crashme - Online in the Cloud

PROGRAM:

NAME

crashme - test operating environment software robustness

SYNOPSIS

crashme [NBYTES] [SRAND] [NTRYS] [NSUB] [VERBOSE]

DESCRIPTION

crashme is a very simple program that tests the operating environment's robustness by
invoking random data as if it were a procedure. The standard signals are caught and
handled with a setjmp back to a loop which will try again to produce a fault by executing
random data. Some people call this stress testing.

COMMAND LINE OPTIONS
[NBYTES]
The [NBYTES] should be an integer, specifying the size of the random data string
in bytes. If given negative then the bytes are printed instead of being executed.
If given with an explicit plus sign then the storage for the bytes is freshly
malloc'ed each time. This can have an effect on machines with separate I and D
cache mechanisms. The argument can also have a dot in it, X.Y, in which case Y is
a increment for a pointer into the random data. The buffer is recalculated only
when the pointer gets near the end of the data.

The are two magic values for [NBYTES] : A value of 81920 avoids malloc and returns
a pointer to static data. This makes the operation of crashme more repeatable on
architectures where malloc is designed to return unpredictable locations. A value
of 1025 avoids a call that sets the protection of the data to READ+WRITE+EXEC.

[SRAND] The [SRAND] is an input seed to the random number generator, passed to srand.

[NTRIES]
The [NTRIES] is how many times to loop before exiting normally from the program.

[NSUB] The [NSUB] is optional, the number of vfork subprocesses running all at once. If
negative run one after another. If given as a time hrs:mns:scs (hours, minutes,
seconds) then one subprocess will be run to completion, followed by another, until
the time limit has been reached. If this argument is given as the empty string or
. then it is ignored.

When in sequential-subprocess mode there is a 30 second time limit on each
subprocess. This is to allow the instruction-set-space random walk to continue
when a process bashes itself into an infinite loop. For example, the ntrys can be
bashed to a very large number with nbytes bashed to zero. (10 second limit on
Windows NT).

The SRAND argument is incremented by one for each subprocess.

[VERBOSE]
The [VERBOSE] arg is optional. 0 is the least verbose, 5 the most.

ENVIRONMENT VARIABLES
CRASHLOG
The CRASHLOG is the name of the file which the parent process opens in write mode
and all child processes open in append mode. There is frequent flushing of the
file but no locking, so the output may be interleaved. If the operating system
crashes then this file might provide a short-cut to a more resent random number
seed sequence to allow for quicker finding of the special case that caused the
crash.

CRASHPRNG
The CRASHPRNG can be set to RAND to use the system-provided rand function, or MT
to use the Mersenne twister (default) as coded by Takuji Nishimura and Makoto
Matsumoto, or VNSQ to use the author's kludge interpretation of Von Neumann's
middle-square method.

EXAMPLE

This is a suggested test, to run it for a least an hour.

crashme +2000 666 100 1:00:00

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