diff options
Diffstat (limited to 'tools/virtiofsd/buffer.c')
| -rw-r--r-- | tools/virtiofsd/buffer.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c new file mode 100644 index 0000000000..27c1377f22 --- /dev/null +++ b/tools/virtiofsd/buffer.c @@ -0,0 +1,351 @@ +/* + * FUSE: Filesystem in Userspace + * Copyright (C) 2010 Miklos Szeredi <miklos@szeredi.hu> + * + * Functions for dealing with `struct fuse_buf` and `struct + * fuse_bufvec`. + * + * This program can be distributed under the terms of the GNU LGPLv2. + * See the file COPYING.LIB + */ + +#include "qemu/osdep.h" +#include "fuse_i.h" +#include "fuse_lowlevel.h" +#include <assert.h> +#include <errno.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +size_t fuse_buf_size(const struct fuse_bufvec *bufv) +{ + size_t i; + size_t size = 0; + + for (i = 0; i < bufv->count; i++) { + if (bufv->buf[i].size == SIZE_MAX) { + size = SIZE_MAX; + } else { + size += bufv->buf[i].size; + } + } + + return size; +} + +static ssize_t fuse_buf_writev(struct fuse_buf *out_buf, + struct fuse_bufvec *in_buf) +{ + ssize_t res, i, j; + size_t iovcnt = in_buf->count; + struct iovec *iov; + int fd = out_buf->fd; + + iov = calloc(iovcnt, sizeof(struct iovec)); + if (!iov) { + return -ENOMEM; + } + + for (i = 0, j = 0; i < iovcnt; i++) { + /* Skip the buf with 0 size */ + if (in_buf->buf[i].size) { + iov[j].iov_base = in_buf->buf[i].mem; + iov[j].iov_len = in_buf->buf[i].size; + j++; + } + } + + if (out_buf->flags & FUSE_BUF_FD_SEEK) { + res = pwritev(fd, iov, iovcnt, out_buf->pos); + } else { + res = writev(fd, iov, iovcnt); + } + + if (res == -1) { + res = -errno; + } + + free(iov); + return res; +} + +static size_t min_size(size_t s1, size_t s2) +{ + return s1 < s2 ? s1 : s2; +} + +static ssize_t fuse_buf_write(const struct fuse_buf *dst, size_t dst_off, + const struct fuse_buf *src, size_t src_off, + size_t len) +{ + ssize_t res = 0; + size_t copied = 0; + + while (len) { + if (dst->flags & FUSE_BUF_FD_SEEK) { + res = pwrite(dst->fd, (char *)src->mem + src_off, len, + dst->pos + dst_off); + } else { + res = write(dst->fd, (char *)src->mem + src_off, len); + } + if (res == -1) { + if (!copied) { + return -errno; + } + break; + } + if (res == 0) { + break; + } + + copied += res; + if (!(dst->flags & FUSE_BUF_FD_RETRY)) { + break; + } + + src_off += res; + dst_off += res; + len -= res; + } + + return copied; +} + +static ssize_t fuse_buf_read(const struct fuse_buf *dst, size_t dst_off, + const struct fuse_buf *src, size_t src_off, + size_t len) +{ + ssize_t res = 0; + size_t copied = 0; + + while (len) { + if (src->flags & FUSE_BUF_FD_SEEK) { + res = pread(src->fd, (char *)dst->mem + dst_off, len, + src->pos + src_off); + } else { + res = read(src->fd, (char *)dst->mem + dst_off, len); + } + if (res == -1) { + if (!copied) { + return -errno; + } + break; + } + if (res == 0) { + break; + } + + copied += res; + if (!(src->flags & FUSE_BUF_FD_RETRY)) { + break; + } + + dst_off += res; + src_off += res; + len -= res; + } + + return copied; +} + +static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off, + const struct fuse_buf *src, size_t src_off, + size_t len) +{ + char buf[4096]; + struct fuse_buf tmp = { + .size = sizeof(buf), + .flags = 0, + }; + ssize_t res; + size_t copied = 0; + + tmp.mem = buf; + + while (len) { + size_t this_len = min_size(tmp.size, len); + size_t read_len; + + res = fuse_buf_read(&tmp, 0, src, src_off, this_len); + if (res < 0) { + if (!copied) { + return res; + } + break; + } + if (res == 0) { + break; + } + + read_len = res; + res = fuse_buf_write(dst, dst_off, &tmp, 0, read_len); + if (res < 0) { + if (!copied) { + return res; + } + break; + } + if (res == 0) { + break; + } + + copied += res; + + if (res < this_len) { + break; + } + + dst_off += res; + src_off += res; + len -= res; + } + + return copied; +} + +static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off, + const struct fuse_buf *src, size_t src_off, + size_t len) +{ + int src_is_fd = src->flags & FUSE_BUF_IS_FD; + int dst_is_fd = dst->flags & FUSE_BUF_IS_FD; + + if (!src_is_fd && !dst_is_fd) { + char *dstmem = (char *)dst->mem + dst_off; + char *srcmem = (char *)src->mem + src_off; + + if (dstmem != srcmem) { + if (dstmem + len <= srcmem || srcmem + len <= dstmem) { + memcpy(dstmem, srcmem, len); + } else { + memmove(dstmem, srcmem, len); + } + } + + return len; + } else if (!src_is_fd) { + return fuse_buf_write(dst, dst_off, src, src_off, len); + } else if (!dst_is_fd) { + return fuse_buf_read(dst, dst_off, src, src_off, len); + } else { + return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len); + } +} + +static const struct fuse_buf *fuse_bufvec_current(struct fuse_bufvec *bufv) +{ + if (bufv->idx < bufv->count) { + return &bufv->buf[bufv->idx]; + } else { + return NULL; + } +} + +static int fuse_bufvec_advance(struct fuse_bufvec *bufv, size_t len) +{ + const struct fuse_buf *buf = fuse_bufvec_current(bufv); + + bufv->off += len; + assert(bufv->off <= buf->size); + if (bufv->off == buf->size) { + assert(bufv->idx < bufv->count); + bufv->idx++; + if (bufv->idx == bufv->count) { + return 0; + } + bufv->off = 0; + } + return 1; +} + +ssize_t fuse_buf_copy(struct fuse_bufvec *dstv, struct fuse_bufvec *srcv) +{ + size_t copied = 0, i; + + if (dstv == srcv) { + return fuse_buf_size(dstv); + } + + /* + * use writev to improve bandwidth when all the + * src buffers already mapped by the daemon + * process + */ + for (i = 0; i < srcv->count; i++) { + if (srcv->buf[i].flags & FUSE_BUF_IS_FD) { + break; + } + } + if ((i == srcv->count) && (dstv->count == 1) && + (dstv->idx == 0) && + (dstv->buf[0].flags & FUSE_BUF_IS_FD)) { + dstv->buf[0].pos += dstv->off; + return fuse_buf_writev(&dstv->buf[0], srcv); + } + + for (;;) { + const struct fuse_buf *src = fuse_bufvec_current(srcv); + const struct fuse_buf *dst = fuse_bufvec_current(dstv); + size_t src_len; + size_t dst_len; + size_t len; + ssize_t res; + + if (src == NULL || dst == NULL) { + break; + } + + src_len = src->size - srcv->off; + dst_len = dst->size - dstv->off; + len = min_size(src_len, dst_len); + + res = fuse_buf_copy_one(dst, dstv->off, src, srcv->off, len); + if (res < 0) { + if (!copied) { + return res; + } + break; + } + copied += res; + + if (!fuse_bufvec_advance(srcv, res) || + !fuse_bufvec_advance(dstv, res)) { + break; + } + + if (res < len) { + break; + } + } + + return copied; +} + +void *fuse_mbuf_iter_advance(struct fuse_mbuf_iter *iter, size_t len) +{ + void *ptr; + + if (len > iter->size - iter->pos) { + return NULL; + } + + ptr = iter->mem + iter->pos; + iter->pos += len; + return ptr; +} + +const char *fuse_mbuf_iter_advance_str(struct fuse_mbuf_iter *iter) +{ + const char *str = iter->mem + iter->pos; + size_t remaining = iter->size - iter->pos; + size_t i; + + for (i = 0; i < remaining; i++) { + if (str[i] == '\0') { + iter->pos += i + 1; + return str; + } + } + return NULL; +} |