trace function calls with gdb

trace.py

#!/usr/bin/env python

import re
import sys
import subprocess
import tempfile

nm = 'nm'
gdb = 'gdb'

backtrace = 1
ours, theirs = [], []

i = 0
for arg in sys.argv[1:]:
    if arg == '--':
        i = 1
    elif i == 0 and arg.startswith('--backtrace='):
        backtrace = int(arg[12:])
    else:
        (theirs if i else ours).append(arg)

regex = re.compile('|'.join('(%s)' % s for s in ours))

if not theirs:
    print "Usage: %s regex [...] -- program [args]" % sys.argv[0]
    sys.exit(1)

program, args = theirs[0], theirs[1:]

# not very memory efficient
stdout, stderr = subprocess.Popen([nm, '-C', program], stdout=subprocess.PIPE).communicate()
if stderr:
    print stderr
    sys.exit(1)

f = tempfile.NamedTemporaryFile()
f.write("set height 0\n") # disable gdb's pager
f.write("set breakpoint pending on\n")

template = """
break %(name)s
commands
silent
backtrace %(backtrace)d
continue
end
"""

for line in stdout.split("\n"):
    fields = line.split(None, 2) # address, type, name
    if len(fields) == 3 and fields[1] in 'TUVWtuvw' and regex.search(fields[2]):
        f.write(template % dict(name=fields[2], backtrace=backtrace))
f.flush()

retcode = subprocess.call(
    [gdb, '-x', f.name, '--args', program] + args)
sys.exit(retcode)