Add more tests

test/test_arena.c

@@ -2,19 +2,15 @@
 #include "arena.h"
 #include "knob.h"
 
-#include <stdlib.h> // exit(), EXIT_FAILURE
+#include <signal.h>
-#include <string.h> // memset
 #include <stdio.h>  // fprintf
+#include <stdlib.h> // exit, EXIT_FAILURE
+#include <string.h> // memset
+#include <sys/wait.h> // waitpid
 #include <unistd.h> // sysconf
 
-
-
 int main()
 {
-    // calling print functions early makes my strace output more readable
-    printf("\n");
-    fprintf(stderr, "\n");
-
     size_t page_size = sysconf(_SC_PAGE_SIZE);
     if (page_size == -1) {
         perror("sysconf");
@@ -26,14 +22,15 @@ int main()
      * ===============================
      */
     {
-        write(STDERR_FILENO, "\n\n", 2);
+        fprintf(stderr, "creating new arena with arena_new()\n    ");
         arena_t a = arena_new();
         if (arena_new_failed(&a)) {
             fprintf(stderr, "arena_new failed\n");
             exit(EXIT_FAILURE);
         }
+        fprintf(stderr, "OK\n");
 
-        // test many small allocations
+        fprintf(stderr, "attempting many small allocations\n    ");
         for (int i = 0; i < page_size * 8; i++) {
             char* s = arena_alloc(&a, 4 * sizeof *s);
             if (!s) {
@@ -42,23 +39,26 @@ int main()
             }
             memset(s, 'a', 4);
         }
+        fprintf(stderr, "OK\n");
 
-        // test a few allocations above the cap*2
+        fprintf(stderr, "testing allocations of cap * 3 + 123\n    ");
         for (int i = 0; i < 2; i++) {
             size_t n = a.cap * 3 + 123;
-            printf("allocating %d bytes\n", n);
             volatile char* s = arena_alloc(&a, n);
             if (!s) {
                 fprintf(stderr, "arena_alloc failed\n");
                 exit(EXIT_FAILURE);
             }
         }
+        fprintf(stderr, "OK\n");
 
+        fprintf(stderr, "calling arena_delete() on arena from arena_new()\n    ");
         int ok = arena_delete(&a);
         if (ok == -1) {
             fprintf(stderr, "arena_delete failed\n");
             exit(EXIT_FAILURE);
         }
+        fprintf(stderr, "OK\n");
     }
 
     /*
@@ -66,13 +66,18 @@ int main()
      * ===============================
      */
     {
-        write(STDERR_FILENO, "\n\n", 2);
+        fprintf(stderr, "creating new arena with arena_attach() and malloc()\n    ");
         char* p = malloc(page_size);
+        if (!p) {
+            perror("malloc");
+            exit(EXIT_FAILURE);
+        }
         arena_t a = arena_attach(p, page_size);
+        fprintf(stderr, "OK\n");
 
         bool failed = false;
 
-        // attempt to grow more than the buffer size
+        fprintf(stderr, "try to grow more than the buffer size (should fail)\n    ");
         int i;
         for (i=0; i < page_size + 1; i++) {
             char* s = arena_alloc(&a, 8);
@@ -81,27 +86,68 @@ int main()
                 break;
             }
         }
-
         if (!failed) {
             fprintf(stderr, "allocation was supposed to fail, but didn't\n");
             exit(EXIT_FAILURE);
         } else if (i != page_size / KNOB_ALIGNMENT ) {
-            fprintf(stderr, "allocation failed after %d allocations, should instead fail after %d. Bad!\n", i, page_size/sizeof(void*));
+            fprintf(stderr, "allocation failed after %d allocations, but should fail after %d!\n", i, page_size/sizeof(void*));
             exit(EXIT_FAILURE);
-        } else {
-            fprintf(stderr, "arena from arena_attach failed after %d allocations, good!", i);
         }
+        fprintf(stderr, "OK\n");
 
-        // deleting an arena not made with arena_new should fail
+        fprintf(stderr, "deleting an arena not made with arena_new (should fail)\n    ");
         int ok = arena_delete(&a);
         if (ok != -1) {
             fprintf(stderr, "arena_delete was supposed to fail, but didn't\n");
             exit(EXIT_FAILURE);
         }
+        fprintf(stderr, "OK\n");
 
         free(arena_detatch(a));
     }
 
+    /*
+     * test the memory protection
+     * ===============================
+     */
+    {
+        fprintf(stderr, "attempting to access memory beyond arena cap (should sigsegv)\n    ");
+        pid_t p;
+        switch (p = fork()) {
+        case -1: /* error */
+            perror(fork());
+            exit(EXIT_FAILURE);
+
+        case 0: /* child */
+            arena_t a = arena_new();
+            if (arena_new_failed(&a)) {
+                fprintf(stderr, "arena_new failed\n");
+                exit(EXIT_FAILURE);
+            }
+
+            char* s = arena_alloc(&a, 12345);
+            if (!s) {
+                fprintf(stderr, "arena_alloc failed\n");
+                exit(EXIT_FAILURE);
+            }
+
+            // should sigsegv
+            a.data[a.cap] = 1;
+            exit(EXIT_SUCCESS);
+        }
+
+        int status;
+        int ok = waitpid(p, &status, 0);
+        if (!ok) {
+            perror("waitpid");
+        }
+
+        if (!( WIFSIGNALED(status) && WTERMSIG(status) == SIGSEGV)) {
+            fprintf(stderr, "allocating beyond arena cap succeeded when it shouldn't!\n");
+            exit(EXIT_FAILURE);
+        }
+        fprintf(stderr, "OK\n");
+    }
 
     return EXIT_SUCCESS;
 }