frama-c — a static analyzer for C programs
frama-c-gui — the graphical interface of frama-c
frama-c [ options ] files
frama-c is a suite of tools dedicated to the analysis of source code written in C. It gathers several analysis techniques in a single collaborative framework. This framework can be extended by additional plugins placed in the $FRAMAC_PLUGIN directory. The command
will provide the full list of the plugins that are currently installed.
frama-c-gui is the graphical user interface of frama-c. It features the same options as the command-line version.
ivette is a new, Electron-based graphical user interface for frama-c. It also features the same options as the command-line version.
By default, Frama-C recognizes .c files as C files needing pre-processing and .i files as C files having been already pre-processed. Some plugins may extend the list of recognized files. Pre-processing can be customized through the -cpp-command and -cpp-extra-args options.
Options taking an additional parameter can also be written under the form
This form is mandatory when param starts with a dash (`-').
Most options that take no parameter have a corresponding
option which has the opposite effect.
gives a short usage notice.
prints the list of options recognized by Frama-C’s kernel
prints a help message for each other option given on the command line
- -verbose n
sets verbosity level. Defaults to 1. Setting it to 0 will output less progress messages. This level can also be set on a per-plugin basis, with option -plugin-verbose n. Verbosity level of the kernel can be controlled with option -kernel-verbose n.
- -debug n
sets debugging level. Defaults to 0, meaning no debugging messages. This option has the same per-plugin (and kernel) specializations as -verbose.
sets verbosity and debugging level to 0.
Options controlling Frama-C’s kernel
- -absolute-valid-range min-max
considers that all numerical addresses in the range min-max are valid. Bounds are parsed as OCaml integer constants. By default, all numerical addresses are considered invalid.
- -add-symbolic-path p1:n1[,p2:n2[...,pn:nn]]
replaces each path pi with the name ni when displaying file locations in messages.
merges function definitions modulo renaming. Defaults to no.
allows duplication of small blocks during normalization of tests and loops. Otherwise, normalization uses labels and gotos. Bigger blocks and blocks with non-trivial control flow are never duplicated. Defaults to yes.
reads ACSL annotations. This is the default. Annotations are pre-processed by default. Use -no-pp-annot if you don’t want to expand macros in annotations.
computes AST differences between a loaded session (loaded with -load) and the current sources. These can then be used by plug-ins supporting incremental analyses.
- -autocomplete p1,...,pn
lists the options of plugins p1,...,pn in a format suitable for autocompletion scripts.
- -big-ints-hex max
integers larger than max are displayed in hexadecimal (by default, all integers are displayed in decimal).
performs integrity checks on the internal AST (for developers only).
generates contracts for assembly code written according to gcc’s extended syntax. Defaults to yes.
automatically marks contracts generated from asm as valid. Defaults to no.
allows implicit cast between the value returned by a function and the lvalue it is assigned to. Otherwise, a temporary variable is used and the cast is made explicit. Defaults to yes.
folds all syntactically constant expressions in the code before analyses. Defaults to no.
variables with const qualifier must be actually constant. Defaults to yes. The opposite option is -unsafe-writable.
when analyzing an annotation, the default behavior (the -no version of this option) when a typechecking error occurs is to reject the source file as is the case for typechecking errors within the C code. With this option on, the typechecker will only output a warning and discard the annotation but type-checking will continue (errors in C code are still fatal, though).
Deprecated: use -kernel-warn-key annot-error instead.
- -cpp-command cmd
uses cmd as the command to pre-process C files. Defaults to the CPP environment variable or to
gcc -C -E -I.
if it is not set. If unset, the command is built as follows:
%1 and %2 can be used into the CPP string to mark the position of and respectively. Note that this option is often better replaced by -cpp-extra-args.
- -cpp-extra-args args
gives additional arguments to the pre-processor. Pre-processing annotations is done in two separate pre-processing stages. The first one is a normal pass on the C code which retains macro definitions. These are then used in the second pass during which annotations are pre-processed. args are used only for the first pass, so that arguments that should not be used twice (such as additional include directives or macro definitions) must thus go there instead of -cpp-command.
- -cpp-extra-args-per-file file1:args1,...,filen:argsn
like -cpp-extra-args, but the arguments only apply to the specified files.
indicates that the chosen preprocessor complies to some Frama-C requirements, such as accepting the same set of options as GNU cpp, and accepting architecture-specific options such as -m32/-m64. Default values depend on the installed preprocessor at configure time. See also -pp-annot.
when on, load all the dynamic plugins found in the search path (see -print-plugin-path for more information on the default search path). Otherwise, only plugins requested by -load-plugin will be loaded. Defaults to on.
- -enums repr
choose the way the representation of enumerated types is determined. frama-c -enums help gives the list of available options. Default is gcc-enums.
- -float-digits n
when outputting floating-point numbers, display n digits. Defaults to 12.
floating point operations flush to zero.
display floats as hexadecimal.
display floats with the standard OCaml routine.
display float intervals as [ lower_bound++width ].
adds -I$FRAMAC_SHARE/libc to the options given to the cpp command. If -cpp-frama-c-compliant is not false, also adds -nostdinc to prevent an inconsistent mix of system and Frama-C header files. Defaults to yes.
- -implicit-function-declaration action
warns or aborts when a function is called before it has been declared. action can be one of ignore, warn, or error. Defaults to warn.
Deprecated: use -kernel-warn-key typing:implicit-function-declaration instead.
implicit initialization of locals sets padding bits to 0. If false, padding bits are left uninitialized. Defaults to yes.
- -inline-calls f1,...,fn
syntactically inlines calls to functions f1,...,fn. Use @inline to select all functions with attribute inline. Recursive functions are inlined only at the first level. Calls via function pointers are not inlined.
- -json-compilation-database path
use path as a JSON compilation database (see <https://clang.llvm.org/docs/JSONCompilationDatabase.html> for more information): each file preprocessed by Frama-C will include corresponding -I and -D flags according to the specifications in path. If path is a directory, use <path>/compile_commands.json. Disabled by default.
tries to preserve comments when pretty-printing the source code. Defaults to no.
when -simplify-cfg is set, keeps switch statements. Defaults to no.
- -kernel-log kind:file
copies log messages from the Frama-C’s kernel to file. kind specifies which kinds of messages to be copied (e.g. w for warnings, e for errors, etc.). See -kernel-help for more details. Can also be set on a per-plugin basis, with option -<plugin>-log.
- -kernel-msg-key k1,...,kn
controls the emission of messages based on categories. Use -kernel-msg-key help to get a list of available categories, and -kernel-msg-key=“*” to control all categories. To disable a category, add a - before its name; to enable a category, simply add its name, with an optional + before it. For instance, -kernel-msg-key=-k1,k2 will disable messages from category k1 and enable those from category k2. Can also be set on a per-plugin basis, with option -<plugin>-msg-key. Note that each plugin has its own set of categories.
- -kernel-warn-key k1=a1,...,kn=an
controls the emission of warnings based on categories: for each warning category k, associate action a. Use -kernel-warn-key help to get a list of available warning categories and their currently associated actions. The following actions can be set per category: active (warn), feedback, error, abort, once, feedback-once, err-once. Omitting the action is equivalent to setting it to active. Warning categories can also be set on a per-plugin basis, with option -<plugin>-warn-key.
indicates that the entry point is called during program execution. This implies in particular that global variables cannot be assumed to have their initial values. The default is -no-lib-entry: the entry point is also the starting point of the program and globals have their initial value.
- -load file
loads the (previously saved) state contained in file.
- -load-library library_1,...,library_n
dynamically load libraries. Loading order is preserved. Libraries are loaded between plugins and modules.
- -load-module SPEC_1,...,SPEC_n
dynamically load modules. Each can be an object file, with or without extension, or a Findlib package. Loading order is preserved, but after plugins and libraries.
- -load-plugin plugin_1,...,plugin_n
dynamically load plugins. Loading order is preserved. Plugins are loaded before libraries and modules.
- -machdep machine
uses machine as the current machine-dependent configuration (size of the various integer types, endiandness, ...). The list of currently supported machines is available through option -machdep help. Default is x86_64.
- -main f
sets f as the entry point of the analysis. Defaults to main. By default, it is considered as the starting point of the program under analysis. Use -lib-entry if f is supposed to be called in the middle of an execution.
prints an obfuscated version of the code (where original identifiers are replaced by meaningless ones) and exits. The correspondence table between original and new symbols is kept at the beginning of the result.
- -ocode file
redirects pretty-printed code to file instead of standard output.
During the normalization phase, some variables may get renamed when different variables with the same name can co-exist (e.g. a global variable and a formal parameter). When this option is on, a message is printed each time this occurs. Defaults to no.
pre-processes annotations. This is currently only possible when using gcc (or GNU cpp) pre-processor. The default is to pre-process annotations when the default pre-processor is identified as GNU or GNU-like. See also -cpp-frama-c-compliant.
pretty-prints the source code as normalized by CIL. Defaults to no.
outputs the preprocessing commands for all input files.
outputs extensive Frama-C configuration data in JSON format.
expands #include directives in the pretty-printed CIL code for files in the Frama-C standard library. Defaults to no.
outputs the directory where the Frama-C kernel library is installed.
alias of -print-share-path.
outputs the directory where Frama-C searches its plugins.
outputs the directory where Frama-C stores shareable files (e.g. standard library, machdeps, shared Makefiles).
transforms throw and try/catch statements into normal C functions. Defaults to no, unless the input source language has an exception mechanism.
- -remove-inlined f1,...,fn
removes inlined functions f1,...,fn from the AST, which must have been given to -inline-calls. Note: this option does not check if the given functions were fully inlined.
- -remove-projects p1,...,pn
removes the given projects p1,...,pn. @all_but_current removes all projects but the current one.
keeps function prototypes that have an ACSL specification but are not used in the code. This is the default. Functions having the attribute FRAMAC_BUILTIN are always kept.
remove types and struct/union/enum declarations that are not referenced anywhere else in the code. This is the default. Use -keep-unused-types to keep these definitions.
for multidimensional arrays or arrays that are fields inside structs, assumes that all accesses must be in bound (set by default). The opposite option is -unsafe-arrays.
- -save file
saves Frama-C’s state into file after analyses have taken place.
- -session s
sets s as the directory in which session files are searched.
the current project becomes the default one (and so future -then sequences are applied on it). Defaults to no.
removes break, continue and switch statements before analyses. Defaults to no.
simplifies trivial loops such as do ... while (0) loops. Defaults to yes.
allows one to compose analyses: a first run of Frama-C will occur with the options before -then and a second run will be done with the options after -then on the current project from the first run.
like -then, but the second group of actions is executed on the last project created by a program transformer.
- -then-on prj
similar to -then except that the second run is performed in project prj. If no such project exists, Frama-C exits with an error.
like -then-last, but also removes the previous current project.
- -time file
appends user time and date in the given file when Frama-C exits.
forces typechecking of the source files. This option is only relevant if no further analysis is requested (as typechecking will implicitly occur before the analysis is launched).
- -ulevel n
syntactically unroll loops n times before the analysis. This can be quite costly and some plugins (e.g. Eva) provide more efficient ways to perform the same thing. See their respective manuals for more information. This can also be activated on a per-loop basis via the loop pragma unroll directive. A negative value for n will inhibit such pragmas.
ignores UNROLL loop pragmas disabling unrolling.
[-no]-unicode outputs ACSL formulas with UTF-8 characters. This is the default. When given the -no-unicode option, Frama-C will use the ASCII version instead. See the ACSL manual for the correspondence.
checks that read/write accesses occurring in an unspecified order (according to the C standard’s notion of sequence points) are performed on separate locations. With -no-unspecified-access, assumes that it is always the case (this is the default).
outputs the version string of Frama-C.
- -warn-decimal-float freq
warns when a floating-point constant cannot be exactly represented (e.g. 0.1). freq can be one of none, once, or all.
Deprecated: use -kernel-warn-key parser:decimal-float=once (and variants) instead.
generate alarms for invalid pointer arithmetic. Defaults to no.
generate alarms for signed left shifts on negative values. Defaults to yes.
generate alarms for signed right shifts on negative values. Defaults to no.
generates alarms when the downcast of a pointer may exceed the destination range. Defaults to yes.
generates alarms when signed downcasts may exceed the destination range. Defaults to no.
generates alarms for signed operations that overflow. Defaults to yes.
generates alarms when unsigned downcasts may exceed the destination range. Defaults to no.
generates alarms for unsigned operations that overflow. Defaults to no.
generates alarms for reads of trap representations of _Bool lvalues. Defaults to yes.
For each plugin, the command
will give the list of options that are specific to the plugin.
Invalid user input
User interruption (kill or equivalent)
- 4 5 6
Exit statuses greater than 2 can be considered as a bug (or a feature request for the case of exit status 3) and may be reported on Frama-C’s BTS (see below).
It is possible to control the places where Frama-C looks for its files through the following variables.
The directory where kernel’s compiled interfaces are installed.
The directory where Frama-C data (e.g. its version of the standard library) is installed.
Frama-C user manual: https://frama-c.com/download/frama-c-user-manual.pdf
Frama-C homepage: https://frama-c.com
Frama-C BTS: https://git.frama-c.com/pub/frama-c/issues
The man page frama-c-gui(1) is an alias of frama-c(1).