From 55f4e4a5ec657a017e3bf75299ad71fd1c968dd3 Mon Sep 17 00:00:00 2001 From: The Android Open Source Project Date: Tue, 21 Oct 2008 07:00:00 -0700 Subject: Initial Contribution --- block-cow.c | 271 ------------------------------------------------------------ 1 file changed, 271 deletions(-) delete mode 100644 block-cow.c (limited to 'block-cow.c') diff --git a/block-cow.c b/block-cow.c deleted file mode 100644 index 6af8b74..0000000 --- a/block-cow.c +++ /dev/null @@ -1,271 +0,0 @@ -/* - * Block driver for the COW format - * - * Copyright (c) 2004 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. - */ -#ifndef _WIN32 -#include "vl.h" -#include "block_int.h" -#include - -/**************************************************************/ -/* COW block driver using file system holes */ - -/* user mode linux compatible COW file */ -#define COW_MAGIC 0x4f4f4f4d /* MOOO */ -#define COW_VERSION 2 - -struct cow_header_v2 { - uint32_t magic; - uint32_t version; - char backing_file[1024]; - int32_t mtime; - uint64_t size; - uint32_t sectorsize; -}; - -typedef struct BDRVCowState { - int fd; - 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; - int64_t cow_sectors_offset; -} BDRVCowState; - -static int cow_probe(const uint8_t *buf, int buf_size, const char *filename) -{ - const struct cow_header_v2 *cow_header = (const void *)buf; - - if (buf_size >= sizeof(struct cow_header_v2) && - be32_to_cpu(cow_header->magic) == COW_MAGIC && - be32_to_cpu(cow_header->version) == COW_VERSION) - return 100; - else - return 0; -} - -static int cow_open(BlockDriverState *bs, const char *filename) -{ - BDRVCowState *s = bs->opaque; - int fd; - struct cow_header_v2 cow_header; - int64_t size; - - fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE); - if (fd < 0) { - fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE); - if (fd < 0) - return -1; - } - s->fd = fd; - /* see if it is a cow image */ - if (read(fd, &cow_header, sizeof(cow_header)) != sizeof(cow_header)) { - goto fail; - } - - if (be32_to_cpu(cow_header.magic) != COW_MAGIC || - be32_to_cpu(cow_header.version) != COW_VERSION) { - goto fail; - } - - /* cow image found */ - size = be64_to_cpu(cow_header.size); - bs->total_sectors = size / 512; - - pstrcpy(bs->backing_file, sizeof(bs->backing_file), - cow_header.backing_file); - -#if 0 - 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 != be32_to_cpu(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; - } -#endif - /* mmap the bitmap */ - s->cow_bitmap_size = ((bs->total_sectors + 7) >> 3) + sizeof(cow_header); - s->cow_bitmap_addr = mmap(get_mmap_addr(s->cow_bitmap_size), - s->cow_bitmap_size, - PROT_READ | PROT_WRITE, - MAP_SHARED, s->fd, 0); - if (s->cow_bitmap_addr == MAP_FAILED) - goto fail; - s->cow_bitmap = s->cow_bitmap_addr + sizeof(cow_header); - s->cow_sectors_offset = (s->cow_bitmap_size + 511) & ~511; - return 0; - fail: - close(fd); - return -1; -} - -static inline void cow_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 inline 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; -} - -static int cow_is_allocated(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, int *pnum) -{ - BDRVCowState *s = bs->opaque; - return is_changed(s->cow_bitmap, sector_num, nb_sectors, pnum); -} - -static int cow_read(BlockDriverState *bs, int64_t sector_num, - uint8_t *buf, int nb_sectors) -{ - BDRVCowState *s = bs->opaque; - int ret, n; - - while (nb_sectors > 0) { - if (is_changed(s->cow_bitmap, sector_num, nb_sectors, &n)) { - lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET); - ret = read(s->fd, buf, n * 512); - if (ret != n * 512) - return -1; - } else { - memset(buf, 0, n * 512); - } - nb_sectors -= n; - sector_num += n; - buf += n * 512; - } - return 0; -} - -static int cow_write(BlockDriverState *bs, int64_t sector_num, - const uint8_t *buf, int nb_sectors) -{ - BDRVCowState *s = bs->opaque; - int ret, i; - - lseek(s->fd, s->cow_sectors_offset + sector_num * 512, SEEK_SET); - ret = write(s->fd, buf, nb_sectors * 512); - if (ret != nb_sectors * 512) - return -1; - for (i = 0; i < nb_sectors; i++) - cow_set_bit(s->cow_bitmap, sector_num + i); - return 0; -} - -static void cow_close(BlockDriverState *bs) -{ - BDRVCowState *s = bs->opaque; - munmap(s->cow_bitmap_addr, s->cow_bitmap_size); - close(s->fd); -} - -static int cow_create(const char *filename, int64_t image_sectors, - const char *image_filename, int flags) -{ - int fd, cow_fd; - struct cow_header_v2 cow_header; - struct stat st; - - if (flags) - return -ENOTSUP; - - cow_fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE, - 0644); - if (cow_fd < 0) - return -1; - memset(&cow_header, 0, sizeof(cow_header)); - cow_header.magic = cpu_to_be32(COW_MAGIC); - cow_header.version = cpu_to_be32(COW_VERSION); - if (image_filename) { - fd = open(image_filename, O_RDONLY | O_BINARY); - if (fd < 0) { - close(cow_fd); - return -1; - } - if (fstat(fd, &st) != 0) { - close(fd); - return -1; - } - close(fd); - cow_header.mtime = cpu_to_be32(st.st_mtime); - realpath(image_filename, cow_header.backing_file); - } - cow_header.sectorsize = cpu_to_be32(512); - cow_header.size = cpu_to_be64(image_sectors * 512); - write(cow_fd, &cow_header, sizeof(cow_header)); - /* resize to include at least all the bitmap */ - ftruncate(cow_fd, sizeof(cow_header) + ((image_sectors + 7) >> 3)); - close(cow_fd); - return 0; -} - -static void cow_flush(BlockDriverState *bs) -{ - BDRVCowState *s = bs->opaque; - fsync(s->fd); -} - -BlockDriver bdrv_cow = { - "cow", - sizeof(BDRVCowState), - cow_probe, - cow_open, - cow_read, - cow_write, - cow_close, - cow_create, - cow_flush, - cow_is_allocated, -}; -#endif -- cgit v1.1