Commit | Line | Data |
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4c36ddbe AT |
1 | /* |
2 | Copyright (C) Andrew Tridgell 1998 | |
a261989c | 3 | Copyright (C) 2002 by Martin Pool |
4c36ddbe AT |
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 | ||
25 | static char last_byte; | |
26 | static int last_sparse; | |
27 | extern int sparse_files; | |
28 | ||
29 | int 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 | ||
9dd891bb | 40 | static int write_sparse(int f,char *buf,size_t len) |
4c36ddbe | 41 | { |
a261989c | 42 | size_t l1=0, l2=0; |
4c36ddbe AT |
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 | ||
4440b8aa | 53 | if (l1 > 0) { |
4c36ddbe | 54 | do_lseek(f,l1,SEEK_CUR); |
4440b8aa | 55 | } |
4c36ddbe AT |
56 | |
57 | if (l1 == len) | |
58 | return len; | |
59 | ||
a261989c MP |
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))) | |
4c36ddbe | 64 | return (l1+ret); |
4c36ddbe AT |
65 | |
66 | if (l2 > 0) | |
67 | do_lseek(f,l2,SEEK_CUR); | |
68 | ||
69 | return len; | |
70 | } | |
71 | ||
72 | ||
73 | ||
9dd891bb | 74 | int write_file(int f,char *buf,size_t len) |
4c36ddbe AT |
75 | { |
76 | int ret = 0; | |
77 | ||
4440b8aa | 78 | if (!sparse_files) { |
4c36ddbe | 79 | return write(f,buf,len); |
4440b8aa | 80 | } |
4c36ddbe AT |
81 | |
82 | while (len>0) { | |
83 | int len1 = MIN(len, SPARSE_WRITE_SIZE); | |
84 | int r1 = write_sparse(f, buf, len1); | |
85 | if (r1 <= 0) { | |
86 | if (ret > 0) return ret; | |
87 | return r1; | |
88 | } | |
89 | len -= r1; | |
90 | buf += r1; | |
91 | ret += r1; | |
92 | } | |
93 | return ret; | |
94 | } | |
95 | ||
96 | ||
97 | ||
4440b8aa AT |
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 */ | |
4c36ddbe AT |
102 | struct map_struct *map_file(int fd,OFF_T len) |
103 | { | |
4440b8aa AT |
104 | struct map_struct *map; |
105 | map = (struct map_struct *)malloc(sizeof(*map)); | |
106 | if (!map) out_of_memory("map_file"); | |
107 | ||
108 | map->fd = fd; | |
109 | map->file_size = len; | |
110 | map->p = NULL; | |
111 | map->p_size = 0; | |
112 | map->p_offset = 0; | |
113 | map->p_fd_offset = 0; | |
114 | map->p_len = 0; | |
115 | ||
116 | return map; | |
4c36ddbe AT |
117 | } |
118 | ||
4440b8aa | 119 | /* slide the read window in the file */ |
4c36ddbe AT |
120 | char *map_ptr(struct map_struct *map,OFF_T offset,int len) |
121 | { | |
122 | int nread; | |
4440b8aa AT |
123 | OFF_T window_start, read_start; |
124 | int window_size, read_size, read_offset; | |
4c36ddbe | 125 | |
4440b8aa | 126 | if (len == 0) { |
4c36ddbe | 127 | return NULL; |
4440b8aa | 128 | } |
4c36ddbe | 129 | |
4440b8aa AT |
130 | /* can't go beyond the end of file */ |
131 | if (len > (map->file_size - offset)) { | |
132 | len = map->file_size - offset; | |
4c36ddbe | 133 | } |
4c36ddbe | 134 | |
4440b8aa | 135 | /* in most cases the region will already be available */ |
4c36ddbe AT |
136 | if (offset >= map->p_offset && |
137 | offset+len <= map->p_offset+map->p_len) { | |
138 | return (map->p + (offset - map->p_offset)); | |
139 | } | |
140 | ||
4c36ddbe | 141 | |
4440b8aa AT |
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 */ | |
146 | } else { | |
147 | window_start = 0; | |
148 | } | |
149 | window_size = MAX_MAP_SIZE; | |
150 | if (window_start + window_size > map->file_size) { | |
151 | window_size = map->file_size - window_start; | |
152 | } | |
153 | if (offset + len > window_start + window_size) { | |
154 | window_size = (offset+len) - window_start; | |
4c36ddbe AT |
155 | } |
156 | ||
4440b8aa AT |
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; | |
162 | } | |
4c36ddbe | 163 | |
4440b8aa AT |
164 | /* now try to avoid re-reading any bytes by reusing any bytes from the previous |
165 | buffer. */ | |
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); | |
173 | } else { | |
174 | read_start = window_start; | |
175 | read_size = window_size; | |
176 | read_offset = 0; | |
4c36ddbe AT |
177 | } |
178 | ||
4440b8aa AT |
179 | if (read_size <= 0) { |
180 | rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size); | |
181 | } else { | |
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); | |
186 | } | |
187 | map->p_fd_offset = read_start; | |
188 | } | |
189 | ||
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); | |
195 | } | |
196 | map->p_fd_offset += nread; | |
4c36ddbe | 197 | } |
4440b8aa AT |
198 | |
199 | map->p_offset = window_start; | |
200 | map->p_len = window_size; | |
4c36ddbe | 201 | |
4440b8aa | 202 | return map->p + (offset - map->p_offset); |
4c36ddbe AT |
203 | } |
204 | ||
205 | ||
206 | void unmap_file(struct map_struct *map) | |
207 | { | |
4c36ddbe AT |
208 | if (map->p) { |
209 | free(map->p); | |
210 | map->p = NULL; | |
211 | } | |
212 | memset(map, 0, sizeof(*map)); | |
213 | free(map); | |
214 | } | |
215 |