debugserver

debugserver is a console app that as server for remote gdb debugging. It is installed when a device is marked for development. It can be found in /Developer/usr/bin/debugserver. This is also the process invoked by Xcode to debug applications on the device.

Command line options

debugserver can be invoked with

debugserver [<options>] host:<port> [<prog-name> <arg1> <arg2> ...]

Where options can be:

Option	Effect
`-a` process	Attach `debugserver` to process. The process can be a pid or executable name.
`-d` integer	Assign the waitfor-duration.
`-f` ?	?
`-g`	Turn on debugging.
`-i` integer	Assign the waitfor-interval.
`-l` filename	Log to file. Set filename to stdout to log to standard output.
`-t`	Use task ID instead of process ID.
`-v`	Verbose.
`-w` ?	?
`-x` method `--launch`=method	How to launch the program. Can be one of: auto: Auto-detect the best launch method to use. fork: Launch program using `fork(2)` and `exec(3)`. posix: Launch program using `posix_spawn(2)`. spring: Launch program via SpringBoard.
`--lockdown`	Obtain parameters from `lockdown` (?)

Patching for process attaching

The vanilla debugserver cannot attach to any processes due to lack of entitlement to allow task_for_pid(). An entitlement must be inserted to the binary to allow this.

0. cd ~
1. Thin the binary because ldid does not support fat binaries:

lipo -thin armv6 /Developer/usr/bin/debugserver -output ~/debugserver

2. Save for following as ent.xml:

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>com.apple.springboard.debugapplications</key>
	<true/>
	<key>get-task-allow</key>
	<true/>
	<key>task_for_pid-allow</key>
	<true/>
	<key>run-unsigned-code</key>
	<true/>
</dict>
</plist>

3. Apply the entitlement with ldid:

ldid -Sent.xml debugserver

Example session

TODO.

References

iphone-debugserver project — http://code.google.com/p/iphone-debugserver/