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disk-image.c
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disk-image.c
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#include "kvm/disk-image.h"
#include "kvm/util.h"
#include <sys/types.h>
#include <inttypes.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
static const char QCOW_MAGIC[] = { 'Q', 'F', 'I', 0xfb };
struct qcow_header {
uint8_t magic[5];
};
static bool disk_image__is_qcow(struct disk_image *self)
{
struct qcow_header *header = self->mmap;
return !memcmp(header->magic, QCOW_MAGIC, ARRAY_SIZE(QCOW_MAGIC));
}
struct disk_image *disk_image__open(const char *filename)
{
struct disk_image *self;
struct stat st;
self = malloc(sizeof *self);
if (!self)
return NULL;
self->fd = open(filename, O_RDONLY);
if (self->fd < 0)
goto failed_free;
if (fstat(self->fd, &st) < 0)
goto failed_close_fd;
self->size = st.st_size;
self->mmap = mmap(NULL, self->size, PROT_READ|PROT_WRITE, MAP_PRIVATE, self->fd, 0);
if (self->mmap == MAP_FAILED)
goto failed_close_fd;
if (disk_image__is_qcow(self))
die("QCOW disk image format is not supported.");
return self;
failed_close_fd:
close(self->fd);
failed_free:
free(self);
return NULL;
}
void disk_image__close(struct disk_image *self)
{
if (munmap(self->mmap, self->size) < 0)
warning("munmap() failed");
if (close(self->fd) < 0)
warning("close() failed");
free(self);
}
int disk_image__read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)
{
uint64_t offset = sector << SECTOR_SHIFT;
if (offset + dst_len > self->size)
return -1;
memcpy(dst, self->mmap + offset, dst_len);
return 0;
}
int disk_image__write_sector(struct disk_image *self, uint64_t sector, void *src, uint32_t src_len)
{
uint64_t offset = sector << SECTOR_SHIFT;
if (offset + src_len > self->size)
return -1;
memcpy(self->mmap + offset, src, src_len);
return 0;
}