upstream/mercurial-mirror Files · contrib/fuzz/fuzzutil.cc

fuzz: extract some common utilities and use modern C++ idioms...

fuzz: extract some common utilities and use modern C++ idioms Alex Gaynor suggested we should probably copy the left and right sides of diffs to new blocks so we can detect over-reads in the diffing code, and I agree. Once I got into that, I realized we should do things with C++17 idioms rather than keep using malloc() and free(). This change is the result. I tried to split it more than this and failed. Everything still compiles and works in the oss-fuzz container, so I think we can count on C++17 being available! Differential Revision: https://phab.mercurial-scm.org/D3675

Augie Fackler - - Load All Authors

File last commit:

r38191:fa0ddd5e default


                r38191:fa0ddd5e

default

Download file

             fuzzutil.cc
        
                    26 lines
            
             | 885 B
            
                | text/x-c
            
             |
                CppLexer
            
             / contrib / fuzz / fuzzutil.cc
          
                    History
                
                 |
                  Annotation
                 | Raw
                 |Copy content
                 |Copy permalink

      #include "fuzzutil.h"

      #include <utility>

      std::optional<two_inputs> SplitInputs(const uint8_t *Data, size_t Size)

      {

      	if (!Size) {

      		return std::nullopt;

      	}

      	// figure out a random point in [0, Size] to split our input.

      	size_t left_size = (Data[0] / 255.0) * (Size - 1);

      	// Copy inputs to new allocations so if bdiff over-reads

      	// AddressSanitizer can detect it.

      	std::unique_ptr<char[]> left(new char[left_size]);

      	memcpy(left.get(), Data + 1, left_size);

      	// right starts at the next byte after left ends

      	size_t right_size = Size - (left_size + 1);

      	std::unique_ptr<char[]> right(new char[right_size]);

      	memcpy(right.get(), Data + 1 + left_size, right_size);

      	LOG(2) << "inputs are  " << left_size << " and " << right_size

      	       << " bytes" << std::endl;

      	two_inputs result = {std::move(right), right_size, std::move(left),

      	                     left_size};

      	return result;

      }

	Site-wide shortcuts
/	Use quick search box
g h	Goto home page
g g	Goto my private gists page
g G	Goto my public gists page
g 0-9	Goto bookmarked items from 0-9
n r	New repository page
n g	New gist page

	Repositories
g s	Goto summary page
g c	Goto changelog page
g f	Goto files page
g F	Goto files page with file search activated
g p	Goto pull requests page
g o	Goto repository settings
g O	Goto repository access permissions settings
t s	Toggle sidebar on some pages

				#include "fuzzutil.h"

				#include <utility>

				std::optional<two_inputs> SplitInputs(const uint8_t *Data, size_t Size)
				{
				if (!Size) {
				return std::nullopt;
				}
				// figure out a random point in [0, Size] to split our input.
				size_t left_size = (Data[0] / 255.0) * (Size - 1);

				// Copy inputs to new allocations so if bdiff over-reads
				// AddressSanitizer can detect it.
				std::unique_ptr<char[]> left(new char[left_size]);
				memcpy(left.get(), Data + 1, left_size);
				// right starts at the next byte after left ends
				size_t right_size = Size - (left_size + 1);
				std::unique_ptr<char[]> right(new char[right_size]);
				memcpy(right.get(), Data + 1 + left_size, right_size);
				LOG(2) << "inputs are " << left_size << " and " << right_size
				<< " bytes" << std::endl;
				two_inputs result = {std::move(right), right_size, std::move(left),
				left_size};
				return result;
				}