在linux上的二进制文件中，在x00的特定偏移量之后提取字符串

Question

i seeking for the simplest way of extracting a string inside a binary file on linux (command line). As example in my case the string begins with offset 138 and ends with the first hex 00.

The last days i tried arround with hexdump and also read the documentation about several times. Sadly in all what i tried i only got as result the hex values together with the strings instead of the clean string.

So my question is, what could be the simplest solution? Should i more focus on a scripting language like python, php or is there something i don't know to reach it easier?

Answer 1

You can do this simply by reading from the file at offset 138 into buffer until you reach 0x00 like so...

// Open the file for read
$fp = fopen($fileName, "rb");
// Set the file pointer to a byte offset of 138 to begin reading
fseek($fp, 138);
$reached = false;
$buffer = "";
// Read into the buffer until we reac 0x00
do {
    $buffer .= fread($fp, 8192);
    $end = strpos($buffer, "\x00");
    if ($end !== false || feof($fp)) {
        $str = substr($buffer, 0, $end);
        $reached = true;
    }
} while(!$reached);

// $str will contain the string you're looking for