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/* Copyrighted (C) 2001 RidgeRun,Inc (glonnon@ridgerun.com)
* With modifications by Jeff Dike, James McMechan, and Steve Schmidtke.
* Licensed under the GPL
*/
#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <fcntl.h>
#include <string.h>
#include <byteswap.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/param.h>
#include "cow.h"
static inline int ubd_test_bit(__u64 bit, unsigned long *data)
{
int bits, off;
__u64 n;
bits = sizeof(data[0]) * 8;
n = bit / bits;
off = bit % bits;
//1UL to prevent sign-extension, which turns 0x8000000 into
//0xffffffff8000000
return((data[n] & (1UL << off)) != 0);
}
static inline void ubd_set_bit(__u64 bit, unsigned long *data)
{
int bits, off;
__u64 n;
bits = sizeof(data[0]) * 8;
n = bit / bits;
off = bit % bits;
//1UL to prevent sign-extension, which turns 0x8000000 into
//0xffffffff8000000
data[n] |= (1UL << off);
}
int create_backing_file(char *in, char *out, char *actual_backing)
{
int cow_fd, back_fd, in_fd, out_fd;
struct stat buf;
unsigned long *bitmap;
unsigned long bitmap_len;
unsigned sectorsize, sectors;
void *sector, *zeros;
__u64 size, offset, i; /* i is u64 to prevent 32 bit overflow */
__u32 version, alignment;
int data_offset;
char *backing_file;
time_t mtime;
int bitmap_offset, perms, n;
if((cow_fd = open(in, O_RDONLY)) < 0){
perror("COW file open");
exit(1);
}
if(read_cow_header(file_reader, &cow_fd, &version, &backing_file,
&mtime, &size, §orsize, &alignment,
&bitmap_offset)){
fprintf(stderr, "Reading COW header failed\n");
exit(1);
}
if(actual_backing != NULL)
backing_file = actual_backing;
if(stat(backing_file, &buf) < 0) {
perror("Stating backing file");
exit(1);
}
if(buf.st_size != size){
fprintf(stderr,"Size mismatch (%ld vs %ld) of COW header "
"vs backing file \"%s\"\n", (long int) size,
(long int) buf.st_size, backing_file);
exit(1);
}
if(buf.st_mtime != mtime) {
fprintf(stderr,"mtime mismatch (%ld vs %ld) of COW "
"header vs backing file \"%s\"\n", mtime, buf.st_mtime,
backing_file);
exit(1);
}
perms = (out != NULL) ? O_RDONLY : O_RDWR;
if((back_fd = open(backing_file, perms)) < 0){
perror("Opening backing file");
exit(1);
}
if(out != NULL){
if((out_fd = creat(out, 0644)) < 0){
perror("Output file open");
exit(1);
}
}
else out_fd = back_fd;
cow_sizes(version, size, sectorsize, alignment, bitmap_offset,
&bitmap_len, &data_offset);
bitmap = (unsigned long *) malloc(bitmap_len);
if(bitmap == NULL) {
perror("Can't allocate bitmap");
exit(1);
}
if(pread(cow_fd, bitmap, bitmap_len, bitmap_offset) != bitmap_len){
perror("Reading COW bitmap");
exit(1);
}
sectors = size / sectorsize;
sector = malloc(sectorsize);
zeros = malloc(sectorsize);
if((sector == NULL) || (zeros == NULL)){
perror("Malloc of buffers");
exit(1);
}
memset(zeros, 0, sectorsize);
for(i = 0; i < sectors; i++){
offset = i * sectorsize;
if(ubd_test_bit(i, bitmap)){
offset += data_offset;
in_fd = cow_fd;
}
else in_fd = back_fd;
/* If we're doing a destructive merge, and the backing file
* sector is up to date, then there's nothing to do.
*/
if((out_fd == back_fd) && (in_fd == back_fd))
continue;
if(pread(in_fd, sector, sectorsize, offset) != sectorsize){
perror("Reading data");
exit(1);
}
/* Sparse file creation - if the sector is all zeros and it's
* not the last sector (which always gets written out in order
* to make the file size right), maybe it doesn't need to be
* written out.
*/
if((i < sectors - 1) && !memcmp(sector, zeros, sectorsize)){
/* If we're doing a non-destructive merge, then zero
* sectors can just be skipped.
*/
if(out_fd != back_fd)
continue;
/* Otherwise, we are doing a destructive merge, and
* we need to check the backing file for a zero
* sector.
*/
n = pread(back_fd, sector, sectorsize, i * sectorsize);
if(n != sectorsize){
perror("Checking backing file for zeros");
exit(1);
}
if(!memcmp(sector, zeros, sectorsize))
continue;
/* The backing file sector isn't zeros, so the sector
* of zeros in the COW file needs to be written out.
*/
memset(sector, 0, sectorsize);
}
/* The offset can't be 'offset' because that's used as an
* input offset, which may be offset by the COW header.
*/
n = pwrite(out_fd, sector, sectorsize, i * sectorsize);
if(n != sectorsize){
perror("Writing data");
exit(1);
}
}
free(bitmap);
free(sector);
free(zeros);
close(cow_fd);
close(out_fd);
close(back_fd);
return(0);
}
static char *usage_string =
"%s usage:\n"
"\t%s [ -b <actual backing file> ] <COW file> <new backing file>\n"
"\t%s [ -b <actual backing file> ] -d <COW file>\n"
"Creates a new filesystem image from the COW file and its backing file.\n"
"Specifying -d will cause a destructive, in-place merge of the COW file into\n"
"its current backing file\n"
"Specifying -b overrides the backing_file specified in the COW file. This is\n"
"needed when dealing with a COW file that was created inside a chroot jail.\n"
"%s supports version 1,2 and 3 COW files.\n"
"";
static int Usage(char *prog) {
fprintf(stderr, usage_string, prog, prog, prog, prog);
exit(1);
}
int main(int argc, char **argv)
{
char *prog = argv[0];
char *actual_backing_file = NULL;
int in_place = 0;
argv++;
argc--;
if(argc == 0)
Usage(prog);
if(!strcmp(argv[0], "-d")){
in_place = 1;
argv++;
argc--;
}
if(!strcmp(argv[0], "-b")){
actual_backing_file = argv[1];
argv += 2;
argc -= 2;
}
if(in_place){
if(argc != 1) Usage(prog);
create_backing_file(argv[0], NULL, actual_backing_file);
}
else {
if(argc != 2) Usage(prog);
create_backing_file(argv[0], argv[1], actual_backing_file);
}
return 0;
}
/*
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/
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