Update lusol.c (CRAN valgrid issue)

valgrind reporting a realloc(3) call with size = 0

R-proj/DESCRIPTION

@@ -12,8 +12,8 @@ Description: Provides an R interface for 'volesti' C++ package. 'volesti' comput
              for sampling, rounding and rotating polytopes. Moreover, 'volesti' provides algorithms for
              estimating copulas useful in computational finance. Methods implemented in 'volesti' are described
              in A. Chalkis and V. Fisikopoulos (2022) <doi:10.32614/RJ-2021-077> and references therein.
-Version: 1.1.2-6
-Date: 2023-04-11
+Version: 1.1.2-7
+Date: 2023-10-18
 Maintainer: Vissarion Fisikopoulos <[email protected]>
 Depends: Rcpp (>= 0.12.17)
 Imports: methods, stats

R-proj/src/Rproj_externals/lp_solve/lusol.c

@@ -63,6 +63,17 @@ void *clean_realloc(void *oldptr, int width, int newsize, int oldsize)
 {
   newsize *= width;
   oldsize *= width;
+  /* this works around valgrind reporting a realloc(3) call with size = 0.
+     According to https://linux.die.net/man/3/realloc glibc frees the
+     memory in this case, and (maybe?) returns NULL:
+     > if size is equal to zero, and ptr is not NULL, then the call
+     > is equivalent to free(ptr). */
+#ifdef __linux__
+  if (oldptr != NULL && newsize == 0) {
+    free(oldptr);
+    return NULL;
+  }
+#endif
   oldptr = LUSOL_REALLOC(oldptr, newsize);
   if(newsize > oldsize)
 /*    MEMCLEAR(oldptr+oldsize, newsize-oldsize); */

cran_gen/NEWS.md

@@ -50,3 +50,7 @@
 # volesti 1.1.2-6
 
 - Fix UBSAN issues (lp_presolve)
+
+# volesti 1.1.2-7
+
+- Fix valgrind reporting a realloc(3) call with size = 0 (lp_presolve)