_len &&
168 window_start + window_size >= map->p_offset + map->p_len) {
169 read_start = map->p_offset + map->p_len;
170 read_offset = read_start - window_start;
171 read_size = window_size - read_offset;
172 memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
174 read_start = window_start;
175 read_size = window_size;
179 if (read_size <= 0) {
180 rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size);
182 if (map->p_fd_offset != read_start) {
183 if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) {
184 rprintf(FERROR,"lseek failed in map_ptr\n");
185 exit_cleanup(RERR_FILEIO);
187 map->p_fd_offset = read_start;
190 if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) {
191 if (nread < 0) nread = 0;
192 /* the best we can do is zero the buffer - the file
193 has changed mid transfer! */
194 memset(map->p+read_offset+nread, 0, read_size - nread);
196 map->p_fd_offset += nread;
199 map->p_offset = window_start;
200 map->p_len = window_size;
202 return map->p + (offset - map->p_offset);
206 void unmap_file(struct map_struct *map)
212 memset(map, 0, sizeof(*map));