oracular (1) goto-instrument.1.gz
NAME
goto-instrument - Perform analysis or instrumentation of goto binaries
SYNOPSIS
goto-instrument [-?] [-h] [--help]
show help
goto-instrument --version
show version and exit
goto-instrument [options] in [out]
perform analysis or instrumentation
DESCRIPTION
goto-instrument reads a GOTO binary, performs a given program transformation, and then writes the
resulting program as GOTO binary on disk.
OPTIONS
Dump Source:
--dump-c
generate C source
--dump-c-type-header m
generate a C header for types local in m
--dump-cpp
generate C++ source
--no-system-headers
generate C source expanding libc includes
--use-all-headers
generate C source with all includes
--harness
include input generator in output
--horn print program as constrained horn clauses
Diagnosis:
--show-properties
show the properties, but don't run analysis
--document-properties-html
generate HTML property documentation
--document-properties-latex
generate Latex property documentation
--show-symbol-table
show loaded symbol table
--list-symbols
list symbols with type information
--show-goto-functions
show loaded goto program
--list-goto-functions
list loaded goto functions
--count-eloc
count effective lines of code
--list-eloc
list full path names of lines containing code
--print-global-state-size
count the total number of bits of global objects
--print-path-lengths
print statistics about control-flow graph paths
--show-locations
show all source locations
--dot generate CFG graph in DOT format
--print-internal-representation
show verbose internal representation of the program
--list-undefined-functions
list functions without body
--list-calls-args
list all function calls with their arguments
--call-graph
show graph of function calls
--reachable-call-graph
show graph of function calls potentially reachable from main function
--show-class-hierarchy
show the class hierarchy
--validate-goto-model
enable additional well-formedness checks on the goto program
--validate-ssa-equation
enable additional well-formedness checks on the SSA representation
--validate-goto-binary
check the well-formedness of the passed in GOTO binary and then exit
--interpreter
do concrete execution
Data-flow analyses:
--show-struct-alignment
show struct members that might be concurrently accessed
--show-threaded
show instructions that may be executed by more than one thread
--show-local-safe-pointers
show pointer expressions that are trivially dominated by a not-null check
--show-safe-dereferences
show pointer expressions that are trivially dominated by a not-null check *and* used as a
dereference operand
--show-value-sets
show points-to information (using value sets)
--show-global-may-alias
show may-alias information over globals
--show-local-bitvector-analysis
show procedure-local pointer analysis
--escape-analysis
perform escape analysis
--show-escape-analysis
show results of escape analysis
--custom-bitvector-analysis
perform configurable bitvector analysis
--show-custom-bitvector-analysis
show results of configurable bitvector analysis
--interval-analysis
perform interval analysis
--show-intervals
show results of interval analysis
--show-uninitialized
show maybe-uninitialized variables
--show-points-to
show points-to information
--show-rw-set
show read-write sets
--show-call-sequences
show function call sequences
--show-reaching-definitions
show reaching definitions
--show-dependence-graph
show program-dependence graph
--show-sese-regions
show single-entry-single-exit regions
Safety checks:
--no-assertions
ignore user assertions
--bounds-check
enable array bounds checks
--pointer-check
enable pointer checks
--memory-leak-check
enable memory leak checks
--memory-cleanup-check
Enable memory cleanup checks: assert that all dynamically allocated memory is explicitly freed
before terminating the program.
--div-by-zero-check
enable division by zero checks for integer division
--float-div-by-zero-check
enable division by zero checks for floating-point division
--signed-overflow-check
enable signed arithmetic over- and underflow checks
--unsigned-overflow-check
enable arithmetic over- and underflow checks
--pointer-overflow-check
enable pointer arithmetic over- and underflow checks
--conversion-check
check whether values can be represented after type cast
--undefined-shift-check
check shift greater than bit-width
--float-overflow-check
check floating-point for +/-Inf
--nan-check
check floating-point for NaN
--enum-range-check
checks that all enum type expressions have values in the enum range
--pointer-primitive-check
checks that all pointers in pointer primitives are valid or null
--retain-trivial-checks
include checks that are trivially true
--error-label label
check that label is unreachable
--no-built-in-assertions
ignore assertions in built-in library
--no-assertions
ignore user assertions
--no-assumptions
ignore user assumptions
--assert-to-assume
convert user assertions to assumptions
--uninitialized-check
add checks for uninitialized locals (experimental)
--stack-depth n
add check that call stack size of non-inlined functions never exceeds n
--race-check
add floating-point data race checks
Semantic transformations:
--nondet-volatile
--nondet-volatile-variable variable
By default, cbmc(1) treats volatile variables the same as non-volatile variables. That is, it
assumes that a volatile variable does not change between subsequent reads, unless it was written
to by the program. With the above options, goto-instrument can be instructed to instrument the
given goto program such as to (1) make reads from all volatile expressions non-deterministic
(--nondet-volatile), (2) make reads from specific variables non-deterministic
(--nondet-volatile-variable), or (3) model reads from specific variables by given models
(--nondet-volatile-model).
Below we give two usage examples for the options. Consider the following test, for function
get_celsius and with harness test_get_celsius:
#include <assert.h>
#include <limits.h>
#include <stdint.h>
// hardware sensor for temperature in kelvin
extern volatile uint16_t temperature;
int get_celsius() {
if (temperature > (1000 + 273)) {
return INT_MIN; // value indicating error
}
return temperature - 273;
}
void test_get_celsius() {
int t = get_celsius();
assert(t == INT_MIN || t <= 1000);
assert(t == INT_MIN || t >= -273);
}
Here the variable temperature corresponds to a hardware sensor. It returns the current temperature
on each read. The get_celsius function converts the value in Kelvin to degrees Celsius, given the
value is in the expected range. However, it has a bug where it reads temperature a second time
after the check, which may yield a value for which the check would not succeed. Verifying this
program as is with cbmc(1) would yield a verification success. We can use goto-instrument to make
reads from temperature non-deterministic:
goto-cc -o get_celsius_test.gb get_celsius_test.c
goto-instrument --nondet-volatile-variable temperature \
get_celsius_test.gb get_celsius_test-mod.gb
cbmc --function test_get_celsius get_celsius_test-mod.gb
Here the final invocation of cbmc(1) correctly reports a verification failure.
--nondet-volatile-model variable:model
Simply treating volatile variables as non-deterministic may for some use cases be too inaccurate.
Consider the following test, for function get_message and with harness test_get_message:
#include <assert.h>
#include <stdint.h>
extern volatile uint32_t clock;
typedef struct message {
uint32_t timestamp;
void *data;
} message_t;
void *read_data();
message_t get_message() {
message_t msg;
msg.timestamp = clock;
msg.data = read_data();
return msg;
}
void test_get_message() {
message_t msg1 = get_message();
message_t msg2 = get_message();
assert(msg1.timestamp <= msg2.timestamp);
}
The harness verifies that get_message assigns non-decreasing time stamps to the returned messages.
However, simply treating clock as non-deterministic would not suffice to prove this property.
Thus, we can supply a model for reads from clock:
// model for reads of the variable clock
uint32_t clock_read_model() {
static uint32_t clock_value = 0;
uint32_t increment;
__CPROVER_assume(increment <= 100);
clock_value += increment;
return clock_value;
}
The model is stateful in that it keeps the current clock value between invocations in the variable
clock_value. On each invocation, it increments the clock by a non-deterministic value in the range
0 to 100. We can tell goto-instrument to use the model clock_read_model for reads from the
variable clock as follows:
goto-cc -o get_message_test.gb get_message_test.c
goto-instrument --nondet-volatile-model clock:clock_read_model \
get_message_test.gb get_message_test-mod.gb
cbmc --function get_message_test get_message_test-mod.gb
Now the final invocation of cbmc(1) reports verification success.
--isr function
instruments an interrupt service routine
--mmio instruments memory-mapped I/O
--nondet-static
add nondeterministic initialization of variables with static lifetime
--nondet-static-exclude e
same as nondet-static except for the variable e (use multiple times if required)
--nondet-static-matching r
add nondeterministic initialization of variables with static lifetime matching regex r
--function-enter f
--function-exit f
--branch f
instruments a call to f at the beginning, the exit, or a branch point, respectively
--splice-call caller,callee
prepends a call to callee in the body of caller
--check-call-sequence seq
instruments checks to assert that all call sequences match seq
--undefined-function-is-assume-false
convert each call to an undefined function to assume(false)
--insert-final-assert-false function
generate assert(false) at end of function
--generate-function-body regex
This transformation inserts implementations of functions without definition, i.e., a body. The
behavior of the generated function is chosen via --generate-function-body-options option:
--generate-function-body-options option
One of assert-false, assume-false, nondet-return, assert-false-assume-false and
havoc[,params:regex][,globals:regex][,params:p_n1;p_n2;..] (default: nondet-return)
assert-false: The body consists of a single command: assert(0).
assume-false: The body consists of a single command: assume(0).
assert-false-assume-false: Two commands as above.
nondet-return: The generated function returns a non-deterministic value of its return type.
havoc[,params:p-regex][,globals:g-regex]: Assign non-deterministic values to the targets of
pointer-to-non-constant parameters matching the regular expression p-regex, and non-constant
globals matching g-regex, and then (in case of non-void function) returning as with nondet-return.
The following example demonstrates the use:
// main.c
int global;
const int c_global;
int function(int *param, const int *c_param);
Often we want to avoid overwriting internal symbols, i.e., those with an __ prefix, which is done
using the pattern (?!__).
goto-cc main.c -o main.gb
goto-instrument main.gb main-out.gb \
--generate-function-body-options 'havoc,params:(?!__).*,globals:(?!__).*' \
--generate-funtion-body function
This leads to a GOTO binary equivalent to the following C code:
// main-mod.c
int function(int *param, const int *c_param) {
*param = nondet_int();
global = nondet_int();
return nondet_int();
}
The parameters should that should be non-deterministically updated can be specified either by a
regular expression (as above) or by a semicolon-separated list of their numbers. For example
havoc,params:0;3;4 will assign non-deterministic values to the first, fourth, and fifth parameter.
Note that only parameters of pointer type can be havoced and goto-instrument will produce an error
report if given a parameter number associated with a non-pointer parameter. Requesting to havoc a
parameter with a number higher than the number of parameters a given function takes will also
results in an error report.
--generate-havocing-body option fun_name,params:p_n1;p_n2;..
--generate-havocing-body option fun_name[,call-site-id,params:p_n1;p_n2;..>]+
Request a different implementation for a number of call-sites of a single function. The option
--generate-havocing-body inserts new functions for selected call-sites and replaces the calls to
the origin function with calls to the respective new functions.
// main.c
int function(int *first, int *second, int *third);
int main() {
int a = 10;
int b = 10;
int c = 10;
function(&a, &b, &c);
function(&a, &b, &c);
}
The user can specify different behavior for each call-site as follows:
goto-cc main.c -o main.gb
goto-instrument main.gb main-mod.gb \
--generate-havocing-body 'function,1,params:0;2,2,params:1'
This results in a GOTO binary equivalent to:
// main-mod.c
int function_1(int *first, int *second, int *third) {
*first = nondet_int();
*third = nondet_int();
}
int function_2(int *first, int *second, int *third) { *second = nondet_int(); }
int main() {
int a = 10;
int b = 10;
int c = 10;
function_1(&a, &b, &c);
function_2(&a, &b, &c);
}
--restrict-function-pointer
pointer_name/target[,targets]* Replace function pointers by a user-defined set of targets. This
may be required when --remove-function-pointers creates to large a set of direct calls. Consider
the example presented for --remove-function-pointers. Assume that call will always receive
pointers to either f or g during actual executions of the program, and symbolic execution for h is
too expensive to simply ignore the cost of its branch.
To facilitate the controlled replace, we will label the places in each function where function
pointers are being called, to this pattern:
function-name.function_pointer_call.N
where N is refers to the N-th function call via a function pointer in function-name, i.e., the
first call to a function pointer in a function will have N=1, the fifth N=5 etc. Alternatively,
if the calls carry labels in the source code, we can also refer to a function pointer as
function-name.label
To implement this assumption that the first call to a function pointer in function call an only be
a call to f or g, use
goto-instrument --restrict-function-pointer \
call.function_pointer_call.1/f,g in.gb out.gb
The resulting output (written to GOTO binary out.gb) looks similar to the original example, except
now there will not be a call to h:
void call(fptr_t fptr) {
int r;
if (fptr == &f) {
r = f(10);
} else if (fptr == &g) {
r = g(10);
} else {
// sanity check
assert(false);
assume(false);
}
return r;
}
As another example imagine we have a simple virtual filesystem API and implementation like this:
typedef struct filesystem_t filesystem_t;
struct filesystem_t {
int (*open)(filesystem_t *filesystem, const char *file_name);
};
int fs_open(filesystem_t *filesystem, const char *file_name) {
filesystem->open(filesystem, file_name);
}
int nullfs_open(filesystem_t *filesystem, const char *file_name) { return -1; }
filesystem_t nullfs_val = {.open = nullfs_open};
filesystem *const nullfs = &nullfs_val;
filesystem_t *get_fs_impl() {
// some fancy logic to determine
// which filesystem we're getting -
// in-memory, backed by a database, OS file system
// - but in our case, we know that
// it always ends up being nullfs
// for the cases we care about
return nullfs;
}
int main(void) {
filesystem_t *fs = get_fs_impl();
assert(fs_open(fs, "hello.txt") != -1);
}
In this case, the assumption is that in function main, fs can be nothing other than nullfs. But
perhaps due to the logic being too complicated, symbolic execution ends up being unable to figure
this out, so in the call to fs_open we end up branching on all functions matching the signature of
filesystem_t::open, which could be quite a few functions within the program. Worst of all, if its
address is ever taken in the program, as far as function pointer removal via
--remove-function-pointers is concerned it could be fs_open itself due to it having a matching
signature, leading to symbolic execution being forced to follow a potentially infinite recursion
until its unwind limit.
In this case we can again restrict the function pointer to the value which we know it will have:
goto-instrument --restrict-function-pointer \
fs_open.function_pointer_call.1/nullfs_open in.gb out.gb
--function-pointer-restrictions-file file_name
If you have many places where you want to restrict function pointers, it'd be a nuisance to have
to specify them all on the command line. In these cases, you can specify a file to load the
restrictions from instead, which you can give the name of a JSON file with this format:
{
"function_call_site_name": ["function1", "function2", ...],
...
}
If you pass in multiple files, or a mix of files and command line restrictions, the final
restrictions will be a set union of all specified restrictions.
Note that if something goes wrong during type checking (i.e., making sure that all function
pointer replacements refer to functions in the symbol table that have the correct type), the error
message will refer to the command line option --restrict-function-pointer regardless of whether
the restriction in question came from the command line or a file.
--restrict-function-pointer-by-name symbol_name/target[,targets]*
Restrict a function pointer where symbol_name is the unmangled name, before labeling function
pointers.
--remove-calls-no-body
remove calls to functions without a body
--add-library
add models of C library functions
--malloc-may-fail
allow malloc calls to return a null pointer
--malloc-fail-assert
set malloc failure mode to assert-then-assume
--malloc-fail-null
set malloc failure mode to return null
--no-malloc-may-fail
do not allow malloc calls to fail by default
--string-abstraction
track C string lengths and zero-termination
--model-argc-argv n
Create up to n non-deterministic C strings as entries to argv and set argc accordingly. In absence
of such modelling, argv is left uninitialized except for a terminating NULL pointer. Consider the
following example:
// needs_argv.c
#include <assert.h>
int main(int argc, char *argv[]) {
if (argc >= 2)
assert(argv[1] != 0);
return 0;
}
If cbmc(1) is run directly on this example, it will report a failing assertion for the lack of
modeling of argv. To make the assertion succeed, as expected, use:
goto-cc needs_argv.c
goto-instrument --model-argc-argv 2 a.out a.out
cbmc a.out
--remove-function-body f
remove the implementation of function f (may be repeated)
--replace-calls f:g
replace calls to f with calls to g
--max-nondet-tree-depth N
limit size of nondet (e.g. input) object tree; at level N pointers are set to null
--min-null-tree-depth N
minimum level at which a pointer can first be NULL in a recursively nondet initialized struct
Semantics-preserving transformations:
--ensure-one-backedge-per-target
transform loop bodies such that there is a single edge back to the loop head
--drop-unused-functions
drop functions trivially unreachable from main function
--remove-pointers
converts pointer arithmetic to base+offset expressions
--constant-propagator
propagate constants and simplify expressions
--inline
perform full inlining
--partial-inline
perform partial inlining
--function-inline function
transitively inline all calls function makes
--no-caching
disable caching of intermediate results during transitive function inlining
--log file
log in JSON format which code segments were inlined, use with --function-inline
--remove-function-pointers
Resolve calls via function pointers to direct function calls. Candidate functions are chosen based
on their signature and whether or not they have their address taken somewhere in the program The
following example illustrates the approach taken. Given that there are functions with these
signatures available in the program:
int f(int x);
int g(int x);
int h(int x);
And we have a call site like this:
typedef int (*fptr_t)(int x);
void call(fptr_t fptr) {
int r = fptr(10);
assert(r > 0);
}
Function pointer removal will turn this into code similar to this:
void call(fptr_t fptr) {
int r;
if (fptr == &f) {
r = f(10);
} else if (fptr == &g) {
r = g(10);
} else if (fptr == &h) {
r = h(10);
} else {
// sanity check
assert(false);
assume(false);
}
return r;
}
Beware that there may be many functions matching a particular signature, and some of them may be
costly to a subsequently run analysis. Consider using --restrict-function-pointer to manually
specify this set of functions, or --value-set-fi-fp-removal.
--remove-const-function-pointers
remove function pointers that are constant or constant part of an array
--value-set-fi-fp-removal
Build a flow-insensitive value set and replace function pointers by a case statement over the
possible assignments. If the set of possible assignments is empty the function pointer is removed
using the standard --remove-function-pointers pass.
Loop information and transformations:
--show-loops
show the loops in the program
--unwind nr
unwind nr times
--unwindset [T:]L:B,...
unwind loop L with a bound of B (optionally restricted to thread T) (use --show-loops to get the
loop IDs)
--unwindset-file file
read unwindset from file
--partial-loops
permit paths with partial loops
--no-unwinding-assertions
do not generate unwinding assertions
--unwinding-assertions
generate unwinding assertions (enabled by default; overrides --no-unwinding-assertions when both
of these are given)
--continue-as-loops
add loop for remaining iterations after unwound part
--k-induction k
check loops with k-induction
--step-case
k-induction: do step-case
--base-case
k-induction: do base-case
--havoc-loops
over-approximate all loops
--accelerate
add loop accelerators
--z3 use Z3 when computing loop accelerators
--skip-loops loop-ids
add gotos to skip selected loops during execution
--show-lexical-loops
Show lexical loops. A lexical loop is a block of goto program instructions with a single entry
edge at the top and a single backedge leading from bottom to top, where "top" and "bottom" refer
to program order. The loop may have holes: instructions which sit in between the top and bottom in
program order, but which can't reach the loop backedge. Lexical loops are a subset of the natural
loops, which are cheaper to compute and include most natural loops generated from typical C code.
--show-natural-loops
Show natural loop heads. A natural loop is when the nodes and edges of a graph make one self-
encapsulating circle with no incoming edges from external nodes. For example A -> B -> C -> D -> A
is a natural loop, but if B has an incoming edge from X, then it isn't a natural loop, because X
is an external node. Outgoing edges don't affect the natural-ness of a loop.
Memory model instrumentations:
--mm [tso|pso|rmo|power]
Instruments the program so that it can be verified for different weak memory models with a model-
checker verifying sequentially consistent programs.
--scc detects critical cycles per SCC (one thread per SCC)
--one-event-per-cycle
only instruments one event per cycle
--minimum-interference
instruments an optimal number of events
--my-events
only instruments events whose ids appear in inst.evt
--read-first, --write-first
only instrument cycles where a read or write occurs as first event, respectively
--max-var N
limit cycles to N variables read/written
--max-po-trans N
limit cycles to N program-order edges
--ignore-arrays
instrument arrays as a single object
--cav11
always instrument shared variables, even when they are not part of any cycle
--force-loop-duplication, --no-loop-duplication
optional program transformation to construct cycles in program loops
--cfg-kill
enables symbolic execution used to reduce spurious cycles
--no-dependencies
no dependency analysis
--no-po-rendering
no representation of the threads in the dot
--hide-internals
do not include thread-internal (Rfi) events in dot output
--render-cluster-file
clusterises the dot by files
--render-cluster-function
clusterises the dot by functions
Slicing:
--fp-reachability-slice f
Remove instructions that cannot appear on a trace that visits all given functions. The list of
functions has to be given as a comma separated list f.
--reachability-slice
remove instructions that cannot appear on a trace from entry point to a property
--reachability-slice-fb
remove instructions that cannot appear on a trace from entry point through a property
--full-slice
slice away instructions that don't affect assertions
--property id
slice with respect to specific property id only
--slice-global-inits
slice away initializations of unused global variables
--aggressive-slice
remove bodies of any functions not on the shortest path between the start function and the
function containing the property(s)
--aggressive-slice-call-depth n
used with --aggressive-slice, preserves all functions within n function calls of the functions on
the shortest path
--aggressive-slice-preserve-function f
force the aggressive slicer to preserve function f
--aggressive-slice-preserve-functions-containing f
force the aggressive slicer to preserve all functions with names containing f
--aggressive-slice-preserve-all-direct-paths
force aggressive slicer to preserve all direct paths
Code contracts:
--apply-loop-contracts
-disable-loop-contracts-side-effect-check
UNSOUND OPTION. Disable checking the absence of side effects in loop contract clauses. In absence
of such checking, loop contracts clauses will accept more expressions, such as pure functions and
statement expressions. But user have to make sure the loop contracts are side-effect free by them
self to get a sound result.
-loop-contracts-no-unwind
do not unwind transformed loops
-loop-contracts-file file
annotate loop contracts from the file to the goto program
--replace-call-with-contract fun
replace calls to fun with fun's contract
--enforce-contract fun
wrap fun with an assertion of its contract
--enforce-contract-rec fun
wrap fun with an assertion of its contract that can handle recursive calls
--dfcc fun
instrument dynamic frame condition checks method using fun as entry point
User-interface options:
--flush
flush every line of output
--xml output files in XML where supported
--xml-ui
use XML-formatted output
--json-ui
use JSON-formatted output
--verbosity n
verbosity level
--timestamp [monotonic|wall]
Print microsecond-precision timestamps. monotonic: stamps increase monotonically. wall: ISO-8601
wall clock timestamps.
ENVIRONMENT
All tools honor the TMPDIR environment variable when generating temporary files and directories.
BUGS
If you encounter a problem please create an issue at https://github.com/diffblue/cbmc/issues
SEE ALSO
cbmc(1), goto-cc(1)
COPYRIGHT
2008-2013, Daniel Kroening