C# BinaryWriter 搜索

Question

i have some error in my code i need any one to help me please :)

i have offset and when i try to patch it with C# i get a strange result

this.openFileDialog1.FileName = "Sro_Client.exe";
if (this.openFileDialog1.ShowDialog() == DialogResult.OK)
{
    FileStream output = new FileStream(this.openFileDialog1.FileName
                                       , FileMode.Open);
    BinaryWriter writer = new BinaryWriter(output);
    byte[] bytes = new byte[] { byte.Parse(this.textBox1.Text) };
    byte[] buffer = new byte[] { Convert.ToByte(this.textBox1.Text) };
    writer.Seek(0x135FB3, SeekOrigin.Begin);
    writer.Write(bytes, 0, 1);
    writer.Close();
    MessageBox.Show("Successfully patched Sro_Client.exe.");
}

the original offset is PUSH 6E , so my program must change it when i write in textbox1 like 90 convert it to hex like this website and change it to : PUSH 5a

so it must be now : 00135FB3 6A 5A PUSH 5A but my program change it to 00135FB3 5A POP EDX

i need to know what is wrong on my code please

thanks

sorry for my bad english ;)

Answer 1

You can't insert data to a file directly using the C# IO classes. The easiest way would be to either read it into a buffer and manipulate the buffer, or write the first part to a temp file, then insert your new data, and then write the remainder of the file and then rename it. Alternatively you can append some data at the end of the file and move everything up to create the right amount of usable space where you want to insert your data.

Take a look at http://www.codeproject.com/Articles/17716/Insert-Text-into-Existing-Files-in-C-Without-Temp

Answer 2

Are you sure you have the right offset ? Seems to me like 0x00135FB3 is offset of instruction and 0x00135FB4 is offset of argument; have you tried:

writer.Seek(0x135FB4, SeekOrigin.Begin);

in your code instead ?