NAME¶

libfiu - Fault injection in userspace

SYNOPSYS¶

/* Core API */
#include <fiu.h>
 
int fiu_init(unsigned int flags);
int fiu_fail(const char *name);
void *fiu_failinfo(void);
[void] fiu_do_on(char *name, action); [macro]
[void] fiu_exit_on(char *name); [macro]
[void] fiu_return_on(char *name, retval); [macro]
 
/* Control API */
#include <fiu-control.h>
 
int fiu_enable(const char *name, int failnum,
		void *failinfo, unsigned int flags);
int fiu_enable_random(const char *name, int failnum,
		void *failinfo, unsigned int flags, float probability);
typedef int external_cb_t(const char *name, int *failnum,
		void **failinfo, unsigned int *flags);
int fiu_enable_external(const char *name, int failnum,
		void *failinfo, unsigned int flags,
		external_cb_t *external_cb);
int fiu_enable_stack(const char *name, int failnum,
		void *failinfo, unsigned int flags,
		void *func, int func_pos_in_stack);
int fiu_enable_stack_by_name(const char *name, int failnum,
		void *failinfo, unsigned int flags,
		const char *func_name, int func_pos_in_stack);
int fiu_disable(const char *name);
int fiu_rc_fifo(const char *basename);
 

DESCRIPTION¶

libfiu is a library for fault injection. It provides functions to mark "points of failure" inside your code (the "core API"), and functions to enable/disable the failure of those points (the "control API"). The core API is used inside the code wanting to perform fault injection on. The control API is used inside the testing code, in order to control the injection of failures. This page is an API reference and not a complete manual, and as such does not go into detail about how to use the library. The library's manual can be found in the distribution.

CORE API¶

To use the core API, you should #include <fiu.h> (or <fiu-local.h>, see below). Because fault injection is usually a debugging/testing facility, unwanted at runtime, some special considerations were taken to minimize the impact of the core API. First of all, if FIU_ENABLE is not defined, then fiu.h will define empty stubs for all the core API, effectively disabling fault injection completely. Also, the special header fiu-local.h is shipped with libfiu. It is meant to be included in your project to avoid having libfiu as a mandatory build-time dependency. You can add it to your project, and #include it instead of fiu.h. It will take care of including the real fiu.h only when FIU_ENABLE is defined. It is entirely optional, but recommended. See the library's manual for more details.

fiu_init(flags)

Initializes the library. Ideally, you should only call this once, although it can cope with multiple calls. The flags parameter is currently unused and must be set to 0. Returns 0 on success, < 0 on error.

 

fiu_fail(name)

Returns the failure status of the given point of failure. 0 means it should not fail. By default, all points of failure do not fail; they're enabled in runtime using the control API.

 

fiu_failinfo()

Returns the information associated with the last failure, or NULL if there isn't one. This function is thread-aware and will only return information about failures in the calling thread.

 

fiu_do_on(name, action) [macro]

This is a macro that uses fiu_fail() to perform the given action when the given point of failure fails. The action can be any valid C statement.

 

fiu_exit_on(name) [macro]

This is a macro that uses fiu_fail() to exit the process when the given point of failure fails. The process is exit using exit(3), which is given the status EXIT_FAILURE.

 

fiu_return_on(name, retval) [macro]

This is a macro that uses fiu_fail() to make the current function return the given value (whose type obviously depends on the return type of the function).

 

CONTROL API¶

To use the control API, you should #include <fiu-control.h>.

fiu_enable(name, failnum, failinfo, flags)

Enables the given point of failure. failnum is what fiu_fail() will return, and must be != 0. failinfo is what fiu_failinfo() will return when called after the given point of failure has failed. flags can be either 0 or FIU_ONETIME, which indicates that this point of failure should only fail once. Returns 0 if success, < 0 otherwise. If the point of failure was already enabled, this overwrites the previous values.

 

Successive calls to fiu_fail() will return failnum until this point of failure is disabled. If FIU_ONETIME was passed in the flags, this point of failure is disabled immediately after failing once.

 

If the name ends with an asterisk, then it this will match all points of failure that begin with the given name (excluding the asterisk, of course).

 

fiu_enable_random(name, failnum, failinfo, flags, probability)

Enables the given point of failure, with the given probability (between 0 and 1). The rest of the parameters, as well as the return value, are the same as the ones in fiu_enable().

 

fiu_enable_external(name, failnum, failinfo, flags, external_cb)

Enables the given point of failure, leaving the decision whether to fail or not to the given external function, which should return 0 if it is not to fail, or 1 otherwise. The rest of the parameters, as well as the return value, are the same as the ones in fiu_enable().

 

int fiu_enable_stack(name, failnum, failinfo, flags, func, func_pos_in_stack)

Enables the given point of failure, but only if func is in the stack at func_pos_in_stack.

 

func must be a function pointer, and func_pos_in_stack is the position where we expect the function to be, or -1 for "any" (values other than -1 are not yet supported). The rest of the parameters, as well as the return value, are the same as the ones in fiu_enable().

 

This function relies on some GNU extensions, so it may be not available in all platforms.

 

int fiu_enable_stack_by_name(name, failnum, failinfo, flags, func_name, func_pos_in_stack)

Enables the given point of failure, but only if func_name is in the stack at func_pos_in_stack.

 

func must be the name of a function (resolved at runtime using dlsym()); the rest of the parameters, as well as the return value, are the same as the ones in fiu_enable_stack.

 

This function relies on some GNU extensions, so it may be not available in all platforms.

 

fiu_disable(name)

Disables the given point of failure, undoing the actions of the fiu_enable*() functions.

 

fiu_rc_fifo(basename)

Enables remote control over named pipes with the given basename. See the remote control documentation that comes with the library for more detail.

 

THREAD SAFETY¶

The library is thread-safe. The list of enabled failure points is shared among all threads. Care should be taken in the user-provided functions given to fiu_enable_external(), as they can be run in parallel.

SEE ALSO¶

fiu-run(1), fiu-ctrl(1).

BUGS¶

If you want to report bugs, or have any questions or comments, just let me know at albertito@blitiri.com.ar. For more information about libfiu, you can go to http://blitiri.com.ar/p/libfiu.