Is there a way to get android "history" system log?

Question

I am developing a system log app for users to check their device's log. We all know that using logcat an app can read the system log in real-time, but is there a way to read the "history" system log, like for one week? (our app may be down during the week)

UPDATED:

I am also the builder of the custom Android OS, based on AOSP. The system log app is also running in this OS only. So I have the ability to develop drivers, framework layer and system apps besides normal apps.

If a normal app cannot accomplish the task, how about developing a driver additionally? I know that there is a driver module named "logger" in the kernel, which is in charge of the logging. Maybe I can add some code to "logger" and let it dump the logs into files: log_20140629.txt, log_20140630.txt and so on. Every file contains the log in that whole day. Then my app just read these files. Is this idea possible?

Answer 1

We all know that using logcat an app can read the system log in real-time

Only on devices running Android 4.1 and lower, or possibly on rooted devices. Android apps on Android 4.2+ cannot hold the READ_LOGS permission.

but is there a way to read the "history" system log, like for one week?

I have no idea what the "'history' system log" is. If you mean "the system log's history", LogCat exists as a ring buffer. This buffer used to be 64KB a long time ago, and I do not know if they increased its size. On many production devices, this will hold minutes to hours of history, not days.