diff options
author | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2019-11-28 12:22:49 +0000 |
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committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2020-01-23 16:41:36 +0000 |
commit | ffcf8d9f8649c6e56b1193bbbc9c9f7388920043 (patch) | |
tree | 7d890222f8d581d2aae343734108716f94794bff /tools/virtiofsd/buffer.c | |
parent | a62a9e192bc5f0aa0bc076b51db5a069add87c78 (diff) |
virtiofsd: Add auxiliary .c's
Add most of the non-main .c files we need from upstream fuse-3.8.0
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'tools/virtiofsd/buffer.c')
-rw-r--r-- | tools/virtiofsd/buffer.c | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c new file mode 100644 index 0000000000..5ab9b87455 --- /dev/null +++ b/tools/virtiofsd/buffer.c @@ -0,0 +1,321 @@ +/* + 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 +*/ + +#define _GNU_SOURCE + +#include "config.h" +#include "fuse_i.h" +#include "fuse_lowlevel.h" +#include <string.h> +#include <unistd.h> +#include <errno.h> +#include <assert.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 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; +} + +#ifdef HAVE_SPLICE +static ssize_t fuse_buf_splice(const struct fuse_buf *dst, size_t dst_off, + const struct fuse_buf *src, size_t src_off, + size_t len, enum fuse_buf_copy_flags flags) +{ + int splice_flags = 0; + off_t *srcpos = NULL; + off_t *dstpos = NULL; + off_t srcpos_val; + off_t dstpos_val; + ssize_t res; + size_t copied = 0; + + if (flags & FUSE_BUF_SPLICE_MOVE) + splice_flags |= SPLICE_F_MOVE; + if (flags & FUSE_BUF_SPLICE_NONBLOCK) + splice_flags |= SPLICE_F_NONBLOCK; + + if (src->flags & FUSE_BUF_FD_SEEK) { + srcpos_val = src->pos + src_off; + srcpos = &srcpos_val; + } + if (dst->flags & FUSE_BUF_FD_SEEK) { + dstpos_val = dst->pos + dst_off; + dstpos = &dstpos_val; + } + + while (len) { + res = splice(src->fd, srcpos, dst->fd, dstpos, len, + splice_flags); + if (res == -1) { + if (copied) + break; + + if (errno != EINVAL || (flags & FUSE_BUF_FORCE_SPLICE)) + return -errno; + + /* Maybe splice is not supported for this combination */ + return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, + len); + } + if (res == 0) + break; + + copied += res; + if (!(src->flags & FUSE_BUF_FD_RETRY) && + !(dst->flags & FUSE_BUF_FD_RETRY)) { + break; + } + + len -= res; + } + + return copied; +} +#else +static ssize_t fuse_buf_splice(const struct fuse_buf *dst, size_t dst_off, + const struct fuse_buf *src, size_t src_off, + size_t len, enum fuse_buf_copy_flags flags) +{ + (void) flags; + + return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len); +} +#endif + + +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, enum fuse_buf_copy_flags flags) +{ + 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 if (flags & FUSE_BUF_NO_SPLICE) { + return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len); + } else { + return fuse_buf_splice(dst, dst_off, src, src_off, len, flags); + } +} + +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, + enum fuse_buf_copy_flags flags) +{ + size_t copied = 0; + + if (dstv == srcv) + return fuse_buf_size(dstv); + + 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, flags); + 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; +} |