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qemu/migration/qemu-file.c

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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include <zlib.h>
#include "qemu-common.h"
#include "qemu/error-report.h"
#include "qemu/iov.h"
#include "migration.h"
#include "qemu-file.h"
#include "trace.h"
#define IO_BUF_SIZE 32768
#define MAX_IOV_SIZE MIN(IOV_MAX, 64)
struct QEMUFile {
const QEMUFileOps *ops;
const QEMUFileHooks *hooks;
void *opaque;
int64_t bytes_xfer;
int64_t xfer_limit;
int64_t pos; /* start of buffer when writing, end of buffer
when reading */
int buf_index;
int buf_size; /* 0 when writing */
uint8_t buf[IO_BUF_SIZE];
DECLARE_BITMAP(may_free, MAX_IOV_SIZE);
struct iovec iov[MAX_IOV_SIZE];
unsigned int iovcnt;
int last_error;
};
/*
* Stop a file from being read/written - not all backing files can do this
* typically only sockets can.
*/
int qemu_file_shutdown(QEMUFile *f)
{
if (!f->ops->shut_down) {
return -ENOSYS;
}
return f->ops->shut_down(f->opaque, true, true);
}
/*
* Result: QEMUFile* for a 'return path' for comms in the opposite direction
* NULL if not available
*/
QEMUFile *qemu_file_get_return_path(QEMUFile *f)
{
if (!f->ops->get_return_path) {
return NULL;
}
return f->ops->get_return_path(f->opaque);
}
bool qemu_file_mode_is_not_valid(const char *mode)
{
if (mode == NULL ||
(mode[0] != 'r' && mode[0] != 'w') ||
mode[1] != 'b' || mode[2] != 0) {
fprintf(stderr, "qemu_fopen: Argument validity check failed\n");
return true;
}
return false;
}
QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
{
QEMUFile *f;
f = g_new0(QEMUFile, 1);
f->opaque = opaque;
f->ops = ops;
return f;
}
void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks)
{
f->hooks = hooks;
}
/*
* Get last error for stream f
*
* Return negative error value if there has been an error on previous
* operations, return 0 if no error happened.
*
*/
int qemu_file_get_error(QEMUFile *f)
{
return f->last_error;
}
void qemu_file_set_error(QEMUFile *f, int ret)
{
if (f->last_error == 0) {
f->last_error = ret;
}
}
bool qemu_file_is_writable(QEMUFile *f)
{
return f->ops->writev_buffer;
}
static void qemu_iovec_release_ram(QEMUFile *f)
{
struct iovec iov;
unsigned long idx;
/* Find and release all the contiguous memory ranges marked as may_free. */
idx = find_next_bit(f->may_free, f->iovcnt, 0);
if (idx >= f->iovcnt) {
return;
}
iov = f->iov[idx];
/* The madvise() in the loop is called for iov within a continuous range and
* then reinitialize the iov. And in the end, madvise() is called for the
* last iov.
*/
while ((idx = find_next_bit(f->may_free, f->iovcnt, idx + 1)) < f->iovcnt) {
/* check for adjacent buffer and coalesce them */
if (iov.iov_base + iov.iov_len == f->iov[idx].iov_base) {
iov.iov_len += f->iov[idx].iov_len;
continue;
}
if (qemu_madvise(iov.iov_base, iov.iov_len, QEMU_MADV_DONTNEED) < 0) {
error_report("migrate: madvise DONTNEED failed %p %zd: %s",
iov.iov_base, iov.iov_len, strerror(errno));
}
iov = f->iov[idx];
}
if (qemu_madvise(iov.iov_base, iov.iov_len, QEMU_MADV_DONTNEED) < 0) {
error_report("migrate: madvise DONTNEED failed %p %zd: %s",
iov.iov_base, iov.iov_len, strerror(errno));
}
memset(f->may_free, 0, sizeof(f->may_free));
}
/**
* Flushes QEMUFile buffer
*
* If there is writev_buffer QEMUFileOps it uses it otherwise uses
* put_buffer ops. This will flush all pending data. If data was
* only partially flushed, it will set an error state.
*/
void qemu_fflush(QEMUFile *f)
{
ssize_t ret = 0;
ssize_t expect = 0;
if (!qemu_file_is_writable(f)) {
return;
}
if (f->iovcnt > 0) {
expect = iov_size(f->iov, f->iovcnt);
ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos);
qemu_iovec_release_ram(f);
}
if (ret >= 0) {
f->pos += ret;
}
/* We expect the QEMUFile write impl to send the full
* data set we requested, so sanity check that.
*/
if (ret != expect) {
qemu_file_set_error(f, ret < 0 ? ret : -EIO);
}
f->buf_index = 0;
f->iovcnt = 0;
}
void ram_control_before_iterate(QEMUFile *f, uint64_t flags)
{
int ret = 0;
if (f->hooks && f->hooks->before_ram_iterate) {
ret = f->hooks->before_ram_iterate(f, f->opaque, flags, NULL);
if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
}
void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
{
int ret = 0;
if (f->hooks && f->hooks->after_ram_iterate) {
ret = f->hooks->after_ram_iterate(f, f->opaque, flags, NULL);
if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
}
void ram_control_load_hook(QEMUFile *f, uint64_t flags, void *data)
{
int ret = -EINVAL;
if (f->hooks && f->hooks->hook_ram_load) {
ret = f->hooks->hook_ram_load(f, f->opaque, flags, data);
if (ret < 0) {
qemu_file_set_error(f, ret);
}
} else {
/*
* Hook is a hook specifically requested by the source sending a flag
* that expects there to be a hook on the destination.
*/
if (flags == RAM_CONTROL_HOOK) {
qemu_file_set_error(f, ret);
}
}
}
size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
ram_addr_t offset, size_t size,
uint64_t *bytes_sent)
{
if (f->hooks && f->hooks->save_page) {
int ret = f->hooks->save_page(f, f->opaque, block_offset,
offset, size, bytes_sent);
if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
f->bytes_xfer += size;
}
if (ret != RAM_SAVE_CONTROL_DELAYED &&
ret != RAM_SAVE_CONTROL_NOT_SUPP) {
if (bytes_sent && *bytes_sent > 0) {
qemu_update_position(f, *bytes_sent);
} else if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
return ret;
}
return RAM_SAVE_CONTROL_NOT_SUPP;
}
/*
* Attempt to fill the buffer from the underlying file
* Returns the number of bytes read, or negative value for an error.
*
* Note that it can return a partially full buffer even in a not error/not EOF
* case if the underlying file descriptor gives a short read, and that can
* happen even on a blocking fd.
*/
static ssize_t qemu_fill_buffer(QEMUFile *f)
{
int len;
int pending;
assert(!qemu_file_is_writable(f));
pending = f->buf_size - f->buf_index;
if (pending > 0) {
memmove(f->buf, f->buf + f->buf_index, pending);
}
f->buf_index = 0;
f->buf_size = pending;
len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
IO_BUF_SIZE - pending);
if (len > 0) {
f->buf_size += len;
f->pos += len;
} else if (len == 0) {
qemu_file_set_error(f, -EIO);
} else if (len != -EAGAIN) {
qemu_file_set_error(f, len);
}
return len;
}
void qemu_update_position(QEMUFile *f, size_t size)
{
f->pos += size;
}
/** Closes the file
*
* Returns negative error value if any error happened on previous operations or
* while closing the file. Returns 0 or positive number on success.
*
* The meaning of return value on success depends on the specific backend
* being used.
*/
int qemu_fclose(QEMUFile *f)
{
int ret;
qemu_fflush(f);
ret = qemu_file_get_error(f);
if (f->ops->close) {
int ret2 = f->ops->close(f->opaque);
if (ret >= 0) {
ret = ret2;
}
}
/* If any error was spotted before closing, we should report it
* instead of the close() return value.
*/
if (f->last_error) {
ret = f->last_error;
}
g_free(f);
trace_qemu_file_fclose();
return ret;
}
static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size,
bool may_free)
{
/* check for adjacent buffer and coalesce them */
if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
f->iov[f->iovcnt - 1].iov_len &&
may_free == test_bit(f->iovcnt - 1, f->may_free))
{
f->iov[f->iovcnt - 1].iov_len += size;
} else {
if (may_free) {
set_bit(f->iovcnt, f->may_free);
}
f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
f->iov[f->iovcnt++].iov_len = size;
}
if (f->iovcnt >= MAX_IOV_SIZE) {
qemu_fflush(f);
}
}
void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, size_t size,
bool may_free)
{
if (f->last_error) {
return;
}
f->bytes_xfer += size;
add_to_iovec(f, buf, size, may_free);
}
void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size)
{
size_t l;
if (f->last_error) {
return;
}
while (size > 0) {
l = IO_BUF_SIZE - f->buf_index;
if (l > size) {
l = size;
}
memcpy(f->buf + f->buf_index, buf, l);
f->bytes_xfer += l;
add_to_iovec(f, f->buf + f->buf_index, l, false);
f->buf_index += l;
if (f->buf_index == IO_BUF_SIZE) {
qemu_fflush(f);
}
if (qemu_file_get_error(f)) {
break;
}
buf += l;
size -= l;
}
}
void qemu_put_byte(QEMUFile *f, int v)
{
if (f->last_error) {
return;
}
f->buf[f->buf_index] = v;
f->bytes_xfer++;
add_to_iovec(f, f->buf + f->buf_index, 1, false);
f->buf_index++;
if (f->buf_index == IO_BUF_SIZE) {
qemu_fflush(f);
}
}
void qemu_file_skip(QEMUFile *f, int size)
{
if (f->buf_index + size <= f->buf_size) {
f->buf_index += size;
}
}
/*
* Read 'size' bytes from file (at 'offset') without moving the
* pointer and set 'buf' to point to that data.
*
* It will return size bytes unless there was an error, in which case it will
* return as many as it managed to read (assuming blocking fd's which
* all current QEMUFile are)
*/
size_t qemu_peek_buffer(QEMUFile *f, uint8_t **buf, size_t size, size_t offset)
{
ssize_t pending;
size_t index;
assert(!qemu_file_is_writable(f));
assert(offset < IO_BUF_SIZE);
assert(size <= IO_BUF_SIZE - offset);
/* The 1st byte to read from */
index = f->buf_index + offset;
/* The number of available bytes starting at index */
pending = f->buf_size - index;
/*
* qemu_fill_buffer might return just a few bytes, even when there isn't
* an error, so loop collecting them until we get enough.
*/
while (pending < size) {
int received = qemu_fill_buffer(f);
if (received <= 0) {
break;
}
index = f->buf_index + offset;
pending = f->buf_size - index;
}
if (pending <= 0) {
return 0;
}
if (size > pending) {
size = pending;
}
*buf = f->buf + index;
return size;
}
/*
* Read 'size' bytes of data from the file into buf.
* 'size' can be larger than the internal buffer.
*
* It will return size bytes unless there was an error, in which case it will
* return as many as it managed to read (assuming blocking fd's which
* all current QEMUFile are)
*/
size_t qemu_get_buffer(QEMUFile *f, uint8_t *buf, size_t size)
{
size_t pending = size;
size_t done = 0;
while (pending > 0) {
size_t res;
uint8_t *src;
res = qemu_peek_buffer(f, &src, MIN(pending, IO_BUF_SIZE), 0);
if (res == 0) {
return done;
}
memcpy(buf, src, res);
qemu_file_skip(f, res);
buf += res;
pending -= res;
done += res;
}
return done;
}
/*
* Read 'size' bytes of data from the file.
* 'size' can be larger than the internal buffer.
*
* The data:
* may be held on an internal buffer (in which case *buf is updated
* to point to it) that is valid until the next qemu_file operation.
* OR
* will be copied to the *buf that was passed in.
*
* The code tries to avoid the copy if possible.
*
* It will return size bytes unless there was an error, in which case it will
* return as many as it managed to read (assuming blocking fd's which
* all current QEMUFile are)
*
* Note: Since **buf may get changed, the caller should take care to
* keep a pointer to the original buffer if it needs to deallocate it.
*/
size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, size_t size)
{
if (size < IO_BUF_SIZE) {
size_t res;
uint8_t *src;
res = qemu_peek_buffer(f, &src, size, 0);
if (res == size) {
qemu_file_skip(f, res);
*buf = src;
return res;
}
}
return qemu_get_buffer(f, *buf, size);
}
/*
* Peeks a single byte from the buffer; this isn't guaranteed to work if
* offset leaves a gap after the previous read/peeked data.
*/
int qemu_peek_byte(QEMUFile *f, int offset)
{
int index = f->buf_index + offset;
assert(!qemu_file_is_writable(f));
assert(offset < IO_BUF_SIZE);
if (index >= f->buf_size) {
qemu_fill_buffer(f);
index = f->buf_index + offset;
if (index >= f->buf_size) {
return 0;
}
}
return f->buf[index];
}
int qemu_get_byte(QEMUFile *f)
{
int result;
result = qemu_peek_byte(f, 0);
qemu_file_skip(f, 1);
return result;
}
int64_t qemu_ftell_fast(QEMUFile *f)
{
int64_t ret = f->pos;
int i;
for (i = 0; i < f->iovcnt; i++) {
ret += f->iov[i].iov_len;
}
return ret;
}
int64_t qemu_ftell(QEMUFile *f)
{
qemu_fflush(f);
return f->pos;
}
int qemu_file_rate_limit(QEMUFile *f)
{
if (qemu_file_get_error(f)) {
return 1;
}
if (f->xfer_limit > 0 && f->bytes_xfer > f->xfer_limit) {
return 1;
}
return 0;
}
int64_t qemu_file_get_rate_limit(QEMUFile *f)
{
return f->xfer_limit;
}
void qemu_file_set_rate_limit(QEMUFile *f, int64_t limit)
{
f->xfer_limit = limit;
}
void qemu_file_reset_rate_limit(QEMUFile *f)
{
f->bytes_xfer = 0;
}
void qemu_put_be16(QEMUFile *f, unsigned int v)
{
qemu_put_byte(f, v >> 8);
qemu_put_byte(f, v);
}
void qemu_put_be32(QEMUFile *f, unsigned int v)
{
qemu_put_byte(f, v >> 24);
qemu_put_byte(f, v >> 16);
qemu_put_byte(f, v >> 8);
qemu_put_byte(f, v);
}
void qemu_put_be64(QEMUFile *f, uint64_t v)
{
qemu_put_be32(f, v >> 32);
qemu_put_be32(f, v);
}
unsigned int qemu_get_be16(QEMUFile *f)
{
unsigned int v;
v = qemu_get_byte(f) << 8;
v |= qemu_get_byte(f);
return v;
}
unsigned int qemu_get_be32(QEMUFile *f)
{
unsigned int v;
v = (unsigned int)qemu_get_byte(f) << 24;
v |= qemu_get_byte(f) << 16;
v |= qemu_get_byte(f) << 8;
v |= qemu_get_byte(f);
return v;
}
uint64_t qemu_get_be64(QEMUFile *f)
{
uint64_t v;
v = (uint64_t)qemu_get_be32(f) << 32;
v |= qemu_get_be32(f);
return v;
}
/* return the size after compression, or negative value on error */
static int qemu_compress_data(z_stream *stream, uint8_t *dest, size_t dest_len,
const uint8_t *source, size_t source_len)
{
int err;
err = deflateReset(stream);
if (err != Z_OK) {
return -1;
}
stream->avail_in = source_len;
stream->next_in = (uint8_t *)source;
stream->avail_out = dest_len;
stream->next_out = dest;
err = deflate(stream, Z_FINISH);
if (err != Z_STREAM_END) {
return -1;
}
return stream->next_out - dest;
}
/* Compress size bytes of data start at p and store the compressed
* data to the buffer of f.
*
* When f is not writable, return -1 if f has no space to save the
* compressed data.
* When f is wirtable and it has no space to save the compressed data,
* do fflush first, if f still has no space to save the compressed
* data, return -1.
*/
ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
const uint8_t *p, size_t size)
{
ssize_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int32_t);
if (blen < compressBound(size)) {
if (!qemu_file_is_writable(f)) {
return -1;
}
qemu_fflush(f);
blen = IO_BUF_SIZE - sizeof(int32_t);
if (blen < compressBound(size)) {
return -1;
}
}
blen = qemu_compress_data(stream, f->buf + f->buf_index + sizeof(int32_t),
blen, p, size);
if (blen < 0) {
return -1;
}
qemu_put_be32(f, blen);
if (f->ops->writev_buffer) {
add_to_iovec(f, f->buf + f->buf_index, blen, false);
}
f->buf_index += blen;
if (f->buf_index == IO_BUF_SIZE) {
qemu_fflush(f);
}
return blen + sizeof(int32_t);
}
/* Put the data in the buffer of f_src to the buffer of f_des, and
* then reset the buf_index of f_src to 0.
*/
int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src)
{
int len = 0;
if (f_src->buf_index > 0) {
len = f_src->buf_index;
qemu_put_buffer(f_des, f_src->buf, f_src->buf_index);
f_src->buf_index = 0;
f_src->iovcnt = 0;
}
return len;
}
/*
* Get a string whose length is determined by a single preceding byte
* A preallocated 256 byte buffer must be passed in.
* Returns: len on success and a 0 terminated string in the buffer
* else 0
* (Note a 0 length string will return 0 either way)
*/
size_t qemu_get_counted_string(QEMUFile *f, char buf[256])
{
size_t len = qemu_get_byte(f);
size_t res = qemu_get_buffer(f, (uint8_t *)buf, len);
buf[res] = 0;
return res == len ? res : 0;
}
/*
* Put a string with one preceding byte containing its length. The length of
* the string should be less than 256.
*/
void qemu_put_counted_string(QEMUFile *f, const char *str)
{
size_t len = strlen(str);
assert(len < 256);
qemu_put_byte(f, len);
qemu_put_buffer(f, (const uint8_t *)str, len);
}
/*
* Set the blocking state of the QEMUFile.
* Note: On some transports the OS only keeps a single blocking state for
* both directions, and thus changing the blocking on the main
* QEMUFile can also affect the return path.
*/
void qemu_file_set_blocking(QEMUFile *f, bool block)
{
if (f->ops->set_blocking) {
f->ops->set_blocking(f->opaque, block);
}
}
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