conditionally enable differential fuzzing (#381)

configure.ac

@@ -395,6 +395,12 @@ AC_ARG_ENABLE(fuzz_support,
                              [enable fuzzer support]),
               , enable_fuzz_support=no)
 
+# Handle --enable-diff-fuzz-support
+AC_ARG_ENABLE(diff_fuzz_support,
+              AS_HELP_STRING([--enable-diff-fuzz-support],
+                             [enable differential fuzzer support]),
+              , enable_diff_fuzz_support=no)
+
 # Handle --disable-stack-for-recursion
 # This option became obsolete at release 10.30.
 AC_ARG_ENABLE(stack-for-recursion,,
@@ -529,12 +535,26 @@ AM_CONDITIONAL(WITH_JIT, test "x$enable_jit" = "xyes")
 AM_CONDITIONAL(WITH_UNICODE, test "x$enable_unicode" = "xyes")
 AM_CONDITIONAL(WITH_VALGRIND, test "x$enable_valgrind" = "xyes")
 AM_CONDITIONAL(WITH_FUZZ_SUPPORT, test "x$enable_fuzz_support" = "xyes")
+AM_CONDITIONAL(WITH_DIFF_FUZZ_SUPPORT, test "x$enable_diff_fuzz_support" = "xyes")
 
 if test "$enable_fuzz_support" = "yes" -a "$enable_pcre2_8" = "no"; then
   echo "** ERROR: Fuzzer support requires the 8-bit library"
   exit 1
 fi
 
+if test "$enable_diff_fuzz_support" = "yes"; then
+  if test "$enable_fuzz_support" = "no"; then
+    echo "** ERROR: Differential fuzzing support requires fuzzing support"
+    exit 1
+  fi
+  if test "$enable_jit" = "no"; then
+    echo "** ERROR: Differential fuzzing support requires Just-in-Time compilation support"
+    exit 1
+  fi
+  AC_DEFINE([SUPPORT_DIFF_FUZZ], [], [
+    Define to any value to enable differential fuzzing support.])
+fi
+
 # Checks for typedefs, structures, and compiler characteristics.
 
 AC_C_CONST
@@ -1162,6 +1182,7 @@ $PACKAGE-$VERSION configuration summary:
     Valgrind support ................... : ${enable_valgrind}
     Code coverage ...................... : ${enable_coverage}
     Fuzzer support ..................... : ${enable_fuzz_support}
+    Differential fuzzer support ........ : ${enable_diff_fuzz_support}
     Use %zu and %td .................... : ${enable_percent_zt}
 
 EOF

src/config.h.in

@@ -55,7 +55,7 @@ sure both macros are undefined; an emulation function will then be used. */
 /* Define this if your compiler supports __attribute__((uninitialized)) */
 #undef HAVE_ATTRIBUTE_UNINITIALIZED
 
-/* Define to 1 if you have the 'bcopy' function. */
+/* Define to 1 if you have the `bcopy' function. */
 #undef HAVE_BCOPY
 
 /* Define this if your compiler provides __builtin_mul_overflow() */
@@ -82,16 +82,16 @@ sure both macros are undefined; an emulation function will then be used. */
 /* Define to 1 if you have the <limits.h> header file. */
 #undef HAVE_LIMITS_H
 
-/* Define to 1 if you have the 'memfd_create' function. */
+/* Define to 1 if you have the `memfd_create' function. */
 #undef HAVE_MEMFD_CREATE
 
-/* Define to 1 if you have the 'memmove' function. */
+/* Define to 1 if you have the `memmove' function. */
 #undef HAVE_MEMMOVE
 
 /* Define to 1 if you have the <minix/config.h> header file. */
 #undef HAVE_MINIX_CONFIG_H
 
-/* Define to 1 if you have the 'mkostemp' function. */
+/* Define to 1 if you have the `mkostemp' function. */
 #undef HAVE_MKOSTEMP
 
 /* Define if you have POSIX threads libraries and header files. */
@@ -112,7 +112,7 @@ sure both macros are undefined; an emulation function will then be used. */
 /* Define to 1 if you have the `realpath' function. */
 #undef HAVE_REALPATH
 
-/* Define to 1 if you have the 'secure_getenv' function. */
+/* Define to 1 if you have the `secure_getenv' function. */
 #undef HAVE_SECURE_GETENV
 
 /* Define to 1 if you have the <stdint.h> header file. */
@@ -124,7 +124,7 @@ sure both macros are undefined; an emulation function will then be used. */
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
-/* Define to 1 if you have the 'strerror' function. */
+/* Define to 1 if you have the `strerror' function. */
 #undef HAVE_STRERROR
 
 /* Define to 1 if you have the <strings.h> header file. */
@@ -287,11 +287,14 @@ sure both macros are undefined; an emulation function will then be used. */
    unless SUPPORT_JIT is also defined. */
 #undef SLJIT_PROT_EXECUTABLE_ALLOCATOR
 
-/* Define to 1 if all of the C89 standard headers exist (not just the ones
+/* Define to 1 if all of the C90 standard headers exist (not just the ones
    required in a freestanding environment). This macro is provided for
    backward compatibility; new code need not use it. */
 #undef STDC_HEADERS
 
+/* Define to any value to enable differential fuzzing support. */
+#undef SUPPORT_DIFF_FUZZ
+
 /* Define to any value to enable support for Just-In-Time compiling. */
 #undef SUPPORT_JIT
 
@@ -339,7 +342,7 @@ sure both macros are undefined; an emulation function will then be used. */
 /* Define to any value for valgrind support to find invalid memory reads. */
 #undef SUPPORT_VALGRIND
 
-/* Enable extensions on AIX, Interix, z/OS.  */
+/* Enable extensions on AIX 3, Interix.  */
 #ifndef _ALL_SOURCE
 # undef _ALL_SOURCE
 #endif
@@ -400,15 +403,11 @@ sure both macros are undefined; an emulation function will then be used. */
 #ifndef __STDC_WANT_IEC_60559_DFP_EXT__
 # undef __STDC_WANT_IEC_60559_DFP_EXT__
 #endif
-/* Enable extensions specified by C23 Annex F.  */
-#ifndef __STDC_WANT_IEC_60559_EXT__
-# undef __STDC_WANT_IEC_60559_EXT__
-#endif
 /* Enable extensions specified by ISO/IEC TS 18661-4:2015.  */
 #ifndef __STDC_WANT_IEC_60559_FUNCS_EXT__
 # undef __STDC_WANT_IEC_60559_FUNCS_EXT__
 #endif
-/* Enable extensions specified by C23 Annex H and ISO/IEC TS 18661-3:2015.  */
+/* Enable extensions specified by ISO/IEC TS 18661-3:2015.  */
 #ifndef __STDC_WANT_IEC_60559_TYPES_EXT__
 # undef __STDC_WANT_IEC_60559_TYPES_EXT__
 #endif
@@ -437,21 +436,15 @@ sure both macros are undefined; an emulation function will then be used. */
 /* Number of bits in a file offset, on hosts where this is settable. */
 #undef _FILE_OFFSET_BITS
 
-/* Define to 1 on platforms where this makes off_t a 64-bit type. */
+/* Define for large files, on AIX-style hosts. */
 #undef _LARGE_FILES
 
-/* Number of bits in time_t, on hosts where this is settable. */
-#undef _TIME_BITS
-
-/* Define to 1 on platforms where this makes time_t a 64-bit type. */
-#undef __MINGW_USE_VC2005_COMPAT
-
-/* Define to empty if 'const' does not conform to ANSI C. */
+/* Define to empty if `const' does not conform to ANSI C. */
 #undef const
 
 /* Define to the type of a signed integer type of width exactly 64 bits if
    such a type exists and the standard includes do not define it. */
 #undef int64_t
 
-/* Define as 'unsigned int' if <stddef.h> doesn't define. */
+/* Define to `unsigned int' if <sys/types.h> does not define. */
 #undef size_t

src/pcre2_fuzzsupport.c

@@ -132,6 +132,7 @@ for (int index = 0; index < count; index++)
 /* This function describes the current test case being evaluated, then aborts */
 
 #ifdef SUPPORT_JIT
+#ifdef SUPPORT_DIFF_FUZZ
 static void describe_failure(
   const char *task,
   const unsigned char *data,
@@ -204,6 +205,7 @@ if (matches_jit >= 0)
 abort();
 }
 #endif
+#endif
 
 /* This is the callout function. Its only purpose is to halt matching if there
 are more than 100 callouts, as one way of stopping too much time being spent on
@@ -393,6 +395,7 @@ for (i = 0; i < 2; i++)
         errorcode_jit = pcre2_match(code, (PCRE2_SPTR)data, (PCRE2_SIZE)match_size, 0,
           match_options & ~PCRE2_NO_JIT, match_data_jit, match_context);
 
+#ifdef SUPPORT_DIFF_FUZZ
         matches = errorcode;
         matches_jit = errorcode_jit;
 
@@ -446,6 +449,7 @@ for (i = 0; i < 2; i++)
               pcre2_substring_free(bufferptr_jit);
             }
           }
+#endif
         }
 #endif