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 | ||
9533e15a S |
72 | /* |
73 | * write_file does not allow incomplete writes. It loops internally | |
74 | * until len bytes are written or errno is set. | |
75 | */ | |
9dd891bb | 76 | int write_file(int f,char *buf,size_t len) |
4c36ddbe AT |
77 | { |
78 | int ret = 0; | |
79 | ||
4c36ddbe | 80 | while (len>0) { |
9533e15a S |
81 | int r1; |
82 | if (sparse_files) { | |
83 | int len1 = MIN(len, SPARSE_WRITE_SIZE); | |
84 | r1 = write_sparse(f, buf, len1); | |
85 | } else { | |
86 | r1 = write(f, buf, len); | |
87 | } | |
4c36ddbe AT |
88 | if (r1 <= 0) { |
89 | if (ret > 0) return ret; | |
90 | return r1; | |
91 | } | |
92 | len -= r1; | |
93 | buf += r1; | |
94 | ret += r1; | |
95 | } | |
96 | return ret; | |
97 | } | |
98 | ||
99 | ||
100 | ||
4440b8aa AT |
101 | /* this provides functionality somewhat similar to mmap() but using |
102 | read(). It gives sliding window access to a file. mmap() is not | |
103 | used because of the possibility of another program (such as a | |
104 | mailer) truncating the file thus giving us a SIGBUS */ | |
4c36ddbe AT |
105 | struct map_struct *map_file(int fd,OFF_T len) |
106 | { | |
4440b8aa AT |
107 | struct map_struct *map; |
108 | map = (struct map_struct *)malloc(sizeof(*map)); | |
109 | if (!map) out_of_memory("map_file"); | |
110 | ||
111 | map->fd = fd; | |
112 | map->file_size = len; | |
113 | map->p = NULL; | |
114 | map->p_size = 0; | |
115 | map->p_offset = 0; | |
116 | map->p_fd_offset = 0; | |
117 | map->p_len = 0; | |
118 | ||
119 | return map; | |
4c36ddbe AT |
120 | } |
121 | ||
4440b8aa | 122 | /* slide the read window in the file */ |
4c36ddbe AT |
123 | char *map_ptr(struct map_struct *map,OFF_T offset,int len) |
124 | { | |
125 | int nread; | |
4440b8aa AT |
126 | OFF_T window_start, read_start; |
127 | int window_size, read_size, read_offset; | |
4c36ddbe | 128 | |
4440b8aa | 129 | if (len == 0) { |
4c36ddbe | 130 | return NULL; |
4440b8aa | 131 | } |
4c36ddbe | 132 | |
4440b8aa AT |
133 | /* can't go beyond the end of file */ |
134 | if (len > (map->file_size - offset)) { | |
135 | len = map->file_size - offset; | |
4c36ddbe | 136 | } |
4c36ddbe | 137 | |
4440b8aa | 138 | /* in most cases the region will already be available */ |
4c36ddbe AT |
139 | if (offset >= map->p_offset && |
140 | offset+len <= map->p_offset+map->p_len) { | |
141 | return (map->p + (offset - map->p_offset)); | |
142 | } | |
143 | ||
4c36ddbe | 144 | |
4440b8aa AT |
145 | /* nope, we are going to have to do a read. Work out our desired window */ |
146 | if (offset > 2*CHUNK_SIZE) { | |
147 | window_start = offset - 2*CHUNK_SIZE; | |
148 | window_start &= ~((OFF_T)(CHUNK_SIZE-1)); /* assumes power of 2 */ | |
149 | } else { | |
150 | window_start = 0; | |
151 | } | |
152 | window_size = MAX_MAP_SIZE; | |
153 | if (window_start + window_size > map->file_size) { | |
154 | window_size = map->file_size - window_start; | |
155 | } | |
156 | if (offset + len > window_start + window_size) { | |
157 | window_size = (offset+len) - window_start; | |
4c36ddbe AT |
158 | } |
159 | ||
4440b8aa AT |
160 | /* make sure we have allocated enough memory for the window */ |
161 | if (window_size > map->p_size) { | |
162 | map->p = (char *)Realloc(map->p, window_size); | |
163 | if (!map->p) out_of_memory("map_ptr"); | |
164 | map->p_size = window_size; | |
165 | } | |
4c36ddbe | 166 | |
4440b8aa AT |
167 | /* now try to avoid re-reading any bytes by reusing any bytes from the previous |
168 | buffer. */ | |
169 | if (window_start >= map->p_offset && | |
170 | window_start < map->p_offset + map->p_len && | |
171 | window_start + window_size >= map->p_offset + map->p_len) { | |
172 | read_start = map->p_offset + map->p_len; | |
173 | read_offset = read_start - window_start; | |
174 | read_size = window_size - read_offset; | |
175 | memmove(map->p, map->p + (map->p_len - read_offset), read_offset); | |
176 | } else { | |
177 | read_start = window_start; | |
178 | read_size = window_size; | |
179 | read_offset = 0; | |
4c36ddbe AT |
180 | } |
181 | ||
4440b8aa AT |
182 | if (read_size <= 0) { |
183 | rprintf(FINFO,"Warning: unexpected read size of %d in map_ptr\n", read_size); | |
184 | } else { | |
185 | if (map->p_fd_offset != read_start) { | |
186 | if (do_lseek(map->fd,read_start,SEEK_SET) != read_start) { | |
187 | rprintf(FERROR,"lseek failed in map_ptr\n"); | |
188 | exit_cleanup(RERR_FILEIO); | |
189 | } | |
190 | map->p_fd_offset = read_start; | |
191 | } | |
192 | ||
193 | if ((nread=read(map->fd,map->p + read_offset,read_size)) != read_size) { | |
194 | if (nread < 0) nread = 0; | |
195 | /* the best we can do is zero the buffer - the file | |
196 | has changed mid transfer! */ | |
197 | memset(map->p+read_offset+nread, 0, read_size - nread); | |
198 | } | |
199 | map->p_fd_offset += nread; | |
4c36ddbe | 200 | } |
4440b8aa AT |
201 | |
202 | map->p_offset = window_start; | |
203 | map->p_len = window_size; | |
4c36ddbe | 204 | |
4440b8aa | 205 | return map->p + (offset - map->p_offset); |
4c36ddbe AT |
206 | } |
207 | ||
208 | ||
209 | void unmap_file(struct map_struct *map) | |
210 | { | |
4c36ddbe AT |
211 | if (map->p) { |
212 | free(map->p); | |
213 | map->p = NULL; | |
214 | } | |
215 | memset(map, 0, sizeof(*map)); | |
216 | free(map); | |
217 | } | |
218 |