PHP: create file from an HEX string

Question

I have the content of a file represented as an Hex string and I want to re-create that file from that hex string. How can I do it?

Additional information
The hex string is taken from firefox memory cache entries such as the one below:

about:cache-entry?client=HTTP&sb=1&key=http://www.google.co.uk/images/nav_logo40.png

I am processing the <pre> element from these entries to extract and concatenate the HEX values. So from the below data output line obtained from a cache entry:

00000000:  89  50  4e  47  0d  0a  1a  0a  00  00  00  0d  49  48  44  52  .PNG........IHDR

I am producing this

89504e470d0a1a0a0000000d49484452

I am repeating the same process for every line so that I end up with 1 big string containing all hex values concatenated.

Expand your question. What has been "hexed"? Are you talking about encoding of binary values of the file or something else? — Michael J.V.
– Michael J.V., Commented Apr 14, 2011 at 11:54
You can use this little script for extracting cache entries of firefox and chrome. — zxcmehran
– zxcmehran, Commented Oct 17, 2015 at 17:25

Gumbo · Accepted Answer · 2011-04-14 11:57:10Z

6

You can use pack:

file_put_contents($filename, pack('H*', $hex));

That will turn a string of octets in hexadecimal notation into binary:

var_dump(pack('H*', '313233'));  // string(3) "123"

answered Apr 14, 2011 at 11:57

Gumbo

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2 Comments

Max Corbeau Over a year ago

I tested your method but it doesn't work. Could you please re-assess my question taking into account what I added into Additional information?

Max Corbeau Over a year ago

Indeed it does. My mistake. My script wasn't getting the hex output properly. All fixed now :)

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