Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback design to work with QEMU and rust-vmm vhost-user backend without require any changes. Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9
author: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> 2023-10-10 11:40:56 +0000
committer: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com> 2023-10-10 11:40:56 +0000
commit: e02cda008591317b1625707ff8e115a4841aa889 (patch)
tree: aee302e3cf8b59ec2d32ec481be3d1afddfc8968 /migration/qemu-file.c
parent: cc668e6b7e0ffd8c9d130513d12053cf5eda1d3b (diff)
1 files changed, 868 insertions, 0 deletions
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
new file mode 100644
index 000000000..6338d8e2f
--- /dev/null
+++ b/migration/qemu-file.c
@@ -0,0 +1,868 @@
+/*
+ * 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/error-report.h"
+#include "qemu/iov.h"
+#include "migration.h"
+#include "qemu-file.h"
+#include "trace.h"
+#include "qapi/error.h"
+
+#define IO_BUF_SIZE 32768
+#define MAX_IOV_SIZE MIN_CONST(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;
+    Error *last_error_obj;
+    /* has the file has been shutdown */
+    bool shutdown;
+    /* Whether opaque points to a QIOChannel */
+    bool has_ioc;
+};
+
+/*
+ * Stop a file from being read/written - not all backing files can do this
+ * typically only sockets can.
+ */
+int qemu_file_shutdown(QEMUFile *f)
+{
+    int ret;
+
+    f->shutdown = true;
+    if (!f->ops->shut_down) {
+        return -ENOSYS;
+    }
+    ret = f->ops->shut_down(f->opaque, true, true, NULL);
+
+    if (!f->last_error) {
+        qemu_file_set_error(f, -EIO);
+    }
+    return ret;
+}
+
+/*
+ * 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, bool has_ioc)
+{
+    QEMUFile *f;
+
+    f = g_new0(QEMUFile, 1);
+
+    f->opaque = opaque;
+    f->ops = ops;
+    f->has_ioc = has_ioc;
+    return f;
+}
+
+
+void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks)
+{
+    f->hooks = hooks;
+}
+
+/*
+ * Get last error for stream f with optional Error*
+ *
+ * Return negative error value if there has been an error on previous
+ * operations, return 0 if no error happened.
+ * Optional, it returns Error* in errp, but it may be NULL even if return value
+ * is not 0.
+ *
+ */
+int qemu_file_get_error_obj(QEMUFile *f, Error **errp)
+{
+    if (errp) {
+        *errp = f->last_error_obj ? error_copy(f->last_error_obj) : NULL;
+    }
+    return f->last_error;
+}
+
+/*
+ * Set the last error for stream f with optional Error*
+ */
+void qemu_file_set_error_obj(QEMUFile *f, int ret, Error *err)
+{
+    if (f->last_error == 0 && ret) {
+        f->last_error = ret;
+        error_propagate(&f->last_error_obj, err);
+    } else if (err) {
+        error_report_err(err);
+    }
+}
+
+/*
+ * 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 qemu_file_get_error_obj(f, NULL);
+}
+
+/*
+ * Set the last error for stream f
+ */
+void qemu_file_set_error(QEMUFile *f, int ret)
+{
+    qemu_file_set_error_obj(f, ret, NULL);
+}
+
+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
+ *
+ * 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;
+    Error *local_error = NULL;
+
+    if (!qemu_file_is_writable(f)) {
+        return;
+    }
+
+    if (f->shutdown) {
+        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,
+                                    &local_error);
+
+        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_obj(f, ret < 0 ? ret : -EIO, local_error);
+    }
+    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;
+    Error *local_error = NULL;
+
+    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;
+
+    if (f->shutdown) {
+        return 0;
+    }
+
+    len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
+                             IO_BUF_SIZE - pending, &local_error);
+    if (len > 0) {
+        f->buf_size += len;
+        f->pos += len;
+    } else if (len == 0) {
+        qemu_file_set_error_obj(f, -EIO, local_error);
+    } else if (len != -EAGAIN) {
+        qemu_file_set_error_obj(f, len, local_error);
+    } else {
+        error_free(local_error);
+    }
+
+    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, NULL);
+        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;
+    }
+    error_free(f->last_error_obj);
+    g_free(f);
+    trace_qemu_file_fclose();
+    return ret;
+}
+
+/*
+ * Add buf to iovec. Do flush if iovec is full.
+ *
+ * Return values:
+ * 1 iovec is full and flushed
+ * 0 iovec is not flushed
+ *
+ */
+static int 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 (f->iovcnt >= MAX_IOV_SIZE) {
+            /* Should only happen if a previous fflush failed */
+            assert(f->shutdown || !qemu_file_is_writable(f));
+            return 1;
+        }
+        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);
+        return 1;
+    }
+
+    return 0;
+}
+
+static void add_buf_to_iovec(QEMUFile *f, size_t len)
+{
+    if (!add_to_iovec(f, f->buf + f->buf_index, len, false)) {
+        f->buf_index += len;
+        if (f->buf_index == IO_BUF_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_buf_to_iovec(f, l);
+        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_buf_to_iovec(f, 1);
+}
+
+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 = NULL;
+
+        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 (f->shutdown) {
+        return 1;
+    }
+    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_file_update_transfer(QEMUFile *f, int64_t len)
+{
+    f->bytes_xfer += len;
+}
+
+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.
+ *
+ * Since the file is dummy file with empty_ops, return -1 if f has no space to
+ * save the compressed data.
+ */
+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)) {
+        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);
+    add_buf_to_iovec(f, blen);
+    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, NULL);
+    }
+}
+
+/*
+ * Return the ioc object if it's a migration channel.  Note: it can return NULL
+ * for callers passing in a non-migration qemufile.  E.g. see qemu_fopen_bdrv()
+ * and its usage in e.g. load_snapshot().  So we need to check against NULL
+ * before using it.  If without the check, migration_incoming_state_destroy()
+ * could fail for load_snapshot().
+ */
+QIOChannel *qemu_file_get_ioc(QEMUFile *file)
+{
+    return file->has_ioc ? QIO_CHANNEL(file->opaque) : NULL;
+}
author	Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>	2023-10-10 11:40:56 +0000
committer	Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>	2023-10-10 11:40:56 +0000
commit	e02cda008591317b1625707ff8e115a4841aa889 (patch)
tree	aee302e3cf8b59ec2d32ec481be3d1afddfc8968 /migration/qemu-file.c
parent	cc668e6b7e0ffd8c9d130513d12053cf5eda1d3b (diff)