Client and server for a process to request attach by gdlv.

These two packages allow a program to request that a debugger attach to it. The motivating use case is debugging a compiler, because compilers are often run by other processes in ways that are tedious to capture and reproduce. Adding a debugger-invocation when things go wrong, or just before the problematic file and line nmumber are processed, may help in understanding a bug and its cause.

Debug server

• listen on a port
• receive a pid:binaryname request on a port, reply "1\n" (yes) or "0\n" (no) to signal intent to debug.
• start gdlv on process.

Client of debug server

• if environment variable "DEBUG_SERVER" is defined, expect it to be a localhost port to connect to.
• assuming it is defined, open a connection, send "pid:binary\n", wait for response.
• if response is "1\n", sleep 60 seconds waiting for server to start gdlv and attach