#!/bin/bash
# Finds all packet-FOO.c having an assignment matching:
#   FOO_handle = create_dissector_handle(..., ...)
# Tested using clang-query 3.7.0 (part of clang-tools-extra).
#
# Usage:
#
#   Ensure that builddir and srcdir variables below are set
#   Ensure that compile_commands.json exists in builddir (see below).
#   Run `./fgind-assignments-handle > scan.log` to write matching contexts to file
#   Use the displayed awk command for further processing (see bottom).
#
# Author: Peter Wu <peter@lekensteyn.nl>

# path to builddir (should contain compile_commands.json, use
# cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=1)
builddir=/tmp/wsbuild
# path to source directory (will be scanned for files matching the function
srcdir=/tmp/wireshark

set -e -u

matcher='
binaryOperator(hasOperatorName("="), hasRHS(callExpr(callee(functionDecl(hasName("create_dissector_handle"))))))
'

matcher="$(sed '/^ *#/d;s/^ *//;s/ *$//' <<<"$matcher" | tr -d '\n')"
args=(
    # Add this if you get an error about missing std headers
    #-extra-arg=-I/usr/lib/clang/3.7.0/include/
    -p "$builddir"

    # Use "print" to show the full processed line. Use "diag" for a short line.
    # Use "dump" for a raw AST tree.
    -c "set output print"
    #-c "set output dump"
    #-c "set output diag"

    -c "match ${matcher}"
)

# Write file names matching the function names to a file (cache it in case this
# script is interrupted).
tmp=/tmp/files.txt
[ -s "$tmp" ] ||
grep -rl --exclude=\* --include=\*.c --exclude-dir=asn1 "$srcdir" \
    -e 'create_dissector_handle' > "$tmp"

# Start the hunt!
cat "$tmp" |
#head | grep ssl|
xargs -rt -P$(nproc) -n10 clang-query "${args[@]}"
# add -t to xargs for verbose debugging (print commands as they are executed)
# -P is used for parallel jobs
# -n limits files per command. Use this to tune memory usage.

rm "$tmp"
cat <<'EOF' >&2

# Use this for analysis:
awk '/"[r]oot" binds here/{i=2} !/clang-query/&&i>0{printf("%s\033[m\n", $0);i--}' /tmp/results.txt |
gawk -F'[:=]' 'f{v=$1; gsub(" ","",v); if(sub(/_handle$/,"",v)==0)f="";
dis=gensub(/.*\/packet-(.+)[.]c$/,"\\1","g",f);gsub("-","",dis); gsub("_","",v);
if(dis==v)print f":"l;f=""} /packet-.*"root"/{f=$1;l=$2}' |
sed 's,/tmp/wireshark/,,'
EOF

# vim: set sw=4 ts=4 et: