Add and use _nofree variants of safe_realloc functions

Parts of the code use realloc like

x = safe_realloc(x, somesize);

when this is the case, the safe_realloc variant used must free the
old memory block in case it fails, otherwise it will leak. However,
there are also instances in the code where handling is different:

if (0 == (x = safe_realloc(y, somesize)))
    return false

in this case, y should not be freed, as y is not set to NULL we
could encounter double frees. Here the safe_realloc_nofree
functions are used.

1 files changed, 37 insertions, 4 deletions

diff --git a/include/share/alloc.h b/include/share/alloc.h
index 9b53b010..74f444d6 100644
--- a/include/share/alloc.h
+++ b/include/share/alloc.h
@@ -161,17 +161,30 @@ static inline void *safe_realloc_(void *ptr, size_t size)
 		free(oldptr);
 	return newptr;
 }
-static inline void *safe_realloc_add_2op_(void *ptr, size_t size1, size_t size2)
+static inline void *safe_realloc_nofree_add_2op_(void *ptr, size_t size1, size_t size2)
+{
+	size2 += size1;
+	if(size2 < size1)
+		return 0;
+	return realloc(ptr, size2);
+}
+
+static inline void *safe_realloc_add_3op_(void *ptr, size_t size1, size_t size2, size_t size3)
 {
 	size2 += size1;
 	if(size2 < size1) {
 		free(ptr);
 		return 0;
 	}
-	return realloc(ptr, size2);
+	size3 += size2;
+	if(size3 < size2) {
+		free(ptr);
+		return 0;
+	}
+	return safe_realloc_(ptr, size3);
 }
 
-static inline void *safe_realloc_add_3op_(void *ptr, size_t size1, size_t size2, size_t size3)
+static inline void *safe_realloc_nofree_add_3op_(void *ptr, size_t size1, size_t size2, size_t size3)
 {
 	size2 += size1;
 	if(size2 < size1)
@@ -182,7 +195,7 @@ static inline void *safe_realloc_add_3op_(void *ptr, size_t size1, size_t size2,
 	return realloc(ptr, size3);
 }
 
-static inline void *safe_realloc_add_4op_(void *ptr, size_t size1, size_t size2, size_t size3, size_t size4)
+static inline void *safe_realloc_nofree_add_4op_(void *ptr, size_t size1, size_t size2, size_t size3, size_t size4)
 {
 	size2 += size1;
 	if(size2 < size1)
@@ -207,6 +220,15 @@ static inline void *safe_realloc_mul_2op_(void *ptr, size_t size1, size_t size2)
 	return safe_realloc_(ptr, size1*size2);
 }
 
+static inline void *safe_realloc_nofree_mul_2op_(void *ptr, size_t size1, size_t size2)
+{
+	if(!size1 || !size2)
+		return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
+	if(size1 > SIZE_MAX / size2)
+		return 0;
+	return realloc(ptr, size1*size2);
+}
+
 /* size1 * (size2 + size3) */
 static inline void *safe_realloc_muladd2_(void *ptr, size_t size1, size_t size2, size_t size3)
 {
@@ -220,4 +242,15 @@ static inline void *safe_realloc_muladd2_(void *ptr, size_t size1, size_t size2,
 	return safe_realloc_mul_2op_(ptr, size1, size2);
 }
 
+/* size1 * (size2 + size3) */
+static inline void *safe_realloc_nofree_muladd2_(void *ptr, size_t size1, size_t size2, size_t size3)
+{
+	if(!size1 || (!size2 && !size3))
+		return realloc(ptr, 0); /* preserve POSIX realloc(ptr, 0) semantics */
+	size2 += size3;
+	if(size2 < size3)
+		return 0;
+	return safe_realloc_nofree_mul_2op_(ptr, size1, size2);
+}
+
 #endif