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ffcf8d9f | 1 | /* |
7387863d DDAG |
2 | * FUSE: Filesystem in Userspace |
3 | * Copyright (C) 2010 Miklos Szeredi <miklos@szeredi.hu> | |
4 | * | |
5 | * Functions for dealing with `struct fuse_buf` and `struct | |
6 | * fuse_bufvec`. | |
7 | * | |
8 | * This program can be distributed under the terms of the GNU LGPLv2. | |
9 | * See the file COPYING.LIB | |
10 | */ | |
ffcf8d9f | 11 | |
09863ebc | 12 | #include "qemu/osdep.h" |
ffcf8d9f DDAG |
13 | #include "fuse_i.h" |
14 | #include "fuse_lowlevel.h" | |
7387863d DDAG |
15 | #include <assert.h> |
16 | #include <errno.h> | |
9ceaaa15 | 17 | #include <stdlib.h> |
ffcf8d9f DDAG |
18 | #include <string.h> |
19 | #include <unistd.h> | |
ffcf8d9f DDAG |
20 | |
21 | size_t fuse_buf_size(const struct fuse_bufvec *bufv) | |
22 | { | |
7387863d DDAG |
23 | size_t i; |
24 | size_t size = 0; | |
25 | ||
26 | for (i = 0; i < bufv->count; i++) { | |
27 | if (bufv->buf[i].size == SIZE_MAX) { | |
28 | size = SIZE_MAX; | |
29 | } else { | |
30 | size += bufv->buf[i].size; | |
31 | } | |
32 | } | |
33 | ||
34 | return size; | |
9ceaaa15 | 35 | } |
36 | ||
9ceaaa15 | 37 | static ssize_t fuse_buf_writev(struct fuse_buf *out_buf, |
38 | struct fuse_bufvec *in_buf) | |
39 | { | |
40 | ssize_t res, i, j; | |
41 | size_t iovcnt = in_buf->count; | |
42 | struct iovec *iov; | |
43 | int fd = out_buf->fd; | |
44 | ||
45 | iov = calloc(iovcnt, sizeof(struct iovec)); | |
46 | if (!iov) { | |
47 | return -ENOMEM; | |
48 | } | |
49 | ||
50 | for (i = 0, j = 0; i < iovcnt; i++) { | |
51 | /* Skip the buf with 0 size */ | |
52 | if (in_buf->buf[i].size) { | |
53 | iov[j].iov_base = in_buf->buf[i].mem; | |
54 | iov[j].iov_len = in_buf->buf[i].size; | |
55 | j++; | |
56 | } | |
57 | } | |
58 | ||
59 | if (out_buf->flags & FUSE_BUF_FD_SEEK) { | |
60 | res = pwritev(fd, iov, iovcnt, out_buf->pos); | |
61 | } else { | |
62 | res = writev(fd, iov, iovcnt); | |
63 | } | |
64 | ||
65 | if (res == -1) { | |
66 | res = -errno; | |
67 | } | |
68 | ||
69 | free(iov); | |
70 | return res; | |
ffcf8d9f DDAG |
71 | } |
72 | ||
73 | static size_t min_size(size_t s1, size_t s2) | |
74 | { | |
7387863d | 75 | return s1 < s2 ? s1 : s2; |
ffcf8d9f DDAG |
76 | } |
77 | ||
78 | static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
79 | const struct fuse_buf *src, size_t src_off, |
80 | size_t len) | |
ffcf8d9f | 81 | { |
7387863d DDAG |
82 | ssize_t res = 0; |
83 | size_t copied = 0; | |
84 | ||
85 | while (len) { | |
86 | if (dst->flags & FUSE_BUF_FD_SEEK) { | |
87 | res = pwrite(dst->fd, (char *)src->mem + src_off, len, | |
88 | dst->pos + dst_off); | |
89 | } else { | |
90 | res = write(dst->fd, (char *)src->mem + src_off, len); | |
91 | } | |
92 | if (res == -1) { | |
93 | if (!copied) { | |
94 | return -errno; | |
95 | } | |
96 | break; | |
97 | } | |
98 | if (res == 0) { | |
99 | break; | |
100 | } | |
101 | ||
102 | copied += res; | |
103 | if (!(dst->flags & FUSE_BUF_FD_RETRY)) { | |
104 | break; | |
105 | } | |
106 | ||
107 | src_off += res; | |
108 | dst_off += res; | |
109 | len -= res; | |
110 | } | |
111 | ||
112 | return copied; | |
ffcf8d9f DDAG |
113 | } |
114 | ||
115 | static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
116 | const struct fuse_buf *src, size_t src_off, |
117 | size_t len) | |
ffcf8d9f | 118 | { |
7387863d DDAG |
119 | ssize_t res = 0; |
120 | size_t copied = 0; | |
121 | ||
122 | while (len) { | |
123 | if (src->flags & FUSE_BUF_FD_SEEK) { | |
124 | res = pread(src->fd, (char *)dst->mem + dst_off, len, | |
125 | src->pos + src_off); | |
126 | } else { | |
127 | res = read(src->fd, (char *)dst->mem + dst_off, len); | |
128 | } | |
129 | if (res == -1) { | |
130 | if (!copied) { | |
131 | return -errno; | |
132 | } | |
133 | break; | |
134 | } | |
135 | if (res == 0) { | |
136 | break; | |
137 | } | |
138 | ||
139 | copied += res; | |
140 | if (!(src->flags & FUSE_BUF_FD_RETRY)) { | |
141 | break; | |
142 | } | |
143 | ||
144 | dst_off += res; | |
145 | src_off += res; | |
146 | len -= res; | |
147 | } | |
148 | ||
149 | return copied; | |
ffcf8d9f DDAG |
150 | } |
151 | ||
152 | static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
153 | const struct fuse_buf *src, size_t src_off, |
154 | size_t len) | |
ffcf8d9f | 155 | { |
7387863d DDAG |
156 | char buf[4096]; |
157 | struct fuse_buf tmp = { | |
158 | .size = sizeof(buf), | |
159 | .flags = 0, | |
160 | }; | |
161 | ssize_t res; | |
162 | size_t copied = 0; | |
163 | ||
164 | tmp.mem = buf; | |
165 | ||
166 | while (len) { | |
167 | size_t this_len = min_size(tmp.size, len); | |
168 | size_t read_len; | |
169 | ||
170 | res = fuse_buf_read(&tmp, 0, src, src_off, this_len); | |
171 | if (res < 0) { | |
172 | if (!copied) { | |
173 | return res; | |
174 | } | |
175 | break; | |
176 | } | |
177 | if (res == 0) { | |
178 | break; | |
179 | } | |
180 | ||
181 | read_len = res; | |
182 | res = fuse_buf_write(dst, dst_off, &tmp, 0, read_len); | |
183 | if (res < 0) { | |
184 | if (!copied) { | |
185 | return res; | |
186 | } | |
187 | break; | |
188 | } | |
189 | if (res == 0) { | |
190 | break; | |
191 | } | |
192 | ||
193 | copied += res; | |
194 | ||
195 | if (res < this_len) { | |
196 | break; | |
197 | } | |
198 | ||
199 | dst_off += res; | |
200 | src_off += res; | |
201 | len -= res; | |
202 | } | |
203 | ||
204 | return copied; | |
ffcf8d9f DDAG |
205 | } |
206 | ||
ffcf8d9f | 207 | static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off, |
7387863d | 208 | const struct fuse_buf *src, size_t src_off, |
8c3fe75e | 209 | size_t len) |
ffcf8d9f | 210 | { |
7387863d DDAG |
211 | int src_is_fd = src->flags & FUSE_BUF_IS_FD; |
212 | int dst_is_fd = dst->flags & FUSE_BUF_IS_FD; | |
213 | ||
214 | if (!src_is_fd && !dst_is_fd) { | |
215 | char *dstmem = (char *)dst->mem + dst_off; | |
216 | char *srcmem = (char *)src->mem + src_off; | |
217 | ||
218 | if (dstmem != srcmem) { | |
219 | if (dstmem + len <= srcmem || srcmem + len <= dstmem) { | |
220 | memcpy(dstmem, srcmem, len); | |
221 | } else { | |
222 | memmove(dstmem, srcmem, len); | |
223 | } | |
224 | } | |
225 | ||
226 | return len; | |
227 | } else if (!src_is_fd) { | |
228 | return fuse_buf_write(dst, dst_off, src, src_off, len); | |
229 | } else if (!dst_is_fd) { | |
230 | return fuse_buf_read(dst, dst_off, src, src_off, len); | |
231 | } else { | |
232 | return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len); | |
233 | } | |
ffcf8d9f DDAG |
234 | } |
235 | ||
236 | static const struct fuse_buf *fuse_bufvec_current(struct fuse_bufvec *bufv) | |
237 | { | |
7387863d DDAG |
238 | if (bufv->idx < bufv->count) { |
239 | return &bufv->buf[bufv->idx]; | |
240 | } else { | |
241 | return NULL; | |
242 | } | |
ffcf8d9f DDAG |
243 | } |
244 | ||
245 | static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len) | |
246 | { | |
7387863d DDAG |
247 | const struct fuse_buf *buf = fuse_bufvec_current(bufv); |
248 | ||
249 | bufv->off += len; | |
250 | assert(bufv->off <= buf->size); | |
251 | if (bufv->off == buf->size) { | |
252 | assert(bufv->idx < bufv->count); | |
253 | bufv->idx++; | |
254 | if (bufv->idx == bufv->count) { | |
255 | return 0; | |
256 | } | |
257 | bufv->off = 0; | |
258 | } | |
259 | return 1; | |
ffcf8d9f DDAG |
260 | } |
261 | ||
8c3fe75e | 262 | ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv) |
ffcf8d9f | 263 | { |
c465bba2 | 264 | size_t copied = 0, i; |
7387863d DDAG |
265 | |
266 | if (dstv == srcv) { | |
267 | return fuse_buf_size(dstv); | |
268 | } | |
269 | ||
c465bba2 | 270 | /* |
271 | * use writev to improve bandwidth when all the | |
272 | * src buffers already mapped by the daemon | |
273 | * process | |
274 | */ | |
275 | for (i = 0; i < srcv->count; i++) { | |
276 | if (srcv->buf[i].flags & FUSE_BUF_IS_FD) { | |
277 | break; | |
278 | } | |
279 | } | |
280 | if ((i == srcv->count) && (dstv->count == 1) && | |
281 | (dstv->idx == 0) && | |
282 | (dstv->buf[0].flags & FUSE_BUF_IS_FD)) { | |
283 | dstv->buf[0].pos += dstv->off; | |
284 | return fuse_buf_writev(&dstv->buf[0], srcv); | |
285 | } | |
286 | ||
7387863d DDAG |
287 | for (;;) { |
288 | const struct fuse_buf *src = fuse_bufvec_current(srcv); | |
289 | const struct fuse_buf *dst = fuse_bufvec_current(dstv); | |
290 | size_t src_len; | |
291 | size_t dst_len; | |
292 | size_t len; | |
293 | ssize_t res; | |
294 | ||
295 | if (src == NULL || dst == NULL) { | |
296 | break; | |
297 | } | |
298 | ||
299 | src_len = src->size - srcv->off; | |
300 | dst_len = dst->size - dstv->off; | |
301 | len = min_size(src_len, dst_len); | |
302 | ||
8c3fe75e | 303 | res = fuse_buf_copy_one(dst, dstv->off, src, srcv->off, len); |
7387863d DDAG |
304 | if (res < 0) { |
305 | if (!copied) { | |
306 | return res; | |
307 | } | |
308 | break; | |
309 | } | |
310 | copied += res; | |
311 | ||
312 | if (!fuse_bufvec_advance(srcv, res) || | |
313 | !fuse_bufvec_advance(dstv, res)) { | |
314 | break; | |
315 | } | |
316 | ||
317 | if (res < len) { | |
318 | break; | |
319 | } | |
320 | } | |
321 | ||
322 | return copied; | |
ffcf8d9f | 323 | } |
dad157e8 SH |
324 | |
325 | void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len) | |
326 | { | |
327 | void *ptr; | |
328 | ||
329 | if (len > iter->size - iter->pos) { | |
330 | return NULL; | |
331 | } | |
332 | ||
333 | ptr = iter->mem + iter->pos; | |
334 | iter->pos += len; | |
335 | return ptr; | |
336 | } | |
337 | ||
338 | const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter) | |
339 | { | |
340 | const char *str = iter->mem + iter->pos; | |
341 | size_t remaining = iter->size - iter->pos; | |
342 | size_t i; | |
343 | ||
344 | for (i = 0; i < remaining; i++) { | |
345 | if (str[i] == '\0') { | |
346 | iter->pos += i + 1; | |
347 | return str; | |
348 | } | |
349 | } | |
350 | return NULL; | |
351 | } |