tree-wide: use reallocarray instead of our home-grown realloc_multiply (#8279)

There isn't much difference, but in general we prefer to use the standard
functions. glibc provides reallocarray since version 2.26.

I moved explicit_bzero is configure test to the bottom, so that the two stdlib
functions are at the bottom.

3 files changed, 7 insertions, 5 deletions

diff --git a/src/basic/alloc-util.h b/src/basic/alloc-util.h
index 02dee37d3..ec7808c1f 100644
--- a/src/basic/alloc-util.h
+++ b/src/basic/alloc-util.h
@@ -74,12 +74,14 @@ _malloc_  _alloc_(1, 2) static inline void *malloc_multiply(size_t size, size_t
         return malloc(size * need);
 }
 
-_alloc_(2, 3) static inline void *realloc_multiply(void *p, size_t size, size_t need) {
+#if !HAVE_REALLOCARRAY
+_alloc_(2, 3) static inline void *reallocarray(void *p, size_t need, size_t size) {
         if (size_multiply_overflow(size, need))
                 return NULL;
 
         return realloc(p, size * need);
 }
+#endif
 
 _alloc_(2, 3) static inline void *memdup_multiply(const void *p, size_t size, size_t need) {
         if (size_multiply_overflow(size, need))
diff --git a/src/basic/strv.c b/src/basic/strv.c
index 85c55041e..7898e8340 100644
--- a/src/basic/strv.c
+++ b/src/basic/strv.c
@@ -413,7 +413,7 @@ int strv_push(char ***l, char *value) {
         if (m < n)
                 return -ENOMEM;
 
-        c = realloc_multiply(*l, sizeof(char*), m);
+        c = reallocarray(*l, m, sizeof(char*));
         if (!c)
                 return -ENOMEM;
 
@@ -438,7 +438,7 @@ int strv_push_pair(char ***l, char *a, char *b) {
         if (m < n)
                 return -ENOMEM;
 
-        c = realloc_multiply(*l, sizeof(char*), m);
+        c = reallocarray(*l, m, sizeof(char*));
         if (!c)
                 return -ENOMEM;
 
@@ -554,7 +554,7 @@ int strv_extend_front(char ***l, const char *value) {
         if (!v)
                 return -ENOMEM;
 
-        c = realloc_multiply(*l, sizeof(char*), m);
+        c = reallocarray(*l, m, sizeof(char*));
         if (!c) {
                 free(v);
                 return -ENOMEM;
diff --git a/src/libelogind/sd-bus/bus-error.c b/src/libelogind/sd-bus/bus-error.c
index c9517499d..3939d0a4e 100644
--- a/src/libelogind/sd-bus/bus-error.c
+++ b/src/libelogind/sd-bus/bus-error.c
@@ -595,7 +595,7 @@ _public_ int sd_bus_error_add_map(const sd_bus_error_map *map) {
                         if (additional_error_maps[n] == map)
                                 return 0;
 
-        maps = realloc_multiply(additional_error_maps, sizeof(struct sd_bus_error_map*), n + 2);
+        maps = reallocarray(additional_error_maps, n + 2, sizeof(struct sd_bus_error_map*));
         if (!maps)
                 return -ENOMEM;