get string from ptrace registery

To get a string from the ptrace registry in C, you can follow these steps:

1. Include the necessary header files:
2. #include <sys/ptrace.h>: This header file provides the necessary functions and constants for using ptrace.

3. #include <sys/user.h>: This header file defines the struct user_regs_struct, which contains the register values.

4. Attach to the target process using ptrace:

5. Use the ptrace function with the PTRACE_ATTACH command to attach to the target process. This allows you to access its registers and memory.

6. Wait for the target process to stop:

7. Use the waitpid function to wait for the target process to stop. This ensures that the process is in a stable state before accessing its registers.

8. Get the register values:

9. Use the ptrace function with the PTRACE_GETREGS command to retrieve the register values of the target process.

10. The register values are stored in the struct user_regs_struct object.

11. Extract the string from the register:

12. The register values may contain a pointer to the string you want to retrieve.
13. Use the appropriate register (e.g., RAX, RBX, RDI, etc.) based on the architecture and calling convention of the target process.

14. Dereference the pointer to access the string.

15. Detach from the target process:

16. Use the ptrace function with the PTRACE_DETACH command to detach from the target process.

Here's an example code snippet that demonstrates these steps:

#include <sys/ptrace.h>
#include <sys/user.h>
#include <stdio.h>

int main() {
    pid_t pid = <target_process_id>; // Replace <target_process_id> with the actual process ID of the target process

    if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) == -1) {
        perror("ptrace attach");
        return 1;
    }

    waitpid(pid, NULL, 0);

    struct user_regs_struct regs;
    if (ptrace(PTRACE_GETREGS, pid, NULL, &regs) == -1) {
        perror("ptrace getregs");
        return 1;
    }

    // Extract the string from the register
    char str = (char)regs.rdi; // Assuming the string is stored in the RDI register

    printf("String: %s\n", str);

    if (ptrace(PTRACE_DETACH, pid, NULL, NULL) == -1) {
        perror("ptrace detach");
        return 1;
    }

    return 0;
}

Please note that the specific register and its usage may vary depending on the architecture and calling convention of the target process. You need to determine the appropriate register to extract the string based on the specific scenario.

I hope this helps! Let me know if you have any further questions.