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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" | |
ffcf8d9f DDAG |
15 | |
16 | size_t fuse_buf_size(const struct fuse_bufvec *bufv) | |
17 | { | |
7387863d DDAG |
18 | size_t i; |
19 | size_t size = 0; | |
20 | ||
21 | for (i = 0; i < bufv->count; i++) { | |
22 | if (bufv->buf[i].size == SIZE_MAX) { | |
23 | size = SIZE_MAX; | |
24 | } else { | |
25 | size += bufv->buf[i].size; | |
26 | } | |
27 | } | |
28 | ||
29 | return size; | |
9ceaaa15 | 30 | } |
31 | ||
9ceaaa15 | 32 | static ssize_t fuse_buf_writev(struct fuse_buf *out_buf, |
33 | struct fuse_bufvec *in_buf) | |
34 | { | |
35 | ssize_t res, i, j; | |
36 | size_t iovcnt = in_buf->count; | |
37 | struct iovec *iov; | |
38 | int fd = out_buf->fd; | |
39 | ||
d14d4f4f | 40 | iov = g_try_new0(struct iovec, iovcnt); |
9ceaaa15 | 41 | if (!iov) { |
42 | return -ENOMEM; | |
43 | } | |
44 | ||
45 | for (i = 0, j = 0; i < iovcnt; i++) { | |
46 | /* Skip the buf with 0 size */ | |
47 | if (in_buf->buf[i].size) { | |
48 | iov[j].iov_base = in_buf->buf[i].mem; | |
49 | iov[j].iov_len = in_buf->buf[i].size; | |
50 | j++; | |
51 | } | |
52 | } | |
53 | ||
54 | if (out_buf->flags & FUSE_BUF_FD_SEEK) { | |
55 | res = pwritev(fd, iov, iovcnt, out_buf->pos); | |
56 | } else { | |
57 | res = writev(fd, iov, iovcnt); | |
58 | } | |
59 | ||
60 | if (res == -1) { | |
61 | res = -errno; | |
62 | } | |
63 | ||
d14d4f4f | 64 | g_free(iov); |
9ceaaa15 | 65 | return res; |
ffcf8d9f DDAG |
66 | } |
67 | ||
68 | static size_t min_size(size_t s1, size_t s2) | |
69 | { | |
7387863d | 70 | return s1 < s2 ? s1 : s2; |
ffcf8d9f DDAG |
71 | } |
72 | ||
73 | static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
74 | const struct fuse_buf *src, size_t src_off, |
75 | size_t len) | |
ffcf8d9f | 76 | { |
7387863d DDAG |
77 | ssize_t res = 0; |
78 | size_t copied = 0; | |
79 | ||
80 | while (len) { | |
81 | if (dst->flags & FUSE_BUF_FD_SEEK) { | |
82 | res = pwrite(dst->fd, (char *)src->mem + src_off, len, | |
83 | dst->pos + dst_off); | |
84 | } else { | |
85 | res = write(dst->fd, (char *)src->mem + src_off, len); | |
86 | } | |
87 | if (res == -1) { | |
88 | if (!copied) { | |
89 | return -errno; | |
90 | } | |
91 | break; | |
92 | } | |
93 | if (res == 0) { | |
94 | break; | |
95 | } | |
96 | ||
97 | copied += res; | |
98 | if (!(dst->flags & FUSE_BUF_FD_RETRY)) { | |
99 | break; | |
100 | } | |
101 | ||
102 | src_off += res; | |
103 | dst_off += res; | |
104 | len -= res; | |
105 | } | |
106 | ||
107 | return copied; | |
ffcf8d9f DDAG |
108 | } |
109 | ||
110 | static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
111 | const struct fuse_buf *src, size_t src_off, |
112 | size_t len) | |
ffcf8d9f | 113 | { |
7387863d DDAG |
114 | ssize_t res = 0; |
115 | size_t copied = 0; | |
116 | ||
117 | while (len) { | |
118 | if (src->flags & FUSE_BUF_FD_SEEK) { | |
119 | res = pread(src->fd, (char *)dst->mem + dst_off, len, | |
120 | src->pos + src_off); | |
121 | } else { | |
122 | res = read(src->fd, (char *)dst->mem + dst_off, len); | |
123 | } | |
124 | if (res == -1) { | |
125 | if (!copied) { | |
126 | return -errno; | |
127 | } | |
128 | break; | |
129 | } | |
130 | if (res == 0) { | |
131 | break; | |
132 | } | |
133 | ||
134 | copied += res; | |
135 | if (!(src->flags & FUSE_BUF_FD_RETRY)) { | |
136 | break; | |
137 | } | |
138 | ||
139 | dst_off += res; | |
140 | src_off += res; | |
141 | len -= res; | |
142 | } | |
143 | ||
144 | return copied; | |
ffcf8d9f DDAG |
145 | } |
146 | ||
147 | static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
148 | const struct fuse_buf *src, size_t src_off, |
149 | size_t len) | |
ffcf8d9f | 150 | { |
7387863d DDAG |
151 | char buf[4096]; |
152 | struct fuse_buf tmp = { | |
153 | .size = sizeof(buf), | |
154 | .flags = 0, | |
155 | }; | |
156 | ssize_t res; | |
157 | size_t copied = 0; | |
158 | ||
159 | tmp.mem = buf; | |
160 | ||
161 | while (len) { | |
162 | size_t this_len = min_size(tmp.size, len); | |
163 | size_t read_len; | |
164 | ||
165 | res = fuse_buf_read(&tmp, 0, src, src_off, this_len); | |
166 | if (res < 0) { | |
167 | if (!copied) { | |
168 | return res; | |
169 | } | |
170 | break; | |
171 | } | |
172 | if (res == 0) { | |
173 | break; | |
174 | } | |
175 | ||
176 | read_len = res; | |
177 | res = fuse_buf_write(dst, dst_off, &tmp, 0, read_len); | |
178 | if (res < 0) { | |
179 | if (!copied) { | |
180 | return res; | |
181 | } | |
182 | break; | |
183 | } | |
184 | if (res == 0) { | |
185 | break; | |
186 | } | |
187 | ||
188 | copied += res; | |
189 | ||
190 | if (res < this_len) { | |
191 | break; | |
192 | } | |
193 | ||
194 | dst_off += res; | |
195 | src_off += res; | |
196 | len -= res; | |
197 | } | |
198 | ||
199 | return copied; | |
ffcf8d9f DDAG |
200 | } |
201 | ||
ffcf8d9f | 202 | static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off, |
7387863d | 203 | const struct fuse_buf *src, size_t src_off, |
8c3fe75e | 204 | size_t len) |
ffcf8d9f | 205 | { |
7387863d DDAG |
206 | int src_is_fd = src->flags & FUSE_BUF_IS_FD; |
207 | int dst_is_fd = dst->flags & FUSE_BUF_IS_FD; | |
208 | ||
209 | if (!src_is_fd && !dst_is_fd) { | |
210 | char *dstmem = (char *)dst->mem + dst_off; | |
211 | char *srcmem = (char *)src->mem + src_off; | |
212 | ||
213 | if (dstmem != srcmem) { | |
214 | if (dstmem + len <= srcmem || srcmem + len <= dstmem) { | |
215 | memcpy(dstmem, srcmem, len); | |
216 | } else { | |
217 | memmove(dstmem, srcmem, len); | |
218 | } | |
219 | } | |
220 | ||
221 | return len; | |
222 | } else if (!src_is_fd) { | |
223 | return fuse_buf_write(dst, dst_off, src, src_off, len); | |
224 | } else if (!dst_is_fd) { | |
225 | return fuse_buf_read(dst, dst_off, src, src_off, len); | |
226 | } else { | |
227 | return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len); | |
228 | } | |
ffcf8d9f DDAG |
229 | } |
230 | ||
231 | static const struct fuse_buf *fuse_bufvec_current(struct fuse_bufvec *bufv) | |
232 | { | |
7387863d DDAG |
233 | if (bufv->idx < bufv->count) { |
234 | return &bufv->buf[bufv->idx]; | |
235 | } else { | |
236 | return NULL; | |
237 | } | |
ffcf8d9f DDAG |
238 | } |
239 | ||
240 | static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len) | |
241 | { | |
7387863d DDAG |
242 | const struct fuse_buf *buf = fuse_bufvec_current(bufv); |
243 | ||
7fa87944 HL |
244 | if (!buf) { |
245 | return 0; | |
246 | } | |
247 | ||
7387863d DDAG |
248 | bufv->off += len; |
249 | assert(bufv->off <= buf->size); | |
250 | if (bufv->off == buf->size) { | |
251 | assert(bufv->idx < bufv->count); | |
252 | bufv->idx++; | |
253 | if (bufv->idx == bufv->count) { | |
254 | return 0; | |
255 | } | |
256 | bufv->off = 0; | |
257 | } | |
258 | return 1; | |
ffcf8d9f DDAG |
259 | } |
260 | ||
8c3fe75e | 261 | ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv) |
ffcf8d9f | 262 | { |
c465bba2 | 263 | size_t copied = 0, i; |
7387863d DDAG |
264 | |
265 | if (dstv == srcv) { | |
266 | return fuse_buf_size(dstv); | |
267 | } | |
268 | ||
c465bba2 | 269 | /* |
270 | * use writev to improve bandwidth when all the | |
271 | * src buffers already mapped by the daemon | |
272 | * process | |
273 | */ | |
274 | for (i = 0; i < srcv->count; i++) { | |
275 | if (srcv->buf[i].flags & FUSE_BUF_IS_FD) { | |
276 | break; | |
277 | } | |
278 | } | |
279 | if ((i == srcv->count) && (dstv->count == 1) && | |
280 | (dstv->idx == 0) && | |
281 | (dstv->buf[0].flags & FUSE_BUF_IS_FD)) { | |
282 | dstv->buf[0].pos += dstv->off; | |
283 | return fuse_buf_writev(&dstv->buf[0], srcv); | |
284 | } | |
285 | ||
7387863d DDAG |
286 | for (;;) { |
287 | const struct fuse_buf *src = fuse_bufvec_current(srcv); | |
288 | const struct fuse_buf *dst = fuse_bufvec_current(dstv); | |
289 | size_t src_len; | |
290 | size_t dst_len; | |
291 | size_t len; | |
292 | ssize_t res; | |
293 | ||
294 | if (src == NULL || dst == NULL) { | |
295 | break; | |
296 | } | |
297 | ||
298 | src_len = src->size - srcv->off; | |
299 | dst_len = dst->size - dstv->off; | |
300 | len = min_size(src_len, dst_len); | |
301 | ||
8c3fe75e | 302 | res = fuse_buf_copy_one(dst, dstv->off, src, srcv->off, len); |
7387863d DDAG |
303 | if (res < 0) { |
304 | if (!copied) { | |
305 | return res; | |
306 | } | |
307 | break; | |
308 | } | |
309 | copied += res; | |
310 | ||
311 | if (!fuse_bufvec_advance(srcv, res) || | |
312 | !fuse_bufvec_advance(dstv, res)) { | |
313 | break; | |
314 | } | |
315 | ||
316 | if (res < len) { | |
317 | break; | |
318 | } | |
319 | } | |
320 | ||
321 | return copied; | |
ffcf8d9f | 322 | } |
dad157e8 SH |
323 | |
324 | void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len) | |
325 | { | |
326 | void *ptr; | |
327 | ||
328 | if (len > iter->size - iter->pos) { | |
329 | return NULL; | |
330 | } | |
331 | ||
332 | ptr = iter->mem + iter->pos; | |
333 | iter->pos += len; | |
334 | return ptr; | |
335 | } | |
336 | ||
337 | const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter) | |
338 | { | |
339 | const char *str = iter->mem + iter->pos; | |
340 | size_t remaining = iter->size - iter->pos; | |
341 | size_t i; | |
342 | ||
343 | for (i = 0; i < remaining; i++) { | |
344 | if (str[i] == '\0') { | |
345 | iter->pos += i + 1; | |
346 | return str; | |
347 | } | |
348 | } | |
349 | return NULL; | |
350 | } |