mmap anonymous

userland/c/malloc.c

@@ -5,18 +5,27 @@
 #include <stdlib.h>
 
 int main(void) {
-    size_t bytes = sizeof(int) * 2;
-    /* Allocate 2 ints. */
-    int *is = malloc(bytes);
+    int *is;
+    size_t nbytes = 2 * sizeof(*is);
+
+    /* Allocate 2 ints. Note that unlike traditional stack arrays (non-VLA)
+     * this value does not have to be determined at compile time! */
+    is = malloc(nbytes);
+
     /* This can happen for example if we ask for too much memory. */
     if (is == NULL) {
         perror("malloc");
         exit(EXIT_FAILURE);
     }
+
+    /* Write to and read from the allocated memory. */
     is[0] = 1;
+    is[1] = 2;
     assert(is[0] == 1);
+    assert(is[1] == 2);
+
     /* Free the allocated memory. */
     free(is);
+
     return EXIT_SUCCESS;
 }
-