bdlt_fuzzutil

Detailed Description

Provide creation of bdlt data types from fuzz data.

Outline

• Purpose
• Classes
• Description
  • Usage
    • Example 1: Provide bdlt::Datetime within a Range

Purpose

Provide creation of bdlt data types from fuzz data.

Classes

• bdlt::FuzzUtil: functions to create bdlt data types from fuzz data

See also

bslim_fuzzdataview, bslim_fuzzutil

Description

This component defines a struct, bdlt::FuzzUtil, which serves as a namespace for functions to create bdlt date and time types from supplied fuzz input data.

Effectively, given a random sequence of bytes provided by a fuzz harness, like libFuzzer, this component can be used to generate arbitrary date and time values determined by that random sequence. This can be used to fuzz test an interface using date/time values. See the BDE fuzz-testing guide for more detail.

The operations to produce date and time types allow restrictions on ranges of dates to be produced, since it is common for operations to be valid only on a certain range of dates. The same is not typically true for time and time-zone offset, so operations that restrict the range of values produced for those attributes are not currently provided.

Usage

This section illustrates intended use of this component.

Example 1: Provide bdlt::Datetime within a Range

The provided fuzz data is here represented by an array of bytes:

const uint8_t data[] = {0x8A, 0x19, 0x0D, 0x44, 0x37, 0x0D,
                        0x38, 0x5E, 0x9B, 0xAA, 0xF3, 0xDA};

First, we default construct a bslim::FuzzDataView object, fdv:

bslim::FuzzDataView fdv(data, sizeof(data));
 
assert(12 == fdv.length());

Next, we construct Date objects to represent the begin and end of the time interval in which we wish to construct our new Date from the fuzz data:

 bdlt::Date begin(1833, 5, 7);
 bdlt::Date end(1897, 4, 3);

Finally, we create a Date object, within, by employing bdlt_fuzzutil :

bdlt::Date within = bdlt::FuzzUtil::consumeDateInRange(&fdv, begin, end);
 
assert(begin  <= within);
assert(within <= end);