(gdb) bt
#0  0x0080e2e3 in strlen () from /lib/tls/libc.so.6
#1  0x00f2cf37 in function_fieldqty (chan=0x9dcf0a0, cmd=0x507fd80 "FIELDQTY", parse=0x507fd89 "HASHKEYS(access_control)", buf=0x507ed70 "", len=4096)
    at func_strings.c:58
#2  0x080b5af2 in ast_func_read (chan=0x9dcf0a0, function=0x507fd80 "FIELDQTY", workspace=0x507ed70 "", len=4096) at pbx.c:1501
#3  0x080b5ed7 in pbx_substitute_variables_helper_full (c=0x9dcf0a0, headp=0x9dcf3e4, cp1=0x9cf1e08 "NUM_FIELDS=${FIELDQTY(HASHKEYS(access_control)|,)}",
    cp2=0x508500b "", count=8180) at pbx.c:1619
#4  0x080b6239 in pbx_substitute_variables_helper (c=0x9dcf0a0, cp1=0x9cf1e08 "NUM_FIELDS=${FIELDQTY(HASHKEYS(access_control)|,)}",
    cp2=0x5085000 "NUM_FIELDS=", count=8191) at pbx.c:1701
#5  0x080b6342 in pbx_substitute_variables (passdata=0x5085000 "NUM_FIELDS=", datalen=8192, c=0x9dcf0a0, e=0x9cf1f40) at pbx.c:1719
#6  0x080b6551 in pbx_extension_helper (c=0x9dcf0a0, con=0x0, context=0x9dcf220 "sub-access_control", exten=0x9dcf270 "s", priority=7, label=0x0,
    callerid=0x9dc2c98 "4166289921", action=E_SPAWN) at pbx.c:1765
#7  0x080b7847 in ast_spawn_extension (c=0x9dcf0a0, context=0x9dcf220 "sub-access_control", exten=0x9dcf270 "s", priority=7,
    callerid=0x9dc2c98 "4166289921") at pbx.c:2248
#8  0x080b7d35 in __ast_pbx_run (c=0x9dcf0a0) at pbx.c:2348
#9  0x080b8a32 in pbx_thread (data=0x9dcf0a0) at pbx.c:2561
#10 0x080efa55 in dummy_start (data=0x9dcf5d0) at utils.c:545
#11 0x00332371 in start_thread () from /lib/tls/libpthread.so.0
#12 0x0086cffe in clone () from /lib/tls/libc.so.6
(gdb) bt full
#0  0x0080e2e3 in strlen () from /lib/tls/libc.so.6
No symbol table info available.
#1  0x00f2cf37 in function_fieldqty (chan=0x9dcf0a0, cmd=0x507fd80 "FIELDQTY", parse=0x507fd89 "HASHKEYS(access_control)", buf=0x507ed70 "", len=4096)
    at func_strings.c:58
        varname = 0x0
        varsubst = 0x15 ""
        varval = '\0' <repeats 8191 times>
        varval2 = 0x507cd00 ""
        fieldcount = 0
        args = {argc = 2, argv = 0x507cce4, varname = 0x507fd89 "HASHKEYS(access_control)", delim = 0x507fda2 ","}
#2  0x080b5af2 in ast_func_read (chan=0x9dcf0a0, function=0x507fd80 "FIELDQTY", workspace=0x507ed70 "", len=4096) at pbx.c:1501
        args = 0x507fd89 "HASHKEYS(access_control)"
        acfptr = (struct ast_custom_function *) 0xf326a0
        __PRETTY_FUNCTION__ = "ast_func_read"
#3  0x080b5ed7 in pbx_substitute_variables_helper_full (c=0x9dcf0a0, headp=0x9dcf3e4, cp1=0x9cf1e08 "NUM_FIELDS=${FIELDQTY(HASHKEYS(access_control)|,)}",
    cp2=0x508500b "", count=8180) at pbx.c:1619
        cp4 = 0x333d27 "\201ÃÍ\202"
        tmp = 0x9cf1e08 "NUM_FIELDS=${FIELDQTY(HASHKEYS(access_control)|,)}"
        whereweare = 0x9cf1e3a ""
        length = 176
        offset = 0
        offset2 = 2147483647
        isfunction = 2
        workspace = 0x507ed70 ""
        ltmp = 0x0
        var = 0x507fd80 "FIELDQTY"
        nextvar = 0x9cf1e13 "${FIELDQTY(HASHKEYS(access_control)|,)}"
        nextexp = 0x0
        nextthing = 0x9cf1e13 "${FIELDQTY(HASHKEYS(access_control)|,)}"
        vars = 0x507fd80 "FIELDQTY"
        vare = 0x9cf1e3a ""
        pos = 11
        brackets = 0
        needsub = 0
        len = 36
        __PRETTY_FUNCTION__ = "pbx_substitute_variables_helper_full"
#4  0x080b6239 in pbx_substitute_variables_helper (c=0x9dcf0a0, cp1=0x9cf1e08 "NUM_FIELDS=${FIELDQTY(HASHKEYS(access_control)|,)}",
    cp2=0x5085000 "NUM_FIELDS=", count=8191) at pbx.c:1701
No locals.
#5  0x080b6342 in pbx_substitute_variables (passdata=0x5085000 "NUM_FIELDS=", datalen=8192, c=0x9dcf0a0, e=0x9cf1f40) at pbx.c:1719
No locals.
#6  0x080b6551 in pbx_extension_helper (c=0x9dcf0a0, con=0x0, context=0x9dcf220 "sub-access_control", exten=0x9dcf270 "s", priority=7, label=0x0,
    callerid=0x9dc2c98 "4166289921", action=E_SPAWN) at pbx.c:1765
        e = (struct ast_exten *) 0x9cf1f40
        app = (struct ast_app *) 0x9c8f2c0
        res = 0
        q = {incstack = {0x0 <repeats 128 times>}, stacklen = 0, status = 5, swo = 0x0, data = 0x0, foundcontext = 0x9dcf220 "sub-access_control"}
        passdata = "NUM_FIELDS=", '\0' <repeats 8180 times>
        matching_action = 0
        __PRETTY_FUNCTION__ = "pbx_extension_helper"
#7  0x080b7847 in ast_spawn_extension (c=0x9dcf0a0, context=0x9dcf220 "sub-access_control", exten=0x9dcf270 "s", priority=7,
    callerid=0x9dc2c98 "4166289921") at pbx.c:2248
No locals.
#8  0x080b7d35 in __ast_pbx_run (c=0x9dcf0a0) at pbx.c:2348
        dst_exten = "0pÕ\t", '\0' <repeats 16 times>, "Ø\b{\000\000\000ö·", '\0' <repeats 48 times>, "Dj\200\0000pÕ\t\001\000\000\000Ps\b\005f,y\000ÜqÕ\t\214'\214\000\001\000\000\000\001\000\000\000\000\000\000\000ðâa\000\000Eõ\tø¡`\000ô¿\214\000HØ\214\000Dj\200\000\020\000\000\000:s\200\000°`\200\000¨5É\000\f\000\000\000ô¿\214\000\f\000\000\000@Ø\214\000\230s\b\005v\221\200\000@Ø\214\000\f\000\000\000\030\000\000\000ø\004\002\000\f\000\000\000\b\033ö\tô¿3\000\000\000\000\000°{\b\005Ès\b\005;ë\016\b\001\000\000\000'=3\000@Ø\214\000ÐõÜ\t\000\000\000\000"...
        pos = 0
        digit = 0
        found = 1
        res = 0
        autoloopflag = 0
        error = 0
        __PRETTY_FUNCTION__ = "__ast_pbx_run"
#9  0x080b8a32 in pbx_thread (data=0x9dcf0a0) at pbx.c:2561
        c = (struct ast_channel *) 0x9dcf0a0
#10 0x080efa55 in dummy_start (data=0x9dcf5d0) at utils.c:545
        _buffer = {__routine = 0x8068329 <ast_unregister_thread>, __arg = 0x5087bb0, __canceltype = 0, __prev = 0x0}
        ret = (void *) 0x8ca6f4
        a = {start_routine = 0x80b8a1b <pbx_thread>, data = 0x9dcf0a0,
  name = 0x9dcf5e0 "pbx_thread", ' ' <repeats 11 times>, "started at [ 2585] pbx.c ast_pbx_start()"}
#11 0x00332371 in start_thread () from /lib/tls/libpthread.so.0
No symbol table info available.
#12 0x0086cffe in clone () from /lib/tls/libc.so.6
No symbol table info available.