I don't know, this works fine for me:

$s = pack "L", 0x03141593;  # 4 byte string 
$p = pack "P", $s;          # pointer
printf "%08X\n", unpack "L", unpack "P4", $p;
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Result:

03141593

It would appear to me that your code looks fine.

update No it doesn't. pack "P", $string returns a packed pointer, i.e. a 4 byte structure, containing a packed integer with the numeric pointer value. unpack "P", $packed_pointer does the reverse: first unpacking the address from the 4 bytes, and then unpacking the string it points at. So it does a double unpack.

$s = "Kettle Of Fish";      # 14 byte string
$p = pack "P", $s;          # packed pointer
printf "Length of the pointer: %d\n", length $p;
printf "10 byte string: %s\n", unpack "P10", $p;
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Result:

Length of the pointer: 4
10 byte string: Kettle Of 

In summary: you'd have to convert your numerical pointer to a packed integer, and then unpack using "P4". You can then unpack the integer in that string.

$int= unpack "L", unpack "P4", pack "L", $addr;
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