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/*
* 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 <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 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;
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);
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;
}
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