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vladak/tar-trivial.md

Last active May 24, 2024 13:11
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trivial example of how tar creates uncompressed archive
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tar-trivial.md

Firstly, let's create a file of 512 bytes, i.e. matching the tar block size exactly, full of 'A' characters:

$ python3 -c 'print("A" * 512, end="")' > 512A.out

We can see that the length of the file is indeed 512 bytes and that the contents match our expectations:

$ ls -ld 512A.out 
-rw-rw-r-- 1 foobar foobar 512 kvě 24 14:23 512A.out
$ hexdump -C -v 512A.out 
00000000  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000010  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000020  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000030  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000040  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000050  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000060  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000070  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000080  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000090  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000000a0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000000b0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000000c0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000000d0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000000e0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000000f0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000100  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000110  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000120  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000130  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000140  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000150  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000160  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000170  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000180  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000190  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000001a0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000001b0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000001c0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000001d0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000001e0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000001f0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000200

Next, create a tar archive containing just this file:

$ tar cf trivial.tar 512A.out 
$ ls -ld trivial.tar 
-rw-rw-r-- 1 foobar foobar 10240 kvě 24 14:23 trivial.tar

Now let's take a look at how the archive is laid out on disk:

$ hexdump -C -v trivial.tar 
00000000  35 31 32 41 2e 6f 75 74  00 00 00 00 00 00 00 00  |512A.out........|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000060  00 00 00 00 30 30 30 30  36 36 34 00 30 30 30 31  |....0000664.0001|
00000070  37 35 30 00 30 30 30 31  37 35 30 00 30 30 30 30  |750.0001750.0000|
00000080  30 30 30 31 30 30 30 00  31 34 36 32 34 31 30 33  |0001000.14624103|
00000090  32 36 30 00 30 31 31 35  37 30 00 20 30 00 00 00  |260.011570. 0...|
000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000100  00 75 73 74 61 72 20 20  00 76 6b 6f 74 61 6c 00  |.ustar  .foobar.|
00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000120  00 00 00 00 00 00 00 00  00 76 6b 6f 74 61 6c 00  |.........foobar.|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000140  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000150  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000160  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000170  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000180  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000190  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000200  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000210  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000220  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000230  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000240  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000250  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000260  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000270  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000280  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000290  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000002a0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000002b0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000002c0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000002d0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000002e0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000002f0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000300  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000310  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000320  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000330  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000340  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000350  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000360  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000370  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000380  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000390  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000003a0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000003b0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000003c0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000003d0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000003e0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
000003f0  41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  |AAAAAAAAAAAAAAAA|
00000400  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000410  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000420  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000430  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000440  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000450  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000460  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000470  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000480  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000490  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000004a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000004b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000004c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000004d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000004e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000004f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000500  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000510  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000520  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000530  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000540  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000550  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000560  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000570  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000580  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000590  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000005a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000005b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000005c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000005d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000005e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000005f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000600  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000610  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000620  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000630  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000640  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000650  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000660  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000670  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000680  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000690  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000006a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000006b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000006c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000006d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000006e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000006f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000700  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000710  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000720  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000730  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000740  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000750  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000760  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000770  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000780  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000790  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000007a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000007b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000007c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000007d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000007e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000007f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000800  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|


...


000027e0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000027f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00002800

The first block (up to the offset 0x00000200) is the tar header, the next block is the content of the 512A.out file that was used to create the archive. Next, there are blocks of zeroes.

Now, it would be sufficient to have just 2 blocks of zeroes following the content of the file to signify the end of the archive, however for reasons this tar implementation chose to add bunch more zero blocks, up to the total size of 10240 bytes (640 lines of hexdump output not counting the last line with empty data content). This is the minimal size of the archive for this implementation, however it does not matter as long as there are 2 zero blocks after the last block with file contents.

@vladak
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vladak commented May 24, 2024

Here's a simple program that reads the archive in 512 byte chunks:

#include <stdio.h>
#include <assert.h>

static void
dumpit(char *buf, size_t len)
{
	for (size_t i = 0; i < len; i++) {
		printf("%02x ", buf[i]);
		if (i > 0 && ((i + 1) % 8) == 0)
			printf(" ");
		if (i > 0 && ((i + 1) % 16) == 0)
			printf("\n");
	}
	printf("\n");
}

int
main(int argc, char *argv[])
{
	assert(argc == 2);

	FILE *fp = fopen(argv[1], "r");
	assert(fp != NULL);

	char buf[512];
	size_t ret;
	do {
		ret = fread(buf, 1, sizeof (buf), fp);
		printf("size: %zd\n", ret);
		if (ret == sizeof (buf)) {
			dumpit(buf, ret);
		}
	} while (ret == sizeof (buf) && ferror(fp) == 0);
}

When run on the trivial.tar file, it outputs the following:

size: 512
35 31 32 41 2e 6f 75 74  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 30 30 30 30  36 36 34 00 30 30 30 31  
37 35 30 00 30 30 30 31  37 35 30 00 30 30 30 30  
30 30 30 31 30 30 30 00  31 34 36 32 34 31 30 33  
32 36 30 00 30 31 31 35  37 30 00 20 30 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 75 73 74 61 72 20 20  00 76 6b 6f 74 61 6c 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 76 6b 6f 74 61 6c 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  

size: 512
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  
41 41 41 41 41 41 41 41  41 41 41 41 41 41 41 41  

size: 512
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  

size: 512
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  

... (more zero blocks omitted)

This matches the hexdump output above.

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