what system calls are used to copy files in Linux

[John269]

I am modifying ext4 filesystem to add a simple encryption to files contents. I started by changing readand write system calls to change the contents right before write and after read system calls.

now copying files in terminal is working just as I expected but when I try to copy a file using a GUI based file manager (pcmanfm in this case) it is corrupting the contents.

my question is: what system calls are used for reading/writing files besides normal .read and .write?

Any Ideal Suggestion ??

[John269]

I am modifying ext4 filesystem to add a simple encryption to files contents. I started by changing read and write system calls to change the contents right before write and after read system calls.

now copying files in terminal is working just as I expected but when I try to copy a file using a GUI based file manager (pcmanfm in this case) it is corrupting the contents.

my question is: what system calls are used for reading/writing files besides normal .read and .write?