1: /*
2: * File IO utilities used in rsync.
3: *
4: * Copyright (C) 1998 Andrew Tridgell
5: * Copyright (C) 2002 Martin Pool
6: * Copyright (C) 2004-2013 Wayne Davison
7: *
8: * This program is free software; you can redistribute it and/or modify
9: * it under the terms of the GNU General Public License as published by
10: * the Free Software Foundation; either version 3 of the License, or
11: * (at your option) any later version.
12: *
13: * This program is distributed in the hope that it will be useful,
14: * but WITHOUT ANY WARRANTY; without even the implied warranty of
15: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16: * GNU General Public License for more details.
17: *
18: * You should have received a copy of the GNU General Public License along
19: * with this program; if not, visit the http://fsf.org website.
20: */
21:
22: #include "rsync.h"
23: #include "inums.h"
24:
25: #ifndef ENODATA
26: #define ENODATA EAGAIN
27: #endif
28:
29: /* We want all reads to be aligned on 1K boundries. */
30: #define ALIGN_BOUNDRY 1024
31: /* How far past the boundary is an offset? */
32: #define ALIGNED_OVERSHOOT(oft) ((oft) & (ALIGN_BOUNDRY-1))
33: /* Round up a length to the next boundary */
34: #define ALIGNED_LENGTH(len) ((((len) - 1) | (ALIGN_BOUNDRY-1)) + 1)
35:
36: extern int sparse_files;
37:
38: static OFF_T sparse_seek = 0;
39:
40: int sparse_end(int f, OFF_T size)
41: {
42: int ret;
43:
44: if (!sparse_seek)
45: return 0;
46:
47: #ifdef HAVE_FTRUNCATE
48: ret = do_ftruncate(f, size);
49: #else
50: if (do_lseek(f, sparse_seek-1, SEEK_CUR) != size-1)
51: ret = -1;
52: else {
53: do {
54: ret = write(f, "", 1);
55: } while (ret < 0 && errno == EINTR);
56:
57: ret = ret <= 0 ? -1 : 0;
58: }
59: #endif
60:
61: sparse_seek = 0;
62:
63: return ret;
64: }
65:
66:
67: static int write_sparse(int f, char *buf, int len)
68: {
69: int l1 = 0, l2 = 0;
70: int ret;
71:
72: for (l1 = 0; l1 < len && buf[l1] == 0; l1++) {}
73: for (l2 = 0; l2 < len-l1 && buf[len-(l2+1)] == 0; l2++) {}
74:
75: sparse_seek += l1;
76:
77: if (l1 == len)
78: return len;
79:
80: if (sparse_seek)
81: do_lseek(f, sparse_seek, SEEK_CUR);
82: sparse_seek = l2;
83:
84: while ((ret = write(f, buf + l1, len - (l1+l2))) <= 0) {
85: if (ret < 0 && errno == EINTR)
86: continue;
87: sparse_seek = 0;
88: return ret;
89: }
90:
91: if (ret != (int)(len - (l1+l2))) {
92: sparse_seek = 0;
93: return l1+ret;
94: }
95:
96: return len;
97: }
98:
99:
100: static char *wf_writeBuf;
101: static size_t wf_writeBufSize;
102: static size_t wf_writeBufCnt;
103:
104: int flush_write_file(int f)
105: {
106: int ret = 0;
107: char *bp = wf_writeBuf;
108:
109: while (wf_writeBufCnt > 0) {
110: if ((ret = write(f, bp, wf_writeBufCnt)) < 0) {
111: if (errno == EINTR)
112: continue;
113: return ret;
114: }
115: wf_writeBufCnt -= ret;
116: bp += ret;
117: }
118: return ret;
119: }
120:
121:
122: /*
123: * write_file does not allow incomplete writes. It loops internally
124: * until len bytes are written or errno is set.
125: */
126: int write_file(int f, char *buf, int len)
127: {
128: int ret = 0;
129:
130: while (len > 0) {
131: int r1;
132: if (sparse_files > 0) {
133: int len1 = MIN(len, SPARSE_WRITE_SIZE);
134: r1 = write_sparse(f, buf, len1);
135: } else {
136: if (!wf_writeBuf) {
137: wf_writeBufSize = WRITE_SIZE * 8;
138: wf_writeBufCnt = 0;
139: wf_writeBuf = new_array(char, wf_writeBufSize);
140: if (!wf_writeBuf)
141: out_of_memory("write_file");
142: }
143: r1 = (int)MIN((size_t)len, wf_writeBufSize - wf_writeBufCnt);
144: if (r1) {
145: memcpy(wf_writeBuf + wf_writeBufCnt, buf, r1);
146: wf_writeBufCnt += r1;
147: }
148: if (wf_writeBufCnt == wf_writeBufSize) {
149: if (flush_write_file(f) < 0)
150: return -1;
151: if (!r1 && len)
152: continue;
153: }
154: }
155: if (r1 <= 0) {
156: if (ret > 0)
157: return ret;
158: return r1;
159: }
160: len -= r1;
161: buf += r1;
162: ret += r1;
163: }
164: return ret;
165: }
166:
167:
168: /* This provides functionality somewhat similar to mmap() but using read().
169: * It gives sliding window access to a file. mmap() is not used because of
170: * the possibility of another program (such as a mailer) truncating the
171: * file thus giving us a SIGBUS. */
172: struct map_struct *map_file(int fd, OFF_T len, int32 read_size, int32 blk_size)
173: {
174: struct map_struct *map;
175:
176: if (!(map = new0(struct map_struct)))
177: out_of_memory("map_file");
178:
179: if (blk_size && (read_size % blk_size))
180: read_size += blk_size - (read_size % blk_size);
181:
182: map->fd = fd;
183: map->file_size = len;
184: map->def_window_size = ALIGNED_LENGTH(read_size);
185:
186: return map;
187: }
188:
189:
190: /* slide the read window in the file */
191: char *map_ptr(struct map_struct *map, OFF_T offset, int32 len)
192: {
193: OFF_T window_start, read_start;
194: int32 window_size, read_size, read_offset, align_fudge;
195:
196: if (len == 0)
197: return NULL;
198: if (len < 0) {
199: rprintf(FERROR, "invalid len passed to map_ptr: %ld\n",
200: (long)len);
201: exit_cleanup(RERR_FILEIO);
202: }
203:
204: /* in most cases the region will already be available */
205: if (offset >= map->p_offset && offset+len <= map->p_offset+map->p_len)
206: return map->p + (offset - map->p_offset);
207:
208: /* nope, we are going to have to do a read. Work out our desired window */
209: align_fudge = (int32)ALIGNED_OVERSHOOT(offset);
210: window_start = offset - align_fudge;
211: window_size = map->def_window_size;
212: if (window_start + window_size > map->file_size)
213: window_size = (int32)(map->file_size - window_start);
214: if (window_size < len + align_fudge)
215: window_size = ALIGNED_LENGTH(len + align_fudge);
216:
217: /* make sure we have allocated enough memory for the window */
218: if (window_size > map->p_size) {
219: map->p = realloc_array(map->p, char, window_size);
220: if (!map->p)
221: out_of_memory("map_ptr");
222: map->p_size = window_size;
223: }
224:
225: /* Now try to avoid re-reading any bytes by reusing any bytes from the previous buffer. */
226: if (window_start >= map->p_offset && window_start < map->p_offset + map->p_len
227: && window_start + window_size >= map->p_offset + map->p_len) {
228: read_start = map->p_offset + map->p_len;
229: read_offset = (int32)(read_start - window_start);
230: read_size = window_size - read_offset;
231: memmove(map->p, map->p + (map->p_len - read_offset), read_offset);
232: } else {
233: read_start = window_start;
234: read_size = window_size;
235: read_offset = 0;
236: }
237:
238: if (read_size <= 0) {
239: rprintf(FERROR, "invalid read_size of %ld in map_ptr\n",
240: (long)read_size);
241: exit_cleanup(RERR_FILEIO);
242: }
243:
244: if (map->p_fd_offset != read_start) {
245: OFF_T ret = do_lseek(map->fd, read_start, SEEK_SET);
246: if (ret != read_start) {
247: rsyserr(FERROR, errno, "lseek returned %s, not %s",
248: big_num(ret), big_num(read_start));
249: exit_cleanup(RERR_FILEIO);
250: }
251: map->p_fd_offset = read_start;
252: }
253: map->p_offset = window_start;
254: map->p_len = window_size;
255:
256: while (read_size > 0) {
257: int32 nread = read(map->fd, map->p + read_offset, read_size);
258: if (nread <= 0) {
259: if (!map->status)
260: map->status = nread ? errno : ENODATA;
261: /* The best we can do is zero the buffer -- the file
262: * has changed mid transfer! */
263: memset(map->p + read_offset, 0, read_size);
264: break;
265: }
266: map->p_fd_offset += nread;
267: read_offset += nread;
268: read_size -= nread;
269: }
270:
271: return map->p + align_fudge;
272: }
273:
274:
275: int unmap_file(struct map_struct *map)
276: {
277: int ret;
278:
279: if (map->p) {
280: free(map->p);
281: map->p = NULL;
282: }
283: ret = map->status;
284: memset(map, 0, sizeof map[0]);
285: free(map);
286:
287: return ret;
288: }
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