/* * QEMU System Emulator block driver * * Copyright (c) 2003 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 <stdlib.h> #include <stdio.h> #include <stdarg.h> #include <string.h> #include <getopt.h> #include <inttypes.h> #include <unistd.h> #include <sys/mman.h> #include <fcntl.h> #include <signal.h> #include <time.h> #include <sys/time.h> #include <malloc.h> #include <termios.h> #include <sys/poll.h> #include <errno.h> #include <sys/wait.h> #include <netinet/in.h> #include "vl.h" #define NO_THUNK_TYPE_SIZE #include "thunk.h" struct BlockDriverState { int fd; /* if -1, only COW mappings */ int64_t total_sectors; int read_only; uint8_t *cow_bitmap; /* if non NULL, COW mappings are used first */ uint8_t *cow_bitmap_addr; /* mmap address of cow_bitmap */ int cow_bitmap_size; int cow_fd; int64_t cow_sectors_offset; char filename[1024]; }; BlockDriverState *bdrv_open(const char *filename, int snapshot) { BlockDriverState *bs; int fd, cow_fd; int64_t size; char template[] = "/tmp/vl.XXXXXX"; struct cow_header_v2 cow_header; struct stat st; bs = malloc(sizeof(BlockDriverState)); if(!bs) return NULL; bs->read_only = 0; bs->fd = -1; bs->cow_fd = -1; bs->cow_bitmap = NULL; strcpy(bs->filename, filename); /* open standard HD image */ fd = open(filename, O_RDWR | O_LARGEFILE); if (fd < 0) { /* read only image on disk */ fd = open(filename, O_RDONLY | O_LARGEFILE); if (fd < 0) { perror(filename); goto fail; } if (!snapshot) bs->read_only = 1; } bs->fd = fd; /* see if it is a cow image */ if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) { fprintf(stderr, "%s: could not read header\n", filename); goto fail; } if (cow_header.magic == htonl(COW_MAGIC) && cow_header.version == htonl(COW_VERSION)) { /* cow image found */ size = cow_header.size; #ifndef WORDS_BIGENDIAN size = bswap64(size); #endif bs->total_sectors = size / 512; bs->cow_fd = fd; bs->fd = -1; if (cow_header.backing_file[0] != '\0') { if (stat(cow_header.backing_file, &st) != 0) { fprintf(stderr, "%s: could not find original disk image '%s'\n", filename, cow_header.backing_file); goto fail; } if (st.st_mtime != htonl(cow_header.mtime)) { fprintf(stderr, "%s: original raw disk image '%s' does not match saved timestamp\n", filename, cow_header.backing_file); goto fail; } fd = open(cow_header.backing_file, O_RDONLY | O_LARGEFILE); if (fd < 0) goto fail; bs->fd = fd; } /* mmap the bitmap */ bs->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header); bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), bs->cow_bitmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, bs->cow_fd, 0); if (bs->cow_bitmap_addr == MAP_FAILED) goto fail; bs->cow_bitmap = bs->cow_bitmap_addr + sizeof(cow_header); bs->cow_sectors_offset = (bs->cow_bitmap_size + 511) & ~511; snapshot = 0; } else { /* standard raw image */ size = lseek64(fd, 0, SEEK_END); bs->total_sectors = size / 512; bs->fd = fd; } if (snapshot) { /* create a temporary COW file */ cow_fd = mkstemp(template); if (cow_fd < 0) goto fail; bs->cow_fd = cow_fd; unlink(template); /* just need to allocate bitmap */ bs->cow_bitmap_size = (bs->total_sectors + 7) >> 3; bs->cow_bitmap_addr = mmap(get_mmap_addr(bs->cow_bitmap_size), bs->cow_bitmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (bs->cow_bitmap_addr == MAP_FAILED) goto fail; bs->cow_bitmap = bs->cow_bitmap_addr; bs->cow_sectors_offset = 0; } return bs; fail: bdrv_close(bs); return NULL; } void bdrv_close(BlockDriverState *bs) { /* we unmap the mapping so that it is written to the COW file */ if (bs->cow_bitmap_addr) munmap(bs->cow_bitmap_addr, bs->cow_bitmap_size); if (bs->cow_fd >= 0) close(bs->cow_fd); if (bs->fd >= 0) close(bs->fd); free(bs); } static inline void set_bit(uint8_t *bitmap, int64_t bitnum) { bitmap[bitnum / 8] |= (1 << (bitnum%8)); } static inline int is_bit_set(const uint8_t *bitmap, int64_t bitnum) { return !!(bitmap[bitnum / 8] & (1 << (bitnum%8))); } /* Return true if first block has been changed (ie. current version is * in COW file). Set the number of continuous blocks for which that * is true. */ static int is_changed(uint8_t *bitmap, int64_t sector_num, int nb_sectors, int *num_same) { int changed; if (!bitmap || nb_sectors == 0) { *num_same = nb_sectors; return 0; } changed = is_bit_set(bitmap, sector_num); for (*num_same = 1; *num_same < nb_sectors; (*num_same)++) { if (is_bit_set(bitmap, sector_num + *num_same) != changed) break; } return changed; } /* commit COW file into the raw image */ int bdrv_commit(BlockDriverState *bs) { int64_t i; uint8_t *cow_bitmap; if (!bs->cow_bitmap) { fprintf(stderr, "Already committed to %s\n", bs->filename); return 0; } if (bs->read_only) { fprintf(stderr, "Can't commit to %s: read-only\n", bs->filename); return -1; } cow_bitmap = bs->cow_bitmap; for (i = 0; i < bs->total_sectors; i++) { if (is_bit_set(cow_bitmap, i)) { unsigned char sector[512]; if (bdrv_read(bs, i, sector, 1) != 0) { fprintf(stderr, "Error reading sector %lli: aborting commit\n", (long long)i); return -1; } /* Make bdrv_write write to real file for a moment. */ bs->cow_bitmap = NULL; if (bdrv_write(bs, i, sector, 1) != 0) { fprintf(stderr, "Error writing sector %lli: aborting commit\n", (long long)i); bs->cow_bitmap = cow_bitmap; return -1; } bs->cow_bitmap = cow_bitmap; } } fprintf(stderr, "Committed snapshot to %s\n", bs->filename); return 0; } /* return -1 if error */ int bdrv_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors) { int ret, n, fd; int64_t offset; while (nb_sectors > 0) { if (is_changed(bs->cow_bitmap, sector_num, nb_sectors, &n)) { fd = bs->cow_fd; offset = bs->cow_sectors_offset; } else { fd = bs->fd; offset = 0; } if (fd < 0) { /* no file, just return empty sectors */ memset(buf, 0, n * 512); } else { offset += sector_num * 512; lseek64(fd, offset, SEEK_SET); ret = read(fd, buf, n * 512); if (ret != n * 512) { return -1; } } nb_sectors -= n; sector_num += n; buf += n * 512; } return 0; } /* return -1 if error */ int bdrv_write(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { int ret, fd, i; int64_t offset, retl; if (bs->read_only) return -1; if (bs->cow_bitmap) { fd = bs->cow_fd; offset = bs->cow_sectors_offset; } else { fd = bs->fd; offset = 0; } offset += sector_num * 512; retl = lseek64(fd, offset, SEEK_SET); if (retl == -1) { return -1; } ret = write(fd, buf, nb_sectors * 512); if (ret != nb_sectors * 512) { return -1; } if (bs->cow_bitmap) { for (i = 0; i < nb_sectors; i++) set_bit(bs->cow_bitmap, sector_num + i); } return 0; } void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr) { *nb_sectors_ptr = bs->total_sectors; }