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What is ptrace used for in Linux?
The ptrace() system call provides a means by which one process (the “tracer”) may observe and control the execution of another process (the “tracee”), and examine and change the tracee’s memory and registers. It is primarily used to implement breakpoint debugging and system call tracing.
How is ptrace implemented?
The ptrace system call allows the parent process to inspect the attached child. For example, in Linux, strace (which is implemented with the ptrace system call) can inspect the system calls invoked by the child process. When the attached child process invokes a system call, the ptracing parent process can be notified.
How is debugger implemented?
The simplified answer is: When you put a break-point into the program, the debugger replaces your code at that point with a int3 instruction which is a software interrupt. As an effect the program is suspended and the debugger is called.
How is ptrace used in system call tracing?
The ptrace() system call provides a means by which one process (the “tracer”) may observe and control the execution of another process (the “tracee”), and examine and change the tracee’s memory and registers. It is primarily used to implement breakpoint debugging and system call tracing.
How to get the exit status from ptrace?
The tracee’s exit status can be retrieved with PTRACE_GETEVENTMSG . when registers are still available, allowing the tracer to see where the exit occurred, whereas the normal exit notification is done after the process is finished exiting.
What is ptrace in Android shunix used for?
The ptrace () system call provides a means by which one process (the “tracer”) may observe and control the execution of another process (the “tracee”), and examine and change the tracee’s memory and registers. It is primarily used to implement breakpoint debugging and system call tracing.
How is ptrace used in breakpoint debugging?
It is primarily used to implement breakpoint debugging and system call tracing. A tracee first needs to be attached to the tracer. Attachment and subsequent commands are per thread: in a multithreaded process, every thread can be individually attached to a (potentially different) tracer, or left not attached and thus not debugged.