Hi I've often wanted to extract information from a large build in some way that's more reliable than grep. The GNU make (--print-data-base) option has been a very useful way to see what the complicated makefiles I was working on finally evaluated to. The only negative about it from my point of view is that it was still a makefile in the end and still had to be parsed.
So recently I tried cloning the print-data-base feature into something that
delivered JSON. Now it should be trivial to get a list of targets of some
particular type - even with a tool like "jq".
The result so far is lacking a lot but I am running out of free time to
work on it and I thought that I might as well seek feedback now in the
event that there's anyone else out there who finds this of interest.
At a high level the output looks like a straight dump of make's internal
data structures but there is a tonne of detail about each variable and each
file which I've left out to make this overview simple:
{
"MakefileName": {
"variables": {
"global": {
"pkgdatadir" : {
"origin": "makefile",
"private": false,
"source": "Makefile",
"line": 92,
"assign-recursive": "$(datadir)\/make"
}
},
"pattern-specific-variables": {},
"pattern-specific-rule-count": 0
},
"dirs": [],
"rules": [],
"files": {
"src/w32/w32os.c": {},
"/usr/include/bits/fcntl.h": {},
"dist": {},
}
}
}
The whole thing isn't indented nicely either but one can just run jq on it.
If you looked at an individual file you might see something like this:
"src/w32/w32os.c" : {
"hname": "src\/w32\/w32os.c",
"vpath": "",
"deps": [],
"stem": "",
"also_make": [],
"target-variables": {
},
"last_mtime": 0,
"mtime_before_update": 0,
"considered": 0,
"command_flags": 0,
"update_status": 1,
"command_state": "cs_not_started",
"builtin": false,
"precious": false,
"loaded": false,
"unloaded": false,
"low_resolution_time": false,
"tried_implicit": false,
"updating": false,
"updated": false,
"is_target": false,
"cmd_target": false,
"phony": false,
"intermediate": false,
"is_explicit": true,
"secondary": false,
"notintermediate": false,
"dontcare": false,
"ignore_vpath": false,
"pat_searched": false,
"no_diag": false,
"was_shuffled": false,
"snapped": false
}
HOW TO GET IT:
===============
in the feature/jprint branch on this fork:
https://github.com/tnmurphy/gmake-experimental
I've added a new commandline option:
--print-data-base-json
you can build it and then run it like this:
./make --print-data-base-json
HOW IT GENERATES OUTPUT:
===========================
The idea is that a JSON file is created in each directory where make runs -
this lets the code avoid intermingling output with other bits of make that
would muck up the JSON. For now the files are named with the following
convention: makefile-$PID.json where $PID is the pid of the make process
which created the file. Is this enough? Is it right? I am not sure - it's
interesting. We seem to get 2 files for one directory sometimes - with the
same targets in them - I think it might be a remake. Anyhow this method
seems to keep everything separated for now.
I've also not mentioned that for the "MakefileName" in the example I
actually have inserted the contents of "$(MAKEFILE_LIST)" as that seems
more correct in a way.
There is an attached json produced by running on make itself - which is all
the testing I've done - this is a hack and probably needs real test data
and a load of tests.
Most of the code is in src/jprint.c. I had to export some things in
questionable ways and that is one of many reasons why I would never expect
this feature to get back into GNU make proper. I just think it can exist in
a fork and potentially be of use to someone.
Regards,
Tim Murphy
makefile-30281.json.gz
Description: application/gzip
