From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> This is based on Stefan and Joel's patch that creates a QEMUFile that goes to a memory buffer; from:
http://lists.gnu.org/archive/html/qemu-devel/2013-03/msg05036.html Using the QEMUFile interface, this patch adds support functions for operating on in-memory sized buffers that can be written to or read from. Signed-off-by: Stefan Berger <stef...@linux.vnet.ibm.com> Signed-off-by: Joel Schopp <jsch...@linux.vnet.ibm.com> For fixes/tweeks I've done: Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com> Reviewed-by: Eric Blake <ebl...@redhat.com> --- include/migration/qemu-file.h | 26 +++ include/qemu/typedefs.h | 1 + qemu-file.c | 455 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 482 insertions(+) diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h index c90f529..70ff347 100644 --- a/include/migration/qemu-file.h +++ b/include/migration/qemu-file.h @@ -25,6 +25,8 @@ #define QEMU_FILE_H 1 #include "exec/cpu-common.h" +#include <stdint.h> + /* This function writes a chunk of data to a file at the given position. * The pos argument can be ignored if the file is only being used for * streaming. The handler should try to write all of the data it can. @@ -94,11 +96,19 @@ typedef struct QEMUFileOps { QEMURamSaveFunc *save_page; } QEMUFileOps; +struct QEMUSizedBuffer { + struct iovec *iov; + size_t n_iov; + size_t size; /* total allocated size in all iov's */ + size_t used; /* number of used bytes */ +}; + QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops); QEMUFile *qemu_fopen(const char *filename, const char *mode); QEMUFile *qemu_fdopen(int fd, const char *mode); QEMUFile *qemu_fopen_socket(int fd, const char *mode); QEMUFile *qemu_popen_cmd(const char *command, const char *mode); +QEMUFile *qemu_bufopen(const char *mode, QEMUSizedBuffer *input); int qemu_get_fd(QEMUFile *f); int qemu_fclose(QEMUFile *f); int64_t qemu_ftell(QEMUFile *f); @@ -111,6 +121,22 @@ void qemu_put_byte(QEMUFile *f, int v); void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size); bool qemu_file_mode_is_not_valid(const char *mode); +QEMUSizedBuffer *qsb_create(const uint8_t *buffer, size_t len); +QEMUSizedBuffer *qsb_clone(const QEMUSizedBuffer *); +void qsb_free(QEMUSizedBuffer *); +size_t qsb_set_length(QEMUSizedBuffer *qsb, size_t length); +size_t qsb_get_length(const QEMUSizedBuffer *qsb); +ssize_t qsb_get_buffer(const QEMUSizedBuffer *, off_t start, size_t count, + uint8_t *buf); +ssize_t qsb_write_at(QEMUSizedBuffer *qsb, const uint8_t *buf, + off_t pos, size_t count); + + +/* + * For use on files opened with qemu_bufopen + */ +const QEMUSizedBuffer *qemu_buf_get(QEMUFile *f); + static inline void qemu_put_ubyte(QEMUFile *f, unsigned int v) { qemu_put_byte(f, (int)v); diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h index 04df51b..168a408 100644 --- a/include/qemu/typedefs.h +++ b/include/qemu/typedefs.h @@ -71,6 +71,7 @@ typedef struct SSIBus SSIBus; typedef struct EventNotifier EventNotifier; typedef struct VirtIODevice VirtIODevice; typedef struct QEMUSGList QEMUSGList; +typedef struct QEMUSizedBuffer QEMUSizedBuffer; typedef struct SHPCDevice SHPCDevice; typedef struct FWCfgState FWCfgState; typedef struct PcGuestInfo PcGuestInfo; diff --git a/qemu-file.c b/qemu-file.c index a8e3912..cdda745 100644 --- a/qemu-file.c +++ b/qemu-file.c @@ -878,3 +878,458 @@ uint64_t qemu_get_be64(QEMUFile *f) v |= qemu_get_be32(f); return v; } + +#define QSB_CHUNK_SIZE (1 << 10) +#define QSB_MAX_CHUNK_SIZE (16 * QSB_CHUNK_SIZE) + +/** + * Create a QEMUSizedBuffer + * This type of buffer uses scatter-gather lists internally and + * can grow to any size. Any data array in the scatter-gather list + * can hold different amount of bytes. + * + * @buffer: Optional buffer to copy into the QSB + * @len: size of initial buffer; if @buffer is given, buffer must + * hold at least len bytes + * + * Returns a pointer to a QEMUSizedBuffer or NULL on allocation failure + */ +QEMUSizedBuffer *qsb_create(const uint8_t *buffer, size_t len) +{ + QEMUSizedBuffer *qsb; + size_t alloc_len, num_chunks, i, to_copy; + size_t chunk_size = (len > QSB_MAX_CHUNK_SIZE) + ? QSB_MAX_CHUNK_SIZE + : QSB_CHUNK_SIZE; + + num_chunks = DIV_ROUND_UP(len ? len : QSB_CHUNK_SIZE, chunk_size); + alloc_len = num_chunks * chunk_size; + + qsb = g_try_new0(QEMUSizedBuffer, 1); + if (!qsb) { + return NULL; + } + + qsb->iov = g_try_new0(struct iovec, num_chunks); + if (!qsb->iov) { + g_free(qsb); + return NULL; + } + + qsb->n_iov = num_chunks; + + for (i = 0; i < num_chunks; i++) { + qsb->iov[i].iov_base = g_try_malloc0(chunk_size); + if (!qsb->iov[i].iov_base) { + /* qsb_free is safe since g_free can cope with NULL */ + qsb_free(qsb); + return NULL; + } + + qsb->iov[i].iov_len = chunk_size; + if (buffer) { + to_copy = (len - qsb->used) > chunk_size + ? chunk_size : (len - qsb->used); + memcpy(qsb->iov[i].iov_base, &buffer[qsb->used], to_copy); + qsb->used += to_copy; + } + } + + qsb->size = alloc_len; + + return qsb; +} + +/** + * Free the QEMUSizedBuffer + * + * @qsb: The QEMUSizedBuffer to free + */ +void qsb_free(QEMUSizedBuffer *qsb) +{ + size_t i; + + if (!qsb) { + return; + } + + for (i = 0; i < qsb->n_iov; i++) { + g_free(qsb->iov[i].iov_base); + } + g_free(qsb->iov); + g_free(qsb); +} + +/** + * Get the number of used bytes in the QEMUSizedBuffer + * + * @qsb: A QEMUSizedBuffer + * + * Returns the number of bytes currently used in this buffer + */ +size_t qsb_get_length(const QEMUSizedBuffer *qsb) +{ + return qsb->used; +} + +/** + * Set the length of the buffer; the primary usage of this + * function is to truncate the number of used bytes in the buffer. + * The size will not be extended beyond the current number of + * allocated bytes in the QEMUSizedBuffer. + * + * @qsb: A QEMUSizedBuffer + * @new_len: The new length of bytes in the buffer + * + * Returns the number of bytes the buffer was truncated or extended + * to. + */ +size_t qsb_set_length(QEMUSizedBuffer *qsb, size_t new_len) +{ + if (new_len <= qsb->size) { + qsb->used = new_len; + } else { + qsb->used = qsb->size; + } + return qsb->used; +} + +/** + * Get the iovec that holds the data for a given position @pos. + * + * @qsb: A QEMUSizedBuffer + * @pos: The index of a byte in the buffer + * @d_off: Pointer to an offset that this function will indicate + * at what position within the returned iovec the byte + * is to be found + * + * Returns the index of the iovec that holds the byte at the given + * index @pos in the byte stream; a negative number if the iovec + * for the given position @pos does not exist. + */ +static ssize_t qsb_get_iovec(const QEMUSizedBuffer *qsb, + off_t pos, off_t *d_off) +{ + ssize_t i; + off_t curr = 0; + + if (pos > qsb->used) { + return -1; + } + + for (i = 0; i < qsb->n_iov; i++) { + if (curr + qsb->iov[i].iov_len > pos) { + *d_off = pos - curr; + return i; + } + curr += qsb->iov[i].iov_len; + } + return -1; +} + +/* + * Convert the QEMUSizedBuffer into a flat buffer. + * + * Note: If at all possible, try to avoid this function since it + * may unnecessarily copy memory around. + * + * @qsb: pointer to QEMUSizedBuffer + * @start: offset to start at + * @count: number of bytes to copy + * @buf: a pointer to a buffer to write into (at least @count bytes) + * + * Returns the number of bytes copied into the output buffer + */ +ssize_t qsb_get_buffer(const QEMUSizedBuffer *qsb, off_t start, + size_t count, uint8_t *buffer) +{ + const struct iovec *iov; + size_t to_copy, all_copy; + ssize_t index; + off_t s_off; + off_t d_off = 0; + char *s; + + if (start > qsb->used) { + return 0; + } + + all_copy = qsb->used - start; + if (all_copy > count) { + all_copy = count; + } else { + count = all_copy; + } + + index = qsb_get_iovec(qsb, start, &s_off); + if (index < 0) { + return 0; + } + + while (all_copy > 0) { + iov = &qsb->iov[index]; + + s = iov->iov_base; + + to_copy = iov->iov_len - s_off; + if (to_copy > all_copy) { + to_copy = all_copy; + } + memcpy(&buffer[d_off], &s[s_off], to_copy); + + d_off += to_copy; + all_copy -= to_copy; + + s_off = 0; + index++; + } + + return count; +} + +/** + * Grow the QEMUSizedBuffer to the given size and allocate + * memory for it. + * + * @qsb: A QEMUSizedBuffer + * @new_size: The new size of the buffer + * + * Return: + * a negative error code in case of memory allocation failure + * or + * the new size of the buffer. The returned size may be greater or equal + * to @new_size. + */ +static ssize_t qsb_grow(QEMUSizedBuffer *qsb, size_t new_size) +{ + size_t needed_chunks, i; + + if (qsb->size < new_size) { + struct iovec *new_iov; + size_t size_diff = new_size - qsb->size; + size_t chunk_size = (size_diff > QSB_MAX_CHUNK_SIZE) + ? QSB_MAX_CHUNK_SIZE : QSB_CHUNK_SIZE; + + needed_chunks = DIV_ROUND_UP(size_diff, chunk_size); + + new_iov = g_try_new(struct iovec, qsb->n_iov + needed_chunks); + if (new_iov == NULL) { + return -ENOMEM; + } + + /* Allocate new chunks as needed into new_iov */ + for (i = qsb->n_iov; i < qsb->n_iov + needed_chunks; i++) { + new_iov[i].iov_base = g_try_malloc0(chunk_size); + new_iov[i].iov_len = chunk_size; + if (!new_iov[i].iov_base) { + size_t j; + + /* Free previously allocated new chunks */ + for (j = qsb->n_iov; j < i; j++) { + g_free(new_iov[j].iov_base); + } + g_free(new_iov); + + return -ENOMEM; + } + } + + /* + * Now we can't get any allocation errors, copy over to new iov + * and switch. + */ + for (i = 0; i < qsb->n_iov; i++) { + new_iov[i] = qsb->iov[i]; + } + + qsb->n_iov += needed_chunks; + g_free(qsb->iov); + qsb->iov = new_iov; + qsb->size += (needed_chunks * chunk_size); + } + + return qsb->size; +} + +/** + * Write into the QEMUSizedBuffer at a given position and a given + * number of bytes. This function will automatically grow the + * QEMUSizedBuffer. + * + * @qsb: A QEMUSizedBuffer + * @source: A byte array to copy data from + * @pos: The position within the @qsb to write data to + * @size: The number of bytes to copy into the @qsb + * + * Returns @size or a negative error code in case of memory allocation failure, + * or with an invalid 'pos' + */ +ssize_t qsb_write_at(QEMUSizedBuffer *qsb, const uint8_t *source, + off_t pos, size_t count) +{ + ssize_t rc = qsb_grow(qsb, pos + count); + size_t to_copy; + size_t all_copy = count; + const struct iovec *iov; + ssize_t index; + char *dest; + off_t d_off, s_off = 0; + + if (rc < 0) { + return rc; + } + + if (pos + count > qsb->used) { + qsb->used = pos + count; + } + + index = qsb_get_iovec(qsb, pos, &d_off); + if (index < 0) { + return -EINVAL; + } + + while (all_copy > 0) { + iov = &qsb->iov[index]; + + dest = iov->iov_base; + + to_copy = iov->iov_len - d_off; + if (to_copy > all_copy) { + to_copy = all_copy; + } + + memcpy(&dest[d_off], &source[s_off], to_copy); + + s_off += to_copy; + all_copy -= to_copy; + + d_off = 0; + index++; + } + + return count; +} + +/** + * Create a deep copy of the given QEMUSizedBuffer. + * + * @qsb: A QEMUSizedBuffer + * + * Returns a clone of @qsb or NULL on allocation failure + */ +QEMUSizedBuffer *qsb_clone(const QEMUSizedBuffer *qsb) +{ + QEMUSizedBuffer *out = qsb_create(NULL, qsb_get_length(qsb)); + size_t i; + ssize_t res; + off_t pos = 0; + + if (!out) { + return NULL; + } + + for (i = 0; i < qsb->n_iov; i++) { + res = qsb_write_at(out, qsb->iov[i].iov_base, + pos, qsb->iov[i].iov_len); + if (res < 0) { + qsb_free(out); + return NULL; + } + pos += res; + } + + return out; +} + +typedef struct QEMUBuffer { + QEMUSizedBuffer *qsb; + QEMUFile *file; +} QEMUBuffer; + +static int buf_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size) +{ + QEMUBuffer *s = opaque; + ssize_t len = qsb_get_length(s->qsb) - pos; + + if (len <= 0) { + return 0; + } + + if (len > size) { + len = size; + } + return qsb_get_buffer(s->qsb, pos, len, buf); +} + +static int buf_put_buffer(void *opaque, const uint8_t *buf, + int64_t pos, int size) +{ + QEMUBuffer *s = opaque; + + return qsb_write_at(s->qsb, buf, pos, size); +} + +static int buf_close(void *opaque) +{ + QEMUBuffer *s = opaque; + + qsb_free(s->qsb); + + g_free(s); + + return 0; +} + +const QEMUSizedBuffer *qemu_buf_get(QEMUFile *f) +{ + QEMUBuffer *p; + + qemu_fflush(f); + + p = f->opaque; + + return p->qsb; +} + +static const QEMUFileOps buf_read_ops = { + .get_buffer = buf_get_buffer, + .close = buf_close, +}; + +static const QEMUFileOps buf_write_ops = { + .put_buffer = buf_put_buffer, + .close = buf_close, +}; + +QEMUFile *qemu_bufopen(const char *mode, QEMUSizedBuffer *input) +{ + QEMUBuffer *s; + + if (mode == NULL || (mode[0] != 'r' && mode[0] != 'w') || + mode[1] != '\0') { + error_report("qemu_bufopen: Argument validity check failed"); + return NULL; + } + + s = g_malloc0(sizeof(QEMUBuffer)); + if (mode[0] == 'r') { + s->qsb = input; + } + + if (s->qsb == NULL) { + s->qsb = qsb_create(NULL, 0); + } + if (!s->qsb) { + g_free(s); + error_report("qemu_bufopen: qsb_create failed"); + return NULL; + } + + + if (mode[0] == 'r') { + s->file = qemu_fopen_ops(s, &buf_read_ops); + } else { + s->file = qemu_fopen_ops(s, &buf_write_ops); + } + return s->file; +} -- 1.9.3
