2 * FUSE: Filesystem in Userspace
5 * Functions for dealing with `struct fuse_buf` and `struct
8 * This program can be distributed under the terms of the GNU LGPLv2.
9 * See the file COPYING.LIB
12 #include "qemu/osdep.h"
14 #include "fuse_lowlevel.h"
21 size_t fuse_buf_size(const struct fuse_bufvec *bufv)
26 for (i = 0; i < bufv->count; i++) {
27 if (bufv->buf[i].size == SIZE_MAX) {
30 size += bufv->buf[i].size;
37 static ssize_t fuse_buf_writev(struct fuse_buf *out_buf,
38 struct fuse_bufvec *in_buf)
41 size_t iovcnt = in_buf->count;
45 iov = calloc(iovcnt, sizeof(struct iovec));
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;
59 if (out_buf->flags & FUSE_BUF_FD_SEEK) {
60 res = pwritev(fd, iov, iovcnt, out_buf->pos);
62 res = writev(fd, iov, iovcnt);
73 static size_t min_size(size_t s1, size_t s2)
75 return s1 < s2 ? s1 : s2;
78 static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off,
79 const struct fuse_buf *src, size_t src_off,
86 if (dst->flags & FUSE_BUF_FD_SEEK) {
87 res = pwrite(dst->fd, (char *)src->mem + src_off, len,
90 res = write(dst->fd, (char *)src->mem + src_off, len);
103 if (!(dst->flags & FUSE_BUF_FD_RETRY)) {
115 static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off,
116 const struct fuse_buf *src, size_t src_off,
123 if (src->flags & FUSE_BUF_FD_SEEK) {
124 res = pread(src->fd, (char *)dst->mem + dst_off, len,
127 res = read(src->fd, (char *)dst->mem + dst_off, len);
140 if (!(src->flags & FUSE_BUF_FD_RETRY)) {
152 static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off,
153 const struct fuse_buf *src, size_t src_off,
157 struct fuse_buf tmp = {
167 size_t this_len = min_size(tmp.size, len);
170 res = fuse_buf_read(&tmp, 0, src, src_off, this_len);
182 res = fuse_buf_write(dst, dst_off, &tmp, 0, read_len);
195 if (res < this_len) {
207 static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off,
208 const struct fuse_buf *src, size_t src_off,
211 int src_is_fd = src->flags & FUSE_BUF_IS_FD;
212 int dst_is_fd = dst->flags & FUSE_BUF_IS_FD;
214 if (!src_is_fd && !dst_is_fd) {
215 char *dstmem = (char *)dst->mem + dst_off;
216 char *srcmem = (char *)src->mem + src_off;
218 if (dstmem != srcmem) {
219 if (dstmem + len <= srcmem || srcmem + len <= dstmem) {
220 memcpy(dstmem, srcmem, len);
222 memmove(dstmem, srcmem, 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);
232 return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len);
236 static const struct fuse_buf *fuse_bufvec_current(struct fuse_bufvec *bufv)
238 if (bufv->idx < bufv->count) {
239 return &bufv->buf[bufv->idx];
245 static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len)
247 const struct fuse_buf *buf = fuse_bufvec_current(bufv);
250 assert(bufv->off <= buf->size);
251 if (bufv->off == buf->size) {
252 assert(bufv->idx < bufv->count);
254 if (bufv->idx == bufv->count) {
262 ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv)
264 size_t copied = 0, i;
267 return fuse_buf_size(dstv);
271 * use writev to improve bandwidth when all the
272 * src buffers already mapped by the daemon
275 for (i = 0; i < srcv->count; i++) {
276 if (srcv->buf[i].flags & FUSE_BUF_IS_FD) {
280 if ((i == srcv->count) && (dstv->count == 1) &&
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);
288 const struct fuse_buf *src = fuse_bufvec_current(srcv);
289 const struct fuse_buf *dst = fuse_bufvec_current(dstv);
295 if (src == NULL || dst == NULL) {
299 src_len = src->size - srcv->off;
300 dst_len = dst->size - dstv->off;
301 len = min_size(src_len, dst_len);
303 res = fuse_buf_copy_one(dst, dstv->off, src, srcv->off, len);
312 if (!fuse_bufvec_advance(srcv, res) ||
313 !fuse_bufvec_advance(dstv, res)) {
325 void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len)
329 if (len > iter->size - iter->pos) {
333 ptr = iter->mem + iter->pos;
338 const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter)
340 const char *str = iter->mem + iter->pos;
341 size_t remaining = iter->size - iter->pos;
344 for (i = 0; i < remaining; i++) {
345 if (str[i] == '\0') {