Re: Adding to or Updating the standard library
Jeremy Cowgar wrote:
>
> CChris wrote:
>
> > Two questions:
> > 1/ How to unit-test that something should crash?
>
> I have not solved that yet. Let me work on that now.
>
Testing if something crashes requires re-thinking the way we think of program
control. For my executable memory allocator, allocate_code() I wrote a test
that first tries to run code allocated by allocate_code() and then tries
the same with allocate().
For allocate() in particular, I made a global flag variable and a crash_routine
handler. The global flag is set to true, when we want it to intercept a crash
and say something like: "code executed from memory using allocate caused an
exception and as it should." When the flag is set to false the the handler
returns 0 and no success message is printed and EUPHORIA calls the other
handlers
if applicable. I set the global flag before executing the code that is supposed
to cause the exception and then I clear the flag afterwards. After clearing the
flag an error message is printed, for it means that the crash routine wasn't
executed. At this point though, the mainline of the program is in a crash
handler!
In the case of allocate_code(), we do not want to see an exception. So, in this
cause the crash handler prints a message saying the test has failed and then
terminates the program. After calling code on allocate_code that could cause
an exception (if there is a bug) it prints a success message.
The program flow reminds me of goto from BASIC.
-- Test the system for :
include xalloc.e as dep
include joy.e as joy
function isspace( integer x )
return find( x, "\t \n" )
end function
integer log
log = open( "wordwrap.txt", "w" )
function visual_slice( joy:string_of_atoms s, integer i1, integer i2, integer
line_length )
integer c, m1, m2
c = 0
m1 = -1
m2 = -1
for i3 = 1 to length(s) do
if s[i3] = '\n' then
c += line_length
elsif s[i3] = '\t' then
c += 8
else
c += 1
end if
if m1 = -1 then
if c > i1 then
m1 = c-1
elsif c = i1 then
m1 = c
end if
end if
if m2 = -1 then
if c > i2 then
m2 = c-1
else
m2 = c
end if
end if
if m2 != -1 then
exit
end if
end for
return s[m1..m2]
end function
-- word_wrap function: Please do not pass strings with TAB characters
function word_wrap( joy:string_of_integers s, integer line_length )
sequence lines
sequence haystack
integer whitelocation
lines = {}
while length(s) do
haystack = s[1..joy:min({length(s),line_length})]
puts( log, "haystack = "&haystack&10 )
if length(s) <= line_length then
lines = append( lines, s )
s = ""
else
-- if no spaces Grab line_length of it
-- if '\n' grab the first one, or the last ' '
-- whichever comes first.
whitelocation = joy:min( {max({length(s),line_length}) + 1} & joy:remove_0s(
{ find( '\n', haystack ), joy:rfind( ' ', haystack ) } ) )
puts( log, "s[1..whitelocation-1]=" & s[1..whitelocation-1] & 10 )
lines = append( lines, s[1..whitelocation-1] )
flush(log)
if whitelocation+1 > length(s)+1 then
s = ""
else
s = s[whitelocation+1..length(s)]
end if
end if
end while
return joy:join( "\n", lines )
end function
object line
procedure PETC()
puts(1,"Press Enter to Continue")
line = gets(0)
puts(1,10)
end procedure
integer calling_memfunction
calling_memfunction = 0
function print_failure(object x)
if calling_memfunction then
puts( 1, word_wrap( "We have found that the xalloc.e routines do not
really make memory executable.\n", 80 ) )
puts( 1, word_wrap( "This conclusively tells us that there is a bug in the
allocate_code() function. Please let me know about this: Email me at
shawn.pringle at gmail.com", 80 ) )
puts( 1, "Test result for allocate_code: FAILURE\n" )
PETC()
abort(0)
end if
return 0
end function
integer calling_dmemfunction
calling_dmemfunction = 0
function dep_is_enabled(object x)
if calling_dmemfunction then
puts(1, word_wrap( "The code allocated with allocate(), however raised
an exception and it SHOULD. Therefore D.E.P. is enabled for the interpreter you
used for this test on your system. This means, your system is configured
correctly to test allocate_code and that allocate_code works properly.\n", 80 ) )
puts(1, "Test result for allocate_code: SUCCESS!\n" )
PETC()
abort(0)
end if
return 0
end function
atom code_space, data_space
sequence multiply_code
atom rexec, rdata
atom x,y
object void
-- machine code taken from callmach.ex
multiply_code = {
-- int argument is at stack offset +4, double is at +8
#DB, #44, #24, #04, -- fild dword ptr +4[esp]
#DC, #4C, #24, #08, -- fmul qword ptr +8[esp]
#C2, #0C - 4 * (platform()=LINUX), #00 -- ret C -- pop 12 (or 8) bytes
-- off the stack
}
crash_routine(routine_id("print_failure"))
crash_routine(routine_id("dep_is_enabled"))
code_space = dep:allocate_code(multiply_code)
data_space = allocate(length(multiply_code))
poke( data_space, multiply_code )
rexec = define_c_func("", code_space, {C_INT, C_DOUBLE}, C_DOUBLE)
rdata = define_c_func("", data_space, {C_INT, C_DOUBLE}, C_DOUBLE )
x = 7
y = 8.5
puts( 1, word_wrap( "We will now call a machine code function using memory
marked as executable.\n", 80 ) )
PETC()
calling_memfunction = 1
void = c_func(rexec, {x, y})
calling_memfunction = 0
printf(1, word_wrap( "The code allocated with allocate_code() was called without
an exception being raised.\nThe function allocate_code() works as it should.\n",
80 ), {} )
puts(1, "\n\n" )
puts(1, word_wrap( "We will now call a machine code function without using
memory marked as executable. This should cause an exception.\n", 80 ) )
PETC()
function ifthenelse( integer condition, sequence s1, object x2 )
if condition then return s1 else return x2 end if
end function
calling_dmemfunction = 1
void = c_func(rdata, {x,y})
calling_dmemfunction = 0
printf(1, word_wrap( "The code allocated with allocate() was also called " &
"without an exception being "&
"raised. This means your system has no DEP for this interpreter " &
" and these tests are " &
"inconclusive. " &
"You need to enable DEP in both your pre-OS hardware configuration screen" &
" at " &
"boot up and your Operating system. "&
"You probably can get into the hardware by pressing the delete key at boot
up. "&
ifthenelse( platform() = WIN32,
"In Windows XP, you can find the configuration for "&
"hardware DEP by first, opening Control_Panel, next from there opening "&
"System, after that clicking the Advanced_Tab, and next clicking the
Performance button and "&
"finally clicking the Data execution Prevention tab. " &
"There you can choose the option for enabling DEP for all processes.", "")&
ifthenelse( platform() = LINUX,
"In Linux, you will need to download some kernel patches to allow, "&
"this to work.", "" ) &
ifthenelse( platform() = DOS32,
"In DOS, there is no way to enable hardware DEP.", "" )&"\n", 80)
, {} )
close(log)
puts(1, "Test result for allocate_code: INCONCLUSIVE!\n" )
PETC()
Shawn Pringle
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