33e3963e1b
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@309 c046a42c-6fe2-441c-8c8c-71466251a162
327 lines
9.1 KiB
C
327 lines
9.1 KiB
C
/*
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* QEMU System Emulator block driver
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*
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* Copyright (c) 2003 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <stdarg.h>
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#include <string.h>
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#include <getopt.h>
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#include <inttypes.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <time.h>
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#include <sys/time.h>
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#include <malloc.h>
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#include <termios.h>
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#include <sys/poll.h>
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#include <errno.h>
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#include <sys/wait.h>
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#include <netinet/in.h>
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#include "vl.h"
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#define NO_THUNK_TYPE_SIZE
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#include "thunk.h"
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struct BlockDriverState {
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int fd; /* if -1, only COW mappings */
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int64_t total_sectors;
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int read_only;
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uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */
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uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */
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int cow_bitmap_size;
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int cow_fd;
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int64_t cow_sectors_offset;
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char filename[1024];
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};
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BlockDriverState *bdrv_open(const char *filename, int snapshot)
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{
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BlockDriverState *bs;
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int fd, cow_fd;
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int64_t size;
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char template[] = "/tmp/vl.XXXXXX";
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struct cow_header_v2 cow_header;
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struct stat st;
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bs = malloc(sizeof(BlockDriverState));
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if(!bs)
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return NULL;
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bs->read_only = 0;
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bs->fd = -1;
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bs->cow_fd = -1;
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bs->cow_bitmap = NULL;
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strcpy(bs->filename, filename);
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/* open standard HD image */
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fd = open(filename, O_RDWR | O_LARGEFILE);
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if (fd < 0) {
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/* read only image on disk */
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fd = open(filename, O_RDONLY | O_LARGEFILE);
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if (fd < 0) {
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perror(filename);
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goto fail;
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}
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if (!snapshot)
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bs->read_only = 1;
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}
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bs->fd = fd;
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/* see if it is a cow image */
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if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) {
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fprintf(stderr, "%s: could not read header\n", filename);
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goto fail;
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}
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if (cow_header.magic == htonl(COW_MAGIC) &&
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cow_header.version == htonl(COW_VERSION)) {
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/* cow image found */
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size = cow_header.size;
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#ifndef WORDS_BIGENDIAN
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size = bswap64(size);
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#endif
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bs->total_sectors = size / 512;
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bs->cow_fd = fd;
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bs->fd = -1;
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if (cow_header.backing_file[0] != '\0') {
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if (stat(cow_header.backing_file, &st) != 0) {
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fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file);
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goto fail;
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}
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if (st.st_mtime != htonl(cow_header.mtime)) {
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fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file);
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goto fail;
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}
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fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE);
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if (fd < 0)
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goto fail;
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bs->fd = fd;
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}
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/* mmap the bitmap */
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bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header);
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bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size),
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bs->cow_bitmap_size,
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PROT_READ | PROT_WRITE,
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MAP_SHARED, bs->cow_fd, 0);
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if (bs->cow_bitmap_addr == MAP_FAILED)
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goto fail;
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bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header);
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bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511;
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snapshot = 0;
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} else {
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/* standard raw image */
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size = lseek64(fd, 0, SEEK_END);
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bs->total_sectors = size / 512;
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bs->fd = fd;
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}
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if (snapshot) {
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/* create a temporary COW file */
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cow_fd = mkstemp(template);
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if (cow_fd < 0)
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goto fail;
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bs->cow_fd = cow_fd;
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unlink(template);
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/* just need to allocate bitmap */
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bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3;
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bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size),
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bs->cow_bitmap_size,
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PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
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if (bs->cow_bitmap_addr == MAP_FAILED)
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goto fail;
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bs->cow_bitmap = bs->cow_bitmap_addr;
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bs->cow_sectors_offset = 0;
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}
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return bs;
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fail:
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bdrv_close(bs);
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return NULL;
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}
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void bdrv_close(BlockDriverState *bs)
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{
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/* we unmap the mapping so that it is written to the COW file */
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if (bs->cow_bitmap_addr)
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munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size);
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if (bs->cow_fd >= 0)
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close(bs->cow_fd);
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if (bs->fd >= 0)
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close(bs->fd);
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free(bs);
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}
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static inline void set_bit(uint8_t *bitmap, int64_t bitnum)
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{
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bitmap[bitnum / 8] |= (1 << (bitnum%8));
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}
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static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum)
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{
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return !!(bitmap[bitnum / 8] & (1 << (bitnum%8)));
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}
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/* Return true if first block has been changed (ie. current version is
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* in COW file). Set the number of continuous blocks for which that
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* is true. */
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static int is_changed(uint8_t *bitmap,
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int64_t sector_num, int nb_sectors,
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int *num_same)
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{
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int changed;
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if (!bitmap || nb_sectors == 0) {
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*num_same = nb_sectors;
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return 0;
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}
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changed = is_bit_set(bitmap, sector_num);
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for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) {
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if (is_bit_set(bitmap, sector_num + *num_same) != changed)
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break;
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}
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return changed;
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}
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/* commit COW file into the raw image */
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int bdrv_commit(BlockDriverState *bs)
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{
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int64_t i;
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uint8_t *cow_bitmap;
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if (!bs->cow_bitmap) {
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fprintf(stderr, "Already committed to %s\n", bs->filename);
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return 0;
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}
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if (bs->read_only) {
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fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename);
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return -1;
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}
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cow_bitmap = bs->cow_bitmap;
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for (i = 0; i < bs->total_sectors; i++) {
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if (is_bit_set(cow_bitmap, i)) {
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unsigned char sector[512];
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if (bdrv_read(bs, i, sector, 1) != 0) {
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fprintf(stderr, "Error reading sector %lli: aborting commit\n",
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(long long)i);
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return -1;
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}
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/* Make bdrv_write write to real file for a moment. */
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bs->cow_bitmap = NULL;
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if (bdrv_write(bs, i, sector, 1) != 0) {
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fprintf(stderr, "Error writing sector %lli: aborting commit\n",
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(long long)i);
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bs->cow_bitmap = cow_bitmap;
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return -1;
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}
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bs->cow_bitmap = cow_bitmap;
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}
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}
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fprintf(stderr, "Committed snapshot to %s\n", bs->filename);
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return 0;
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}
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/* return -1 if error */
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int bdrv_read(BlockDriverState *bs, int64_t sector_num,
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uint8_t *buf, int nb_sectors)
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{
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int ret, n, fd;
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int64_t offset;
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while (nb_sectors > 0) {
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if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) {
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fd = bs->cow_fd;
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offset = bs->cow_sectors_offset;
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} else {
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fd = bs->fd;
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offset = 0;
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}
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if (fd < 0) {
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/* no file, just return empty sectors */
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memset(buf, 0, n * 512);
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} else {
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offset += sector_num * 512;
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lseek64(fd, offset, SEEK_SET);
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ret = read(fd, buf, n * 512);
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if (ret != n * 512) {
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return -1;
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}
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}
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nb_sectors -= n;
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sector_num += n;
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buf += n * 512;
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}
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return 0;
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}
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/* return -1 if error */
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int bdrv_write(BlockDriverState *bs, int64_t sector_num,
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const uint8_t *buf, int nb_sectors)
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{
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int ret, fd, i;
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int64_t offset, retl;
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if (bs->read_only)
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return -1;
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if (bs->cow_bitmap) {
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fd = bs->cow_fd;
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offset = bs->cow_sectors_offset;
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} else {
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fd = bs->fd;
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offset = 0;
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}
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offset += sector_num * 512;
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retl = lseek64(fd, offset, SEEK_SET);
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if (retl == -1) {
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return -1;
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}
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ret = write(fd, buf, nb_sectors * 512);
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if (ret != nb_sectors * 512) {
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return -1;
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}
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if (bs->cow_bitmap) {
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for (i = 0; i < nb_sectors; i++)
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set_bit(bs->cow_bitmap, sector_num + i);
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}
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return 0;
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}
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void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr)
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{
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*nb_sectors_ptr = bs->total_sectors;
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}
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