Perl-compatible Regular Expression functions

Has anyone out there tried to use the "preg_" functions on strings that contain binary data? I basically have files that have a combination of binary and text data, and I want to do search and replace on the text part. Here's the way I've tried it in PHP: (1) Read a file into a string with fread (2) Do a search and replace on the string with "preg_replace" (3) Write the string back to a file with fwrite The fread and fwrite parts work fine with binary data. But the "preg_replace" seems to mangle it (the string gets truncated). I know that SED & Perl search and replace work fine with binary data like this. Any ideas how to do it with PHP? Thanks, Ben Berman benbfly@yahoo.com