qemu/qemu-file.c

881 lines
19 KiB
C

#include "qemu-common.h"
#include "qemu/iov.h"
#include "qemu/sockets.h"
#include "block/coroutine.h"
#include "migration/migration.h"
#include "migration/qemu-file.h"
#include "trace.h"
#define IO_BUF_SIZE 32768
#define MAX_IOV_SIZE MIN(IOV_MAX, 64)
struct QEMUFile {
const QEMUFileOps *ops;
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];
struct iovec iov[MAX_IOV_SIZE];
unsigned int iovcnt;
int last_error;
};
typedef struct QEMUFileStdio {
FILE *stdio_file;
QEMUFile *file;
} QEMUFileStdio;
typedef struct QEMUFileSocket {
int fd;
QEMUFile *file;
} QEMUFileSocket;
static ssize_t socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
int64_t pos)
{
QEMUFileSocket *s = opaque;
ssize_t len;
ssize_t size = iov_size(iov, iovcnt);
len = iov_send(s->fd, iov, iovcnt, 0, size);
if (len < size) {
len = -socket_error();
}
return len;
}
static int socket_get_fd(void *opaque)
{
QEMUFileSocket *s = opaque;
return s->fd;
}
static int socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
QEMUFileSocket *s = opaque;
ssize_t len;
for (;;) {
len = qemu_recv(s->fd, buf, size, 0);
if (len != -1) {
break;
}
if (socket_error() == EAGAIN) {
yield_until_fd_readable(s->fd);
} else if (socket_error() != EINTR) {
break;
}
}
if (len == -1) {
len = -socket_error();
}
return len;
}
static int socket_close(void *opaque)
{
QEMUFileSocket *s = opaque;
closesocket(s->fd);
g_free(s);
return 0;
}
static int stdio_get_fd(void *opaque)
{
QEMUFileStdio *s = opaque;
return fileno(s->stdio_file);
}
static int stdio_put_buffer(void *opaque, const uint8_t *buf, int64_t pos,
int size)
{
QEMUFileStdio *s = opaque;
int res;
res = fwrite(buf, 1, size, s->stdio_file);
if (res != size) {
return -errno;
}
return res;
}
static int stdio_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
QEMUFileStdio *s = opaque;
FILE *fp = s->stdio_file;
int bytes;
for (;;) {
clearerr(fp);
bytes = fread(buf, 1, size, fp);
if (bytes != 0 || !ferror(fp)) {
break;
}
if (errno == EAGAIN) {
yield_until_fd_readable(fileno(fp));
} else if (errno != EINTR) {
break;
}
}
return bytes;
}
static int stdio_pclose(void *opaque)
{
QEMUFileStdio *s = opaque;
int ret;
ret = pclose(s->stdio_file);
if (ret == -1) {
ret = -errno;
} else if (!WIFEXITED(ret) || WEXITSTATUS(ret) != 0) {
/* close succeeded, but non-zero exit code: */
ret = -EIO; /* fake errno value */
}
g_free(s);
return ret;
}
static int stdio_fclose(void *opaque)
{
QEMUFileStdio *s = opaque;
int ret = 0;
if (s->file->ops->put_buffer || s->file->ops->writev_buffer) {
int fd = fileno(s->stdio_file);
struct stat st;
ret = fstat(fd, &st);
if (ret == 0 && S_ISREG(st.st_mode)) {
/*
* If the file handle is a regular file make sure the
* data is flushed to disk before signaling success.
*/
ret = fsync(fd);
if (ret != 0) {
ret = -errno;
return ret;
}
}
}
if (fclose(s->stdio_file) == EOF) {
ret = -errno;
}
g_free(s);
return ret;
}
static const QEMUFileOps stdio_pipe_read_ops = {
.get_fd = stdio_get_fd,
.get_buffer = stdio_get_buffer,
.close = stdio_pclose
};
static const QEMUFileOps stdio_pipe_write_ops = {
.get_fd = stdio_get_fd,
.put_buffer = stdio_put_buffer,
.close = stdio_pclose
};
QEMUFile *qemu_popen_cmd(const char *command, const char *mode)
{
FILE *stdio_file;
QEMUFileStdio *s;
if (mode == NULL || (mode[0] != 'r' && mode[0] != 'w') || mode[1] != 0) {
fprintf(stderr, "qemu_popen: Argument validity check failed\n");
return NULL;
}
stdio_file = popen(command, mode);
if (stdio_file == NULL) {
return NULL;
}
s = g_malloc0(sizeof(QEMUFileStdio));
s->stdio_file = stdio_file;
if (mode[0] == 'r') {
s->file = qemu_fopen_ops(s, &stdio_pipe_read_ops);
} else {
s->file = qemu_fopen_ops(s, &stdio_pipe_write_ops);
}
return s->file;
}
static const QEMUFileOps stdio_file_read_ops = {
.get_fd = stdio_get_fd,
.get_buffer = stdio_get_buffer,
.close = stdio_fclose
};
static const QEMUFileOps stdio_file_write_ops = {
.get_fd = stdio_get_fd,
.put_buffer = stdio_put_buffer,
.close = stdio_fclose
};
static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
int64_t pos)
{
QEMUFileSocket *s = opaque;
ssize_t len, offset;
ssize_t size = iov_size(iov, iovcnt);
ssize_t total = 0;
assert(iovcnt > 0);
offset = 0;
while (size > 0) {
/* Find the next start position; skip all full-sized vector elements */
while (offset >= iov[0].iov_len) {
offset -= iov[0].iov_len;
iov++, iovcnt--;
}
/* skip `offset' bytes from the (now) first element, undo it on exit */
assert(iovcnt > 0);
iov[0].iov_base += offset;
iov[0].iov_len -= offset;
do {
len = writev(s->fd, iov, iovcnt);
} while (len == -1 && errno == EINTR);
if (len == -1) {
return -errno;
}
/* Undo the changes above */
iov[0].iov_base -= offset;
iov[0].iov_len += offset;
/* Prepare for the next iteration */
offset += len;
total += len;
size -= len;
}
return total;
}
static int unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
QEMUFileSocket *s = opaque;
ssize_t len;
for (;;) {
len = read(s->fd, buf, size);
if (len != -1) {
break;
}
if (errno == EAGAIN) {
yield_until_fd_readable(s->fd);
} else if (errno != EINTR) {
break;
}
}
if (len == -1) {
len = -errno;
}
return len;
}
static int unix_close(void *opaque)
{
QEMUFileSocket *s = opaque;
close(s->fd);
g_free(s);
return 0;
}
static const QEMUFileOps unix_read_ops = {
.get_fd = socket_get_fd,
.get_buffer = unix_get_buffer,
.close = unix_close
};
static const QEMUFileOps unix_write_ops = {
.get_fd = socket_get_fd,
.writev_buffer = unix_writev_buffer,
.close = unix_close
};
QEMUFile *qemu_fdopen(int fd, const char *mode)
{
QEMUFileSocket *s;
if (mode == NULL ||
(mode[0] != 'r' && mode[0] != 'w') ||
mode[1] != 'b' || mode[2] != 0) {
fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
return NULL;
}
s = g_malloc0(sizeof(QEMUFileSocket));
s->fd = fd;
if (mode[0] == 'r') {
s->file = qemu_fopen_ops(s, &unix_read_ops);
} else {
s->file = qemu_fopen_ops(s, &unix_write_ops);
}
return s->file;
}
static const QEMUFileOps socket_read_ops = {
.get_fd = socket_get_fd,
.get_buffer = socket_get_buffer,
.close = socket_close
};
static const QEMUFileOps socket_write_ops = {
.get_fd = socket_get_fd,
.writev_buffer = socket_writev_buffer,
.close = socket_close
};
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_socket(int fd, const char *mode)
{
QEMUFileSocket *s;
if (qemu_file_mode_is_not_valid(mode)) {
return NULL;
}
s = g_malloc0(sizeof(QEMUFileSocket));
s->fd = fd;
if (mode[0] == 'w') {
qemu_set_block(s->fd);
s->file = qemu_fopen_ops(s, &socket_write_ops);
} else {
s->file = qemu_fopen_ops(s, &socket_read_ops);
}
return s->file;
}
QEMUFile *qemu_fopen(const char *filename, const char *mode)
{
QEMUFileStdio *s;
if (qemu_file_mode_is_not_valid(mode)) {
return NULL;
}
s = g_malloc0(sizeof(QEMUFileStdio));
s->stdio_file = fopen(filename, mode);
if (!s->stdio_file) {
goto fail;
}
if (mode[0] == 'w') {
s->file = qemu_fopen_ops(s, &stdio_file_write_ops);
} else {
s->file = qemu_fopen_ops(s, &stdio_file_read_ops);
}
return s->file;
fail:
g_free(s);
return NULL;
}
QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
{
QEMUFile *f;
f = g_malloc0(sizeof(QEMUFile));
f->opaque = opaque;
f->ops = ops;
return f;
}
/*
* 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;
}
}
static inline bool qemu_file_is_writable(QEMUFile *f)
{
return f->ops->writev_buffer || f->ops->put_buffer;
}
/**
* Flushes QEMUFile buffer
*
* If there is writev_buffer QEMUFileOps it uses it otherwise uses
* put_buffer ops.
*/
void qemu_fflush(QEMUFile *f)
{
ssize_t ret = 0;
if (!qemu_file_is_writable(f)) {
return;
}
if (f->ops->writev_buffer) {
if (f->iovcnt > 0) {
ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos);
}
} else {
if (f->buf_index > 0) {
ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index);
}
}
if (ret >= 0) {
f->pos += ret;
}
f->buf_index = 0;
f->iovcnt = 0;
if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
void ram_control_before_iterate(QEMUFile *f, uint64_t flags)
{
int ret = 0;
if (f->ops->before_ram_iterate) {
ret = f->ops->before_ram_iterate(f, f->opaque, flags);
if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
}
void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
{
int ret = 0;
if (f->ops->after_ram_iterate) {
ret = f->ops->after_ram_iterate(f, f->opaque, flags);
if (ret < 0) {
qemu_file_set_error(f, ret);
}
}
}
void ram_control_load_hook(QEMUFile *f, uint64_t flags)
{
int ret = -EINVAL;
if (f->ops->hook_ram_load) {
ret = f->ops->hook_ram_load(f, f->opaque, flags);
if (ret < 0) {
qemu_file_set_error(f, ret);
}
} else {
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, int *bytes_sent)
{
if (f->ops->save_page) {
int ret = f->ops->save_page(f, f->opaque, block_offset,
offset, size, bytes_sent);
if (ret != RAM_SAVE_CONTROL_DELAYED) {
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;
}
int qemu_get_fd(QEMUFile *f)
{
if (f->ops->get_fd) {
return f->ops->get_fd(f->opaque);
}
return -1;
}
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, int size)
{
/* 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) {
f->iov[f->iovcnt - 1].iov_len += size;
} else {
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, int size)
{
if (!f->ops->writev_buffer) {
qemu_put_buffer(f, buf, size);
return;
}
if (f->last_error) {
return;
}
f->bytes_xfer += size;
add_to_iovec(f, buf, size);
}
void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
{
int 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;
if (f->ops->writev_buffer) {
add_to_iovec(f, f->buf + f->buf_index, l);
}
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++;
if (f->ops->writev_buffer) {
add_to_iovec(f, f->buf + f->buf_index, 1);
}
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') into buf without moving the
* pointer.
*
* 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)
*/
int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset)
{
int pending;
int 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;
}
memcpy(buf, f->buf + index, size);
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)
*/
int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size)
{
int pending = size;
int done = 0;
while (pending > 0) {
int res;
res = qemu_peek_buffer(f, buf, MIN(pending, IO_BUF_SIZE), 0);
if (res == 0) {
return done;
}
qemu_file_skip(f, res);
buf += res;
pending -= res;
done += res;
}
return done;
}
/*
* 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(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 = 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;
}