C Call Graph.

ccg.py

import subprocess

call = "ctags -no - *.c"
tags = subprocess.check_output(call, shell=True)

funcs = []
for entry in tags.split('\n'):
    tokens = entry.split('\t')
    if tokens[-1].strip() == "f":
        func, source, line, symboltype = tokens
        line = int(line.rstrip(";\""))
        funcs.append((source, line, func))

funcs.sort(key=lambda f: f[1])
funcs.sort(key=lambda f: f[0])

arrows = []
for source, line, func in funcs:
    regex = r'"\(^\|[^a-zA-Z]\)%s("' % func
    call = "grep -nH %s *.c" % regex
    matches = subprocess.check_output(call, shell=True)
    callers = set()
    for entry in matches.split('\n'):
        tokens = entry.split(':')
        if len(tokens) >= 3:
            msource = tokens[0]
            mline = int(tokens[1])
            if msource == source and mline == line:
                continue
            defs = [f[2] for f in funcs
                    if f[0] == msource and f[1] < mline]
            if defs:
                callers.add(defs[-1])
    callers = list(callers)
    callers.sort()
    for caller in callers:
        arrows.append((caller, func))

arrows.sort(key=lambda a: a[0])
arrows.sort(key=lambda a: a[1])
dot = open("ccg.dot", "w")
dot.write("digraph G {\n")
dot.write("    ratio=1.0;\n")
for arrow in arrows:
    dot.write("    %s -> %s;\n" % arrow)
dot.write("}\n")
dot.close()

call = "dot -Tpng ccg.dot -o ccg.png"
subprocess.check_call(call, shell=True)