2 Copyright (C) Andrew Tridgell 1998
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 File IO utilities used in rsync
24 static char last_byte;
25 static int last_sparse;
26 extern int sparse_files;
31 do_lseek(f,-1,SEEK_CUR);
32 return (write(f,&last_byte,1) == 1 ? 0 : -1);
39 static int write_sparse(int f,char *buf,size_t len)
44 for (l1=0;l1<len && buf[l1]==0;l1++) ;
45 for (l2=0;l2<(len-l1) && buf[len-(l2+1)]==0;l2++) ;
47 last_byte = buf[len-1];
49 if (l1 == len || l2 > 0)
53 do_lseek(f,l1,SEEK_CUR);
59 if ((ret=write(f,buf+l1,len-(l1+l2))) != len-(l1+l2)) {
60 if (ret == -1 || ret == 0) return ret;
65 do_lseek(f,l2,SEEK_CUR);
72 int write_file(int f,char *buf,size_t len)
77 return write(f,buf,len);
81 int len1 = MIN(len, SPARSE_WRITE_SIZE);
82 int r1 = write_sparse(f, buf, len1);
84 if (ret > 0) return ret;
96 /* this provides functionality somewhat similar to mmap() but using
97 read(). It gives sliding window access to a file. mmap() is not
98 used because of the possibility of another program (such as a
99 mailer) truncating the file thus giving us a SIGBUS */
100 struct map_struct *map_file(int fd,OFF_T len)
102 struct map_struct *map;
103 map = (struct map_struct *)malloc(sizeof(*map));
104 if (!map) out_of_memory("map_file");
107 map->file_size = len;
111 map->p_fd_offset = 0;
117 /* slide the read window in the file */
118 char *map_ptr(struct map_struct *map,OFF_T offset,int len)
121 OFF_T window_start, read_start;
122 int window_size, read_size, read_offset;
128 /* can't go beyond the end of file */
129 if (len > (map->file_size - offset)) {
130 len = map->file_size - offset;
133 /* in most cases the region will already be available */
134 if (offset >= map->p_offset &&
135 offset+len <= map->p_offset+map->p_len) {
136 return (map->p + (offset - map->p_offset));
140 /* nope, we are going to have to do a read. Work out our desired window */
141 if (offset > 2*CHUNK_SIZE) {
142 window_start = offset - 2*CHUNK_SIZE;
143 window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */
147 window_size = MAX_MAP_SIZE;
148 if (window_start + window_size > map->file_size) {
149 window_size = map->file_size - window_start;
151 if (offset + len > window_start + window_size) {
152 window_size = (offset+len) - window_start;
155 /* make sure we have allocated enough memory for the window */
156 if (window_size > map->p_size) {
157 map->p = (char *)Realloc(map->p, window_size);
158 if (!map->p) out_of_memory("map_ptr");
159 map->p_size = window_size;
162 /* now try to avoid re-reading any bytes by reusing any bytes from the previous
164 if (window_start >= map->p_offset &&
165 window_start < map->p_offset + map->p_len &&
166 window_start + window_size >= map->p_offset + map->p_len) {
167 read_start = map->p_offset + map->p_len;
168 read_offset = read_start - window_start;
169 read_size = window_size - read_offset;
170 memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
172 read_start = window_start;
173 read_size = window_size;
177 if (read_size <= 0) {
178 rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size);
180 if (map->p_fd_offset != read_start) {
181 if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) {
182 rprintf(FERROR,"lseek failed in map_ptr\n");
183 exit_cleanup(RERR_FILEIO);
185 map->p_fd_offset = read_start;
188 if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) {
189 if (nread < 0) nread = 0;
190 /* the best we can do is zero the buffer - the file
191 has changed mid transfer! */
192 memset(map->p+read_offset+nread, 0, read_size - nread);
194 map->p_fd_offset += nread;
197 map->p_offset = window_start;
198 map->p_len = window_size;
200 return map->p + (offset - map->p_offset);
204 void unmap_file(struct map_struct *map)
210 memset(map, 0, sizeof(*map));