Steve Fink's collection of random tools

These are tools that I think might be useful to other people.

Tools included:

  • json : Interactive navigation of a JSON file
  • debug : Start up a debugger within emacs on various types of files
  • em : Start up emacs on the files touched by a patch, on a relevant line number
  • traverse.py : Gecko-specific, sorta. Utility for traversing a callgraph.
  • wig : Patch harder

Configuration files:

I also have a set of gdb initialization files that I version-control here.

  • gdbstart.py : gdb init file that loads all of the below gdb startup files
  • gdbinit : basic gdb configuration
  • gdbinit.py : gdb python init file, defines some miscellany
  • gdbinit.symbols.py : Ted Mielczarek's source server integration for gdb
  • gdbinit.pahole.py : pahole and overlap commands, loaded by gdbstart.py
  • gdbinit.gecko.py : configuration to assist with debugging Gecko and SpiderMonkey
  • gdbinit.misc : some miscellaneous gdb helper commands
  • gdbinit.rr.py : gdb helper commands for running under rr (lots here!)
  • gdbinit.sfink : a couple of things that depend on my personal file layout

The easiest way to use these is to create a ~/.gdbinit file with something like the following, with the appropriate path to your sfink-tools checkout:

source ~/checkouts/sfink-tools/conf/gdbstart.py

That will load all of the above except for gdbinit.sfink. Alternatively, you could just source the individual files you want to use from the above list.

Other configuration files:

  • hgrc : Mercurial configuration

I use this via a symlink from ~/.hgrc.

json - Interactive navigation of a JSON file

Created to explore a problem with a large sessionstore.js file. It mimics a UNIX shell prompt, allowing you to cd, ls, grep, and similar.

Requires the Perl module 'JSON'. Installable on Fedora with

dnf install perl-JSON

Run json --help for a full help message. Here's an excerpt:

Usage: json <filename.json> [initial-path]

ls [PATH]              - show contents of structure
cd PATH                - change current view to PATH
cat [PATH]             - display the value at the given PATH
delete SPEC            - delete the given key or range of keys (see below
                         for a description of SPEC)
set KEY VALUE          - modify an existing value (VALUE may optionally
                       - be quoted)
mv PATH PATH           - move a subtree
grep [-l] PATTERN PATH - search for PATTERN in given PATH
write [-pretty] [FILENAME]
                       - write out the whole structure as JSON. Use '-' as
                         FILENAME to write to stdout.
pretty                 - prettyprint current structure to stdout
size PATH              - display how many bytes the JSON of the substructure
                         at PATH would take up
load [FILENAME]        - load in the given JSON file (reload current file
                         if no filename given)

debug - Start up a debugger within emacs on various types of files

debug --help for usage.

Usual usage is to prepend whatever command you want to debug with 'debug'.


  • debug firefox -no-remote -P BugPictures

runs firefox within gdb within emacs, with the given arguments

  • debug -i firefox -no-remote -P NakedBugPictures

same, but stops at the gdb prompt before running firefox

  • debug somescript.pl x y z

runs somescript.pl within perldb within emacs, with the given arguments

  • debug --record js testfile.js

records js testfile.js with rr, then replays the recording in gdb in emacs

The script goes to insane lengths to figure out what you really meant to run. For example, if you alias ff in your shell to 'firefox -no-remote', you can just do

debug ff

It will discover that there's no command ff in $PATH and start up a subshell, look for the alias 'ff', and use that command instead.

em - Edit files relevant to a patch

  1. em foo.txt:33 will run emacs +33 foo.txt so will em foo.txt:33: (easier cut & paste of trailing colon for error messages) and foo.txt will be found anywhere in the current hg tree (if not in cwd)
  2. em with no args will run emacs on the files changed in the cwd, or if none, then by the cwd's parent rev
  3. em 01faf51a0acc will run emacs on the files changed by that rev.
  4. em foo.txt.rej will run emacs on both foo.txt and foo.txt.rej, but at the lines containing the first patch hunk and the line number of the original that it applies to (ok, so this is probably where this script jumped the shark.)

If your $EDITOR is not set to emacs, you won't get the fancy line number stuff.

traverse.py - various traversals over the known portion of a callgraph.

The callgraph is in the format generated by the rooting hazard analysis.


route - Find a route from SOURCE to DEST [avoiding FUNC]

Use help <cmd> to figure out what they do; I'm not going to spend time doing that right now.

wig - Apply a patch loosely. Works if the surrounding code has changed.

My usual use is to do some VCS command that spits out .rej files, then do wig file1.rej followed by wig file2.rej etc. That lets me see any failures one at a time. But the tool also supports scanning for all reject files.