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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 DDAG |
11 | |
12 | #define _GNU_SOURCE | |
13 | ||
14 | #include "config.h" | |
15 | #include "fuse_i.h" | |
16 | #include "fuse_lowlevel.h" | |
7387863d DDAG |
17 | #include <assert.h> |
18 | #include <errno.h> | |
ffcf8d9f DDAG |
19 | #include <string.h> |
20 | #include <unistd.h> | |
ffcf8d9f DDAG |
21 | |
22 | size_t fuse_buf_size(const struct fuse_bufvec *bufv) | |
23 | { | |
7387863d DDAG |
24 | size_t i; |
25 | size_t size = 0; | |
26 | ||
27 | for (i = 0; i < bufv->count; i++) { | |
28 | if (bufv->buf[i].size == SIZE_MAX) { | |
29 | size = SIZE_MAX; | |
30 | } else { | |
31 | size += bufv->buf[i].size; | |
32 | } | |
33 | } | |
34 | ||
35 | return size; | |
ffcf8d9f DDAG |
36 | } |
37 | ||
38 | static size_t min_size(size_t s1, size_t s2) | |
39 | { | |
7387863d | 40 | return s1 < s2 ? s1 : s2; |
ffcf8d9f DDAG |
41 | } |
42 | ||
43 | static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
44 | const struct fuse_buf *src, size_t src_off, |
45 | size_t len) | |
ffcf8d9f | 46 | { |
7387863d DDAG |
47 | ssize_t res = 0; |
48 | size_t copied = 0; | |
49 | ||
50 | while (len) { | |
51 | if (dst->flags & FUSE_BUF_FD_SEEK) { | |
52 | res = pwrite(dst->fd, (char *)src->mem + src_off, len, | |
53 | dst->pos + dst_off); | |
54 | } else { | |
55 | res = write(dst->fd, (char *)src->mem + src_off, len); | |
56 | } | |
57 | if (res == -1) { | |
58 | if (!copied) { | |
59 | return -errno; | |
60 | } | |
61 | break; | |
62 | } | |
63 | if (res == 0) { | |
64 | break; | |
65 | } | |
66 | ||
67 | copied += res; | |
68 | if (!(dst->flags & FUSE_BUF_FD_RETRY)) { | |
69 | break; | |
70 | } | |
71 | ||
72 | src_off += res; | |
73 | dst_off += res; | |
74 | len -= res; | |
75 | } | |
76 | ||
77 | return copied; | |
ffcf8d9f DDAG |
78 | } |
79 | ||
80 | static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
81 | const struct fuse_buf *src, size_t src_off, |
82 | size_t len) | |
ffcf8d9f | 83 | { |
7387863d DDAG |
84 | ssize_t res = 0; |
85 | size_t copied = 0; | |
86 | ||
87 | while (len) { | |
88 | if (src->flags & FUSE_BUF_FD_SEEK) { | |
89 | res = pread(src->fd, (char *)dst->mem + dst_off, len, | |
90 | src->pos + src_off); | |
91 | } else { | |
92 | res = read(src->fd, (char *)dst->mem + dst_off, len); | |
93 | } | |
94 | if (res == -1) { | |
95 | if (!copied) { | |
96 | return -errno; | |
97 | } | |
98 | break; | |
99 | } | |
100 | if (res == 0) { | |
101 | break; | |
102 | } | |
103 | ||
104 | copied += res; | |
105 | if (!(src->flags & FUSE_BUF_FD_RETRY)) { | |
106 | break; | |
107 | } | |
108 | ||
109 | dst_off += res; | |
110 | src_off += res; | |
111 | len -= res; | |
112 | } | |
113 | ||
114 | return copied; | |
ffcf8d9f DDAG |
115 | } |
116 | ||
117 | static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off, | |
7387863d DDAG |
118 | const struct fuse_buf *src, size_t src_off, |
119 | size_t len) | |
ffcf8d9f | 120 | { |
7387863d DDAG |
121 | char buf[4096]; |
122 | struct fuse_buf tmp = { | |
123 | .size = sizeof(buf), | |
124 | .flags = 0, | |
125 | }; | |
126 | ssize_t res; | |
127 | size_t copied = 0; | |
128 | ||
129 | tmp.mem = buf; | |
130 | ||
131 | while (len) { | |
132 | size_t this_len = min_size(tmp.size, len); | |
133 | size_t read_len; | |
134 | ||
135 | res = fuse_buf_read(&tmp, 0, src, src_off, this_len); | |
136 | if (res < 0) { | |
137 | if (!copied) { | |
138 | return res; | |
139 | } | |
140 | break; | |
141 | } | |
142 | if (res == 0) { | |
143 | break; | |
144 | } | |
145 | ||
146 | read_len = res; | |
147 | res = fuse_buf_write(dst, dst_off, &tmp, 0, read_len); | |
148 | if (res < 0) { | |
149 | if (!copied) { | |
150 | return res; | |
151 | } | |
152 | break; | |
153 | } | |
154 | if (res == 0) { | |
155 | break; | |
156 | } | |
157 | ||
158 | copied += res; | |
159 | ||
160 | if (res < this_len) { | |
161 | break; | |
162 | } | |
163 | ||
164 | dst_off += res; | |
165 | src_off += res; | |
166 | len -= res; | |
167 | } | |
168 | ||
169 | return copied; | |
ffcf8d9f DDAG |
170 | } |
171 | ||
ffcf8d9f | 172 | static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off, |
7387863d | 173 | const struct fuse_buf *src, size_t src_off, |
8c3fe75e | 174 | size_t len) |
ffcf8d9f | 175 | { |
7387863d DDAG |
176 | int src_is_fd = src->flags & FUSE_BUF_IS_FD; |
177 | int dst_is_fd = dst->flags & FUSE_BUF_IS_FD; | |
178 | ||
179 | if (!src_is_fd && !dst_is_fd) { | |
180 | char *dstmem = (char *)dst->mem + dst_off; | |
181 | char *srcmem = (char *)src->mem + src_off; | |
182 | ||
183 | if (dstmem != srcmem) { | |
184 | if (dstmem + len <= srcmem || srcmem + len <= dstmem) { | |
185 | memcpy(dstmem, srcmem, len); | |
186 | } else { | |
187 | memmove(dstmem, srcmem, len); | |
188 | } | |
189 | } | |
190 | ||
191 | return len; | |
192 | } else if (!src_is_fd) { | |
193 | return fuse_buf_write(dst, dst_off, src, src_off, len); | |
194 | } else if (!dst_is_fd) { | |
195 | return fuse_buf_read(dst, dst_off, src, src_off, len); | |
196 | } else { | |
197 | return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len); | |
198 | } | |
ffcf8d9f DDAG |
199 | } |
200 | ||
201 | static const struct fuse_buf *fuse_bufvec_current(struct fuse_bufvec *bufv) | |
202 | { | |
7387863d DDAG |
203 | if (bufv->idx < bufv->count) { |
204 | return &bufv->buf[bufv->idx]; | |
205 | } else { | |
206 | return NULL; | |
207 | } | |
ffcf8d9f DDAG |
208 | } |
209 | ||
210 | static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len) | |
211 | { | |
7387863d DDAG |
212 | const struct fuse_buf *buf = fuse_bufvec_current(bufv); |
213 | ||
214 | bufv->off += len; | |
215 | assert(bufv->off <= buf->size); | |
216 | if (bufv->off == buf->size) { | |
217 | assert(bufv->idx < bufv->count); | |
218 | bufv->idx++; | |
219 | if (bufv->idx == bufv->count) { | |
220 | return 0; | |
221 | } | |
222 | bufv->off = 0; | |
223 | } | |
224 | return 1; | |
ffcf8d9f DDAG |
225 | } |
226 | ||
8c3fe75e | 227 | ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv) |
ffcf8d9f | 228 | { |
7387863d DDAG |
229 | size_t copied = 0; |
230 | ||
231 | if (dstv == srcv) { | |
232 | return fuse_buf_size(dstv); | |
233 | } | |
234 | ||
235 | for (;;) { | |
236 | const struct fuse_buf *src = fuse_bufvec_current(srcv); | |
237 | const struct fuse_buf *dst = fuse_bufvec_current(dstv); | |
238 | size_t src_len; | |
239 | size_t dst_len; | |
240 | size_t len; | |
241 | ssize_t res; | |
242 | ||
243 | if (src == NULL || dst == NULL) { | |
244 | break; | |
245 | } | |
246 | ||
247 | src_len = src->size - srcv->off; | |
248 | dst_len = dst->size - dstv->off; | |
249 | len = min_size(src_len, dst_len); | |
250 | ||
8c3fe75e | 251 | res = fuse_buf_copy_one(dst, dstv->off, src, srcv->off, len); |
7387863d DDAG |
252 | if (res < 0) { |
253 | if (!copied) { | |
254 | return res; | |
255 | } | |
256 | break; | |
257 | } | |
258 | copied += res; | |
259 | ||
260 | if (!fuse_bufvec_advance(srcv, res) || | |
261 | !fuse_bufvec_advance(dstv, res)) { | |
262 | break; | |
263 | } | |
264 | ||
265 | if (res < len) { | |
266 | break; | |
267 | } | |
268 | } | |
269 | ||
270 | return copied; | |
ffcf8d9f | 271 | } |