1# chainagent
2
3The chainagents agent is a JVMTI agent that chain loads other agents from a file found at a
4location relative to a passed in path. It can be used in combination with android startup_agents
5in order to implement more complicated agent-loading rules.
6
7It will open the file `chain_agents.txt` from the directory passed in as an argument and read it
8line-by-line loading the agents (with the arguments) listed in the file.
9
10Errors in loading are logged then ignored.
11
12# Usage
13### Build
14>    `m libchainagents`
15
16The libraries will be built for 32-bit, 64-bit, host and target. Below examples
17assume you want to use the 64-bit version.
18
19### Command Line
20#### ART
21>    `art -Xplugin:$ANDROID_HOST_OUT/lib64/libopenjdkjvmti.so -agentpath:$ANDROID_HOST_OUT/lib64/libchainagents.so=/some/path/here -Xint helloworld`
22
23* `-Xplugin` and `-agentpath` need to be used, otherwise libtitrace agent will fail during init.
24* If using `libartd.so`, make sure to use the debug version of jvmti.
25
26### chain_agents.txt file format.
27
28The chain-agents file is a list of agent files and arguments to load in the same format as the
29`-agentpath` argument.
30
31#### Example chain_agents.txt file
32
33```
34/data/data/com.android.launcher3/code_cache/libtifast32.so=ClassLoad
35/data/data/com.android.launcher3/code_cache/libtifast64.so=ClassLoad
36```
37